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Dose consumption for quality assurance and maintenance at a dedicated IORT accelerator.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Dedicated accelerators for intraoperative radiation therapy (IORT) are operated at high dose rates in order to achieve short treatment times within which the anaesthetisized patient must be remotely monitored, e.g. via video cameras and telemetric anesthesia instruments. Due to these high dose rates, large doses accumulate from the irradiations necessary for quality assurance (QA) and maintenance. In practice, the dose load for QA, maintenance and repairs will probably by far exceed the patient dose. The total dose consumption for all of these actions must be considered in facility licensing, in radiation protection as...
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Hensley FW Tags: J Appl Clin Med Phys Source Type: journals

Analysis of couch position tolerance limits to detect mistakes in patient setup.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This work investigates the use of the tolerance limits on the treatment couch position to detect mistakes in patient positioning and warn users of possible treatment errors. Computer controlled radiotherapy systems use the position of the treatment couch as a surrogate for patient position and a tolerance limit is applied against a planned position. When the couch is out of tolerance a warning is sent to a user to indicate a possible mistake in setup. A tight tolerance may catch all positioning mistakes while as the same time sending too many warnings; while a loose tolerance will not catch all mistakes. We develop a s...
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Hadley SW, Lam KL, Balter JM Tags: J Appl Clin Med Phys Source Type: journals

Rapid fabrication of custom patient biopsy guides.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Image guided surgery is currently performed using frame-based as well as frameless approaches. In order to reduce the invasive nature of stereotactic guidance as well as to reduce the cost in both equipment and time required within the operating room we investigated the use of rapid prototyping (RP) technology. In our approach we fabricated custom patient specific face-masks and guides that can be applied to the patient during surgery. These guides provide a stereotactic reference for the accurate placement of surgical tools to a pre-planned target along a pre-planned trajectory. While the use of RP machines has previo...
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Rajon DA, Bova FJ, Friedman WA Tags: J Appl Clin Med Phys Source Type: journals

Detection of electron beam energy variations using a computed radiography system.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A method to evaluate the electron beam energy constancy by employing the computed radiography (CR) system has been developed. In this method, a right triangular plastic wedge is used to produce a curve of the CR storage phosphor plate signal versus the wedge thickness. The curve which resembles the percentage depth ionization curve of the clinical electron beams can be used to derive the energy constancy metric EC50. The sensitivity of the method was tested using polystyrene sheets of variable thicknesses. For electron energies up to 12 MeV energy changes induced by 1.5 mm thick polystyrene can be detected, while a 2.3...
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Cai YC, Ge Y, Bernard DA, Turian JV, Chu JC Tags: J Appl Clin Med Phys Source Type: journals

4D-PET data sorting into different number of phases: a NEMA IQ phantom study.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study aims at evaluating the dependence of 4D-PET data sorting on the number of phases in which the respiratory cycle can be divided. The issue is to find the best compromise to reduce the conflicting effects induced by increasing the number of phases: lesion motion on each set of images decreases, but on the other hand image noise increases. The IQ NEMA 2001 IEC body phantom was used to simulate the movement of neoplastic lesions in the thorax and abdomen, investigating the effect of target size (10-37 mm), lesion to background activity concentrations ratio (4-to-1 and 8-to-1), total acquisition time (3, 6, 12, 20 mi...
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Mancosu P, Sghedoni R, Bettinardi V, Fioroni F, Aquilina MA, Grassi E, Fazio F, Borasi G, Gilardi MC Tags: J Appl Clin Med Phys Source Type: journals

Characterization of cylindrical ionization chambers for patient specific IMRT QA.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Proven conventional dosimetry techniques do not provide accuracy and precision in the measurement of inverse planned intensity modulated radiation therapy (IMRT) fields. Dynamic and step-and-shoot multileaf collimation (DMLC/SMLC) challenge current ionization chamber dosimetry practices. Ionization chamber performance in these fields is evaluated for three cylindrical chambers of varying volumes (PinPoint (PP): 0.015 cm3, IC10: 0.13 cm3, Farmer type NE2571 (FT): 0.69 cm3) in terms of measurement reproducibility, dose measurement linearity, and IMRT dose measurements. Fifty IMRT patient specific quality assurance dose m...
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Fraser DJ, Parker W, Seuntjens J Tags: J Appl Clin Med Phys Source Type: journals

A positioning QA procedure for 2D/2D (kV/MV) and 3D/3D (CT/CBCT) image matching for radiotherapy patient setup.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A daily QA procedure for Varian's on-board imager (OBI) and portal vision (PV) device was developed. The procedure was to check: (1) the two imaging device's isocenters (digital graticules) coincides with linac's isocenter (to a pre-specified accuracy) and (2) the positional difference detected by 2D/2D image matching can be reliably transferred to couch motion. A cube isocenter phantom was used and two sets of 1 mm metal balls (bb) were placed on the phantom to define two separate spatial points (locations.) The first set defined the isocenter at the phantom center and the second set defined a point 1.5cm anterior, 1....
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Guan HH, Hammoud R, Yin F Tags: J Appl Clin Med Phys Source Type: journals

Suitability of radiochromic films for dosimetry of very-low energy X-rays.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study examined the response characteristics of three commercially available radiochromic films when exposed to very low energy (50 kVp) X-rays. The aim was to evaluate the films for potential use in 2D dosimetry for a low-kV intraoperative radiotherapy (IORT) device. Dose-response relationships were obtained for Gafchromic(R) EBT, XR-RV2 and XR-QA film in water at several distances from the IORT source in order to evaluate the effect of changes in X-ray spectrum on response. It was found that the dose-rates from the source were excessive for use of the XR-QA film, and that all three film types films showed significant...
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Ebert M, Asad AH, Siddiqui SA Tags: J Appl Clin Med Phys Source Type: journals

A diagnostic tool for basic daily quality assurance of a Tomotherapy Hi*Art machine.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Conclusion: This tool makes it possible to perform an easy-to-use and fast basic daily quality assurance check featuring an output as well as an energy evaluation. Ideally this tool should offer also the combined dosimetry check of jaw width, couch speed, leaf latency, output, leaf/gantry synchrony and lasers. This will be investigated in the future. PMID: 19918225 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Van de Vondel I, Tournel K, Verellen D, Duchateau M, Lelie S, Storme G Tags: J Appl Clin Med Phys Source Type: journals

Clinical implementation of electron energy changes of varian linear accelerators.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study we investigated electron beam characteristics and implemented two new electron beams on two Varian linear accelerators. Comprehensive tests and measurements indicated the new electron beams met all dosimetry parameter criteria and operational safety standards. With these two new electron beams in addition to existing electron beams we were able to provide a choice of electron beams which had d90depth between 1.5 cm and 6.0 cm and from 1.5 cm to 4.0 cm in 0.5 cm increment to meet our clinical need. PMID: 19918226 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Zhang S, Liengsawangwong P, Lindsay P, Prado K, Sun TL, Steadham R, Wang X, Salehpour M, Gillin M Tags: J Appl Clin Med Phys Source Type: journals

From phase-based to displacement-based gating: A software tool to facilitate respiration-gated radiation treatment.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Conclusions: Real-time phase gating can lead to inaccuracies when the breathing trace is irregular or because of other unidentified reasons. In such cases, the in-gate displacement differed by as much as 2 mm between phase-based and displacement-based gating for the real-time phase calculation. Displacement-based gating is equivalent to phase-based gating for retrospectively-calculated phase information. PMID: 19918227 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Santoro JP, Yorke E, Goodman K, Mageras GS Tags: J Appl Clin Med Phys Source Type: journals

Treatment planning of Epithelial Ovarian Cancers using Helical Tomotherapy.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The objective parameters were to obtain uniform and adequate target coverage with maximum OAR sparing. HT plans were generated for five patients with field-width of 5.0/2.5cm, modulation factor of 3.5/3.0, and a pitch of 0.3. A dose of 25Gy in 25 fractions was prescribed to the abdomen with a simultaneous boost of 45Gy in 25 fractions to the pelvis. Dose-volume parameters and various indices were analyzed and compared. Mean volume (standard-deviation) of abdominal and pelvic PTV (planning target volume) was 6630 (+/-450) cm3 and 1235 (+/-98)cm3 respectively. Mean length of PTV in cranio-caudal direction was 41(+/-4) cm. Vo...
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Swamidas J, Mahantshetty U, Vineeta G, Deshpande D, Sarin R, Shrivastava S, Engineer R Tags: J Appl Clin Med Phys Source Type: journals

Analysis of the evolution of acceptance indices of quality control parameters for x-ray equipment in the state of são paulo.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Analysis of the evolution of acceptance indices of quality control parameters for x-ray equipment in the state of são paulo. J Appl Clin Med Phys. 2009;10(4):3007 Authors: Ebisawa ML, Magon Mde F, Mascarenhas YM The quality assurance (QA) of radiographic images based on the operating conditions of X-ray equipment is essential for good image quality, accurate medical diagnostics and to prevent the exposure of health professionals and patients to unnecessary doses of ionizing radiation. This paper presents a historical analysis of 1,635 Quality Assurance Technical Reports by Health Institutions in the state ...
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Ebisawa ML, Magon Mde F, Mascarenhas YM Tags: J Appl Clin Med Phys Source Type: journals

Optimization of photon beam energy in aperture-based inverse planning.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Optimal choice of beam energy in radiation therapy is easy in many well-documented cases, but less obvious in some others. Low-energy beams may provide better conformity around the target than their high-energy counterparts due to reduced lateral scatter, but they also contribute to overdosage of peripheral normal tissue. Beam energy was added as an optimization parameter in an automatic aperture-based inverse planning system. We have investigated two sites (prostate and lung), representative of deep-seated and moderately deep-seated tumors. For each case and different numbers of beam incidences, four plans were optimi...
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: St-Hilaire J, Sévigny C, Beaulieu F, Gingras L, Tremblay D, Beaulieu L Tags: J Appl Clin Med Phys Source Type: journals

The effect of interfraction prostate motion on IMRT plans: a dose-volume histogram analysis using a Gaussian error function model.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The Gaussian error function model, containing pairs of error and complementary error functions, was used to carry out cumulative dose-volume histogram (cDVH) analysis on prostate intensity modulated radiation therapy (IMRT) plans with interfraction prostate motion. Cumulative DVHs for clinical target volumes (CTVs) shifted in the anterior-posterior directions based on a 7-beam IMRT plan were calculated and modeled using the Pinnacle3 treatment planning system and a Gaussian error function, respectively. As the parameters in the error function model, namely, a, b and c were related to the shape of the cDVH curve, evalua...
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Chow JC, Jiang R, Markel D Tags: J Appl Clin Med Phys Source Type: journals

Accuracy of automatic couch corrections with on-line volumetric imaging.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Conclusions: Remote automatic couch movement is reliable and effective for adjusting the patient position with precision of ~1 mm. Residual error observed in this study demonstrates that displacement is minimal after remote couch adjustment for all patients. PMID: 19918232 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Li W, Moseley DJ, Manfredi T, Jaffray DA Tags: J Appl Clin Med Phys Source Type: journals

Effect of Collimator and Couch Angle Change on Breast IMRT Dose Distributions.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The objective of this work is to investigate the effects of the collimator and the couch angle change on the dose distribution for breast cancer treatment using intensity modulated tangential photon beams, and thus to determine the clinical acceptable range of the angle change for routine treatment. Ten breast cases treated with intensity modulated tangential photon beams were analyzed in this study. Patient-specific CT data and the RTP files obtained from our home-grown Monte Carlo based breast IMRT treatment planning system were used for IMRT dose re-calculation with collimator or couch angle changes. The isodose distrib...
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Yang J, Ma C, Wang L, Chen L, Li J Tags: J Appl Clin Med Phys Source Type: journals

Algorithm for correcting optimization convergence errors in Eclipse.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
IMRT plans generated in Eclipse use a Dose Volume Optimizer (DVO) algorithm to evaluate dose for optimization and a more accurate algorithm for a final Volume Dose (VD) calculation, the Analytical Anisotropic Algorithm (AAA). The use of the DVO introduces Optimization Convergence Errors (OCE's) into an IMRT plan. Eclipse has a feature where optimization may be performed on top of an existing base plan. When the base plan is an optimized IMRT plan, a second optimization can compensate for errors in the base plan. Errors in the base plan are demonstrated to originate in the DVO. An IMRT plan containing the same field arr...
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Zacarias AS, Mills MD Tags: J Appl Clin Med Phys Source Type: journals

Direct machine parameter optimization for intensity modulated radiation therapy (IMRT) of oropharyngeal cancer - a planning study.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The purpose of the study was to investigate the potential of direct machine parameter optimization (DMPO) to achieve parotid sparing without compromising target coverage in IMRT of oropharyngeal cancer as compared to fluence modulation with subsequent leaf sequencing (IM) and forward planned 2-step arc therapy (IMAT). IMRT plans were generated for 10 oropharyngeal cancer patients using DMPO and IM. The resulting dose volume histograms (DVH) were evaluated with regard to compliance with the dose volume objectives (DVO) and plan quality. DMPO met the DVO for the targets better than IM but violated the DVO to the parotids...
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Dobler B, Koelbl O, Bogner L, Pohl F Tags: J Appl Clin Med Phys Source Type: journals

Comparing planning time, delivery time and plan quality for IMRT, RapidArc and Tomotherapy.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The purpose of this study is to examine plan quality, treatment planning time, estimated treatment delivery time and other dose metrics for 5 and 9 field sliding window IMRT (IMRT5 and IMRT9), single and dual arc Rapid Arc (RA1 and RA2) and Tomotherapy (TOMO). Four cylindrical virtual phantoms were created each with its own distinct set of contours. The contour sets were 2D contours on the axial slice extended in the superior-inferior direction. The prescription dose in all cases was 2 Gy per fraction. IMRT plans were created with 5 or 9 equally spaced beams and RA plans were created with either 1 or 2 complete rotatio...
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Oliver M, Ansbacher W, Beckham WA Tags: J Appl Clin Med Phys Source Type: journals

Prostate positioning errors associated with two automatic registration based image guidance strategies.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The objective of this work is to quantify prostate misplacement that results from automatic bone matching (BM) and image matching (IM) registration algorithms. 204 MVCT images from 8 high risk tomotherapy prostate patients were incorporated into this retrospective study. BM and IM registration algorithms based on maximization of mutual information of bony anatomy only and the entire image, respectively, were used to independently register MVCT images to their respective planning images. A correlation coefficient based algorithm that uses known planning CT contour information was used for automatic prostate localization in ...
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Rivest DR, Riauka TA, Murtha AD, Fallone BG Tags: J Appl Clin Med Phys Source Type: journals

Evaluation of a biplanar diode array dosimeter for quality assurance of step-and-shoot IMRT.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We described and characterized a novel biplanar diode array, and demonstrated its applicability to dosimetric QA of the step-and-shoot IMRT. It is the first commercially available device of its kind specifically designed for measurements at varying gantry angles. The detector consists of a cylindrical PMMA phantom with two orthogonal detector boards. There are a total of 1069 p-type 1 mm wide diode detectors covering the measurement area of 20 x 20 cm2 in each of the measurement planes. The orthogonal detector arrays ensure that the dose modulation information is not lost regardless of the beam incidence angle. For absolut...
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Feygelman V, Forster K, Opp D, Nilsson G Tags: J Appl Clin Med Phys Source Type: journals

Information technology resource management in radiation oncology.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The ever-increasing data demands in a radiation oncology (RO) clinic require medical physicists to have a clearer understanding of the information technology (IT) resource management issues. Clear lines of collaboration and communication among administrators, medical physicists, IT staff, equipment service engineers and vendors need to be established. In order to develop a better understanding of the clinical needs and responsibilities of these various groups, an overview of the role of IT in RO is provided. This is followed by a list of IT related tasks and a resource map. The skill set and knowledge required to imple...
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Siochi RA, Balter P, Bloch C, Bushe H, Mayo C, Curran B, Feng W, Kagadis G, Kirby T, Stern R Tags: J Appl Clin Med Phys Source Type: journals

Editorial: 10 years of the JACMP.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 19918240 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Starkschall G Tags: J Appl Clin Med Phys Source Type: journals

Guest editorial: tenth anniversary of the journal of applied clinical medical physics.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 19918241 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - November 20, 2009 Category: Physics Authors: Almond P Tags: J Appl Clin Med Phys Source Type: journals

Evaluation of the eclipse electron Monte Carlo dose calculation for small fields.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study we compared eMC calculations and measurements of depth doses, isodose distributions and monitor units for several different energy and small field cutout size combinations at different SSDs. Measurements were made using EBT film (International Specialty Products, Wayne, NJ) and a PinPoint Ion Chamber (PTW, Hicksville, NY). Our results indicate that the eMC algorithm can accurately predict depth doses, isodose distributions and monitor units (within 2.5%) for field sizes as small as 3.0 cm diameter for energies in the 6 to 20 MeV range at 100 cm SSD. Therefore, the previous energy dependent rule of thumb does ...
Source: Journal of Applied Clinical Medical Physics - August 21, 2009 Category: Physics Authors: Xu Z, Walsh SE, Telivala TP, Meek AG, Yang G Tags: J Appl Clin Med Phys Source Type: journals

Simplified "on-couch" daily quality assurance procedure for CT simulators.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we tested a simple yet comprehensive daily QA program and phantom that we designed for CT simulators used in radiation oncology that would enable us to use only one tool to perform laser and imaging QA on a flat couch. To construct a modified QA phantom, we attached three adjustable legs and fastened two metric scales (one vertically and one horizontally) to a commercial CT QA phantom. The adjustable legs helped to position the phantom conveniently in the needed position. The two metric scales were used for localization-laser QA, while the phantom body was used for CT imaging QA. We used five different scann...
Source: Journal of Applied Clinical Medical Physics - August 21, 2009 Category: Physics Authors: Liu RR, Prado KL, Gillin MT Tags: J Appl Clin Med Phys Source Type: journals

Assessing prostate, bladder and rectal doses during image guided radiation therapy--need for plan adaptation?Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study evaluates the dosimetric uncertainties caused by inter-fraction organ variation during IGRT for 10 patients using kilovoltage cone beam CT (kvCBCT) on the Elekta Synergy system and Megavoltage CT (MVCT) on the Tomotherapy Hi-ART system. The actual delivered doses to the prostate, bladder and rectum were based on dose recomputation using CT anatomy of the day. The feasibility of dose calculation accuracy in kvCBCT images from the Elekta Synergy system was investigated using the ComTom phantom. Additionally, low contrast resolution, image uniformity and spatial resolution between the three imaging modalities of ki...
Source: Journal of Applied Clinical Medical Physics - August 21, 2009 Category: Physics Authors: Varadhan R, Hui SK, Way S, Nisi K Tags: J Appl Clin Med Phys Source Type: journals

Dosimetric effects near implanted vascular access ports: an examination of external photon beam calculation.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Vascular access ports are used widely in the administering of drugs for radiation oncology patients. Their dosimetric effect on radiation therapy delivery in photon beams has not been rigorously established. In this work the effects on external beam fields when any of a variety of vascular access ports is included in the path of a high energy beam are studied. This medical physics study specifically identifies side-scatter and back-scatter consequences as well as attenuation effects. The study was divided into two parts: Firstly, a total of 18 ports underwent extended HU range CT scanning followed by 3-D computer treat...
Source: Journal of Applied Clinical Medical Physics - August 21, 2009 Category: Physics Authors: Gossman MS, Seuntjens JP, Serban MM, Lawson RC, Robertson MA, Christian KJ, Lopez JP, Justice TE Tags: J Appl Clin Med Phys Source Type: journals

Time delays in gated radiotherapy.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present a technique for calculating the margin necessary to account for time delays and found that the difference between the imaging and treatment time delays required a significant increase in the ITV margin in the direction of tumor motion at the gated level. PMID: 19692973 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - August 21, 2009 Category: Physics Authors: Smith WL, Becker N Tags: J Appl Clin Med Phys Source Type: journals

Application of a 3D volumetric display for radiation therapy treatment planning I: quality assurance procedures.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
To design and implement a set of quality assurance tests for an innovative 3D volumetric display for radiation treatment planning applications. A genuine 3D display (Perspecta Spatial 3D, Actuality-Systems Inc., Bedford, MA) has been integrated with the Pinnacle TPS (Philips Medical Systems, Madison WI), for treatment planning. The Perspecta 3D display renders a 25 cm diameter volume that is viewable from any side, floating within a translucent dome. In addition to displaying all 3D data exported from Pinnacle, the system provides a 3D mouse to define beam angles and apertures and to measure distance. The focus of this...
Source: Journal of Applied Clinical Medical Physics - August 21, 2009 Category: Physics Authors: Gong X, Kirk MC, Napoli J, Stutsman S, Zusag T, Khelashvili G, Chu J Tags: J Appl Clin Med Phys Source Type: journals

Application of holographic display in radiotherapy treatment planning II: a multi-institutional study.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We report on a randomized prospective multi-institutional study to evaluate a novel 3D display for treatment planning.The Perspecta Spatial 3D System produces 360 degrees holograms by projecting crosssectional images on a diffuser screen rotating at 900 rpm. Specially-developed software allows bi-directional transfer of image and dose data between Perspecta and the Pinnacle planning system.Thirty-three patients previously treated at three institutions were included in this IRB-approved study. Patient data were de-identified, randomized, and assigned to different planners. A physician at each institution reviewed the cases ...
Source: Journal of Applied Clinical Medical Physics - August 21, 2009 Category: Physics Authors: Chu JCh, Gong X, Cai Y, Kirk MC, Zusag TW, Shott S, Rivard MJ, Melhus CS, Cardarelli G, Hurley A, Hepel JT, Napoli J, Stutsman S, Abrams RA Tags: J Appl Clin Med Phys Source Type: journals

Evaluation of the effects of sagging shifts on isocenter accuracy and image quality of cone-beam CT from kV on-board imagers.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
To investigate the effects of sagging shifts of three on-board kV imaging systems (OBI) on the isocenter positioning accuracy and image quality of cone-beam CT (CBCT). A cubical phantom having a metal marker in the center that can be aligned with the radiation isocenter was used to measure sagging shifts and their variation with gantry angle on three Varian linacs with kV on-board imaging systems. A marker-tracking algorithm was applied to detect the shadow of the metal marker and localize its center in the two-dimensional cone-beam radiographic projections. This tracking algorithm is based on finding the position of m...
Source: Journal of Applied Clinical Medical Physics - August 21, 2009 Category: Physics Authors: Ali I, Ahmad S Tags: J Appl Clin Med Phys Source Type: journals

Expected clinical impact of the differences between planned and delivered dose distributions in helical tomotherapy for treating head and neck cancer using helical megavoltage CT images.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study aims to investigate the expected effect of patient setup correction using the Hi-Art tomotherapy system by employing radiobiological measures such as the biologically effective uniform dose (BEUD) and the complication-free tumor control probability (P+). In this study, a typical case of lung cancer with metastatic head & neck disease was investigated by developing a Helical Tomotherapy plan. For the Tomotherapy HiArt plan, the dedicated Tomotherapy treatment planning station was used. Three dose distributions (planned and delivered with and without patient setup correction) were compared based on radiobiolog...
Source: Journal of Applied Clinical Medical Physics - August 21, 2009 Category: Physics Authors: Mavroidis P, Stathakis S, Gutierrez A, Esquivel C, Shi C, Papanikolaou N Tags: J Appl Clin Med Phys Source Type: journals

The effect of a limited number of projections and reconstruction algorithms on the image quality of megavoltage digital tomosynthesis.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In order to investigate the effect of the number of projections on digital tomosynthesis image quality, images were acquired over a 40 degree arc and sampled into sets of 2 to 41 projections used as input to three different reconstruction algorithms, namely the shift-and-add, Feldkamp-Davis-Kress filtered back projection algorithms, and the simultaneous algebraic reconstruction technique. The variation of several image characteristics, such as in-plane resolution, contrast to noise ratio, artifact spread, volumetric accuracy and dose, are investigated based on the reconstruction algorithms used and also the number of p...
Source: Journal of Applied Clinical Medical Physics - August 21, 2009 Category: Physics Authors: Sarkar V, Shi C, Rassiah-Szegedi P, Diaz A, Eng T, Papanikolaou N Tags: J Appl Clin Med Phys Source Type: journals

Evaluation of new data processing algorithms for planar gated ventriculography (MUGA).Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Before implementing one of two new LVEF radionuclide gated ventriculogram (MUGA) systems, the results from 315 consecutive parallel patient studies were evaluated. Each gamma-camera acquisition was simultaneously processed by semi-automatic Medasys Pinnacle and by fully-automatic and semi-automatic Philips nuclear medicine computer systems. The Philips systems yielded LVEF results within +/- 5 LVEF percentage points of the Medasys system in fewer than half of the studies. The remaining values were higher or lower than those from the long-used Medasys system. These differences might have changed cancer patient chemother...
Source: Journal of Applied Clinical Medical Physics - August 21, 2009 Category: Physics Authors: Fair JR, Heintz PH, Telepak RJ Tags: J Appl Clin Med Phys Source Type: journals

Determination of the photon beam attenuation by the Brainlab imaging couch: angular and field size dependence.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The objective of the current study was to quantify the attenuation of megavoltage photons through a Brainlab imaging couch top and headrest at various angles and field sizes. At normal incidence, the couch attenuated 6 MV photons by 4.9% and 3.4% for 5 x 5 cm(2) and 10 x 10 cm(2) field sizes respectively. The headrest on the other hand only attenuated 6 MV photons by 2.5% and 1.6% respectively. There was no significant attenuation of the 18 MV beam by either the couch or the headrest. We found the attenuation to be dependent on the gantry angle, with the highest attenuation recorded at 1200. At this angle, the couch attenu...
Source: Journal of Applied Clinical Medical Physics - August 21, 2009 Category: Physics Authors: Njeh CF, Raines TW, Saunders MW Tags: J Appl Clin Med Phys Source Type: journals

New method for obtaining position and time structure of source in HDR remote afterloading brachytherapy unit utilizing light emission from scintillator.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
When using a HDR remote afterloading brachytherapy unit, results of treatment can be greatly influenced by both source position and treatment time. The purpose of this study is to obtain information on the source of the HDR remote afterloading unit, such as its position and time structure, with the use of a simple system consisting of a plastic scintillator block and a charge-coupled device (CCD) camera. The CCD camera was used for recording images of scintillation luminescence at a fixed rate of 30 frames per second in real time. The source position and time structure were obtained by analyzing the recorded images. Fo...
Source: Journal of Applied Clinical Medical Physics - August 21, 2009 Category: Physics Authors: Kojima H, Hanada T, Katsuta S, Yorozu A, Maruyama K Tags: J Appl Clin Med Phys Source Type: journals

eIMRT: a web platform for the verification and optimization of radiation treatment plans.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The eIMRT platform is a remote distributed computing tool that provides users with Internet access to three different services: Monte Carlo optimization of treatment plans, CRT & IMRT treatment optimization, and a database of relevant radiation treatments/clinical cases. These services are accessible through a user-friendly and platform independent web page. Its flexible and scalable design focuses on providing the final users with services rather than a collection of software pieces. All input and output data (CT, contours, treatment plans and dose distributions) are handled using the DICOM format. The design, imp...
Source: Journal of Applied Clinical Medical Physics - August 21, 2009 Category: Physics Authors: González-Castaño DM, Pena J, Gómez F, Gago-Arias A, González-Castaño FJ, Rodríguez-Silva DA, Gómez A, Mouriño C, Pombar M, Sánchez M Tags: J Appl Clin Med Phys Source Type: journals

Image quality & dosimetric property of an investigational imaging beam line MV-CBCT.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Image quality & dosimetric property of an investigational imaging beam line MV-CBCT. J Appl Clin Med Phys. 2009;10(3):3023 Authors: Beltran C, Lukose R, Gangadharan B, Bani-Hashemi A, Faddegon BA To measure and compare the contrast to noise ratio (CNR) as a function of dose for the CBCTs produced by the mega-voltage (MV) imaging beam line (IBL) and the treatment beam line (TBL), and to compare the dose to target and various critical structures of pediatric patients for the IBL CBCT versus standard TBL orthogonal port films. Two Siemens Oncor linear accelerators were modified at our institution such that the...
Source: Journal of Applied Clinical Medical Physics - August 21, 2009 Category: Physics Authors: Beltran C, Lukose R, Gangadharan B, Bani-Hashemi A, Faddegon BA Tags: J Appl Clin Med Phys Source Type: journals

Statistical validation of a new helical tomotherapy patient transfer station.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The purpose of this work is to evaluate statistically the accuracy of a patient transfer station (PTS, TomoTherapy Inc., Madison, WI) that automatically converts one planning-station-generated treatment plan to another one with a different beam model. In our department we have installed 2 HI*ART tomotherapy systems, and patients often need to be transferred from one tomotherapy unit to the other. Thirty patients who underwent patient transfer between the two systems were evaluated. For each patient, dose differences between his/her original plan and PTS-transferred plan were evaluated by comparing doses at 10 randomly ...
Source: Journal of Applied Clinical Medical Physics - August 21, 2009 Category: Physics Authors: Zhuang AH, Liu A, Schultheiss TE, Wong JY Tags: J Appl Clin Med Phys Source Type: journals

Editorial: medical physicists as educators.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 19692987 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - August 21, 2009 Category: Physics Authors: Starkschall G Tags: J Appl Clin Med Phys Source Type: journals

Accurate heterogeneous dose calculation for lung cancer patients without high-resolution CT densities.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The aim of this study was to investigate the relative accuracy of megavoltage photon-beam dose calculations employing either 5 bulk densities or independent voxel densities determined by calibration of the CT Houndsfield number. Full-resolution CT and bulk density treatment plans were generated for 70 lung or esophageal cancer tumors (66 cases) using a commercial treatment planning system with an adaptive convolution dose calculation algorithm (Pinnacle3, Philips Medicals Systems). Bulk densities were applied to segmented regions. Individual and population average densities were compared to the full-resolution plan for...
Source: Journal of Applied Clinical Medical Physics - June 28, 2009 Category: Physics Authors: Saito AI, Li JG, Liu C, Olivier KR, Dempsey JF Tags: J Appl Clin Med Phys Source Type: journals

Evaluation of the dose calculation accuracy in intensity-modulated radiation therapy for mesothelioma, focusing on low doses to the contralateral lung.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In conclusion, there is excellent correlation between TPS and MC calculations for the target doses. The pencil beam algorithm and superposition convolution algorithms both underestimate lung dose parameters, but the superposition convolution dose offers improvements in dose calculation accuracy for these patients. PMID: 19458589 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - June 28, 2009 Category: Physics Authors: Court LE, Ching D, Schofield D, Czerminska M, Allen AM Tags: J Appl Clin Med Phys Source Type: journals

Verification of Varian Enhanced Dynamic Wedge implementation in masterplan treatment planning system.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This paper investigates the accuracy of the two available calculation algorithms of the Oncentra MasterPlan three-dimensional treatment planning system (TPS)-- the pencil beam method and collapsed-cone convolution--in modeling the Varian enhanced dynamic wedge (EDW). Measurements were carried out for a dual high energy (6-15 MV) Varian DHX-S linear accelerator using ionization chambers for beam axis measurements (wedge factors and depth doses), film dosimetry for off-axis dose profiles measurements, and a diode matrix detector for two dimensional absolute dose distributions. Using both calculation algorithms, different...
Source: Journal of Applied Clinical Medical Physics - June 28, 2009 Category: Physics Authors: Pasquino M, Casanova Borca V, Tofani S, Ozzello F Tags: J Appl Clin Med Phys Source Type: journals

Leakage reduction for the Siemens Moduleaf.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The Moduleaf, an add-on miniature multileaf collimator (MMLC) for the Siemens Oncor linear accelerator, provides high resolution field shaping with a maximum inter-leaf leakage dose of 1.50% at 6 MV. However, beyond the maximum treatment field size, the distribution of leakage and scatter along the y axis is different from that of the x axis, with maximum leakage values of 1.53% and 0.39%, respectively. Such differences can not be modeled in the Pinnacle treatment planning system. Also, within the 10 cm x 12 cm treatment region, leakage from the crack between closed leaf ends was 3.76%. To resolve these issues, gaps in...
Source: Journal of Applied Clinical Medical Physics - June 28, 2009 Category: Physics Authors: Siochi RA Tags: J Appl Clin Med Phys Source Type: journals

A comparative study of three CT and MRI registration algorithms in nasopharyngeal carcinoma.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
CONCLUSIONS: All three registration algorithms, mark-and-link, interactive, and NMI, can provide accurate CT/MRI registration. However the mark-and-link method was most time consuming. PMID: 19458592 [PubMed - in process] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - June 28, 2009 Category: Physics Authors: Wang X, Li L, Hu C, Qiu J, Xu Z, Feng Y Tags: J Appl Clin Med Phys Source Type: journals

Dosimetric dependence of the dimensional characteristics on a lead shield in electron radiotherapy: a Monte Carlo study.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study investigates the dosimetric dependence of the dimension of a lead (Pb) layer for shielding using clinical electron beams with different energies. Monte Carlo simulations were used to generate phase space files of the 4, 9 and 16 MeV electron beams produced by a Varian 21 EX linear accelerator using the EGSnrc-based BEAMnrc code, and validated by measurements using films. Pb layers with different thicknesses (2, 4, 6 and 8 mm) and diameters (2.5, 3, 3.5 and 4 cm) were placed at the center of an electron field on a Solid Water phantom. Beam profiles were determined at the depth of maximum dose (d(m)) using Monte C...
Source: Journal of Applied Clinical Medical Physics - June 28, 2009 Category: Physics Authors: Chow JC, Grigorov GN Tags: J Appl Clin Med Phys Source Type: journals

Delivery of four-dimensional radiotherapy with TrackBeam for moving target using an AccuKnife dual-layer MLC: dynamic phantoms study.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we aimed to perform an experimental evaluation based on dynamic phantoms using MLC-based beam tracking. TrackBeam, a prototype real-time beam tracking system, has been assembled and evaluated in our clinic. TrackBeam includes an orthogonal dual-layer micro multi-leaf collimator (DmMLC), an on-board mega-voltage (MV) portal imaging device, and an image processing workstation. With a fiducial marker implanted in a moving target, the on-board imaging device can capture the motion. The TrackBeam workstation processes the online MV fluence and detects and predicts tumor motion. The DmMLC system then dynamically r...
Source: Journal of Applied Clinical Medical Physics - June 28, 2009 Category: Physics Authors: Liu Y, Shi C, Lin B, Ha CS, Papanikolaou N Tags: J Appl Clin Med Phys Source Type: journals

Characterization and clinical evaluation of a novel IMRT quality assurance system.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Intensity-modulated radiation therapy (IMRT) is a complex procedure that involves the delivery of complex intensity patterns from various gantry angles. Due to the complexity of the treatment plans, the standard-of-care is to perform measurement based patient-specific quality assurance (QA). IMRT QA is traditionally done with film for relative dose in a plane and an ion chamber for absolute dose. This is a laborious and time-consuming process. In this work, we characterized, commissioned, and evaluated the QA capabilities of a novel commercial IMRT device Delta4, (Scandidos, Uppsala, Sweden). This device consists of di...
Source: Journal of Applied Clinical Medical Physics - June 28, 2009 Category: Physics Authors: Sadagopan R, Bencomo JA, Martin RL, Nilsson G, Matzen T, Balter PA Tags: J Appl Clin Med Phys Source Type: journals