MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'Journal of Applied Clinical Medical Physics' source. Thu, 09 Feb 2012 20:29:16 +0100 http://www.medworm.com/index.php?rid=5596718&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231205%26dopt%3DAbstract In conclusion, the use of this technique should be considered for patients with bilateral metal hip implants who do not meet dose-volume criteria by conventional IMRT techniques. PMID: 22231205 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5596718 Tue, 17 Jan 2012 11:30:03 +0100 5596718 http://www.medworm.com/index.php?rid=5596717&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231206%26dopt%3DAbstract Authors: Hitchen CJ, Osa EO, Dewyngaert K, Chang J, Narayana A Abstract The purpose of this study was to determine dose to the planning target volume (PTV) and organs at risk (OARs) from portal imaging (PI) of the craniofacial region in pediatric brain tumor patients treated with intensity-modulated radiation therapy (IMRT). Twenty pediatric brain tumor patients were retrospectively studied. Each received portal imaging of treatment fields and orthogonal setup fields in the craniofacial region. The number of PI and monitor units used for PI were documented for each patient. Dose distributions and dose-volume histograms were generated to quantify the maximum, minimum, and mean dose to the PTV, and the mean dose to OARs through PI acquisition. The doses resulting from PI are reported... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5596717 Tue, 17 Jan 2012 11:30:03 +0100 5596717 http://www.medworm.com/index.php?rid=5596716&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231207%26dopt%3DAbstract This study suggests that distortion correction should be validated for each of its applications with an independent "gold standard" phantom. PMID: 22231207 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5596716 Tue, 17 Jan 2012 11:30:03 +0100 5596716 http://www.medworm.com/index.php?rid=5596715&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231208%26dopt%3DAbstract The objective of this study was to assess the level of compliance to quality assurance and image quality standards in computed tomography facilities in Kenyan hospitals. A quality assurance inspection and physical image quality assessment in eighteen representative computed tomography facilities were completed. A quantitative method was developed and used to score the results obtained from the physical image quality measurements using the American Association of Physicists in Medicine (AAPM) water phantom. Inspection was done in order to establish the level of compliance with internationally recognized standards such as those stipulated in the European Guidelines Quality Criteria for Computed Tomography and the International Basic Safety Standards for Protection against Ionizing Radiation.... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5596715 Tue, 17 Jan 2012 11:30:03 +0100 5596715 http://www.medworm.com/index.php?rid=5596714&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231209%26dopt%3DAbstract Authors: Szegedi M, Sarkar V, Rassiah-Szegedi P, Wang B, Huang YJ, Zhao H, Salter B Abstract In the AAPM Report 80,(1) the imaging modality of 4D CT and respiration-correlated CT was declared a "promising solution for obtaining high-quality CT data in the presence of respiratory motion". To gather anatomically correct data over time, the existence of correlation between the internal organ movement and an external surrogate has to be assumed. For the in-house evaluation of such correlation, we retrospectively analyzed 21 four-dimensional computer tomography (4D CT) scans of five patients, out of which the artifacts experienced in three patients are shown here. To provide context and a baseline for the analysis of patient motion, a real-tissue liver phantom was used with a solid wate... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5596714 Tue, 17 Jan 2012 11:30:03 +0100 5596714 http://www.medworm.com/index.php?rid=5596713&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231210%26dopt%3DAbstract Authors: Althof V, Van Haaren P, Westendorp R, Nuver T, Kramer D, Ikink M, Bel A, Minken A Abstract The purpose of this study was to develop and evaluate filmless quality assurance (QA) tools for helical tomotherapy by using the signals from the on-board megavoltage computed tomography (MVCT) detector and applying a dedicated step-wedge phantom. The step-wedge phantom is a 15 cm long step-like aluminum block positioned on the couch. The phantom was moved through the slit beam and MVCT detector signals were analyzed. Two QA procedures were developed, with gantry fixed at 0°: 1) step-wedge procedure: to check beam energy consistency, field width, laser alignment with respect to the virtual isocenter, couch movement, and couch velocity; and 2) completion procedure: to check the accur... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5596713 Tue, 17 Jan 2012 11:30:03 +0100 5596713 http://www.medworm.com/index.php?rid=5596712&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231211%26dopt%3DAbstract Authors: Beltran C Abstract The purpose of this study was to measure and compare the contrast-to-noise ratio (CNR) as a function of dose for the cone-beam CT (CBCT) produced by the imaging beam line (IBL) for the standard and an investigational imaging panel. Two Siemens Artiste linear accelerators were modified at our institution such that the MV-CBCT would operate under an investigational IBL. The imaging panel from one of the machines was replaced with an investigational imaging panel. After the modification, a set of CBCT for a large and small phantom consisting of eight tissue-equivalent inserts was acquired for the standard imager and for the investigational imager with and without the standard copper plate. Ten dose settings for each phantom using the IBL in combination with... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5596712 Tue, 17 Jan 2012 11:30:03 +0100 5596712 http://www.medworm.com/index.php?rid=5596711&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231212%26dopt%3DAbstract Authors: Khelashvili G, Chu J, Diaz A, Turian J Abstract The purpose was to study the dosimetric characteristics of the small diameter (?10.0 mm) BrainLAB cones used for stereotactic radiosurgery (SRS) treatments in conjunction with a Varian Trilogy accelerator. Required accuracy and precision in dose delivery during SRS can be achieved only when the geometric and dosimetric characteristics of the small radiation fields is completely understood. Although a number of investigators have published the dosimetric characteristics of SRS cones, to our knowledge, there is no generally accepted value for the relative output factor (ROF) for the 5.0 mm diameter cone. Therefore, we have investigated the dosimetric properties of the small (? 10.0 mm) diameter BrainLAB SRS cones used in conjun... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5596711 Tue, 17 Jan 2012 11:30:03 +0100 5596711 http://www.medworm.com/index.php?rid=5596710&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231213%26dopt%3DAbstract Authors: Whitmore N, Nalichowski A, Burmeister J Abstract Delivery quality assurance (DQA) of tomotherapy plans is routinely performed with silver halide film which has a limited range due to the effects of saturation. DQA plans with dose values exceeding this limit require the dose of the entire plan to be scaled downward if film is used, to evaluate the dose distribution in two dimensions. The potential loss of fidelity between scaled and unscaled DQA plans as a function of dose scaling is investigated. Three treatment plans for 12 Gy fractions designed for SBRT of the lung were used to create DQA procedures that were scaled between 100% and 10%. The dose was measured with an ionization chamber array and compared to values from the tomotherapy treatment planning system. Film and ... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5596710 Tue, 17 Jan 2012 11:30:03 +0100 5596710 http://www.medworm.com/index.php?rid=5596709&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231214%26dopt%3DAbstract This study shows that the segment weight optimization method significantly reduces the total number of segments and the dose to the rectum for IMRT prostate cancer. It also resulted in fewer monitor units for most of the prostate cases observed in this study. PMID: 22231214 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5596709 Tue, 17 Jan 2012 11:30:03 +0100 5596709 http://www.medworm.com/index.php?rid=5596708&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231215%26dopt%3DAbstract This article presents a study of the effects of the acquisition scan length and number of projections of a Siemens Artiste MV-CBCT system on image quality within the range provided by the manufacturer. It also discusses other aspects not related to image quality one should consider when selecting an acquisition protocol. Noise and uniformity were measured on the image of a cylindrical water phantom. Spatial resolution was measured using the same phantom half filled with water to provide a sharp water/air interface to derive the modulation transfer function (MTF). Contrast-to-noise ratio (CNR) was measured on a pelvis-shaped phantom with four inserts of different electron densities relative to water (1.043, 1.117, 1.513, and 0.459). Uniformity was independent of acquisition protocol. Noise ... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5596708 Tue, 17 Jan 2012 11:30:03 +0100 5596708 http://www.medworm.com/index.php?rid=5596707&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231216%26dopt%3DAbstract Authors: Mancosu P, Navarria P, Castagna L, Roggio A, Pellegrini C, Reggiori G, Fogliata A, Lobefalo F, Castiglioni S, Alongi F, Cozzi L, Santoro A, Scorsetti M Abstract The purpose of this study was to evaluate the possibility of dose distribution optimization for total marrow irradiation (TMI) employing volumetric-modulated arc therapy (VMAT) with RapidArc (RA) technology setting isocenter's positions and jaw's apertures according to patient's anatomical features. Plans for five patients were generated with the RA engine (PROIII): eight arcs were distributed along four isocenters and simultaneously optimized with collimator set to 90°. Two models were investigated for geometrical settings of arcs: (1) in the "symmetric" model, isocenters were equispaced and field apertures were ... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5596707 Tue, 17 Jan 2012 11:30:03 +0100 5596707 http://www.medworm.com/index.php?rid=5596706&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231217%26dopt%3DAbstract Authors: Uniyal SC, Naithani UC, Sharma SD, Srivastava AK Abstract Heterogeneities existing in the patient during treatment are neglected, as the treated subject is considered homogeneous in most of the commercially-available treatment planning systems (TPSs) used for high dose rate (HDR) brachytherapy. The choice of a suitable dosimeter for experimental dosimetry near the HDR source is crucial, mainly due to existence of steep dose gradients. The present work aimed to assess the effect of rectal air heterogeneity and applicator attenuation in the HDR Ir-192 brachytherapy treatment of carcinoma uterine cervix by utilizing GAFCHROMIC EBT2 film dosimetry. The dose to rectal walls under the condition of rectal air heterogeneity was measured experimentally using EBT2 film in a rectal p... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5596706 Tue, 17 Jan 2012 11:30:03 +0100 5596706 http://www.medworm.com/index.php?rid=5596705&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231218%26dopt%3DAbstract Authors: Garcia-Vicente F, Fernandez V, Bermudez R, Gomez A, Perez L, Zapatero A, Torres JJ Abstract The aim of this study is to determine the gantry angle and multileaf collimator (MLC) gap error-detection threshold of a diode helical array with an inserted micro-ionization chamber in order to use this device for the pretreatment quality assurance (QA) of intensity-modulated radiation therapy (IMRT) treatments. Implications on the dose-volume histograms (DVHs) of the patient treatments will also be considered for the establishment of a QA protocol with a reasonable tolerance level. Three dynamic IMRT HN (head and neck) and prostate treatments were studied. Random and systematic variations of gantry angle and systematic errors in MLC gap width of the clinical treatments were analyz... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5596705 Tue, 17 Jan 2012 11:30:03 +0100 5596705 http://www.medworm.com/index.php?rid=5596704&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231219%26dopt%3DAbstract Authors: De Paiva E, Da Rosa LA Abstract The skyshine radiation phenomenon consists of the scattering of primary photon beams in the atmosphere above the roof of a medical linear accelerator facility, generating an additional dose at ground level in the vicinity of the treatment room. Thus, with respect to radioprotection, this situation plays an important role when the roof is designed with little shielding and there are buildings next to the radiotherapy treatment room. In literature, there are few reported skyshine-measured doses and these contain poor agreement with empirical calculations. In this work, we carried out measurements of skyshine photon dose rates produced from eight different 6 and 10 MV medical accelerators. Each measurement was performed outside the room facilit... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5596704 Tue, 17 Jan 2012 11:30:03 +0100 5596704 http://www.medworm.com/index.php?rid=5596703&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231220%26dopt%3DAbstract Authors: Jones AK, Pasciak AS Abstract Part II of this review article presents four case studies for which peak skin doses are calculated following the methods outlined in Part I of this review. The data available in the cases ranges from proprietary dose reports to fluoroscopy time and number of digital acquisition frames only. Flowcharts are provided for each case. These flowcharts outline the calculation steps and data sources used to estimate the peak skin dose. The accuracy that can be achieved using these methods depends on several factors, including the calibration accuracy of dosimetric equipment, accuracy of information reported in the DICOM header and proprietary dose reports, accuracy of quantities measured by the medical physicist, and procedural factors such as rotatio... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5596703 Tue, 17 Jan 2012 11:30:03 +0100 5596703 http://www.medworm.com/index.php?rid=5596702&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231221%26dopt%3DAbstract In this study, we proposed and evaluated a rolling-average (RA) adaptive replanning method to account for the target volume variations. A total of 448 repeated helical computed tomography (HCT) scans from 28 patients were included in the study. Both low-risk patients (LRP, CTV = prostate) and intermediate-risk patients (IRP, CTV = prostate + seminal vesicles) were simulated. The benefit of RA strategy was evaluated geometrically and compared with the standard online IG-only method and a single replanning adaptive hybrid strategy. A new geometric index, cumulative index of target volume (CITV), was used for the evaluation. Two extreme scenarios of target volume changes, Type Ascending and Descending, were simulated by sorting the CTV volumes of actual patient data in order to have a better ... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5596702 Tue, 17 Jan 2012 11:30:03 +0100 5596702 http://www.medworm.com/index.php?rid=5596701&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231222%26dopt%3DAbstract Authors: Hashimoto M, Uematsu M, Ito M, Hama Y, Inomata T, Fujii M, Nishio T, Nakamura N, Nakagawa K Abstract In this paper, we suggest a new method for verifying the motion of a binary multileaf collimator (MLC) in helical tomotherapy. For this we used a combination of a cylindrical scintillator and a general-purpose camcorder. The camcorder records the light from the scintillator following photon irradiation, which we use to track the motion of the binary MLC. The purpose of this study is to demonstrate the feasibility of this method as a binary MLC quality assurance (QA) tool. First, the verification was performed using a simple binary MLC pattern with a constant leaf open time; secondly, verification using the binary MLC pattern used in a clinical setting was also performed. Si... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5596701 Tue, 17 Jan 2012 11:30:03 +0100 5596701 http://www.medworm.com/index.php?rid=5596700&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231223%26dopt%3DAbstract Authors: Battista JJ, Clark BG, Patterson MS, Beaulieu L, Sharpe MB, Schreiner LJ, Macpherson MS, Van Dyk J Abstract The January 2010 articles in The New York Times generated intense focus on patient safety in radiation treatment, with physics staffing identified frequently as a critical factor for consistent quality assurance. The purpose of this work is to review our experience with medical physics staffing, and to propose a transparent and flexible staffing algorithm for general use. Guided by documented times required per routine procedure, we have developed a robust algorithm to estimate physics staffing needs according to center-specific workload for medical physicists and associated support staff, in a manner we believe is adaptable to an evolving radiotherapy practice. We c... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5596700 Tue, 17 Jan 2012 11:30:03 +0100 5596700 http://www.medworm.com/index.php?rid=5596699&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231224%26dopt%3DAbstract Authors: Starkschall G Abstract - PMID: 22231224 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5596699 Tue, 17 Jan 2012 11:30:03 +0100 5596699 http://www.medworm.com/index.php?rid=5596698&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231225%26dopt%3DAbstract Authors: Hendee WR Abstract - PMID: 22231225 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5596698 Tue, 17 Jan 2012 11:30:03 +0100 5596698 http://www.medworm.com/index.php?rid=5438153&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22088998%26dopt%3DAbstract Authors: Fujita H, Morimi S, Yamaguchi M, Fukuda H, Murase K Abstract The aim of the present study was to evaluate the clinical efficacy of the single-shot dual-energy subtraction technique for obtaining portal images. We prepared two storage phosphor plates for this study. A 1 mm thick tungsten sheet was placed between the two storage phosphor plates. A single use of the double-exposure technique provides two portal images simultaneously (i.e., a standard image and a low-contrast image), using the same patient position and with no additional radiation delivered to the patient. A bone-enhanced image is created by image subtraction between these two images. For evaluation of clinical efficacy, three treatment sites - the brain, lung, and pelvis - were imaged. Ten sets of images were... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438153 Wed, 23 Nov 2011 18:48:02 +0100 5438153 http://www.medworm.com/index.php?rid=5438152&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22088999%26dopt%3DAbstract Authors: Aubry JF, Bouchard H, Bessières I, Lacroix F Abstract The purpose of this study is to validate Eclipse's electron Monte Carlo algorithm (eMC) in heterogeneous phantoms using radiochromic films and EGSnrc as a reference Monte Carlo algorithm. Four heterogeneous phantoms are used in this study. Radiochromic films are inserted in these phantoms, including in heterogeneous media, and the measured relative dose distributions are compared to eMC calculations. Phantoms A, B, and C contain 1D heterogeneities, built with layers of lung- (phantom A) and bone- (phantoms B and C) equivalent materials sandwiched in Plastic Water. Phantom D is a thorax anthropomorphic phantom with 2D lung heterogeneities. Electron beams of 6, 9, 12 and 18 MeV from a Varian Clinac 2100 are delivered to ... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438152 Wed, 23 Nov 2011 18:48:02 +0100 5438152 http://www.medworm.com/index.php?rid=5438151&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089000%26dopt%3DAbstract Authors: McMahon R, Zhuang T, Steffey BA, Song H, Craciunescu OI Abstract Studies have shown that source dwells within Varian's HDR CT/MR compatible ring applicators can deviate from intended positions by several millimeters. Quantifying this offset is an important part of commissioning. The aims of this study were to: 1) determine the reproducibility of the offset, 2) study the interobserver variation in the offset's measurement, and 3) quantify the dosimetric impact of the offset. Offsets were measured for four ring applicators: two 30°, one 45°, and one 60°. Dwell positions were measured five times for each ring to determine the reproducibility of source positioning. Experiments were done to compare two separate source wires, as well as different time points within a single s... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438151 Wed, 23 Nov 2011 18:48:02 +0100 5438151 http://www.medworm.com/index.php?rid=5438150&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089001%26dopt%3DAbstract Authors: Diaz Moreno R, Venencia D, Garrigo E, Pipman Y Abstract This work introduces a new method for verifying MLC leaf positions with enough spatial resolution to replace film-based methods in performing QA tests. It is implemented on a 2D ion chamber array, and it is based on the principle of varying signal response of a volumetric detector to partial irradiation. A PTW 2D-ARRAY seven29 (PTW-729 2D) array was used to assess a Siemens OPTIFOCUS MLC. Partial volume response curves for chambers in the array were obtained by irradiating them with the leaves of the MLC, progressively covering varying portions of the chambers correlated with the leaf positions. The readings from the array's chambers are processed with an in-house program; it generates a reference response that transl... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438150 Wed, 23 Nov 2011 18:48:02 +0100 5438150 http://www.medworm.com/index.php?rid=5438149&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089002%26dopt%3DAbstract Authors: Kappadath SC Abstract The purpose of this study was to evaluate the effects of voxel size and iterative reconstruction parameters on the radial and tangential resolution for 99mTc SPECT as a function of radial distance from isocenter. SPECT/CT scans of eight coplanar point sources of size smaller than 1 mm3 containing high concentration 99mTc solution were acquired on a SPECT/CT system with 5/8 inch NaI(Tl) detector and low-energy, high-resolution collimator. The tomographic projection images were acquired in step-and-shoot mode for 360 views over 360° with 250,000 counts per view, a zoom of 2.67, and an image matrix of 256 × 256 pixels that resulted in a 0.9 × 0.9 × 0.9 mm3 SPECT voxel size over 230 mm field-of-view. The projection images were also rebinned to image m... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438149 Wed, 23 Nov 2011 18:48:02 +0100 5438149 http://www.medworm.com/index.php?rid=5438148&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089003%26dopt%3DAbstract This study also combines the impact of these uncertainties on the MammoSite treatment efficacy. The current study demonstrates that the combined uncertainties associated with the MammoSite brachytherapy technique - up to the value of 2 mm balloon deformation, 1 mm source deviation, and 15% contrast concentration - have no impact on the tumor control probability. PMID: 22089003 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438148 Wed, 23 Nov 2011 18:48:02 +0100 5438148 http://www.medworm.com/index.php?rid=5438147&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089004%26dopt%3DAbstract Authors: Pauwels R, Stamatakis H, Manousaridis G, Walker A, Michielsen K, Bosmans H, Bogaerts R, Jacobs R, Horner K, Tsiklakis K Abstract Cone-beam CT (CBCT) has shown to be a useful imaging modality for various dentomaxillofacial applications. However, optimization and quality control of dental CBCT devices is hampered due to the lack of an appropriate tool for image quality assessment. To investigate the application of different image quality parameters for CBCT, a prototype polymethyl methacrylate (PMMA) cylindrical phantom with inserts for image quality analysis was developed. Applicability and reproducibility of the phantom were assessed using seven CBCT devices with different scanning protocols. Image quality parameters evaluated were: CT number correlation, contrast resoluti... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438147 Wed, 23 Nov 2011 18:48:02 +0100 5438147 http://www.medworm.com/index.php?rid=5438146&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089005%26dopt%3DAbstract Authors: Killoran JH, Gerbaudo VH, Mamede M, Ionascu D, Park SJ, Berbeco R Abstract For PET/CT, fast CT acquisition time can lead to errors in attenuation correction, particularly at the lung/diaphragm interface. Gated 4D PET can reduce motion artifacts, though residual artifacts may persist depending on the CT dataset used for attenuation correction. We performed phantom studies to evaluate 4D PET images of targets near a density interface using three different methods for attenuation correction: a single 3D CT (3D CTAC), an averaged 4D CT (CINE CTAC), and a fully phase matched 4D CT (4D CTAC). A phantom was designed with two density regions corresponding to diaphragm and lung. An 8 mL sphere phantom loaded with 18F-FDG was used to represent a lung tumor and background FDG include... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438146 Wed, 23 Nov 2011 18:48:02 +0100 5438146 http://www.medworm.com/index.php?rid=5438145&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089006%26dopt%3DAbstract Authors: Karotki A, Mah K, Meijer G, Meltsner M Abstract The use of magnetic resonance imaging (MRI) alone for radiation planning is limited by the lack of electron density for dose calculations. The purpose of this work is to evaluate the dosimetric accuracy of using bulk electron density as a substitute for computed tomography (CT)-derived electron density in intensity-modulated radiation therapy (IMRT) treatment planning of head and neck (HN) cancers. Ten clinically-approved, CT-based IMRT treatment plans of HN cancer were used for this study. Three dose distributions were calculated and compared for each treatment plan. The first calculation used CT-derived density and was assumed to be the most accurate. The second calculation used a homogeneous patient density of 1 g/cm3. For... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438145 Wed, 23 Nov 2011 18:48:02 +0100 5438145 http://www.medworm.com/index.php?rid=5438144&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089007%26dopt%3DAbstract Authors: Li D, Wang H, Yin Y, Wang X Abstract Incorporating of daily cone-beam computer tomography (CBCT) image into online radiation therapy process can achieve adaptive image-guided radiation therapy (AIGRT). Registration of planning CT (PCT) and daily CBCT are the key issues in this process. In our work, a new multiscale deformable registration method is proposed by combining edge-preserving scale space with the multilevel free-form deformation (FFD) grids for CBCT-based AIGRT system. The edge-preserving scale space, which is able to select edges and contours of images according to their geometric size, is derived from the total variation model with the L1 norm (TV-L1). At each scale, despite the noise and contrast resolution differences between the PCT and CBCT, the selected ed... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438144 Wed, 23 Nov 2011 18:48:02 +0100 5438144 http://www.medworm.com/index.php?rid=5438143&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089008%26dopt%3DAbstract Authors: Piermattei A, Greco F, Azario L, Fidanzio A, Porcelli A, Cilla S, Sabatino D, Russo A, D'Onofrio G, Russo M Abstract Apractical and accurate generalized procedure to reconstruct the isocenter dose Diso for 3D conformal radiotherapy (3DCRT) has been developed for X-ray open beams supplied by linacs of different manufacturers and equipped with aSi electronic portal imaging devices (aSi EPIDs). This paper reports an extension of the method, to be applied at the wedged X-ray beams characterized by the wedge attenuation factor WAF.Using water-equivalent solid phantoms (SPs) of different thicknesses, w, and photon square fields of sizes, L, the generalized midplane doses and generalized transit signals by 38 beams of six different linacs were determined. The generalized data wer... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438143 Wed, 23 Nov 2011 18:48:02 +0100 5438143 http://www.medworm.com/index.php?rid=5438142&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089009%26dopt%3DAbstract Authors: Sharma SD, Kumar S, Srinivasan P, Chourasiya G Abstract A guarded cylindrical graphite ionization chamber of nominal volume 1000 cm3 was designed and fabricated for use as a reference standard for low-dose rate 137Cs brachytherapy sources. The air kerma calibration coefficient (NK) of this ionization chamber was estimated analytically using Burlin's general cavity theory, as well as by the Monte Carlo simulation and validated experimentally using Amersham CDCS-J-type 137Cs reference source. In the analytical method, the NK was calculated for 662 keV gamma rays of 137Cs brachytherapy source. In the Monte Carlo method, the geometry of the measurement setup and physics-related input data of the 137Cs source and the surrounding material were simulated using the Monte Carlo N-P... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438142 Wed, 23 Nov 2011 18:48:02 +0100 5438142 http://www.medworm.com/index.php?rid=5438141&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089010%26dopt%3DAbstract In conclusion, the carbon fiber tabletops decrease the skin-sparing effect of megavoltage photon energies. The increased beam attenuation and skin doses should be taken into account in the process of treatment planning. PMID: 22089010 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438141 Wed, 23 Nov 2011 18:48:02 +0100 5438141 http://www.medworm.com/index.php?rid=5438140&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089011%26dopt%3DAbstract Authors: Manohara SR, Hanagodimath SM, Gerward L Abstract Energy absorption geometric progression (GP) fitting parameters and the corresponding buildup factors have been computed for human organs and tissues, such as adipose tissue, blood (whole), cortical bone, brain (grey/white matter), breast tissue, eye lens, lung tissue, skeletal muscle, ovary, testis, soft tissue, and soft tissue (4-component), for the photon energy range 0.015-15 MeV and for penetration depths up to 40 mfp (mean free path). The chemical composition of human organs and tissues is seen to influence the energy absorption buildup factors. It is also found that the buildup factor of human organs and tissues changes significantly with the change of incident photon energy and effective atomic number, Zeff. These ch... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438140 Wed, 23 Nov 2011 18:48:02 +0100 5438140 http://www.medworm.com/index.php?rid=5438139&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089012%26dopt%3DAbstract This study demonstrates that the couch model created by MBS, which contains geometric and density information of the couch, can be used to detect the beam-couch intersection, and also is able to provide an accurate representation of the couch top attenuation properties in patient dose calculation. PMID: 22089012 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438139 Wed, 23 Nov 2011 18:48:02 +0100 5438139 http://www.medworm.com/index.php?rid=5438138&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089013%26dopt%3DAbstract Authors: Park JM, Choi CH, Ye SJ, Ha SW Abstract We investigated the effect of mixing high- and low-energy photon beams on the quality of intensity-modulated radiation therapy (IMRT) plans for patients with prostate cancer. Three different plans for each of twenty patients were generated using either 6 MV or 15 MV alone, and both 6 and 15 MV beams. All the planning parameters, goals, and constraints were set to be identical except beam energy. The dose distributions were similar in terms of target coverage, conformity, and homogeneity regardless of beam energy. The V70Gy of rectal wall in 6 MV, 15 MV and mixed-energy plans was 16.7%, 17.9%, and 16.3%, respectively, while V40Gy was 55.6%, 53.2%, and 50%. The mean dose to femoral heads in 6 MV, 15 MV, and mixed-energy plans were 31.7... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438138 Wed, 23 Nov 2011 18:48:02 +0100 5438138 http://www.medworm.com/index.php?rid=5438137&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089014%26dopt%3DAbstract Authors: Saidi P, Sadeghi M, Hosseini H, Tenreiro C Abstract This work presents experimental dosimetry results for a new 103Pd brachytherapy seed, in accordance with the AAPM TG-43U1 recommendation that all new low-energy interstitial brachytherapy seeds should undergo one Monte Carlo (MC) and at least one experimental dosimetry characterization. Measurements were performed using TLD-GR200A circular chip dosimeters using standard methods employing thermoluminescent dosimeters in a Perspex phantom. The Monte Carlo N-particle (MCNP) code, version 5 was used to evaluate the dose-rate distributions around this model 103Pd source in water and Perspex phantoms. The consensus value for dose-rate constant of the IR06-103Pd source was found equal to 0.690 cGy·h-1·U-1. The anisotropy funct... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438137 Wed, 23 Nov 2011 18:48:02 +0100 5438137 http://www.medworm.com/index.php?rid=5438136&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089015%26dopt%3DAbstract Authors: Lee TF, Chao PJ, Ting HM, Lo SH, Wang YW, Tuan CC, Fang FM, Su TJ Abstract The purpose of this study was to evaluate and quantify the planning performance of SmartArc-based volumetric-modulated arc radiotherapy (VMAT) versus fixed-beam intensity-modulated radiotherapy (IMRT) for nasopharyngeal carcinoma (NPC) using a sequential mode treatment plan. The plan quality and performance of dual arc-VMAT (DA-VMAT) using the Pinnacle3 Smart-Arc system (clinical version 9.0; Philips,Fitchburg, WI, USA) were evaluated and compared with those of seven-field (7F)-IMRT in 18 consecutive NPC patients. Analysis parameters included the conformity index (CI) and homogeneity index (HI) for the planning target volume (PTV), maximum and mean dose, normal tissue complication probability (NTCP)... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438136 Wed, 23 Nov 2011 18:48:02 +0100 5438136 http://www.medworm.com/index.php?rid=5438135&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089016%26dopt%3DAbstract Authors: Fearon T, Xie H, Cheng JY, Ning H, Zhuge Y, Miller RW Abstract Current estimation of radiation dose from computed tomography (CT) scans on patients has relied on the measurement of Computed Tomography Dose Index (CTDI) in standard cylindrical phantoms, and calculations based on mathematical representations of "standard man". Radiation dose to both adult and pediatric patients from a CT scan has been a concern, as noted in recent reports. The purpose of this study was to investigate the feasibility of adapting a radiation treatment planning system (RTPS) to provide patient-specific CT dosimetry. A radiation treatment planning system was modified to calculate patient-specific CT dose distributions, which can be represented by dose at specific points within an organ of intere... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438135 Wed, 23 Nov 2011 18:48:02 +0100 5438135 http://www.medworm.com/index.php?rid=5438134&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089017%26dopt%3DAbstract Authors: Shah AP, Kupelian PA, Willoughby TR, Meeks SL Abstract In the past 10 years, techniques to improve radiotherapy delivery, such as intensity-modulated radiation therapy (IMRT), image-guided radiation therapy (IGRT) for both inter- and intrafraction tumor localization, and hypofractionated delivery techniques such as stereotactic body radiation therapy (SBRT), have evolved tremendously. This review article focuses on only one part of that evolution, electromagnetic tracking in radiation therapy. Electromagnetic tracking is still a growing technology in radiation oncology and, as such, the clinical applications are limited, the expense is high, and the reimbursement is insufficient to cover these costs. At the same time, current experience with electromagnetic tracking applie... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438134 Wed, 23 Nov 2011 18:48:02 +0100 5438134 http://www.medworm.com/index.php?rid=5438133&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089018%26dopt%3DAbstract Authors: Kampfer S, Schell S, Duma MN, Wilkens JJ, Kneschaurek P Abstract Intensity-modulated radiation therapy (IMRT) requires more beam-on time than normal open field treatment. Consequently, the machines wear out and need more spare parts. A helical tomotherapy treatment unit needs a periodical tungsten target replacement, which is a time consuming event. To be able to predict the next replacement would be quite valuable. We observed unexpected variations towards the end of the target lifetime in the performed pretreatment measurements for patient plan verification. Thus, we retrospectively analyze the measurements of our quality assurance program. The time dependence of the quotient of two simultaneous dose measurements at different depths within a phantom for a fixed open fiel... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438133 Wed, 23 Nov 2011 18:48:02 +0100 5438133 http://www.medworm.com/index.php?rid=5438132&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089019%26dopt%3DAbstract This study investigates the relation between the number of segments and plan quality in VMAT optimization for a single modulated arc. Five prostate, five lung, and five head-and-neck (HN) patient plans were studied retrospectively. For each case, four VMAT plans were generated. The plans differed only in the number of control points used in the optimization process. The control points were spaced 2°, 3°, 4°, and 6° apart, respectively. All of the optimization parameters were the same among the four schemes. The 2° spacing plan was used as a reference to which the other three plans were compared. The plan quality was assessed by comparison of dose indices (DIs) and generalized equivalent uniform doses (gEUDs) for targets and critical structures. All optimization schemes generated clini... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438132 Wed, 23 Nov 2011 18:48:02 +0100 5438132 http://www.medworm.com/index.php?rid=5438131&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089020%26dopt%3DAbstract Authors: Beltran C, Merchant TE Abstract The purpose of this study was to quantify the intrafraction motion of pediatric patients with brain tumors during radiation therapy and investigate any correlation between motion, use of general anesthesia, and daily treatment duration. 100 pediatric patients with a mean age of 8.5 years (range: 1.0 to 17.8) were included in this prospective study. Forty-one patients required general anesthesia during treatment, mean age 4.8 years; 59 patients did not, mean age 11.2 years. Each patient had an intracranial tumor and was treated in the supine position with a thermoplastic facemask and headrest for immobilization. A pretreatment localization CBCT was acquired for each treatment fraction and a post-treatment CBCT was acquired every other fractio... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438131 Wed, 23 Nov 2011 18:48:02 +0100 5438131 http://www.medworm.com/index.php?rid=5438130&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089021%26dopt%3DAbstract The objective of this study was to assess the effect of antiscatter grid use on tomosynthesis image quality. We performed an observer study that rated the image quality of digital tomosynthesis scout radiographs and slice images of a Leeds TO.20 contrast-detail test object embedded in acrylic with and without a grid. We considered 10, 15, 20 and 25 cm of acrylic to represent the wide range of patient thicknesses encountered in pediatric imaging. We also acquired and rated images without a grid at an increased patient dose. The readers counted the total number of visible details in each image as a measure of relative image quality. We observed that the antiscatter grid improves tomosynthesis image quality compared to the grid-out case, which received image quality scores similar to grid-in ... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438130 Wed, 23 Nov 2011 18:48:02 +0100 5438130 http://www.medworm.com/index.php?rid=5438129&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089022%26dopt%3DAbstract Authors: Rowshanfarzad P, Sabet M, O'Connor DJ, Greer PB Abstract There have been several manual, semi-automatic and fully-automatic methods proposed for verification of the position of mechanical isocenter as part of comprehensive quality assurance programs required for linear accelerator-based stereotactic radiosurgery/radiotherapy (SRS/SRT) treatments. In this paper, a systematic review has been carried out to discuss the present methods for isocenter verification and compare their characteristics, to help physicists in making a decision on selection of their quality assurance routine. PMID: 22089022 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438129 Wed, 23 Nov 2011 18:48:02 +0100 5438129 http://www.medworm.com/index.php?rid=5438128&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089023%26dopt%3DAbstract Authors: Jones AK, Pasciak AS Abstract While direct measurement of the peak skin dose resulting from a fluoroscopically-guided procedure is possible, the decision must be made a priori at additional cost and time. It is most often the case that the need for accurate knowledge of the peak skin dose is realized only after a procedure has been completed, or after a suspected reaction has been discovered. Part I of this review article discusses methods for calculating the peak skin dose across a range of clinical scenarios. In some cases, a wealth of data are available, while in other cases few data are available and additional data must be measured in order to estimate the peak skin dose. Data may be gathered from a dose report, the DICOM headers of images, or from staff and physician... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438128 Wed, 23 Nov 2011 18:48:02 +0100 5438128 http://www.medworm.com/index.php?rid=5438127&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22089024%26dopt%3DAbstract Authors: Starkschall G PMID: 22089024 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5438127 Wed, 23 Nov 2011 18:48:02 +0100 5438127 http://www.medworm.com/index.php?rid=5325096&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587167%26dopt%3DAbstract Authors: Fürweger C, Drexler C, Kufeld M, Muacevic A, Wowra B Abstract The image-guided CyberKnife radiosurgery system is apable of tracking spinal targets without fiducial implants. Recently, a new version of this fiducial-free image guidance modality ("enhanced Xsight spine tracking") has been introduced. We assessed the accuracy of this novel technique versus its precursor in a comparative phantom study. The CyberKnife consists of a 6 MV linac on a six-axis robot and a stereoscopic kV image guidance system. An anthropomorphic head-and-neck phantom with a cervical spine section was mounted on the linac nozzle. The robotic manipulator was used to precisely move the phantom to defined positions in the CyberKnife workspace. Multiple stereoscopic images were acquired at different tr... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5325096 Tue, 18 Oct 2011 16:20:03 +0100 5325096 http://www.medworm.com/index.php?rid=5325095&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587196%26dopt%3DAbstract Authors: Chen M, Siochi RA Abstract The purpose of this study was to test the feasibility of using respiratory correlated mega voltage cone-beam computed tomography (MVCBCT), taken during patient localization, to quantify the size and motion of lung tumors. An imaging phantom was constructed of a basswood frame embedded with six different-sized spherical pieces of paraffin wax. The Quasar respiratory motion phantom was programmed to move the imaging phantom using typical respiratory motion. The moving imaging phantom was scanned using various MVCBCT imaging parameters, including two beam line types, two protocols with different ranges of rotation and different imaging doses. A static phantom was also imaged as a control. For all the 3D volumetric images, the contours of the six sph... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5325095 Tue, 18 Oct 2011 16:20:03 +0100 5325095 http://www.medworm.com/index.php?rid=5140593&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844845%26dopt%3DAbstract Authors: Camilus KS, Govindan VK, Sathidevi PS Abstract In most of the approaches of computer-aided detection of breast cancer, one of the preprocessing steps applied to the mammogram is the removal/suppression of pectoral muscle, as its presence within the mammogram may adversely affect the outcome of cancer detection processes. Through this study, we propose an efficient automatic method using the watershed transformation for identifying the pectoral muscle in mediolateral oblique view mammograms. The watershed transformation of the mammogram shows interesting properties that include the appearance of a unique watershed line corresponding to the pectoral muscle edge. In addition to this, it is observed that the pectoral muscle region is oversegmented due to the existence of sever... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140593 Fri, 19 Aug 2011 14:44:13 +0100 5140593 http://www.medworm.com/index.php?rid=5140592&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844846%26dopt%3DAbstract Authors: Chung H, Li J, Samant S Abstract Two-dimensional array dosimeters are commonly used to perform pretreatment quality assurance procedures, which makes them highly desirable for measuring transit fluences for in vivo dose reconstruction. The purpose of this study was to determine if an in vivo dose reconstruction via transit dosimetry using a 2D array dosimeter was possible. To test the accuracy of measuring transit dose distribution using a 2D array dosimeter, we evaluated it against the measurements made using ionization chamber and radiochromic film (RCF) profiles for various air gap distances (distance from the exit side of the solid water slabs to the detector distance; 0 cm, 30 cm, 40 cm, 50 cm, and 60 cm) and solid water slab thicknesses (10 cm and 20 cm). The backpro... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140592 Fri, 19 Aug 2011 14:44:13 +0100 5140592 http://www.medworm.com/index.php?rid=5140591&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844847%26dopt%3DAbstract Authors: Yang B, Dong Z, Lin MH, Ma CM Abstract Due to the angulation of the breast board used for tangential breast irradiation, additional normal lung tissues are included in the supraclavicular field. This work investigates a method to reduce the lung volume and dose delivered during supraclavicular irradiation for breast cancer. Ten patients included for this retrospective study received chest wall and supraclavicular irradiation following radical surgery or breast-conserving surgery. Three-dimensional conformal radiation therapy plans were generated using the CMS XiO treatment planning system. The clinical target volume (CTV) of the supraclavicular irradiation is defined as the subcutaneous tissues from 0.5 cm under the anterior skin surface to a 3 cm depth. Only the ipsilater... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140591 Fri, 19 Aug 2011 14:44:13 +0100 5140591 http://www.medworm.com/index.php?rid=5140590&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844848%26dopt%3DAbstract Authors: Litzenberg DW, Amro H, Prisciandaro JI, Acosta E, Gallagher I, Roberts DA Abstract The purpose of this study was to determine the dosimetric impact of density variations observed in water-equivalent solid slabs. Measurements were performed using two 30 cm × 30 cm water-equivalent slabs, one being 4 cm think and the other 5 cm thick. The location and extent of density variations were determined by computed tomography (CT) scans. Additional imaging measurements were made with an amorphous silicon megavoltage portal imaging device and an ultrasound unit. Dosimetric measurements were conducted with a 2D ion chamber array, and a scanned diode in water. Additional measurements and calculations were made of small rectilinear void inhomogeneities formed with water-equivalent slab... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140590 Fri, 19 Aug 2011 14:44:13 +0100 5140590 http://www.medworm.com/index.php?rid=5140589&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844849%26dopt%3DAbstract Authors: Becker SJ Abstract The use of non-coplanar radiation fields can potentially lead to collisions between the gantry and the couch or patient. The collisions are often not realized until the plan is finished and the fields are checked on the machine, or even later when the patient is already on the table. This paper presents an easy method of gauging if a collision is likely between the gantry and couch or patient during treatment planning. The method involves creating a chart of allowable gantry and couch combinations. The charts contain curves on a polar graph of the gantry and couch angle "plane". The curves display the limits of collisions for each gantry and couch combination for vertical couch positions 10, 15 and 20 cm below isocenter and for couch lateral positions of... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140589 Fri, 19 Aug 2011 14:44:13 +0100 5140589 http://www.medworm.com/index.php?rid=5140588&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844850%26dopt%3DAbstract This study evaluates the magnitude of various simulated RapidArc delivery errors by calculating gEUED on various prostate plans. PMID: 21844850 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140588 Fri, 19 Aug 2011 14:44:13 +0100 5140588 http://www.medworm.com/index.php?rid=5140587&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844851%26dopt%3DAbstract This study was based on retrospective dose calculations of 10 patients treated with a translating couch TBI technique. Dose distributions for CstSpeed and VarSpeed TBI treatments have been computed with Pinnacle3 treatment planning system in homogeneous (Homo) and heterogeneous (Hetero) dose calculation modes. A specific beam model was implemented in Pinnacle3 to allow an accurate dose calculation adapted for TBI special aspects. Better dose coverages were obtained with Homo/VarSpeed treatments compared to Homo/CstSpeed cases including smaller overdosage areas. Large differences between CstSpeed and VarSpeed dose calculations were observed in the brain, spleen, arms, legs, and lateral parts of the abdomen (differences between V100% mean values up to 57.5%). Results also showed that dose di... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140587 Fri, 19 Aug 2011 14:44:13 +0100 5140587 http://www.medworm.com/index.php?rid=5140586&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844852%26dopt%3DAbstract Authors: Peng JL, Liu C, Chen Y, Amdur RJ, Vanek K, Li JG Abstract The purpose was to determine dose-delivery errors resulting from systematic rotational setup errors for fractionated stereotactic radiotherapy using direct simulation in a treatment planning system. Ten patients with brain tumors who received intensity-modulated radiotherapy had dose distributions re-evaluated to assess the impact of systematic rotational setup errors. The dosimetric effect of rotational setup errors was simulated by rotating images and contours using a 3 by 3 rotational matrix. Combined rotational errors of ± 1°, ± 3°, ± 5° and ± 7° and residual translation errors of 1 mm along each axis were simulated. Dosimetric effects of the rotated images were evaluated by recomputing dose distribution... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140586 Fri, 19 Aug 2011 14:44:13 +0100 5140586 http://www.medworm.com/index.php?rid=5140585&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844853%26dopt%3DAbstract Authors: Wang B, Rassiah-Szegedi P, Zhao H, Huang YJ, Sarkar V, Szegedi M, Kokeny KE, Anker CJ, Shrieve DC, Salter BJ Abstract For Stereotactic Body Radiation Therapy (SBRT) treatment of lung and liver, we quantified the differences between two image guidance methods: 4DCT and ExacTrac respiratory-triggered imaging. Five different patients with five liver lesions and one lung lesion for a total of 19 SBRT delivered fractions were studied. For the 4DCT method, a manual registration process was used between the 4DCT image sets from initial simulation and treatment day to determine the required daily image-guided corrections. We also used the ExacTrac respiratory-triggered imaging capability to verify the target positioning, and calculated the differences in image guidance shifts betw... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140585 Fri, 19 Aug 2011 14:44:13 +0100 5140585 http://www.medworm.com/index.php?rid=5140584&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844854%26dopt%3DAbstract Authors: Nobah A, Moftah B, Tomic N, Devic S Abstract Impact of the various kVp settings used during computed tomography (CT) simulation that provides data for heterogeneity corrected dose distribution calculations in patients undergoing external beam radiotherapy with either high-energy photon or electron beams have been investigated. The change of the Hounsfield Unit (HU) values due to the influence of kVp settings and geometrical distribution of various tissue substitute materials has also been studied. The impact of various kVp settings and electron density (ED) distribution on the accuracy of dose calculation in high-energy photon beams was found to be well within 2%. In the case of dose distributions obtained with a commercially available Monte Carlo dose calculation algorith... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140584 Fri, 19 Aug 2011 14:44:13 +0100 5140584 http://www.medworm.com/index.php?rid=5140583&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844855%26dopt%3DAbstract In this study, we use the quadratic calibration method (QCM), in which an EPID image is converted into a matrix of equivalent path lengths (EPLs) and, therefore, exit doses, so as to model doses in conformal and enhanced dynamic wedge (EDW) fields. The QCM involves acquiring series of EPID images at a reference field size for different thicknesses of homogeneous solid water blocks. From these, a set of coefficients is established that is used to compute the EPL of any other irradiated material. To determine the EPL, the irradiated area must be known in order to establish the appropriate scatter correction. A method was devised for the automatic calculation of areas from the EPID image that facilitated the calculation of EPL for any field and exit dose. For EDW fields, the fitting coefficie... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140583 Fri, 19 Aug 2011 14:44:13 +0100 5140583 http://www.medworm.com/index.php?rid=5140582&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844856%26dopt%3DAbstract Authors: Gates LL, Gladstone DJ, Kasibhatla MS, Marshall JF, Seigne JD, Hug E, Hartford AC Abstract We investigated the stability of serrated gold coils (Visicoil) implanted within the prostate glands of patients undergoing definitive external beam radiotherapy for prostate cancer. Radiopaque Visicoils of diameter 0.75 mm and median length 3cm (range 2-4 cm) were implanted, one into each lobe of the prostate glands of 30 patients planned for external beam treatment. The coils were visualized on CT simulation and again after 25 fractions of treatment (5WK). Data from 30 patients were studied, of whom 19 also received androgen ablation therapy. The average change in the distance between the two coils over five weeks of treatment was 0.8mm (± 0.6 mm), with a maximum of 2.5 mm in one ... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140582 Fri, 19 Aug 2011 14:44:13 +0100 5140582 http://www.medworm.com/index.php?rid=5140581&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844857%26dopt%3DAbstract Authors: Yeboah C Abstract A laminated beam-spot camera of length 20 cm and effective cross-sectional area 2.5 cm × 3 cm was designed and constructed for the measurement of X-ray beam-spot sizes on different models of Siemens accelerators. With the accelerator gantry at 180° and camera positioned on an accessory tray holder, an XV film placed in contact with the camera at the distal end of it detected those X-rays that were transmitted through the camera. The FWHM of the detected X-ray intensity profile in the gun-target (G-T) direction or the orthogonal A-B direction was used as a measure of the beam-spot size in that direction. Siemens Mevatron MXEs exhibited a beam-spot size of 1.7± 0.2 mm in both the in-plane and cross-plane directions for 6 MV photon beams. The beam-spot si... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140581 Fri, 19 Aug 2011 14:44:13 +0100 5140581 http://www.medworm.com/index.php?rid=5140580&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844858%26dopt%3DAbstract Authors: Schreibmann E, Fox T, Crocker I Abstract Radiosurgical treatment of cranial or extracranial targets demands accurate positioning of the isocenter at the beam and table isocenter, and immobilization of the target during treatment. For spinal radiosurgery, the standard approach involves matching of cone-beam CT (CBCT) in-room images with the planning CT (pCT) to determine translation and yaw corrections. The purpose of this study was to assess the accuracy of these techniques compared to advanced automatching using mutual information metrics, with consideration given to volume of interest (VOI) and optimizing translations and rotations in all axes. The dosimetric consequences of our current standard matching techniques were also evaluated. Ten consecutive spinal radiosurgery... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140580 Fri, 19 Aug 2011 14:44:13 +0100 5140580 http://www.medworm.com/index.php?rid=5140579&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844859%26dopt%3DAbstract In this study, we established the relationship of relative dose vs. beam angle for two Varian 21EX linacs, one equipped with the Exact couch (standard couch) with sliding side support rails, and the other equipped with the Exact image-guided radiation therapy (IGRT) carbon fiber couch. Measurements were performed using an ion chamber placed at the center of an acrylic cylindrical phantom positioned at the linac isocenter for 6 MV and 18 MV photon beams. Measurements were performed at three different field sizes (3 × 3, 5 × 5, and 10 × 10 cm2), and were repeated with the phantom positioned at different longitudinal locations on the couches. To evaluate beam attenuation by the standard couch in a clinical setting, two test IMRT plans and two test VMAT plans on the standard couch were deli... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140579 Fri, 19 Aug 2011 14:44:13 +0100 5140579 http://www.medworm.com/index.php?rid=5140578&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844860%26dopt%3DAbstract Authors: Dongre PM, Mhatre V, Heigrujam M Abstract Physical and dosimetric characteristics of HDMLC were studied for SRS6, 6, and 10 MV X-rays from Novalis Tx. This in-built tertiary collimator consists of 60 pairs (32 × 0.25 cm; 26 × 0.5 cm and 2 × 0.7 cm) of leaves. Properties of HDMLC studied included alignment, readout and radiation field congruence, radiation penumbra, accuracy and reproducibility of leaf position and gap width, static and dynamic leaf shift, tongue-and-groove effect, leaf transmission and leakage, leaf travel speed, and delivery of dynamic conformal arc and IMRT. All tests were performed using a calibrated ionization chamber, film dosimetry and DynaLog file analysis. Alignment of leaves with isocenter plane was better than 0.03 cm at all gantry and collima... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140578 Fri, 19 Aug 2011 14:44:13 +0100 5140578 http://www.medworm.com/index.php?rid=5140577&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844861%26dopt%3DAbstract In this study, dose rate distribution around a spherical 137Cs pellet source, from a low-dose-rate (LDR) Selectron remote afterloading system used in gynecological brachytherapy, has been determined using experimental and Monte Carlo simulation techniques. Monte Carlo simulations were performed using MCNP4C code, for a single pellet source in water medium and Plexiglas, and measurements were performed in Plexiglas phantom material using LiF TLD chips. Absolute dose rate distribution and the dosimetric parameters, such as dose rate constant, radial dose functions, and anisotropy functions, were obtained for a single pellet source. In order to investigate the effect of the applicator and surrounding pellets on dosimetric parameters of the source, the simulations were repeated for six differe... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140577 Fri, 19 Aug 2011 14:44:13 +0100 5140577 http://www.medworm.com/index.php?rid=5140576&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844862%26dopt%3DAbstract Authors: Sutherland K, Ishikawa M, Bengua G, Ito YM, Miyamoto Y, Shirato H Abstract The purpose of this study was to evaluate a custom portal image - digitally reconstructed radiograph (DRR) registration software application. The software works by transforming the portal image into the coordinate space of the DRR image using three control points placed on each image by the user, and displaying the fused image. In order to test statistically that the software actually improves setup error estimation, an intra- and interobserver phantom study was performed. Portal images of anthropomorphic thoracic and pelvis phantoms with virtually placed irradiation fields at known setup errors were prepared. A group of five doctors was first asked to estimate the setup errors by examining the port... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140576 Fri, 19 Aug 2011 14:44:13 +0100 5140576 http://www.medworm.com/index.php?rid=5140575&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844863%26dopt%3DAbstract In this study, the two systems were assessed on accuracy of both motion tracking and radiation delivery control. To evaluate motion tracking, two artificial motion profiles and five patients' respiratory profiles were used. The motion trajectories acquired by the two gating systems were compared against the references. To assess radiation delivery control, time delays were measured using a single-exposure method. More specifically, radiation is delivered with a 4 mm diameter cone within the phase range of 10%-45% for the BrainLAB ExacTrac system, and within the phase range of 0%-25% for the Varian RPM system during expiration, each for three times. Radiochromic films were used to record the radiation exposures and to calculate the time delays. In the work, the discrepancies were quantified... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140575 Fri, 19 Aug 2011 14:44:13 +0100 5140575 http://www.medworm.com/index.php?rid=5140574&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844864%26dopt%3DAbstract Authors: Martin S, Rodrigues G, Chen Q, Pavamani S, Read N, Ahmad B, Hammond A, Venkatesan V, Renaud J, Yartsev S Abstract The aims of this study were to investigate the variability between physicians in delineation of head and neck tumors on original tomotherapy megavoltage CT (MVCT) studies and corresponding software enhanced MVCT images, and to establish an optimal approach for evaluation of image improvement. Five physicians contoured the gross tumor volume (GTV) for three head and neck cancer patients on 34 original and enhanced MVCT studies. Variation between original and enhanced MVCT studies was quantified by DICE coefficient and the coefficient of variance. Based on volume of agreement between physicians, higher correlation in terms of average DICE coefficients was observe... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140574 Fri, 19 Aug 2011 14:44:13 +0100 5140574 http://www.medworm.com/index.php?rid=5140573&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844865%26dopt%3DAbstract This study investigates the dosimetric benefits of designing patient-specific margins for prostate cancer patients based on 4D localization and tracking. Ten prostate patients, each implanted with three radiofrequency transponders, were localized and tracked for 40 fractions. "Conventional margin" (CM) planning target volumes (PTV) and PTVs resulting from uniform margins of 5 mm (5M) and 7 mm (7M) were explored. Through retrospective review of each patient's tracking data, an individualized margin (IM) design for each patient was determined. IMRT treatment plans with identical constraints were generated for all four margin strategies and compared. The IM plans generally created the smallest PTV volumes. For similar PTV coverage, the IM plans had a lower mean bladder (rectal) dose by an ave... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140573 Fri, 19 Aug 2011 14:44:13 +0100 5140573 http://www.medworm.com/index.php?rid=5140572&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844866%26dopt%3DAbstract Authors: Sengbusch ER, Mackie TR Abstract The purpose of this study was to determine the maximum proton kinetic energy required to treat a given percentage of patients eligible for stereotactic radiosurgery (SRS) with coplanar arc-based proton therapy, contingent upon the number and location of gantry angles used. Treatment plans from 100 consecutive patients treated with SRS at the University of Wisconsin Carbone Cancer Center between June of 2007 and March of 2010 were analyzed. For each target volume within each patient, in-house software was used to place proton pencil beam spots over the distal surface of the target volume from 51 equally-spaced gantry angles of up to 360°. For each beam spot, the radiological path length from the surface of the patient to the distal boundary... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140572 Fri, 19 Aug 2011 14:44:13 +0100 5140572 http://www.medworm.com/index.php?rid=5140571&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844867%26dopt%3DAbstract Authors: Peng JL, Kahler D, Li JG, Amdur RJ, Vanek KN, Liu C Abstract The purpose of this study was to investigate the feasibility of using a single QA device for comprehensive, efficient daily QA of a linear accelerator (Linac) and three image-guided stereotactic positioning systems (IGSPSs). The Sun Nuclear Daily QA 3 (DQA3) device was used to perform daily dosimetry and mechanical accuracy tests for an Elekta Linac, as well as daily image geometric and isocenter coincidence accuracy tests for three IGSPSs: the AlignRT surface imaging system; the frameless SonArray optical tracking System (FSA) and the Elekta kV CBCT. The DQA3 can also be used for couch positioning, repositioning, and rotational tests during the monthly QA. Based on phantom imaging, the Linac coordinate system de... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140571 Fri, 19 Aug 2011 14:44:13 +0100 5140571 http://www.medworm.com/index.php?rid=5140570&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21844868%26dopt%3DAbstract Authors: Starkschall G PMID: 21844868 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=5140570 Fri, 19 Aug 2011 14:44:13 +0100 5140570 http://www.medworm.com/index.php?rid=4903327&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330969%26dopt%3DAbstract Authors: García-Mollá R, Linares R, Ayala R This paper deals with the analysis of the behavior of objective image quality parameters for the new GE Senographe Essential FFDM system, in particular its dependence with beam quality. The detector consists of an indirect conversion a-Si flat panel coupled to a CsI:Tl scintillator. The system under study has gone through a series of relevant modifications in flat panel with respect to the previous model (GE Senographe DS 2000). These changes in the detector modify its performance and are intended to favor advanced applications like tomosynthesis, which uses harder beam spectra and lower doses per exposure than conventional FFDM. Although our system does not have tomosynthesis implemented, we noticed that most clinical explorations were per... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4903327 Tue, 07 Jun 2011 13:15:03 +0100 4903327 http://www.medworm.com/index.php?rid=4903326&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330970%26dopt%3DAbstract Authors: Amin MN, Heaton R, Norrlinger B, Islam MK The dosimetry of very small electron fields can be challenging due to relative shifts in percent depth-dose curves, including the location of dmax, and lack of lateral electronic equilibrium in an ion chamber when placed in the beam. Conventionally a small parallel plate chamber or film is utilized to perform small field electron beam dosimetry. Since modern radiotherapy departments are becoming filmless in favor of electronic imaging, an alternate and readily available clinical dosimeter needs to be explored. We have studied the performance of MOSFET as a relative dosimeter in small field electron beams. The reproducibility, linearity and sensitivity of a high-sensitivity microMOSFET were investigated for clinical electron beams. In a... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4903326 Tue, 07 Jun 2011 13:15:03 +0100 4903326 http://www.medworm.com/index.php?rid=4903325&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330971%26dopt%3DAbstract Authors: Kang H, Lovelock DM, Yorke ED, Kriminski S, Lee N, Amols HI Our goal is to determine an optimized image-guided setup by comparing setup errors determined by two-dimensional (2D) and three-dimensional (3D) image guidance for head and neck cancer (HNC) patients immobilized by customized thermoplastic masks. Nine patients received weekly imaging sessions, for a total of 54, throughout treatment. Patients were first set up by matching lasers to surface marks (initial) and then translationally corrected using manual registration of orthogonal kilovoltage (kV) radiographs with DRRs (2D-2D) on bony anatomy. A kV cone beam CT (kVCBCT) was acquired and manually registered to the simulation CT using only translations (3D-3D) on the same bony anatomy to determine further translational co... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4903325 Tue, 07 Jun 2011 13:15:03 +0100 4903325 http://www.medworm.com/index.php?rid=4903324&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330972%26dopt%3DAbstract Authors: Watanabe Y, Gopishankar N Verification of the dose calculation model and the software used for treatment planning is an important step for accurate radiation delivery in radiation therapy. Using BANG3 polymer gel dosimeter with a 3 Tesla magnetic resonance imaging (MRI) scanner, we examined the accuracy of TomoTherapy treatment planning and radiation delivery. We evaluated one prostate treatment case and found the calculated three-dimensional (3D) dose distributions agree with the measured 3D dose distributions with an exception in the regions where the dose was much smaller (25% or less) than the maximum dose (2.5 Gy). The analysis using the gamma-index (3% dose difference and 3 mm distance-to-agreement) for a volume of 12 cm × 11 cm × 9 cm containing the planning target vo... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4903324 Tue, 07 Jun 2011 13:15:03 +0100 4903324 http://www.medworm.com/index.php?rid=4903323&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330973%26dopt%3DAbstract Authors: Court L, Wagar M, Bogdanov M, Ionascu D, Schofield D, Allen A, Berbeco R, Lingos T The purpose was to evaluate the effect of dose rate on discrepancies between expected and delivered dose caused by the interplay effect. Fifteen separate dynamic IMRT plans and five hybrid IMRT plans were created for five patients (three IMRT plans and one hybrid IMRT plan per patient). The impact of motion on the delivered dose was evaluated experimentally for each treatment field for different dose rates (200 and 400 MU/min), and for a range of target amplitudes and periods. The maximum dose discrepancy for dynamic IMRT fields was 18.5% and 10.3% for dose rates of 400 and 200 MU/min, respectively. The maximum dose discrepancy was larger than this for hybrid plans, but the results were similar ... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4903323 Tue, 07 Jun 2011 13:15:03 +0100 4903323 http://www.medworm.com/index.php?rid=4903322&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330974%26dopt%3DAbstract Authors: Cilla S, Fidanzio A, Greco F, Sabatino D, Russo A, Gargiulo L, Azario L, Piermattei A In-vivo dosimetry techniques are currently being applied only by a few Centers because they require time-consuming implementation measurements, and workload for detector positioning and data analysis. The transit in-vivo dosimetry performed by the electronic portal imaging device (EPID) avoids the problem of solid-state detector positioning on the patient. Moreover, the dosimetric characterization of the recent Elekta aSi EPIDs in terms of signal stability and linearity make these detectors useful for the transit in-vivo dosimetry with 6, 10 and 15 MV photon beams. However, the implementation of the EPID transit dosimetry requires several measurements. Recently, the present authors have devel... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4903322 Tue, 07 Jun 2011 13:15:03 +0100 4903322 http://www.medworm.com/index.php?rid=4903321&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330975%26dopt%3DAbstract Authors: Spadea MF, Baroni G, Gierga DP, Turcotte JC, Chen GT, Sharp GC The purpose of this study is to assess the temporal and reconstruction accuracy of a surface imaging system, the GateCT under ideal conditions, and compare the device with a commonly used respiratory surrogate: the Varian RPM. A clinical CT scanner, run in cine mode, was used with two optical devices, GateCT and RPM, to detect respiratory motion. A radiation detector, GM-10, triggers the X-ray on/off to GateCT system, while the RPM is directly synchronized with the CT scanner through an electronic connection. Two phantoms were imaged: the first phantom translated on a rigid plate along the anterior-posterior (AP) direction, and was used to assess the temporal synchronization of each optical system with the CT scann... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4903321 Tue, 07 Jun 2011 13:15:03 +0100 4903321 http://www.medworm.com/index.php?rid=4903320&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330976%26dopt%3DAbstract Authors: Li G, Xie H, Ning H, Citrin D, Kaushal A, Camphausen K, Miller RW The purpose was to evaluate and correct the co-registration of diagnostic PET/CT and MRI/MRI images for stereotactic radiosurgery (SRS) using 3D volumetric image registration (3DVIR). The 3DVIR utilizes the homogeneity of color distribution over a volumetric anatomical landmark as the registration criterion with submillimeter accuracy. Fifty-three PET/CT and MRI (T1, T2 and FLAIR) image sets of patients with brain lesions were acquired sequentially from a hybrid PET/CT or an MRI scanner with common diagnostic head holding devices. Twenty-five sets of head 18F-FDG-PET/CT images were scanned over a 10-minute interval and 14 whole-body sets were scanned over a 30-minute interval. Fourteen sets of MRI images were ac... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4903320 Tue, 07 Jun 2011 13:15:03 +0100 4903320 http://www.medworm.com/index.php?rid=4903319&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330977%26dopt%3DAbstract We report on our initial experience with daily image guidance for the treatment of a patient with a basal cell carcinoma of the nasal dorsum using bolus electron conformal therapy. We describe our approach to daily alignment using treatment machine-integrated megavoltage (MV) planar imaging in conjunction with cone beam CT (CBCT) volumetric imaging to ensure the best possible setup reproducibility. Based on MV imaging, beam aperture misalignment with the intended treatment region was as large as 0.5 cm in the coronal plane. Four of the five fractions analyzed show induced shifts when compared to digitally reconstructed radiographs (DRR), in the range of 0.2-0.5 cm. Daily inspection of CBCT images show that the bolus device can have significant tilt in any given direction by as much as 13°... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4903319 Tue, 07 Jun 2011 13:15:03 +0100 4903319 http://www.medworm.com/index.php?rid=4903318&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330978%26dopt%3DAbstract This study measures offset as a function of gantry angle in kV and MV imaging systems on four treatment machines to investigate the magnitude of systematic offsets and their reproducibility between systems and machines, as well as over time. It is shown that each machine and energy has a reproducible pattern of offset as a function of gantry angle that is independent of kV/MV agreement, and it varies by machine. kV and MV offset ranges are on the order of 1.5 mm in the R/L and A/P directions, and 0.5 mm in the S/I direction. Variability of kV-MV agreement is on the order of 0.7 mm. At certain angles, combinations of localization images could show a compounded offset of over 2 mm, exceeding the desired certainty threshold. Since these trends are persistent over time for each machine, online... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4903318 Tue, 07 Jun 2011 13:15:03 +0100 4903318 http://www.medworm.com/index.php?rid=4903317&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330979%26dopt%3DAbstract Authors: Jolly D, Alahakone D, Meyer J Since the clinical implementation of novel rotational forms of intensity-modulated radiotherapy, a variety of planning studies have been published that reinforce the major selling points of the technique. Namely, comparable or even improved dose distributions with a reduction in both monitor units and treatment times, when compared with static gantry intensity-modulated radiotherapy. Although the data are promising, a rigorous approach to produce these plans has yet to be established. As a result, this study outlines a robust and streamlined planning strategy with a concentration on RapidArc class solutions for prostate with a simultaneous integrated boost. This planning strategy outlines the field setup, recommended starting objectives, required ... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4903317 Tue, 07 Jun 2011 13:15:03 +0100 4903317 http://www.medworm.com/index.php?rid=4903316&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330980%26dopt%3DAbstract Authors: Dogan N, Song S, Saleh H, Wu J, Murphy MJ The purpose was to assess the variability in automated translational head/neck setup corrections computed from several different imaging modalities and rigid registration methods using patient anatomy. Shifts were calculated using three commercial and one in-house automated rigid registration methods for nine head/neck patients who were imaged with three different image-guidance systems. The mean difference between the daily isocenter shifts determined by the four methods ranged from 2.8 to 12.5 mm for all of the test cases.These differences are much greater than the variability observed for a rigid imaging phantom. Image-guided setup procedures have an uncertainty that depends on the imaging modality, the registration algorithm, the i... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4903316 Tue, 07 Jun 2011 13:15:03 +0100 4903316 http://www.medworm.com/index.php?rid=4903315&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330981%26dopt%3DAbstract Authors: Wooten HO, Klein EE, Gokhroo G, Santanam L A procedure for periodic quality assurance of a video surface imaging system is introduced. AlignRT is a video camera-based patient localization system that captures and compares images of a patient's topography to a DICOM-formatted external contour, then calculates shifts required to accurately reposition the patient. This technical note describes the tools and methods implemented in our department to verify correct and accurate operation of the AlignRT hardware and software components. The procedure described is performed monthly and complements a daily calibration of the system. PMID: 21330981 [PubMed - indexed for MEDLINE] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4903315 Tue, 07 Jun 2011 13:15:03 +0100 4903315 http://www.medworm.com/index.php?rid=4903314&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330982%26dopt%3DAbstract Authors: Silva FA, Souza LF, Salmon CE, Souza DN With the increased incidence of cancer and a similarly increased number of surgeries for insertion of silicone breast implants, it is necessary to assess the effect of such material within the breast tissue, particularly in mammography, because of the reduction in the power of breast cancer diagnosis. In this work, we introduce a breast phantom with silicone implants in order to evaluate the influence of the implant on the visibility of the main mammographic findings: fibers, microcalcifications and tumor masses. In this proposed phantom, the breast tissue was simulated using gel paraffin. In the optical density of phantom mammograms with implants, a reduction in breast tissue visibility was seen corresponding to 23% when compared to a p... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4903314 Tue, 07 Jun 2011 13:15:03 +0100 4903314 http://www.medworm.com/index.php?rid=4903313&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330983%26dopt%3DAbstract Authors: Rong Y, Yadav P, Paliwal B, Shang L, Welsh JS Megavoltage CT (MVCT) simulation on the TomoTherapy Hi·Art system is an alternative to conventional CT for treatment planning in the presence of severe metal artifact. StatRT is a new feature that was implemented on the TomoTherapy operator station for performing online MVCT scanning, treatment planning and treatment delivery in one session. The clinical feasibility of using the StatRT technique and MVCT simulation to palliative treatment for a patient with substantial spinal metallic hardware is described. A patient with metastatic non-small-cell lung cancer involving the thoracic spine underwent conventional kilovoltage CT simulation. The metal artifact due to stainless steel spine-stabilizing rods was too severe for treatment p... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4903313 Tue, 07 Jun 2011 13:15:03 +0100 4903313 http://www.medworm.com/index.php?rid=4903312&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330984%26dopt%3DAbstract Authors: Jangda AQ, Hussein S, Rehman Z As part of quality assurance (QA) in high dose rate brachytherapy, it is necessary to verify that the source dwell positions correspond to the radiographic markers used in simulation and treatment planning. The procedure is well established for linear tandem applicators. However, with the advent of ring applicators, this has become more critical and challenging. This work describes a new approach to determine positional inaccuracies for ring applicators in which the dummy markers are imaged just once and their dwell positions characterized with respect to an applicator-defined axis. The radiograph serves as a reference for dummy markers for comparison with all subsequent measurements in which the active sources are autoradiographed at different o... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4903312 Tue, 07 Jun 2011 13:15:03 +0100 4903312 http://www.medworm.com/index.php?rid=4903311&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330985%26dopt%3DAbstract This study presents some dosimetric evaluations to introduce this applicator to the clinical use. The radiation attenuation characteristics of the applicator were evaluated by means of two dosimetric methods including well-type chamber and radiochromic film. The proposed 110 cm long applicator has a flexible structure made of stainless steel for easy passage through lumens and a needle tip to drill into big tumors. The 2mm diameter of the applicator is thick enough for source transition, while easy passage through any narrow lumen such as endoscope or cystoscope working channel is ensured. Well-chamber results showed an acceptably low attenuation of this steel springy applicator. Performing absolute dosimetry resulted in a correlation coefficient of R = 0.9916 (p-value ≈ 10-7) between st... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4903311 Tue, 07 Jun 2011 13:15:03 +0100 4903311 http://www.medworm.com/index.php?rid=4903310&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330986%26dopt%3DAbstract Authors: Grimm J, Grimm SY, Das IJ, Zhu Y, Yeo I, Xue J, Simpson L, Jacob D, Sarkar A The Stereotactic Alignment for Linear Accelerator (S. A. Linac) system is developed to conveniently improve the alignment accuracy of a conventional linac equipped with stereotactic cones. From the Winston-Lutz test, the SAlinac system performs three-dimensional (3D) reconstruction of the quality assurance (QA) ball coordinates with respect to the radiation isocenter, and combines this information with digital images of the laser target to determine the absolute position of the room lasers. A handheld device provides near-real-time repositioning advice to enable the user to align the QA ball and room lasers to within 0.25 mm of the centroid of the radiation isocenter. The results of 37 Winston-Lutz te... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4903310 Tue, 07 Jun 2011 13:15:03 +0100 4903310 http://www.medworm.com/index.php?rid=4903309&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330987%26dopt%3DAbstract Authors: Reggiori G, Mancosu P, Tozzi A, Cantone MC, Castiglioni S, Lattuada P, Lobefalo F, Cozzi L, Fogliata A, Navarria P, Scorsetti M The purpose of this study was to quantify the relationship between treatment time and dose uncertainty due to intrafraction organ motion in prostate cancer radiotherapy (RT). Ten consecutive patients with prostate cancer treated by radical RT by volumetric modulated arc therapy (RapidArc) were considered. For each patient, pre- and post-treatment cone beam computed tomography (CBCT) was performed in 10 fractions. The prostate, rectum and bladder were contoured on each CBCT. The change in organ position, volume and dosimetric uncertainty induced by organ motion were evaluated. Interval time between the two CBCTs ranged between 4 and 16 min (mean 7.3 ±... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4903309 Tue, 07 Jun 2011 13:15:03 +0100 4903309 http://www.medworm.com/index.php?rid=4903308&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330988%26dopt%3DAbstract Authors: Chandraraj V, Stathakis S, Manickam R, Esquivel C, Supe SS, Papanikolaou N The complexity of VMAT delivery requires new methods and potentially new tools for the commissioning of these systems. It appears that great consideration is needed for quality assurance (QA) of these treatments since there are limited devices that are dedicated to the QA of rotational delivery. In this present study, we have evaluated the consistency and reproducibility of one prostate and one lung VMAT plans for 31 consecutive days using three different approaches: 1) MLC DynaLog files, 2) in vivo measurements using the multiwire ionization chamber DAVID, and 3) using PTWseven29 2D ARRAY with the OCTAVIUS phantom at our Varian Clinac linear accelerator. Overall, the three methods of testing the reprod... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4903308 Tue, 07 Jun 2011 13:15:03 +0100 4903308 http://www.medworm.com/index.php?rid=4903307&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330989%26dopt%3DAbstract In this study, dosimetry predicted by the AAA and collapsed cone convolution (CCC) algorithm was evaluated using the tangential photon beam and phantom geometry. The photon beams of 6 and 15 MV with field sizes of 4 × 4 (or 7 × 7), 10 × 10 and 20 × 20 cm², produced by a Varian 21 EX linear accelerator, were used to test performances of the AAA and CCC using Monte Carlo (MC) simulation (EGSnrc-based code) as a benchmark. Horizontal dose profiles at different depths, phantom skin profiles (i.e., vertical dose profiles at a distance of 2 mm from the phantom lateral surface), gamma dose distributions, and dose-volume histograms (DVHs) of skin slab were determined. For dose profiles at different depths, the CCC agreed better with doses in the air-phantom region, while both the AAA and CCC ... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4903307 Tue, 07 Jun 2011 13:15:03 +0100 4903307 http://www.medworm.com/index.php?rid=4903306&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330992%26dopt%3DAbstract Authors: Siochi RA, Balter P, Bloch CD, Santanam L, Blodgett K, Curran BH, Engelsman M, Feng W, Mechalakos J, Pavord D, Simon T, Sutlieff S, Zhu XR The transfer of radiation therapy data among the various subsystems required for external beam treatments is subject to error. Hence, the establishment and management of a data transfer quality assurance program is strongly recommended. It should cover the QA of data transfers of patient specific treatments, imaging data, manually handled data and historical treatment records. QA of the database state (logical consistency and information integrity) is also addressed to ensure that accurate data are transferred. PMID: 21330992 [PubMed - indexed for MEDLINE] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4903306 Tue, 07 Jun 2011 13:15:03 +0100 4903306 http://www.medworm.com/index.php?rid=4903305&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330993%26dopt%3DAbstract Authors: Gossman MS, Pahikkala AJ, Rising MB, McGinley PH PMID: 21330993 [PubMed - indexed for MEDLINE] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4903305 Tue, 07 Jun 2011 13:15:03 +0100 4903305 http://www.medworm.com/index.php?rid=4853720&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587165%26dopt%3DAbstract In conclusion, DAT is capable of providing conformal dose distributions to the targets accomplishing many of the IMRT dose constraints simultaneously. Experimental dose-validation accuracy, ease of planning and reduced treatment times make DAT both acceptable and attractive for clinical use. PMID: 21587165 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853720 Tue, 24 May 2011 12:15:11 +0100 4853720 http://www.medworm.com/index.php?rid=4853719&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587166%26dopt%3DAbstract Authors: Das S, Isiah R, Rajesh B, Ravindran BP, Singh RR, Backianathan S, Subhashini J The present study is aimed at determination of accuracy of relocation of Gill-Thomas-Cosman frame during fractionated stereotactic radiotherapy. The study aims to quantitatively determine the magnitudes of error in anteroposterior, mediolateral and craniocaudal directions, and determine the margin between clinical target volume to planning target volume based on systematic and random errors. Daily relocation error was measured using depth helmet and measuring probe. Based on the measurements, translational displacements in anteroposterior (z), mediolateral (x), and craniocaudal (y) directions were calculated. Based on the displacements in x, y and z directions, systematic and random error were calcu... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853719 Tue, 24 May 2011 12:15:11 +0100 4853719 http://www.medworm.com/index.php?rid=4853718&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587167%26dopt%3DAbstract Authors: Fürweger C, Drexler C, Kufeld M, Muacevic A, Wowra B The image-guided CyberKnife radiosurgery system is apable of tracking spinal targets without fiducial implants. Recently, a new version of this fiducial-free image guidance modality ("enhanced Xsight spine tracking") has been introduced. We assessed the accuracy of this novel technique versus its precursor in a comparative phantom study. The CyberKnife consists of a 6 MV linac on a six-axis robot and a stereoscopic kV image guidance system. An anthropomorphic head-and-neck phantom with a cervical spine section was mounted on the linac nozzle. The robotic manipulator was used to precisely move the phantom to defined positions in the CyberKnife workspace. Multiple stereoscopic images were acquired at different translational a... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853718 Tue, 24 May 2011 12:15:11 +0100 4853718 http://www.medworm.com/index.php?rid=4853717&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587168%26dopt%3DAbstract In this study, we evaluate the attenuation of the dose due to barium-impregnation in the region between the surface of an electronic brachytherapy (EBT) balloon applicator for accelerated partial breast irradiation (APBI) and the prescription point at 1 cm depth in tissue. To perform the study, depth dose curves were calculated using a general purpose multi-particle transport code (FLUKA) for a range of balloon wall thicknesses with and without barium impregnation. Numerical data were verified with experimental readings using a parallel plate extrapolation ionization chamber for different wall thicknesses. Depth dose curves computed using both numerical and experimental methods show a 6.0% attenuation of the dose at the 1.0 cm prescription line due to the impregnation of barium in the ball... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853717 Tue, 24 May 2011 12:15:11 +0100 4853717 http://www.medworm.com/index.php?rid=4853716&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587169%26dopt%3DAbstract Authors: Gloi AM, Buchana RE, Zuge CL, Goettler AM The purpose is to devise a patient-specific quality assurance procedure for RapidArc radiotherapy using the MapCHECK detector array. We use our existing MapCHECK system and a Solid Water phantom with an embedded ion chamber to develop a quality assurance procedure for RapidArc treatment after commissioning. The ion chamber used to measure the absolute dose is surrounded by 6 cm layers of solid water on the anterior and posterior sides. Partial arcs derived from the treatment planning system were used with MapCHECK to determine the actual shape of the dose and correct for the angular dependence. The ion chamber measurements were within 1% of the absolute doses predicted by the Eclipse treatment system. When using a partial arc from 60°... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853716 Tue, 24 May 2011 12:15:11 +0100 4853716 http://www.medworm.com/index.php?rid=4853715&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587170%26dopt%3DAbstract Authors: Chatzigiannis C, Lymperopoulou G, Sandilos P, Dardoufas C, Yakoumakis E, Georgiou E, Karaiskos P External beam radiation therapy (RT) is often offered to breast cancer patients after surgical mastectomy followed by breast reconstruction with silicone implants. In some cases, the RT is administered while the patient is still implanted with a temporary tissue expander including a high-density metallic port, which is expected to affect the planned dose distribution.This work uses Monte Carlo (MC) simulation in order to evaluate the aforementioned effect when the McGhan Style 133 Tissue Expander with the Magna-Site injection port is used. Simulations have been performed on a patient model built using the actual CT images of the patient for two irradiation schemes, involving two ta... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853715 Tue, 24 May 2011 12:15:11 +0100 4853715 http://www.medworm.com/index.php?rid=4853714&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587171%26dopt%3DAbstract This study evaluated the accuracy of measuring the motion of an internal target using four-dimensional computed tomography (4DCT) scanning and the BrainLAB ExacTrac X-ray imaging system. Displacements of a metal coil implanted in a commercial respiratory phantom were measured in each system and compared to the known motion. A commercial respiratory motion phantom containing a metal coil as a surrogate target was used. Phantom longitudinal motions were sinusoidal with a 4.0 second period and amplitudes ranging from 5-25 mm. We acquired 4DCT and ExacTrac images of the coil at specified respiratory phases and recorded the coordinates of the coil ends. Coil displacement relative to the 0% phase (full-inhale) position were computed for the ExacTrac and 4DCT imaging systems. Coil displacements w... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853714 Tue, 24 May 2011 12:15:11 +0100 4853714 http://www.medworm.com/index.php?rid=4853713&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587172%26dopt%3DAbstract This study was designed to investigate dosimetric variations between proton plans with (PPW) and without (PPWO), a compensator for whole brain radiotherapy (WBRT). The retrospective study on PPW and PPWO in Eclipse and XiO systems and photon plans (XP) using controlled segments in Pinnacle system was performed on nine pediatric patients for craniospinal irradiations. DVHs and derived metrics, such as the homogeneity index (HI), the doses to 2% (D2%) and 5% (D5%) volumes, and mean dose (Dmean) of the whole brain (i.e., PTV), and the organs at risk (OARs) such as lens and skull, were obtained. The PPW plans from both Eclipse and XiO systems uncovered the following advantages: (1) encompassing a cribriform plate area with the 100% isodose line was better than either PPWO or XP, according to c... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853713 Tue, 24 May 2011 12:15:11 +0100 4853713 http://www.medworm.com/index.php?rid=4853712&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587173%26dopt%3DAbstract We present a technique for planning and verification of craniospinal treatment with the patient in the supine position. Treatment delivery and verification is streamlined through the use of modern imaging techniques. Treatments use two lateral brain fields abutted to a single or pair of posterior spine fields. Treatment delivery is simplified by aligning all isocenters in the anterior-posterior and lateral directions. Patient positioning is accomplished via on-board kV imaging. Verification of field shape and junctions is accomplished with BB placement and MV portal imaging. Daily treatment is simplified by using only longitundinal couch shifts, which are recorded in the patient chart and RV database. The technique is simple to implement in a clinic that is already using a similar beam arr... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853712 Tue, 24 May 2011 12:15:11 +0100 4853712 http://www.medworm.com/index.php?rid=4853711&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587174%26dopt%3DAbstract Authors: Tien CJ, Winslow JF, Hintenlang DE In helical computed tomography (CT), reconstruction information from volumes adjacent to the clinical volume of interest (VOI) is required for proper reconstruction. Previous studies have relied upon either operator console readings or indirect extrapolation of measurements in order to determine the over-ranging length of a scan.(1-5) This paper presents a methodology for the direct quantification of over-ranging dose contributions using real-time dosimetry. A Siemens SOMATOM Sensation 16 multislice helical CT scanner is used with a novel real-time "point" fiber-optic dosimeter system with 10 ms temporal resolution to measure over-ranging length, which is also expressed in dose-length-product (DLP).(6) Film was used to benchmark the exact len... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853711 Tue, 24 May 2011 12:15:11 +0100 4853711 http://www.medworm.com/index.php?rid=4853710&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587175%26dopt%3DAbstract Authors: De Paiva E, Da Rosa LA, Brito RR, De Sá LV, Dovales AC, Batista DV, Giannoni RA, Velasco AF The Brazilian Institute of Radiation Protection and Dosimetry (IRD/CNEN) carried out quality assurance regulatory audits in Brazilian radiotherapy facilities from 1995 to 2007. In this work, the set of data collected from 195 radiotherapy facilities that use high-energy photon beams are analyzed. They include results from audits in linear electron accelerators and/or Co-60 units. The inspectors of IRD/CNEN performed the dosimetry of high-energy radiotherapy photon beams according to the IAEA dosimetry protocols TRS 277 and TRS 398, and the values of measurements were compared to stated values. Other aspects of radiological protection were checked during on-site audits such as calibrati... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853710 Tue, 24 May 2011 12:15:11 +0100 4853710 http://www.medworm.com/index.php?rid=4853709&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587176%26dopt%3DAbstract Authors: Gopishankar N, Watanabe Y, Subbiah V One of treatment planning techniques with Leksell GammaPlan (LGP) for Gamma Knife stereotactic radiosurgery (GKSRS) uses multiple matrices with multiple dose prescriptions. Computational complexity increases when shots are placed in multiple matrices with different grid sizes. Hence, the experimental validation of LGP calculated dose distributions is needed for those cases. For the current study, we used BANG3 polymer gel contained in a head-sized glass bottle to simulate the entire treatment process of GKSRS. A treatment plan with three 18 mm shots and one 8 mm shot in separate matrices was created with LGP. The prescribed maximum dose was 8 Gy to three shots and 16 Gy to one of the 18 mm shots. The 3D dose distribution recorded in the gel... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853709 Tue, 24 May 2011 12:15:11 +0100 4853709 http://www.medworm.com/index.php?rid=4853708&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587177%26dopt%3DAbstract This study aimed to compare fixed-field, intensity-modulated radiotherapy (f-IMRT) with intensity-modulated arc therapy (IMAT) treatment plans in dosimetry and practical application for cervical esophageal carcinoma. For ten cervical esophageal carcinoma cases, f-IMRT plan (seven fixed-fields) and two IMAT plans, namely RA (coplanar 360° arcs) and RAx (coplanar 360° arcs without sectors from 80° to 110°, and 250° to 280°), were generated. DVHs were adopted for the statistics of above parameters, as well as conformal index (CI), homogeneity index (HI), dose-volumetric parameters of normal tissues, total accelerator output MUs and total treatment time. There were differences between RAx and f-IMRT, as well as RA in PTV parameters such as HI, V95% and V110%, but not in CI. RAx reduced l... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853708 Tue, 24 May 2011 12:15:11 +0100 4853708 http://www.medworm.com/index.php?rid=4853707&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587178%26dopt%3DAbstract Evaluation of a new VMAT QA device, or the "X" and "O" array geometries. J Appl Clin Med Phys. 2011;12(2):3346 Authors: Feygelman V, Zhang G, Stevens C, Nelms BE We introduce a logical process of three distinct phases to begin the evaluation of a new 3D dosimetry array. The array under investigation is a hollow cylinder phantom with diode detectors fixed in a helical shell forming an "O" axial detector cross section (ArcCHECK), with comparisons drawn to a previously studied 3D array with diodes fixed in two crossing planes forming an "X" axial cross section (Delta4). Phase I testing of the ArcCHECK establishes: robust relative calibration (response equalization) of the individual detectors, minor field size dependency of response not present in a 2D predecessor, and uncorrected... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853707 Tue, 24 May 2011 12:15:11 +0100 4853707 http://www.medworm.com/index.php?rid=4853706&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587179%26dopt%3DAbstract In conclusion, this device is simple to use and provides testing on basic and advanced imaging parameters for daily QA on any imager used in clinical practices. PMID: 21587179 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853706 Tue, 24 May 2011 12:15:11 +0100 4853706 http://www.medworm.com/index.php?rid=4853705&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587180%26dopt%3DAbstract Authors: Allen AM, Albert M, Caglar HB, Zygmanski P, Soto R, Killoran J, Sun Y Locally advanced non-small-cell lung cancer (NSCLC) is a common disease with a low overall survival even with aggressive treatments. Standard imaging (CT and PET/CT) provide no information about normal lung function. We therefore, sought to pilot HeMRI in patients with non-small-cell lung cancer before and after definitive radiotherapy (RT). Five patients with NSCLC receiving RT were enrolled on a prospective IRB approved study. Patients underwent CT, FDG-PET and HeMRI before and (within 10 days) following RT. All images (CT, FDG-PET and HeMRI) were co-registered. The CT and PET GTVs were contoured, as well as the ventilation defects on HeMRI caused by the tumor. Patients also underwent pulmonary function te... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853705 Tue, 24 May 2011 12:15:11 +0100 4853705 http://www.medworm.com/index.php?rid=4853704&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587181%26dopt%3DAbstract Authors: Balderson MJ, Spencer DP, Nygren I, Brown DW Improved treatment techniques in radiation therapy provide incentive to reduce treatment margins, thereby increasing the necessity for more accurate geometrical setup of the linear accelerator and accompanying components. In the present paper, we describe the development of a novel device that enables precise and automated measurement of geometric parameters for the purpose of improving initial setup accuracy, and for standardizing repeated quality control activities. The device consists of a silicon photodiode array, an evaluation board, a data acquisition card, and a laptop. Measurements that demonstrate the utility of the device are also presented. Using the device, we show that the radiation light field congruence for both 6 and... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853704 Tue, 24 May 2011 12:15:11 +0100 4853704 http://www.medworm.com/index.php?rid=4853703&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587182%26dopt%3DAbstract Authors: Matheoud R, Monica PD, Loi G, Vigna L, Krengli M, Inglese E, Brambilla M The purpose of this study was to analyze the behavior of a contouring algorithm for PET images based on adaptive thresholding depending on lesions size and target-to-background (TB) ratio under different conditions of image reconstruction parameters. Based on this analysis, the image reconstruction scheme able to maximize the goodness of fit of the thresholding algorithm has been selected. A phantom study employing spherical targets was designed to determine slice-specific threshold (TS) levels which produce accurate cross-sectional areas. A wide range of TB ratio was investigated. Multiple regression methods were used to fit the data and to construct algorithms depending both on target cross-sectional ar... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853703 Tue, 24 May 2011 12:15:11 +0100 4853703 http://www.medworm.com/index.php?rid=4853702&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587183%26dopt%3DAbstract Authors: Speight RJ, Esmail A, Weston SJ The BQ-CHECK phantom (PTW Freiburg, Germany) has been designed to be used with a 2D ion chamber array to facilitate the quality assurance (QA) of electron and photon beam qualities (BQ). The BQ-CHECK phantom has three wedges covering the diagonal axes of the beam: two opposed aluminum wedges used to measure electron energy and a single copper wedge used to measure photon energy. The purpose of this work was to assess the suitability of the BQ-CHECK phantom for use in a routine QA program.A range of percentage depth dose (PDD) curves for two photon beams and four electron beams were measured using a MP3 plotting tank (PTW Freiburg). These beams were used to irradiate a STARCHECK array (PTW Freiburg) with and without the BQ-CHECK phantom on top of... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853702 Tue, 24 May 2011 12:15:11 +0100 4853702 http://www.medworm.com/index.php?rid=4853701&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587184%26dopt%3DAbstract Authors: Chandraraj V, Stathakis S, Manickam R, Esquivel C, Supe SS, Papanikolaou N For intensity-modulated radiation therapy, evaluation of the measured dose against the treatment planning calculated dose is essential in the context of patient-specific quality assurance. The complexity of volumetric arc radiotherapy delivery attributed to its dynamic and synchronization nature require new methods and potentially new tools for the quality assurance of such techniques. In the present study, we evaluated and compared the dosimetric performance of EDR2 film and three other commercially available quality assurance devices: IBA I'MatriXX array, PTW Seven29 array and the Delta4 array. The evaluation of these dosimetric systems was performed for RapidArc and IMRT deliveries using a Varian Nov... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853701 Tue, 24 May 2011 12:15:11 +0100 4853701 http://www.medworm.com/index.php?rid=4853700&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587185%26dopt%3DAbstract Authors: Grimm J, Lacouture T, Croce R, Yeo I, Zhu Y, Xue J Almost 20 years ago, Emami et al. presented a comprehensive set of dose tolerance limits for normal tissue organs to therapeutic radiation, which has proven essential to the field of radiation oncology. The paradigm of stereotactic body radiotherapy (SBRT) has dramatically different dosing schemes but, to date, there has still been no comprehensive set of SBRT normal organ dose tolerance limits. As an initial step toward that goal, we performed an extensive review of the literature to compare dose limits utilized and reported in existing publications. The impact on dose tolerance limits of some key aspects of the methods and materials of the various authors is discussed. We have organized a table of 500 dose tolerance limits o... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853700 Tue, 24 May 2011 12:15:11 +0100 4853700 http://www.medworm.com/index.php?rid=4853699&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587186%26dopt%3DAbstract This study showed the usability of CTDI as a dose index and DLP as a total dose descriptor in CBCT scans. PMID: 21587186 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853699 Tue, 24 May 2011 12:15:11 +0100 4853699 http://www.medworm.com/index.php?rid=4853698&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587187%26dopt%3DAbstract We present a systematic approach to commissioning of the compensator-based IMRT in Pinnacle treatment planning system for commercially manufactured brass compensators. Some model parameters for the beams modulated by the variable-thickness compensators can only be associated with a single compensator thickness. To intelligently choose that thickness for beam modeling, we empirically determined the most probable filter thickness occurring within the modulated portion of the compensators typically used in clinics. We demonstrated that a set of relative output factors measured with the brass slab of most probable thickness (2 cm) differs from the traditionally used open field set, and leads to improved agreement between measurements and calculations, particularly for the larger field sizes. B... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853698 Tue, 24 May 2011 12:15:11 +0100 4853698 http://www.medworm.com/index.php?rid=4853697&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587188%26dopt%3DAbstract Authors: Takagi H, Obata Y, Kobayashi H, Takenaka K, Hirose Y, Goto H, Hattori T In radiotherapy, setup precision has great influence on the therapeutic effect. In addition, body movements during the irradiation and physical alternations during the treatment period might cause deviation from the planned irradiation dosage distribution. Both of these factors could undesirably influence the dose absorbed by the target. In order to solve these problems, we developed the "body surface navigation and monitoring system" (hereafter referred to as "Navi-system"). The purpose of this study is to review the precision of the Navi-system as well as its usefulness in clinical radiotherapy. The Navi-system consists of a LED projector, a CCD camera, and a personal computer (PC). The LED projector pro... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853697 Tue, 24 May 2011 12:15:11 +0100 4853697 http://www.medworm.com/index.php?rid=4853696&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587189%26dopt%3DAbstract Authors: Ali I, Alsbou N, Herman T, Ahmad S The purpose of this work is to extract three-dimensional (3D) motion trajectories of internal implanted and external skin-attached markers from kV cone-beam projections and reduce image artifact from patient motion in cone-beam computed tomography (CBCT) from on-board imager. Cone beam radiographic projections were acquired for a mobile phantom and liver patients with internal implanted and external skin-attached markers. An algorithm was developed to automatically find the positions of the markers in the projections. It uses normalized cross-correlation between a template image of a metal seed marker and the projections to find the marker position. From these positions and time-tagged angular views, the marker 3D motion trajectory was obtain... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853696 Tue, 24 May 2011 12:15:11 +0100 4853696 http://www.medworm.com/index.php?rid=4853695&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587190%26dopt%3DAbstract Authors: Beltran C, Sharma S, Merchant TE We investigate the role of adaptive radiation therapy in pediatric patients with diffuse pontine glioma and the impact of steroid-related weight gain on treatment parameters utilizing cone-beam CT. Fifteen patients with diffuse pontine glioma were treated with three-dimensional conformal radiation therapy and enrolled on a daily localization protocol. The median age was 6 years (range: 2-13 years). Patient charts were examined to obtain the prescribed daily dose of dexamethasone and weight. The original treatment plan was recalculated based on the data obtained from the daily cone-beam CT. The changes in target and critical structure doses were calculated using gEUD. Correlations between prescribed dexamethasone, weight gain, source-to-skin dis... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853695 Tue, 24 May 2011 12:15:11 +0100 4853695 http://www.medworm.com/index.php?rid=4853694&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587191%26dopt%3DAbstract Authors: Kohno R, Hotta K, Matsuura T, Matsubara K, Nishioka S, Nishio T, Kawashima M, Ogino T We experimentally evaluated the proton beam dose reproducibility, sensitivity, angular dependence and depth-dose relationships for a new Metal Oxide Semiconductor Field Effect Transistor (MOSFET) detector. The detector was fabricated with a thinner oxide layer and was operated at high-bias voltages. In order to accurately measure dose distributions, we developed a practical method for correcting the MOSFET response to proton beams. The detector was tested by examining lateral dose profiles formed by protons passing through an L-shaped bolus. The dose reproducibility, angular dependence and depth-dose response were evaluated using a 190 MeV proton beam. Depth-output curves produced using the M... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853694 Tue, 24 May 2011 12:15:11 +0100 4853694 http://www.medworm.com/index.php?rid=4853693&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587192%26dopt%3DAbstract In conclusion, image quality parameters for XVI and OBI have been quantified and compared for clinical protocols under various mAs settings. These results need to be viewed in the context of a recent study that reported the dose-mAs relationship for the two systems and found that OBI generally delivered higher imaging doses than XVI.(1). PMID: 21587192 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853693 Tue, 24 May 2011 12:15:11 +0100 4853693 http://www.medworm.com/index.php?rid=4853692&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587193%26dopt%3DAbstract Authors: Stanley J, Breitman K, Dunscombe P, Spencer DP, Lau H A database of clinically approved stereotactic radiosurgery treatment plans was created. One hundred and seventy targets in the database were then retrospectively evaluated using conformity indices suggested by RTOG, SALT-Lomax and Paddick. Relationships between the three alternative conformity indices were determined. The Paddick index combines the information provided by the RTOG and SALT-Lomax indices into a single index. The variation in the geometric overlap ratio, which is related to the SALT-Lomax index, was found to be not clinically relevant for our cohort of patients, and thus the Paddick and RTOG indices can be directly related. It was found that access to a dose volume histogram or dose distribution for a treatm... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853692 Tue, 24 May 2011 12:15:11 +0100 4853692 http://www.medworm.com/index.php?rid=4853691&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587194%26dopt%3DAbstract Authors: Silva JS, Cancela J, Teixeira L An oncological patient may go through several tomographic acquisitions during a period of time, needing an appropriate registration. We propose an automatic volumetric intrapatient registration method for tumor follow-up in pulmonary CT exams. The performance of our method is evaluated and compared with other registration methods based on optimization techniques. We also compared the metrics behavior to inspect which metric is more sensitive to changes due to the presence of lung tumors. PMID: 21587194 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853691 Tue, 24 May 2011 12:15:11 +0100 4853691 http://www.medworm.com/index.php?rid=4853690&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587195%26dopt%3DAbstract Authors: Morganti AG, Cilla S, De Gaetano A, Panunzi S, Digesù C, Macchia G, Massaccesi M, Deodato F, Ferrandina G, Cellini N, Scambia G, Piermattei A, Valentini V The purpose was to compare the dosimetric results observed in 201 breast cancer patients submitted to tangential forward intensity-modulated radiation therapy (IMRT) with those observed in 131 patients treated with a standard wedged 3D technique for postoperative treatment of whole breast, according to breast size and supraclavicular node irradiation. Following dosimetric parameters were used for the comparison: Dmax, Dmin, Dmean, V95% and V107% for the irradiated volume; Dmax, Dmean, V80% and V95% for the ipsilateral lung; Dmax, Dmean, V80% and V95% for the heart. Stratification was made according to breast size and suprac... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853690 Tue, 24 May 2011 12:15:11 +0100 4853690 http://www.medworm.com/index.php?rid=4853689&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587196%26dopt%3DAbstract Authors: Chen M, Siochi RA The purpose of this study was to test the feasibility of using respiratory correlated mega voltage cone-beam computed tomography (MVCBCT), taken during patient localization, to quantify the size and motion of lung tumors. An imaging phantom was constructed of a basswood frame embedded with six different-sized spherical pieces of paraffin wax. The Quasar respiratory motion phantom was programmed to move the imaging phantom using typical respiratory motion. The moving imaging phantom was scanned using various MVCBCT imaging parameters, including two beam line types, two protocols with different ranges of rotation and different imaging doses. A static phantom was also imaged as a control. For all the 3D volumetric images, the contours of the six spherical insert... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853689 Tue, 24 May 2011 12:15:11 +0100 4853689 http://www.medworm.com/index.php?rid=4853688&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587197%26dopt%3DAbstract Authors: Starkschall G - PMID: 21587197 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853688 Tue, 24 May 2011 12:15:11 +0100 4853688 http://www.medworm.com/index.php?rid=4853687&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21587198%26dopt%3DAbstract Authors: Amols HI - PMID: 21587198 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4853687 Tue, 24 May 2011 12:15:11 +0100 4853687 http://www.medworm.com/index.php?rid=4522550&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21330994%26dopt%3DAbstract Authors: Starkschall G   PMID: 21330994 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4522550 Sat, 26 Feb 2011 14:15:06 +0100 4522550 http://www.medworm.com/index.php?rid=4184036&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21081870%26dopt%3DAbstract Authors: Krechetov AS, Goer D, Dikeman K, Daves JL, Mills MD The purpose of this investigation is to measure, characterize and report stray photon leakage and scatter radiation measurements from the Mobetron, an intra-operative electron linear accelerator designed for use in an operating room environment. The study is needed due to recent changes to the shielding design of the Mobetron, and also to provide specific information that may be required by regulation in various jurisdictions. An analysis is performed on a number of manufactured units to deter-mine an average 3D stray photon radiation map. This information provides a basis for determining patient-based load restrictions and/or additional shielding for the operating room. The data presented evaluates the number of procedures f... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4184036 Sat, 20 Nov 2010 03:00:08 +0100 4184036 http://www.medworm.com/index.php?rid=4184035&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21081871%26dopt%3DAbstract Authors: Stern RL, Liu T Varian has issued two Product Notification Letters warning of known inaccuracies in dwell positions for their GammaMed HDR ring applicator. This inaccuracy was measured for two sets of applicators. Autoexposed radiographs were taken of the HDR source at different dwell positions and analyzed per Varian recommendations using tools within the BrachyVision treatment planning program. Comparison between programmed and actual dwell positions showed the actual positions shifted distally by an average of 0.34 cm (0.17 cm-0.59 cm) across all positions in all rings. A correction method was developed and tested. During planning, the tip of the ring was extrapolated distally beyond its actual position in the patient image set and a proximal offset of the same distance was... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4184035 Sat, 20 Nov 2010 03:00:08 +0100 4184035 http://www.medworm.com/index.php?rid=4184034&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21081872%26dopt%3DAbstract Authors: Fukuda A Kilovoltage cone beam computed tomography (CBCT) imaging may be useful in verifying patient position in stereotactic radiosurgery (SRS). To evaluate its efficacy, we investigated isocenter differences in the radiation beam and CBCT with respect to the achievable setup of a conventional frame-based SRS system. A verification phantom constructed from two plastic boards and Gafchromic-EBT film (4 × 4 cm2) pricked with a pin, was scanned by simulation CT. An isocenter at the tip of pin was planned in the treatment planning system and positioned using stereotactic coordinates. Star-shot irradiation was performed to evaluate the dif-ference between the radiation isocenter and the target (pinhole). CBCT rotation of 200° with a micro multileaf collimator (m3) was performed ... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4184034 Sat, 20 Nov 2010 03:00:08 +0100 4184034 http://www.medworm.com/index.php?rid=4184033&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21081873%26dopt%3DAbstract Authors: Iftimia I, Cirino ET, Xiong L, Mower HW With the commercial introduction of the Varian RapidArc, a new modality for treatment planning and delivery, the need has arisen for consistent and efficient techniques for performing patient-specific quality assurance (QA) tests. In this paper we present our methodology for a RapidArc treatment plan QA procedure. For our measurements we used a 2D diode array (MapCHECK) embedded at 5 cm water equivalent depth in MapPHAN 5 phantom and an Exradin A16 ion chamber placed in six different positions in a cylindrical homogeneous phantom (QUASAR). We also checked the MUs for the RapidArc plans by using inde-pendent software (RadCalc). The agreement between Eclipse calculations and MapCHECK/MapPHAN5 measurements was evaluated using both absolute ... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4184033 Sat, 20 Nov 2010 03:00:08 +0100 4184033 http://www.medworm.com/index.php?rid=4184032&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21081874%26dopt%3DAbstract This study uses the single-target single-hit model of film response to fit the calibration curves as a function of calibration method, processor condition, field size and depth. Kodak XV film was irradiated perpendicular to the beam axis in a solid water phantom. Standard calibration films (one dose point per film) were irradiated at 90 cm source-to-surface distance (SSD) for various doses (16-128 cGy), depths (0.2, 0.5, 1.5, 5, 10 cm) and field sizes (5 × 5, 10 × 10 and 20 × 20 cm2). The 8-field calibration method (eight dose points per film) was used as a reference for each experiment, taken at 95 cm SSD and 5 cm depth. The delivered doses were measured using an Attix parallel plate chamber for improved accuracy of dose estimation in the buildup region. Three fitting methods with one ... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4184032 Sat, 20 Nov 2010 03:00:08 +0100 4184032 http://www.medworm.com/index.php?rid=4184031&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21081875%26dopt%3DAbstract This study demonstrates that the intrinsic accuracy of iView and PIPSpro were within 1 pixel and 1°. Using a DRR extracted from a 2 mm CT study, the overall accuracy of both methods was about 2 mm and 1°. When thicker CT slices are considered, the global accuracy of both methods worsens, and differences larger than 1.5° between the rotation parameters estimated with iView and PIPSpro are evident. The results obtained with iView and PIPSpro were nearly equivalent. PMID: 21081875 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4184031 Sat, 20 Nov 2010 03:00:08 +0100 4184031 http://www.medworm.com/index.php?rid=4184030&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21081876%26dopt%3DAbstract Authors: Abe E, Mizowaki T, Norihisa Y, Narita Y, Matsuo Y, Narabayashi M, Nagata Y, Hiraoka M The aim of this study was to investigate the impact of multileaf collimator width (MLC-W) on intraprostatic dose painting plans for prostate cancer.Prostate cancer maps based on the histopathological findings were superimposed onto simulation CT images. Clinical target volume (CTV) 1 was defined as the prostate and the base of the seminal vesicles, and CTV2 was defined as the dominant intraprostatic lesions. Planning target volume (PTV) 1 and PTV2 were delineated by adding 5 mm margins to CTV1 and CTV2, respectively. For each case, two dose painting plans were created to deliver 74 Gy to PTV1 and 84 Gy to PTV2 with dynamic multileaf collimator technique using two different MLCs: m3 (MLC-W: 3m... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4184030 Sat, 20 Nov 2010 03:00:08 +0100 4184030 http://www.medworm.com/index.php?rid=4184029&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21081877%26dopt%3DAbstract Authors: Hillbrand M, Georg D The purpose was to identify an optimal set of treatment planning parameters and a minimal necessary dose matrix resolution for treatment planning with spot-scanned protons. Treatment plans based on different combinations of planning parameters and dose grid resolutions (DG) were calculated in a homogeneous geometric phantom for three cubic targets of different size: 8, 64 and 244 cm3. The proton dose was delivered by one single beam. Treatment plans were compared in terms of dose profiles parallel to and perpendicular to the central beam axis, as well as by dose homogeneity and conformity measures. Irrespective of target size, the dose homogeneity and conformity were comparable if the distance between spot layers was in the order of the width of a single B... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4184029 Sat, 20 Nov 2010 03:00:08 +0100 4184029 http://www.medworm.com/index.php?rid=4184028&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21081878%26dopt%3DAbstract Authors: Yadav P, Tolakanahalli R, Rong Y, Paliwal BR Use of helical TomoTherapy-based MVCT imaging for adaptive planning is becoming increasingly popular. Treatment planning and dose calculations based on MVCT require an image value to electron density calibration to remain stable over the course of treatment time. In this work, we have studied the dosimetric impact on TomoTherapy treatment plans due to variation in image value to density table (IVDT) curve as a function of target degradation. We also have investigated the reproducibility and stability of the TomoTherapy MVCT image quality over time. Multiple scans of the TomoTherapy "Cheese" phantom were performed over a period of five months. Over this period, a difference of 4.7% in the HU values was observed in high-density region... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4184028 Sat, 20 Nov 2010 03:00:08 +0100 4184028 http://www.medworm.com/index.php?rid=4184027&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21081879%26dopt%3DAbstract Authors: Giannelli M, Diciotti S, Tessa C, Mascalchi M In EPI-fMRI acquisitions, various readout bandwidth (BW) values are used as a function of gradients' characteristics of the MR scanner system. Echo spacing (ES) is another fundamental parameter of EPI-fMRI sequences, but the employed ES value is not usually reported in fMRI studies. Nyquist ghost is a typical EPI artifact that can degrade the overall quality of fMRI time series. In this work, the authors assessed the basic effect of BW and ES for two clinical 1.5 T MR scanner systems (scanner-A, scanner-B) on Nyquist ghost of gradient-echo EPI-fMRI sequences. BW range was: scanner-A, 1953-3906 Hz/pixel; scanner-B, 1220-2894 Hz/pixel. ES range was: scanner-A, scanner-B: 0.75-1.33 ms. The ghost-to-signal ratio of time series acquisit... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4184027 Sat, 20 Nov 2010 03:00:08 +0100 4184027 http://www.medworm.com/index.php?rid=4184026&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21081880%26dopt%3DAbstract Authors: Nevelsky A, Bernstein Z, Bar-Deroma R, Kuten A, Orion I The design concept and dosimetric characteristics of a new applicator system for intraoperative radiation therapy (IORT) are presented in this work. A new hard-docking commercial system includes polymethylmethacrylate (PMMA) applicators with different diameters and applicator end angles and a set of secondary lead collimators. A telescopic device allows changing of source-to-surface distance (SSD). All measurements were performed for 6, 9, 12 and 18 MeV electron energies. Output factors and percentage depth doses (PDD) were measured in a water phantom using a plane-parallel ion chamber. Isodose contours and radiation leakage were measured using a solid water phantom and radiographic films. The dependence of PDD on SSD was... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4184026 Sat, 20 Nov 2010 03:00:08 +0100 4184026 http://www.medworm.com/index.php?rid=4184025&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21081881%26dopt%3DAbstract The objective was to compare the dosimetry of Helical TomoTherapy (TOMO) and Gamma Knife (GK) treatment plans for tumor and normal brain in the treatment of single and multiple brain tumors. An anthropomorphic Rando Head phantom was used to compare the dosimetry of TOMO and GK. Eight brain tumors of various shapes, sizes and locations were used to generate 10 plans. The radiation dose was 20 Gy prescribed to the 100% isodose line for TOMO plans and to the 50% for the GK plans. Dose Volume Histograms for tumor and brain were com-pared. Equivalent Uniform Dose (gEUD), Tumor Control Probability (TCP) and Normal Tissue Complication Probability (NTCP) were performed and used for plan comparisons. Average minimum, mean, median and maximum tumor doses were 19.93, 27.83, 27.38, 39.60 Gy for GK and... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4184025 Sat, 20 Nov 2010 03:00:08 +0100 4184025 http://www.medworm.com/index.php?rid=4184024&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21081882%26dopt%3DAbstract The objective was to compare intensity-modulated radiation therapy (IMRT) with 3D conformal proton therapy (3DCPT) in the treatment of cervical cancer. In particular, each technique's ability to spare pelvic bone marrow (PBM) was of primary interest in this study. A total of six cervical cancer patients (3 postoperative and 3 intact) were planned and analyzed. All plans had uniform 1.0 cm CTV-PTV margin and satisfied the 95% PTV with 100% isodose (prescription dose = 45 Gy) coverage. Dose-volume histograms (DVH) were analyzed for comparison. The overall PTV and PBM volumes were 1035.9 ± 192.2 cc and 1151.4 ± 198.3 cc, respectively. In terms of PTV dose conformity index (DCI) and dose homogene-ity index (DHI), 3DCPT was slightly superior to IMRT with 1.00 ± 0.001, 1.01 ± 0.02, and 1.10 ... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4184024 Sat, 20 Nov 2010 03:00:08 +0100 4184024 http://www.medworm.com/index.php?rid=4184023&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21081883%26dopt%3DAbstract This article describes the commissioning and quality assurance (QA) procedures developed for this peripheral respiratory training system, the Stanford Respiratory Training (START) system. Using the Varian real-time position management system for the respiratory signal input, the START software was commissioned and able to acquire sample respiratory traces, create a patient-specific guiding waveform, and generate audiovisual signals for improving respiratory regularity. Routine QA tests that include hardware maintenance, visual guiding-waveform creation, auditory sounds synchronization, and feedback assess-ment, have been developed for the START system. The QA procedures developed here for the START system could be easily adapted to other respiratory training systems based on audiovisual bi... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4184023 Sat, 20 Nov 2010 03:00:08 +0100 4184023 http://www.medworm.com/index.php?rid=4184022&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21081884%26dopt%3DAbstract In conclusion, both MatriXX 2D ion chamber array and portal dosimetry showed comparable results and can be use as an alternative to each other for relative photon fluence verification. PMID: 21081884 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics) Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4184022 Sat, 20 Nov 2010 03:00:08 +0100 4184022 http://www.medworm.com/index.php?rid=4184021&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21081885%26dopt%3DAbstract Authors: Chang J, Kim S, Jang DY, Suh TS A multiple-slit collimator (MSC) design was introduced for scatter reduction in cone-beam computed tomography (CBCT). Unlike most other collimators, the open and closed septa of the proposed MSC are placed in an equi-angular interval on a circular track of the central sagittal plane. Therefore, one gantry rotation provides only the half of necessary dataset and two gantry rotations are needed to obtain full information. During the first gantry rotation, the MSC position relative to the source is fixed. For the second rotation, the MSC is rotated by the equi-angle interval. We assume signals under the closed septa are totally attributed to scatter radiation. Then, scatter contributions under open septa are determined by interpolating them.Monte C... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4184021 Sat, 20 Nov 2010 03:00:08 +0100 4184021 http://www.medworm.com/index.php?rid=4184020&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21081886%26dopt%3DAbstract Authors: Fidanzio A, Greco F, Mameli A, Azario L, Balducci M, Gambacorta MA, Frascino V, Cilla S, Sabatino D, Piermattei A An electronic portal imaging device (EPID) is an effective detector for in vivo transit dosimetry. In fact, it supplies two-dimensional information, does not require special efforts to be used during patient treatment, and can supply data in real time. In the present paper, a new procedure has been proposed to improve the EPID invivo dosimetry accuracy by taking into account the patient setup variations. The procedure was applied to the breast tangential irradiation for the reconstruction of the dose at the breast midpoint, Dm. In particular, the patient setup variations were accounted for by comparing EPID images versus digitally reconstructed radiographies. In th... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4184020 Sat, 20 Nov 2010 03:00:08 +0100 4184020 http://www.medworm.com/index.php?rid=4184019&cid=s_35853_75_f&fid=35853&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21081887%26dopt%3DAbstract Authors: Selvam TP, Keshavkumar B Relative absorbed-dose energy response correction R for different detector materials in water, PMMA and polystyrene phantoms are calculated using Monte Carlo-based EGSnrc code system for 125I and 169Yb brachytherapy sources. The values of R obtained for 125I source are 1.41, 0.92, 3.97, 0.47, 8.32 and 1.10, respectively, for detector materials LiF, Li2B4O7 , A12O3, diamond, silicon diode and air. These values are insensitive to source-to-detector distance and phantom material. For 169Yb source, R is sensitive to source-to-detector distance for detector materials other than air and Li2B4O7. For silicon, R increases from 3 to 4.23 when depth in water is increased from 0.5 cm to 15 cm. For 169Yb source, the values of R obtained for air and Li2B4O7 in PMMA... Journal of Applied Clinical Medical Physics journals http://www.medworm.com/rss/comments.php?id=4184019 Sat, 20 Nov 2010 03:00:08 +0100 4184019