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 'Radiological Physics and Technology' source. Thu, 09 Feb 2012 20:29:31 +0100 http://www.medworm.com/index.php?rid=5664524&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Ff2013571685m34v8%2F Abstract  In Japan, radiologists and radiologic technologists are endeavoring to improve the quality of lung CT screening. In particular, preliminary screening by radiologic technologists is expected to decrease radiologists’ burden and improve the accuracy of CT screening. We considered that an application of computer-aided detection (CAD) would also be as useful in preliminary screening as in the radiologist’s regular reading. Our purpose in this study was to investigate the potential of the application of CAD to preliminary screening. CAD software that we developed was applied to 17 lung CT scans that radiologic technologists had pre-interpreted. A radiologist recognized 29 lung nodules from the CT images, whereas radiologic technologists did not recognize 11 of the ... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5664524 Fri, 03 Feb 2012 07:19:35 +0100 5664524 http://www.medworm.com/index.php?rid=5569310&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fj308026rw1536226%2F Abstract  The optimal injection dose for imaging of the pelvic region in 3D FDG PET tests was investigated based on the noise-equivalent count (NEC) rate with use of an anthropomorphic pelvis phantom. Count rates obtained from an anthropomorphic pelvis phantom were compared with those of pelvic images of 60 patients. The correlation between single photon count rates obtained from the pelvic regions of patients and the doses per body weight was also evaluated. The radioactivity at the maximum NEC rate was defined as an optimal injection dose, and the optimal injection dose for the body weight was evaluated. The image noise of a phantom was also investigated. Count rates obtained from an anthropomorphic pelvis phantom corresponded well with those from the human pelvis. The si... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5569310 Fri, 30 Dec 2011 07:10:16 +0100 5569310 http://www.medworm.com/index.php?rid=5473885&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Ff1v7277wn7542v41%2F Abstract  Our purpose in this study was to develop an automated segmentation scheme for multiple sclerosis (MS) lesions in magnetic resonance images using an artificial neural network (ANN)-controlled level-set method. Forty-nine slices with T1-weighted, T2-weighted, and fluid-attenuated inversion recovery images were selected from six examinations of three MS patients including 168 MS lesions for this study. First, MS lesions were enhanced by background subtraction. Initial regions of MS candidates were detected based on a multiple-gray-level thresholding technique and a region-growing technique on the subtraction image. Then, final regions of MS candidates were determined by application of a proposed segmentation method using an ANN-controlled level-set method, which was ... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5473885 Fri, 02 Dec 2011 17:29:11 +0100 5473885 http://www.medworm.com/index.php?rid=5473886&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fg034p64705366674%2F Abstract  Our purpose in this study was to develop a computer-aided detection scheme for identification of hypoattenuation of acute stroke on unenhanced CT images to select patients for thrombolysis of acute stroke. This method is based on a z-score mapping method. The algorithm of the developed method consisted of five main steps: anatomic standardization, calculation of the z-score with a normal reference database, extraction of candidate voxels for hypoattenuation, feature extraction, and classification. The territory of the middle cerebral artery was divided into ten specified regions, according to a visually quantitative CT scoring system, the Alberta Stroke Programme Early CT Score (ASPECTS) method. Each of the ASPECTS-defined regions was classified as hypoattenuation ... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5473886 Wed, 30 Nov 2011 18:41:06 +0100 5473886 http://www.medworm.com/index.php?rid=5465515&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fr1043750jx81k7rg%2F Abstract  We have proposed an OpenPET geometry which consists of two axially separated detector rings. The open gap is suitable for in-beam PET. We have developed the small prototype of the OpenPET especially for a proof of concept of in-beam imaging. This paper presents an overview of the main features implemented in this prototype. We also evaluated the detector performance. This prototype was designed with 2 detector rings having 8 depth-of-interaction detectors. Each detector consisted of 784 Lu2xGd2(1-x)SiO5:Ce (LGSO) which were arranged in a 4-layer design, coupled to a position-sensitive photomultiplier tube (PS-PMT). The size of the LGSO array was smaller than the sensitive area of the PS-PMT, so that we could obtain sufficient LGSO identification. Peripheral LGSOs ... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5465515 Mon, 28 Nov 2011 16:51:32 +0100 5465515 http://www.medworm.com/index.php?rid=5454387&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2F035t71232t340u68%2F Abstract  Previous studies have shown that the organ blood flow (OBF) calculated from the T1-weighted MRI technique was lower than expected. The inflow correction was one of the main corrections for measuring the absolute OBF. Our aim in this study was to investigate the influence of the contrast agent concentration on inflow effect on signal intensity (SI) and to find the gradient of different flow rates at different concentrations by use of inversion recovery T1-weighted turbo fast low angle shot (TurboFLASH) MRI images. We performed these studies at six different concentrations of gadolinium-diethylenetriamine-pantaacetic acid (Gd-DTPA) to find the inflow effect on the SI. A flow phantom made of Perspex was designed that produced four different flow rates at the same time.... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5454387 Wed, 23 Nov 2011 17:44:43 +0100 5454387 http://www.medworm.com/index.php?rid=5404882&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2F554u151wj28q7277%2F Abstract  With use of the phase shift of X-rays that occurs when they pass through an object, phase-contrast imaging (herein referred to as “phase imaging”) can produce images different from those of conventional contact imaging (herein referred to as “conventional imaging”). For this reason, assessment of the image quality based on noise-equivalent quanta (NEQ) and detective quantum efficiency (DQE) which does not include object-based information may not be appropriate for comparison of image quality between phase and conventional images. As an alternative method, we conceived a new image-quality assessment method with images that contain information about an object. First, we constructed images with an object and without an object under the same imaging parameters;... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5404882 Wed, 09 Nov 2011 17:45:46 +0100 5404882 http://www.medworm.com/index.php?rid=5376124&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2F178q54637k366m67%2F Abstract  Recently, a new method for acquiring single photon emission computed tomography (SPECT) data during breath-holding with a high-speed rotation (HSR-SPECT) technique was applied to hepatic-function scintigraphy. This technique can suppress motion artifact caused by respiration. However, it is challenging to apply this technique to patients with respiratory problems. Our purpose in this study was to analyze projection data and correct liver displacement due to irregular respiration during technetium-99m-diethylenetriaminepentaacetic acid galactosyl human serum albumin (99mTc-GSA) liver SPECT scans. We calculated cross-correlation functions (CCFs) for both intra- and inter-projections to correct irregular projections by shifting them in the longitudinal direction enoug... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5376124 Fri, 28 Oct 2011 16:45:10 +0100 5376124 http://www.medworm.com/index.php?rid=5376125&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2F013p1r0023j6324l%2F Abstract  Our purpose in this study was to evaluate the fundamental accuracy of reconstructed dose distributions from the COMPASS system using specific MLC test patterns and complicated IMRT neck plans. The COMPASS-reconstructed dose distributions were compared with those measured with EPID, MapCHECK, and EDR2 film and as well as Monte Carlo-calculated dose profiles with use of square-wave chart patterns of 20-, 10-, and 5-mm gaps and step and pyramid patterns. Additionally, the COMPASS dose distributions for clinical IMRT neck plans were tested. The COMPASS dose profiles were almost in agreement with the Monte Carlo-calculated dose profiles and point doses measured with MapCHECK for 20- and 10-mm gap patterns. The dose profile for a 5-mm gap pattern showed a narrow width d... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5376125 Fri, 28 Oct 2011 16:45:04 +0100 5376125 http://www.medworm.com/index.php?rid=5331146&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fc8vw141632538050%2F Abstract  Our purpose in this study was to assess the radiation dose reduction and the actual exposed scan length of over-range areas using a spiral dynamic z-collimator at different beam pitches and detector coverage. Using glass rod dosimeters, we measured the unilateral over-range scan dose between the beginning of the planned scan range and the beginning of the actual exposed scan range. Scanning was performed at detector coverage of 80.0 and 40.0 mm, with and without the spiral dynamic z-collimator. The dose-saving ratio was calculated as the ratio of the unnecessary over-range dose, with and without the spiral dynamic z-collimator. In 80.0 mm detector coverage without the spiral dynamic z-collimator, the actual exposed scan length for the over-range area was 1... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5331146 Sat, 15 Oct 2011 05:52:24 +0100 5331146 http://www.medworm.com/index.php?rid=5331147&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fu23177u016750636%2F Content Type Journal ArticleCategory EditorialPages 1-4DOI 10.1007/s12194-011-0131-4Authors Kunio Doi, Emeritus Professor, Department of Radiology, University of Chicago, Chicago, IL, USAKozo Morita, Aichi Cancer Center Hospital, Nagoya, JapanSadayuki Sakuma, Emeritus Professor, Nagoya University, Nagoya, JapanMasaki Takahashi, Director, Nagoya Clinical Center, Nagoya, Japan Journal Radiological Physics and TechnologyOnline ISSN 1865-0341Print ISSN 1865-0333 (Source: Radiological Physics and Technology) Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5331147 Thu, 13 Oct 2011 15:47:12 +0100 5331147 http://www.medworm.com/index.php?rid=5321790&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fq417w391543570j3%2F Abstract  In quantitative measurements of small animal PET studies, blood sampling is limited due to the small amounts of blood such animals can provide. In addition, injection doses are quite limited. In this situation, a high-sensitivity well counter would be useful for reducing the amount of the blood sample needed from small animals. Bismuth germinate (BGO) has a high stopping power for high-energy gamma rays compared to NaI(Tl), which is commonly used for conventional well counters. We have developed a BGO well counter and have tested it for blood-sampling measurements in small animals. The BGO well counter uses a square BGO block (59 × 59 × 50 mm) with a square open space (27 × 27 × 34 mm) in the center of the block... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5321790 Tue, 11 Oct 2011 05:51:16 +0100 5321790 http://www.medworm.com/index.php?rid=5293773&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fk7716t8885264351%2F Abstract  Our purpose in this study was to establish a selection standard for anti-scatter grids for a direct conversion flat-panel detector (FPD) system. As indices for grid evaluation, we calculated the selectivity, Bucky factor, and the signal-to-noise ratio improvement factor (SIF) by measuring rates of scatter transmission, primary transmission, and total transmission (based on the digitally displayed measurement values of the FPD system), using 4 acrylic phantoms of different thicknesses. The results showed that the SIF was less than 1.0 when the phantom thickness was 5 cm. When the phantom thickness was 25 cm and the grid ratio was 16:1, the SIF was 1.505 and 1.518 (maximum value) at 90 and 120 kV, respectively. Compared with the grid ratio of 12:1, th... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5293773 Wed, 05 Oct 2011 05:45:17 +0100 5293773 http://www.medworm.com/index.php?rid=5233914&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fd578688375202055%2F Abstract  In block detectors for PET scanners that use different lengths of slits in scintillators to share light among photomultiplier tubes (PMTs), a position histogram is distorted when the depth of interaction (DOI) of the gamma photons is near the PMTs (DOI effect). However, it remains unclear whether a DOI effect is observed for block detectors that use light sharing in scintillators. To investigate the effect, I tested the effect for single- and dual-layer block detectors. In the single-layer block detector, Ce doped Gd2SiO5 (GSO) crystals of 1.9 × 1.9 × 15 mm3 (0.5 mol% Ce) were used. In the dual-layer block detector, GSO crystals of a 1.9 × 1.9 × 6 mm3 (1.5 mol% Ce) were used for the front layer and GSO ... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5233914 Fri, 16 Sep 2011 16:49:53 +0100 5233914 http://www.medworm.com/index.php?rid=5169045&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fp7111p73n5284861%2F Abstract  Our purpose in this study was to investigate the application of B+M-mode ultrasound (B/M-mode) imaging as a new approach to quantifying activity patterns of the geniohyoid muscles during swallowing and to assess how these patterns differ according to age and gender. Sixty healthy volunteers (30 men, 30 women) were divided into three age groups (20–39, 40–59, 60–79 years). The subjects were then given 10 ml of mineral water. Ultrasonographic imaging was repeated 5 times and measurements were averaged. Simultaneous B/M-mode images were captured at two regions along the lateral geniohyoid muscle wall. All geniohyoid muscle movement was recorded by real-time B/M-mode. In all cases, ultrasonographic images of the geniohyoid muscle movement during swallo... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5169045 Tue, 23 Aug 2011 13:19:13 +0100 5169045 http://www.medworm.com/index.php?rid=5169046&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fn581vu8qx8100t34%2F In this study, we investigated whether such artifacts were caused by structural noise from the AEC detector on the basis of the noise power spectrum (NPS) and the mean square error (MSE) of FPD images taken at various tube voltages either with or without the AEC detector. When the NPS was measured without the AEC detector, the NPS did not increase in the low special-frequency band at all radiation qualities tested, irrespective of X-ray calibration tube voltages. However, when the NPS was measured while the AEC detector was used, the NPS increased in the low special-frequency band at all radiation qualities when the X-ray calibration tube voltages were at low levels. Similarly, the MSE increased when the X-ray calibration tube voltages were at low levels. From these results, artifact... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5169046 Tue, 23 Aug 2011 13:19:12 +0100 5169046 http://www.medworm.com/index.php?rid=5156149&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fku20601221201344%2F Abstract  We undertook this study to investigate the usefulness of a dual-input single-compartment model for evaluating thioacetamide (TAA)-induced acute liver injury in rats by use of dynamic contrast-enhanced computed tomography (DCE-CT). The rats in the TAA-treated group were injected intravenously with 140 mg/kg (n = 10) or 280 mg/kg (n = 10) of TAA, whereas those in the control group (n = 10) were injected with saline. The rate constants for the transfer of the contrast agent from the hepatic artery to the liver (K 1a), from the portal vein to the liver (K 1p), and from the liver to the blood (k 2), as well as liver perfusion (LP), the arterial fraction of LP (AFLP), distribution volume (DV), and mean transmit time (MTT) were es... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5156149 Fri, 19 Aug 2011 15:52:44 +0100 5156149 http://www.medworm.com/index.php?rid=5048619&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2F533257053p435377%2F Abstract  Our motivation was to provide an automatic tool for radiologists and orthopedic surgeons for improving the quality of life of an aging population. We propose a method for generating a shape model and a fully automated segmenting scheme for the psoas major muscle in X-ray CT images by using the shape model. Our approach consists of two steps: (1) The generation of a shape model and its application to muscle segmentation. The shape model describes the muscle’s outer shape and has two parameters, an outer shape parameter and a fitting parameter. The former was determined by approximating of the outer shape of the muscle region in training cases. The latter was determined for each test case in the recognition process. (2) Finally, the psoas major muscle was segmente... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5048619 Thu, 14 Jul 2011 05:54:27 +0100 5048619 http://www.medworm.com/index.php?rid=5035609&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fmm62p766v59wjuu2%2F Abstract  In an evaluation of the diagnostic criteria for ultrasonography (US) of transient synovitis in children, in a prospective study, 34 consecutive children with a painful hip underwent US. The ultrasonographic joint space (UJS) and the effusion space were measured in both hips, and the width of the UJS thickness in the asymptomatic hips was compared with that in the symptomatic hips. US showed the presence of a joint effusion in 31 of the 34 children and a bilateral effusion in 3. The US diagnostic criterion for hip effusion consists of a UJS thickness difference >2.0 mm between asymptomatic and symptomatic hips. However, we found that 8 of the 31 UJS measurements compared between symptomatic hips and asymptomatic hips exhibited differences of <2 mm. ... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5035609 Tue, 12 Jul 2011 05:56:53 +0100 5035609 http://www.medworm.com/index.php?rid=4967781&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2F827q754735081whg%2F Abstract  We performed experimental studies on the convolution/superposition method reported in the former companion paper (Iwasaki in Radiol Phys Technol 4, 2011) using 10-MV X-ray beams from open-jaw-collimated fields. The method uses primary and scatter dose kernels formed for energy bins of X-ray spectra reconstructed as a function of off-axis distance. We made a comparison of calculations and measurements in water phantoms and thorax-like phantoms with respect to percentage depth dose curves, tissue–phantom ratio curves, and dose profiles. We made the dose calculation by taking into account the beam-hardening effect with depth and the off-axis radiation-softening effect. We found that the method could be used, in general, for performing accurate dose calculations. ... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=4967781 Tue, 21 Jun 2011 20:55:22 +0100 4967781 http://www.medworm.com/index.php?rid=4967782&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fjx45243234135086%2F Content Type Journal ArticlePages 1-1DOI 10.1007/s12194-011-0126-1 Journal Radiological Physics and TechnologyOnline ISSN 1865-0341Print ISSN 1865-0333 (Source: Radiological Physics and Technology) Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=4967782 Tue, 21 Jun 2011 18:33:43 +0100 4967782 http://www.medworm.com/index.php?rid=4951634&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Ffw857178084k3kp0%2F Abstract  The concept of PACS (picture archiving and communication system) was initiated in 1982 during the SPIE medical imaging conference in New Port Beach, CA. Since then PACS has been matured to become an everyday clinical tool for image archiving, communication, display, and review. This paper follows the continuous development of PACS technology including Web-based PACS, PACS and ePR (electronic patient record), enterprise PACS to ePR with image distribution (ID). The concept of large-scale Web-based enterprise PACS and ePR with image distribution is presented along with its implementation, clinical deployment, and operation. The Hong Kong Hospital Authority’s (HKHA) integration of its home-grown clinical management system (CMS) with PACS and ePR with image distribu... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=4951634 Thu, 16 Jun 2011 05:50:00 +0100 4951634 http://www.medworm.com/index.php?rid=4951635&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fb7h576147q1j2215%2F Abstract  A convolution/superposition method is proposed for use with primary and scatter dose kernels formed for energy bins of X-ray spectra reconstructed as a function of off-axis distance. It should be noted that the number of energy bins is usually about ten, and that the reconstructed X-ray spectra can reasonably be applied to media with a wide range of effective Z numbers, ranging from water to lead. The study was carried out for 10-MV X-ray doses in water and thorax-like phantoms with the use of open-jaw-collimated fields. The dose calculations were made separately for primary, scatter, and electron contamination dose components, for which we used two extended radiation sources: one was on the X-ray target and the other on the flattening filter. To calculate the in-a... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=4951635 Wed, 15 Jun 2011 06:18:55 +0100 4951635 http://www.medworm.com/index.php?rid=4932643&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2F022k8455076ul322%2F In conclusion, this study will be useful for investigating the feasibility of MH with Resovist® and optimizing the parameters for it. Content Type Journal ArticlePages 1-9DOI 10.1007/s12194-011-0123-4Authors Kenya Murase, Division of Medical Technology and Science, Faculty of Health Science, Department of Medical Physics and Engineering, Graduate School of Medicine, Osaka University, 1-7 Yamadaoka, Suita, Osaka 565-0871, JapanJunko Oonoki, Division of Medical Technology and Science, Faculty of Health Science, Department of Medical Physics and Engineering, Graduate School of Medicine, Osaka University, 1-7 Yamadaoka, Suita, Osaka 565-0871, JapanHiroshige Takata, Division of Medical Technology and Science, Faculty of Health Science, Department of Medical Physics and Engineering, Grad... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=4932643 Sat, 11 Jun 2011 06:30:11 +0100 4932643 http://www.medworm.com/index.php?rid=4920247&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2F1060644888247445%2F Abstract  Today, interventional radiology (IR) X-ray units are required for display of doses at an interventional reference point (IRP) for the operator (IR physician). The dose displayed at the IRP (the reference dose) of an X-ray unit has been reported to be helpful for characterizing patient exposure in real time. However, no detailed report has evaluated the accuracy of the reference doses displayed on X-ray equipment. Thus, in this study, we compared the displayed reference dose to the actual measured value in many IR X-ray systems. Although the displayed reference doses of many IR X-ray systems agreed with the measured actual values within approximately 15%, the doses of a few IR units were not close. Furthermore, some X-ray units made in Japan displayed reference dos... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=4920247 Sat, 04 Jun 2011 06:06:14 +0100 4920247 http://www.medworm.com/index.php?rid=4910642&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fk5w382lx70522661%2F In conclusion, the present study showed that reduction in the hippocampal volume over one decade was small compared to the standard deviation in each group. This study is useful for improving our understanding of the correlation between menopause and hippocampal volume reduction. Content Type Journal ArticlePages 1-4DOI 10.1007/s12194-011-0120-7Authors Masami Goto, Department of Radiological Technology, University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655 JapanOsamu Abe, Department of Radiology, Nihon University School of Medicine, Tokyo, JapanTosiaki Miyati, Graduate School of Medical Science, Kanazawa University, Kanazawa, JapanSachiko Inano, Department of Radiology, University of Tokyo Hospital, Tokyo, JapanNaoto Hayashi, Department of Computational Diagnostic ... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=4910642 Mon, 23 May 2011 05:34:58 +0100 4910642 http://www.medworm.com/index.php?rid=4910643&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fw3767558745x51l3%2F Abstract  We have retrospectively investigated 15 nasopharyngeal carcinoma patients treated at our institution between March 2007 and August 2009. We used simultaneous integrated-boost whole field intensity-modulated radiation therapy (SIB WF-IMRT) to treat the entire planning target volume in the head and neck cancer. All of the SIB WF-IMRT plans were replanned by use of the junctioned intensity modulated radiation therapy (J-IMRT) technique for comparison. The effect on target coverage and sparing of organs at risk, including laryngeal sparing in the optimal SIB WF-IMRT plan was compared with that achieved with use of the J-IMRT technique. The mean larynx dose and standard deviation was 25.2 ± 5.8 Gy for SIB WF-IMRT and 19.8 ± 16.8 Gy for J-... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=4910643 Tue, 10 May 2011 06:04:10 +0100 4910643 http://www.medworm.com/index.php?rid=4910644&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fr875p27k8lx7736t%2F This study proceeded in three steps: (1) determination of the domain and scope of the terminology, (2) lexical extraction, and (3) construction of hierarchical structures. We extracted terms mainly from three reference books and constructed the hierarchical structures manually. We compared features of the terms extracted from the three reference books. We constructed a terminology consisting of 440 subclasses grouped into 19 top-level classes: anatomic entity, image quality factor, findings, material, risk, breast, histological classification of breast tumors, role, foreign body, mammographic technique, physics, purpose of mammography examination, explanation of mammography examination, image development, abbreviation, quality control, equipment, interpretation, and evaluation of clini... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=4910644 Mon, 02 May 2011 05:44:08 +0100 4910644 http://www.medworm.com/index.php?rid=4910645&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fr0043025p6362520%2F Abstract  The X-ray source or focal radiation is one of the factors that can degrade the conformal field edge in stereotactic body radiotherapy. For that reason, it is very important to estimate the total focal radiation profiles of linear accelerators, which consists of X-ray focal-spot radiation and extra-focal radiation profiles. Our purpose in this study was to propose an experimental method for estimating the focal-spot and extra-focal radiation profiles of linear accelerators based on triple Gaussian functions. We measured the total X-ray focal radiation profiles of the accelerators by moving a slit in conjunction with a photon field p-type silicon diode. The slit width was changed so that the extra-focal radiation could be optimally included in the total focal radiat... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=4910645 Wed, 23 Mar 2011 16:57:08 +0100 4910645 http://www.medworm.com/index.php?rid=4910646&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2F12k8501v5594k804%2F Abstract  The effect of copper (Cu) filtration on image quality and dose in different digital X-ray systems was investigated. Two computed radiography systems and one digital radiography detector were used. Three different polymethylmethacrylate blocks simulated the pediatric body. The effect of Cu filters of 0.1, 0.2, and 0.3 mm thickness on the entrance surface dose (ESD) and the corresponding effective doses (EDs) were measured at tube voltages of 60, 66, and 73 kV. Image quality was evaluated in a contrast-detail phantom with an automated analyzer software. Cu filters of 0.1, 0.2, and 0.3 mm thickness decreased the ESD by 25–32%, 32–39%, and 40–44%, respectively, the ranges depending on the respective tube voltages. There was no consistent decline i... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=4910646 Tue, 22 Mar 2011 18:11:43 +0100 4910646 http://www.medworm.com/index.php?rid=4910647&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fx85214340810v535%2F Abstract  Our purpose was to evaluate the usefulness of digital magnification mammography with matched incident exposure by investigating the physical imaging properties and doing an observer performance test. A computed radiography system and a mammographic unit were used in this study. Contact and magnification radiographies of 1.2–1.8 in combination with focal spot sizes of 0.1 mm without grid and 0.3 mm with grid were performed. Physical imaging properties, namely, scatter fraction, total modulation transfer function (MTF) including the presampled MTF and the MTF of focal spot size, and Wiener spectrum (WS), were measured. Detail visibility was evaluated by use of free-response receiver operating characteristic analysis of the detectability of simulated micr... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=4910647 Thu, 17 Mar 2011 18:13:07 +0100 4910647 http://www.medworm.com/index.php?rid=4910648&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fl0338vuw62x36426%2F Abstract  The delivered dose of high-energy photon beams is measured with radiochromic film. Previous studies sought to improve the system sensitivity of radiochromic film dosimetry by use of band-pass filters. However, band-pass filters reduce the scanning light intensity. To avoid a reduction of the signal-to-noise ratio, one must increase the scanner light intensity. Our purposes in this study were to develop an optical system model of GAFCHROMIC EBT2 radiochromic film dosimetry, and to estimate the system sensitivity characteristics by employing a combination of band-pass filters and scanner light intensities. The spectra of the scanner light source, band-pass filter, and irradiated EBT2 films were measured with a spectrometer. Meanwhile, the intensity of a light path f... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=4910648 Wed, 16 Mar 2011 11:59:27 +0100 4910648 http://www.medworm.com/index.php?rid=4910649&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fc881264363755856%2F Abstract  The characteristics of flat-panel detectors (FPD) are degraded by exposure to radiation. Degradation in a FPD progresses locally and has a nonlinear relationship to the radiation dose. In order to manage FPD systems properly, one must perform quality control (QC) such as evaluation of image degradation. However, no evaluation method for degradation has been established. In this paper, we first review the structure and degradation mechanism of FPDs, and then we propose a daily QC system for FPDs. To evaluate the degradation of FPDs, we investigated the number of defective pixels and lines, as well as the offset level of the pixel output. Furthermore, we developed daily QC software for FPD that can evaluate the image quality and is operationally simple. In the exper... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=4910649 Wed, 16 Mar 2011 11:59:26 +0100 4910649 http://www.medworm.com/index.php?rid=4910650&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fk356w4338455134t%2F Abstract  Conventionally, block detectors, which consist of a two-dimensionally segmented scintillator array with inserted reflectors, are often used for PET. On the other hand, PET detectors with a monolithic block have been investigated because they are expected to offer higher resolution than do segmented crystal arrays. However, previous reports focused on detectors dedicated as small-animal PET, and the thickness was not good enough to stop 511-keV radiation. We developed a PET detector that uses a large and thick monolithic LYSO and 64-channel PS-PMT. When the LYSO was covered with reflectors, the spatial resolution, which was 3 mm FWHM at the center, rapidly became worse at the edge. We eliminated the loss of spatial resolution by replacing the reflectors with b... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=4910650 Mon, 21 Feb 2011 17:04:57 +0100 4910650 http://www.medworm.com/index.php?rid=4910652&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Ft328447486v632k8%2F Abstract  Liquid-crystal displays (LCDs) used for medical imaging, such as luminance characteristics and panel surface processing, have been developed as a medium substituting for film. There are various models of and specifications for display, but those compatible with high-resolution radiographic diagnostic images have been required with the recent progression of high-resolution modalities. Displays are necessary for faithful presentation of radiographic diagnostic images acquired by X-ray systems. In independent sub-pixel driving (ISD) technology, aiming at high-resolution display, three sub-pixels contained in one pixel of the LCD independently display images, which increases the threefold resolutions in direction of the sub-pixels, facilitating faithful image display ... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=4910652 Thu, 17 Feb 2011 07:04:41 +0100 4910652 http://www.medworm.com/index.php?rid=4910653&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2F5n295v2874826844%2F Abstract  Misregistration errors occur at the periphery of the hepatic region due to respiratory- and interval-related changes in hepatic shape. To reduce these misregistration errors, we developed a temporal and dynamic subtraction technique to enhance small hepatocellular carcinoma (HCC) by using a 3D nonlinear image-warping technique. The study population consisted of 21 patients with HCC. We registered the present and previous arterial-phase CT images or the present nonenhanced and arterial-phase CT images obtained in the same position by 3D global-matching plus 3D nonlinear image-warping. Temporal subtraction images were obtained by subtraction of the previous arterial-phase CT image from the warped present arterial-phase CT image. Dynamic subtraction images were obtai... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=4910653 Wed, 12 Jan 2011 17:09:38 +0100 4910653 http://www.medworm.com/index.php?rid=5018268&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fe86366w66gm32352%2F In this study, we applied the temporal subtraction method for lung cancer screening and evaluated the clinical usefulness by comparing the review time and the detection accuracy of lung cancers without and with subtraction images. Since 1996, we have been performing screening chest radiography for a mass survey of lung cancers in the Iwate Prefecture, Japan, by using a van equipped with a computed radiography system and a digital archive system. During the 12 years from 1997 to 2008, a total of 186,340 examinations were performed, and 121,526 (65.2%) temporal subtraction images were provided in the lung cancer screening. Twenty-four abnormal cases with lung cancer and 270 normal cases were selected from the lung cancer screening. Five radiologists participated in an observer per... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018268 Fri, 17 Dec 2010 17:42:10 +0100 5018268 http://www.medworm.com/index.php?rid=5018269&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fp618734028600867%2F Abstract  Time-spatial labeling inversion pulse (time-SLIP), which is a technique of nonenhanced magnetic resonance angiography (MRA) based on arterial spin labeling (ASL), is used in various situations. Although subtraction between the images obtained with and without ASL is usually employed in cerebral time-SLIP MRA, to reduce the imaging time, dual inversion recovery (IR) has been applied for suppression of the background signals in this study. Appropriate timings for the 1st IR, 2nd IR, and the interval of data acquisition were investigated using computer simulation and a phantom experiment. With a short interval of data acquisition, the visibility of the simulated vessel was inadequate because replacement of the suppressed flow was insufficient. With a long interval of... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018269 Tue, 30 Nov 2010 17:55:37 +0100 5018269 http://www.medworm.com/index.php?rid=5018270&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fp6957l2q68536187%2F Abstract  Our aim in this study was to evaluate hyoid bone movement trajectories and the age-related changes during swallowing in healthy subjects by ultrasonography. Data were obtained from 30 healthy volunteers (15 men, 15 women) in three age groups (20–39, 40–59, 60–79 years). The subjects were examined while sitting in an upright position, with the back against a wall to control movement. The transducer was placed in a longitudinal scan above the larynx. The subjects were then given 5 mL of mineral water. The water bolus was held in their mouth until they were forced to do a rapid swallow. The imaging was repeated five times for averaging. The movement was divided into 4 phases: slowly ascending phase (A–B, Elevation); rapidly ascending phase (B–C, A... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018270 Thu, 14 Oct 2010 06:16:13 +0100 5018270 http://www.medworm.com/index.php?rid=5018271&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fm120h688088621tp%2F Abstract  Our purpose in this study was to develop an automated method for segmentation of white matter (WM) and gray matter (GM) regions with multiple sclerosis (MS) lesions in magnetic resonance (MR) images. The brain parenchymal (BP) region was derived from a histogram analysis for a T1-weighted image. The WM regions were segmented by addition of MS candidate regions, which were detected by our computer-aided detection system for the MS lesions, and subtraction of a basal ganglia and thalamus template from “tentative” WM regions. The GM regions were obtained by subtraction of the WM regions from the BP region. We applied our proposed method to T1-weighted, T2-weighted, and fluid-attenuated inversion-recovery images acquired from 7 MS patients and 7 control subjects o... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018271 Thu, 30 Sep 2010 08:00:49 +0100 5018271 http://www.medworm.com/index.php?rid=5018272&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2F61737v2103145382%2F Abstract  Magnetic resonance imaging (MRI) is useful in the quantitative evaluation of brain atrophy, because the superior contrast resolution facilitates separation of the gray and white matter. Quantitative assessment of brain atrophy has mainly been performed by manual measurement, which requires considerable time and effort to determine the brain volume. Therefore, computer-aided quantitative measurement methods for the diagnosis of brain atrophy are required. We have developed a method of segmenting the cerebrum, cerebellum–brainstem, and temporal lobe simultaneously on MR images obtained in a single sequence. It is important to measure the volume of not only these regions but also the frontal lobe in clinical use. However, for segmenting the frontal lobe, it is nece... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018272 Tue, 28 Sep 2010 19:07:28 +0100 5018272 http://www.medworm.com/index.php?rid=5018273&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fp515711347587hq7%2F Abstract  Our aim in this study was to determine an optimal delay time of hepatic arterial phase (HAP) imaging of hypervascular hepatocellular carcinomas (HCCs) in dynamic contrast-enhanced MDCT (DCE-CT) by use of the bolus-tracking method. The time-enhancement curves (TECs) of the aorta and the contrast of the hepatic arterial and portal system (APC) in the pharmacokinetic analysis were calculated. The clinical study included 41 patients with known or suspected HCC who underwent DCE-CT. The TECs of the aorta and the tumor–liver contrast (TLC) in the clinical study were calculated. On pharmacokinetic analysis, the peak aortic enhancement and the peak APC simulated under conditions of an injection duration of 30 s and an iodine load of 500 mg I/kg body weight wer... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018273 Fri, 24 Sep 2010 17:09:26 +0100 5018273 http://www.medworm.com/index.php?rid=5018274&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fd541585780u73j32%2F In this study, the extent of skin shift and its effect on navigation accuracy were determined by use of both preoperative magnetic resonance imaging (MRI) scans acquired before fixation and intraoperative MRI scans acquired after fixation. We measured the displacement of the fiducial markers by using fusion images obtained by integrating preoperative and intraoperative MRI scans. We also evaluated the navigation accuracy of registration based on preoperative and on intraoperative MRI. The mean (±SD) extent of skin shift was 5.34 (±2.65) mm. The navigation accuracy of registration based on preoperative MRI was 4.06 (±2.25) mm, and that of registration based on intraoperative MRI was 2.51 (±1.32) mm. No significant correlation was observed between the extent of skin shift and the ... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018274 Thu, 09 Sep 2010 16:46:52 +0100 5018274 http://www.medworm.com/index.php?rid=5018275&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fl956vr55r3321012%2F In this study, rest–stress myocardial perfusion imaging (MPI) with technetium-99m-tetrofosmin (Tc-99m TF) was performed with the use of a Vac-Loc cushion, a patient immobilizer commonly used for radiotherapy, for immobilizing school-age patients. The immobilizer attenuated the gamma radiation by 6%. By visual assessment, physical motion-related artifacts were markedly improved in images acquired with the immobilizer, compared to those without. In the assessment of image reproducibility with the immobilizer, taking the reproducibility as 2.5Σ + 0.7σ, there were deviations of 4.45, 5.28, and 3.28 mm along the X-, Y-, and Z-axes, respectively, demonstrating a high reproducibility and a negligible rest–stress position error. It is suggested that for radiotherapy, the... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018275 Thu, 09 Sep 2010 16:46:51 +0100 5018275 http://www.medworm.com/index.php?rid=5018276&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2F47j41472703w95w3%2F Abstract  Our purpose in this study was to investigate the expression differences in report assignments between students in nursing and radiologic technology departments. We have known that faculties could identify differences, such as word usage, through grading their students’ assignments. However, there are no reports in the literature dealing with expression differences in vocabulary usage in medical informatics education based on statistical techniques or other quantitative measures. The report assignment asked for students’ opinions in the event that they found a rare case of a disease in a hospital after they graduated from professional school. We processed student report data automatically, and we applied the space vector model and TF/IDF (term frequency/inverse... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018276 Thu, 09 Sep 2010 16:46:50 +0100 5018276 http://www.medworm.com/index.php?rid=5018277&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fm1567028260ttt00%2F Abstract  The radiation field shape for cardiac catheterization has changed from being circular to being rectangular with the spread of flat-panel detector systems. A rectangular radiation field provides a wide fluoroscopy field to the four corners of a subject area; however, in cardiac catheterization, there is not much usable information around the four corners at several angles, and this tends to be regarded as a meaningless radiation exposure. Hence, overlap of radiation fields has been of concern recently. The authors changed field sizes/fluoroscopy angles and examined entrance dose rates to study radiation field shapes and configurations of radiation exposure to patients, and they discussed a radiation exposure reduction method. In measurements of phantom entrance dos... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018277 Thu, 26 Aug 2010 07:48:01 +0100 5018277 http://www.medworm.com/index.php?rid=5018278&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2F2g4u71p3v852237j%2F Abstract  We evaluated the effect of the displayed image sizes on observers’ ability to detect nodular ground-glass opacity (n-GGO) on CT and investigated the optimal viewing size for soft-copy reading at CT screening for lung cancer. A total of 46 patients’ high-resolution computed tomography (HRCT) images (22 patients with one GGO; 24 without GGO) were displayed on a monochromatic liquid crystal display monitor at a resolution of 1,200 × 1,600. HRCT was presented on the screen with cine-mode display. We compared two viewing sizes (original size, i.e., the image displayed with a zoom factor of 1 in which each pixel value in the image is displayed as one pixel on the display: 13 cm × 13 cm; fit size, i.e., by zooming the captured image unt... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018278 Wed, 18 Aug 2010 17:44:32 +0100 5018278 http://www.medworm.com/index.php?rid=5018279&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fq33624np87122866%2F This study suggested that the measurement of the change in the Mn concentration due to glucose stimulation using PZAAS was effective for evaluating β-cell function in the pancreas. Content Type Journal ArticlePages 7-12DOI 10.1007/s12194-010-0098-6Authors Mamoru Nagata, Division of Medical Technology and Science, Department of Medical Physics and Engineering, Faculty of Health Science, Graduate School of Medicine, Osaka University, 1-7 Yamadaoka, Suita, Osaka 565-0871, JapanToshio Kagawa, Division of Medical Technology and Science, Department of Medical Physics and Engineering, Faculty of Health Science, Graduate School of Medicine, Osaka University, 1-7 Yamadaoka, Suita, Osaka 565-0871, JapanDaichi Koutou, Division of Medical Technology and Science, Department of Medical Physics ... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018279 Mon, 16 Aug 2010 17:27:20 +0100 5018279 http://www.medworm.com/index.php?rid=5018280&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2F00605843473ng157%2F Abstract  As one type of basic physical data related to the calculation of the construction of X-ray examination room shielding, we investigated the air-kerma rate 1 m from the source of the useful beam focus per unit current time product. Compared to the X-ray energy penetration values obtained in prior research, we obtained higher values. We found three causes for this discrepancy: (1) the X-ray tube total filtration (increasing total filtration reduces air kerma), (2) the tube voltage ripple percentage (increased voltage ripple reduces air kerma, and (3) the target angle (increasing the target angle increases the air kerma). On standardizing (1)–(3), we confirmed that our values mostly matched those obtained in past research. Consequently, when one employs the air... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018280 Tue, 06 Jul 2010 17:07:27 +0100 5018280 http://www.medworm.com/index.php?rid=5018281&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fh74148p225467014%2F Content Type Journal ArticlePages 186-186DOI 10.1007/s12194-010-0096-8 Journal Radiological Physics and TechnologyOnline ISSN 1865-0341Print ISSN 1865-0333 Journal Volume Volume 3 Journal Issue Volume 3, Number 2 (Source: Radiological Physics and Technology) Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018281 Wed, 23 Jun 2010 20:13:37 +0100 5018281 http://www.medworm.com/index.php?rid=5018282&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fp5118600543g7681%2F Abstract  The goal of this study was to investigate the effect of the different luminance settings of a high-brightness color liquid-crystal display (LCD) on the detectability of a simple grayscale object with low contrast by use of receiver operating characteristic (ROC) analysis. The detectability of a high-brightness color LCD with two maximum-luminance settings (500 and 170 cd/m2) was compared with the detectability of a monochrome LCD (500 cd/m2). The two LCDs used in this study were calibrated to the grayscale standard display function. The average areas under the ROC curve (AUCs) and the standard deviations for all thirteen observers for the 500 cd/m2 color LCD, 500 cd/m2 monochrome LCD, and 170 cd/m2 color LCD were 0.937 ± 0.040, 0.9... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018282 Mon, 14 Jun 2010 13:52:46 +0100 5018282 http://www.medworm.com/index.php?rid=5018283&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2F5431188804786042%2F Abstract  To investigate the most advanced ontology research in health care and its impact on the radiologic domain, we proposed a concept identification and abstraction technique called “Concept Step”. This technique identifies a MeSH term, medical subject headings used in PubMed, in a sentence and climbs up through its hierarchy to reach an abstract concept. We developed original Java software to implement this technique. We tested it on 2,774 abstracts in health-care ontology research retrieved from MEDLINE on 23 October 2008. The total number of MeSH terms was 112,690. We counted a total of 33 MeSH terms (0.029%) in the radiologic domain. The most frequently occurring term was “radiology”, which occurred 21 times in the article set. Other frequent terms were “... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018283 Fri, 21 May 2010 21:17:37 +0100 5018283 http://www.medworm.com/index.php?rid=5018284&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2F71581h3643758621%2F Abstract  A dual electron multileaf collimator (eMLC) has recently been proposed and ascertained to be effective in the collimation of therapy electron beams. The EGSnrc Monte Carlo code has been used in the optimization of the dual eMLC by simulation of the Varian 2100C medical linear accelerator with the applicator completely replaced by the dual eMLC, and calculation of the dose distributions in a water phantom. The planar fluence results showed that the material combination of 2-cm-thick brass and 2-cm-thick tungsten (eMLCT1) as upper and lower eMLCs, respectively, offers minimal radiation leakage outside the treatment field. Dose calculation results used in estimation of the maximum dose, depth of the maximum dose, surface dose, bremsstrahlung background, and penumbra ... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018284 Thu, 13 May 2010 08:59:05 +0100 5018284 http://www.medworm.com/index.php?rid=5018285&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Ft7717tt50n918116%2F Abstract  The first objective in this study was to identify the errors of incidents and accidents that occurred in general and mobile X-ray examinations. Based on the analysis of results, the second purpose in this study was to propose useful measures to prevent such errors. As much as 553 radiological technologists in the Gunma Prefecture were surveyed on their experience with errors related to general and mobile X-ray examinations. The questionnaire asked for descriptions of errors experienced during examinations and the responses given (multiple answers possible), and evaluations of the degree of busyness on a five-point scale. A total of 115 questionnaires were returned. Analysis revealed that there was no significant relationship between errors and degree of busyness f... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018285 Sat, 24 Apr 2010 08:10:14 +0100 5018285 http://www.medworm.com/index.php?rid=5018286&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fp5716585h44832w1%2F In this study, we calculated perturbation correction factors for cylindrical ionization chambers in high-energy photon beams by using Monte Carlo simulations. We modeled four Farmer-type cylindrical chambers with the EGSnrc/Cavity code and calculated the cavity or electron fluence correction factor, P cav, the displacement correction factor, P dis, the wall correction factor, P wall, the stem correction factor, P stem, the central electrode correction factor, P cel, and the overall perturbation correction factor, P Q. The calculated P dis values for PTW30010/30013 chambers were 0.9967 ± 0.0017, 0.9983 ± 0.0019, and 0.9980 ± 0.0019, respectively, for 60Co, 4 MV, and 10 MV photon beams. The value for a 60Co beam was about 1.0% higher than t... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018286 Thu, 22 Apr 2010 09:29:05 +0100 5018286 http://www.medworm.com/index.php?rid=5018287&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fxv752247v6687764%2F Abstract  In diagnosis and treatment of knee joint diseases, it is effective to study the three-dimensional (3D) motion of the patient’s knee joint involving the femur, tibia, and patella. A 2D/3D registration method with use of fluoroscopy and CT images is promising for this purpose. However, there is no report showing whether the dynamic 3D motion of the patella can be obtained. In this study, we tried to examine dynamic 3D motion of the knee joint which included the patella. First, in order to investigate the accuracy of the position estimation, we conducted an experiment on a pig knee joint which had several fiducial markers placed on it, and we found that errors in the estimation of rotation and translation were less than 1 mm and 1 deg. We then carried out... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018287 Sat, 03 Apr 2010 07:17:14 +0100 5018287 http://www.medworm.com/index.php?rid=5018288&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fu04q663060245878%2F Abstract  The purpose of this study was to obtain the neutron energy spectrum on the surface of the moderator of the Tokyo University reactor YAYOI and to investigate the origins of peaks observed in the neutron energy spectrum by use of the Monte Carlo Code PHITS for evaluating biological studies. The moderator system was modeled with the use of details from an article that reported a calculation result and a measurement result for a neutron spectrum on the surface of the moderator of the reactor. Our calculation results with PHITS were compared to those obtained with the discrete ordinate code ANISN described in the article. In addition, the changes in the neutron spectrum at the boundaries of materials in the moderator system were examined with PHITS. Also, microdosimetr... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018288 Fri, 02 Apr 2010 08:52:59 +0100 5018288 http://www.medworm.com/index.php?rid=5018289&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2F8150r84660632067%2F Abstract  An energy-discrimination K-edge X-ray computed tomography (CT) system is useful for increasing the contrast resolution of a target region by utilizing contrast media. The CT system has a cadmium telluride (CdTe) detector, and a projection curve is obtained by linear scanning with use of the CdTe detector in conjunction with an X-stage. An object is rotated by a rotation step angle with use of a turntable between the linear scans. Thus, CT is carried out by repetition of the linear scanning and the rotation of an object. Penetrating X-ray photons from the object are detected by the CdTe detector, and event signals of X-ray photons are produced with use of charge-sensitive and shaping amplifiers. Both the photon energy and the energy width are selected by use of a m... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018289 Tue, 16 Mar 2010 14:53:00 +0100 5018289 http://www.medworm.com/index.php?rid=5018290&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2F83167154338117r3%2F Abstract  The influence of age and physique on dual-energy X-ray absorptiometry (DXA) and quantitative ultrasound (QUS) was investigated in young, middle-aged, and older women. The validity of the bilateral calcaneal QUS values was investigated regarding the bone mineral density (BMD) values on DXA of the lumbar spine, left femoral neck, and left femur as the optimal standards. The subjects were 55 young women (19.6 ± 1.0 years), and 152 middle-aged and older women (62.9 ± 7.2 years). The BMD on DXA was significantly correlated with the bone strength on QUS in both young and middle-aged or older women, but the positive likelihood ratios of the standard QUS values recommended by the manufacturer to the optimum standards on DXA were low, suggest... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018290 Fri, 26 Feb 2010 16:44:27 +0100 5018290 http://www.medworm.com/index.php?rid=5018291&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fyg723wv17h65pk10%2F This study shows that different sequences and different T I and T S values can have an effect on the correlation between the SI and concentration. Regardless of the values of T I, T S, and the different IR and SR sequences chosen, the linear relationship between the SI and concentration was about twice that previously reported (i.e., 0.8 mmol/L, R 2 = 0.95). Content Type Journal ArticlePages 120-126DOI 10.1007/s12194-010-0087-9Authors Mahmood Nazarpoor, Tabriz University of Medical Sciences Department of Radiology, Faculty of Paramedicine Tabriz Iran Journal Radiological Physics and TechnologyOnline ISSN 1865-0341Print ISSN 1865-0333 Journal Volume Volume 3 Journal Issue Volume 3, Number 2 (Source: Radiological Physics and Technology) Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018291 Fri, 26 Feb 2010 16:44:25 +0100 5018291 http://www.medworm.com/index.php?rid=5018293&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fw52653l5874k8445%2F Content Type Journal ArticlePages 185-185DOI 10.1007/s12194-010-0085-yAuthors Tomoya Nakamura, Tokai University Hachioji Hospital Department of Radiology 1838 Ishikawa Hachioji 192-0032 JapanTosiaki Miyati, Kanazawa University Division of Health Sciences, Graduate School of Medical Science 5-11-80 Kodatsuno Kanazawa 920-0942 JapanHarumasa Kasai, Nagoya City University Hospital Department of Radiology 1 Kawasumi, Mizuho, Mizuho-ku Nagoya 467-8602 JapanNaoki Ohno, Kanazawa University Division of Health Sciences, Graduate School of Medical Science 5-11-80 Kodatsuno Kanazawa 920-0942 JapanMasato Yamada, Nagoya City University Hospital Department of Radiology 1 Kawasumi, Mizuho, Mizuho-ku Nagoya 467-8602 JapanMitsuhito Mase, Nagoya City University Graduate School of Medical Sciences Departm... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018293 Tue, 23 Feb 2010 08:08:50 +0100 5018293 http://www.medworm.com/index.php?rid=5018292&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fe7vv2242231qh716%2F Abstract  The aim of the study was to evaluate the perturbation correction factors at a reference depth for cylindrical ionization chambers in high-energy electron beams by means of the EGSnrc Monte Carlo user code cavity. The cylindrical chambers used in this study were the Farmer-type of PTW30010, PTW30011, PTW30012, and PTW30013 models. We calculated the wall correction factor, P wall, the cavity or electron fluence correction factor, P cav, the stem correction factor, P stem, the central electrode correction factor, P cel, and the overall perturbation correction factor, P Q, for each chamber. The calculated P cav values were higher by from 2 to 1% than those recommended by the IAEA-TRS-398 code of practice, in an energy range of 6–18 MeV. The P wall values al... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018292 Tue, 23 Feb 2010 08:08:50 +0100 5018292 http://www.medworm.com/index.php?rid=3306288&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fw52653l5874k8445%2F Content Type Journal ArticleCategory ErratumDOI 10.1007/s12194-010-0085-yAuthors Tomoya Nakamura, Tokai University Hachioji Hospital Department of Radiology 1838 Ishikawa Hachioji 192-0032 JapanTosiaki Miyati, Kanazawa University Division of Health Sciences, Graduate School of Medical Science 5-11-80 Kodatsuno Kanazawa 920-0942 JapanHarumasa Kasai, Nagoya City University Hospital Department of Radiology 1 Kawasumi, Mizuho, Mizuho-ku Nagoya 467-8602 JapanNaoki Ohno, Kanazawa University Division of Health Sciences, Graduate School of Medical Science 5-11-80 Kodatsuno Kanazawa 920-0942 JapanMasato Yamada, Nagoya City University Hospital Department of Radiology 1 Kawasumi, Mizuho, Mizuho-ku Nagoya 467-8602 JapanMitsuhito Mase, Nagoya City University Graduate School of Medical Sciences Depa... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=3306288 Tue, 23 Feb 2010 08:08:50 +0100 3306288 http://www.medworm.com/index.php?rid=3306287&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fe7vv2242231qh716%2F Abstract  The aim of the study was to evaluate the perturbation correction factors at a reference depth for cylindrical ionization chambers in high-energy electron beams by means of the EGSnrc Monte Carlo user code cavity. The cylindrical chambers used in this study were the Farmer-type of PTW30010, PTW30011, PTW30012, and PTW30013 models. We calculated the wall correction factor, P wall, the cavity or electron fluence correction factor, P cav, the stem correction factor, P stem, the central electrode correction factor, P cel, and the overall perturbation correction factor, P Q, for each chamber. The calculated P cav values were higher by from 2 to 1% than those recommended by the IAEA-TRS-398 code of practice, in an energy range of 6–18 MeV. The P wall values al... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=3306287 Tue, 23 Feb 2010 08:08:50 +0100 3306287 http://www.medworm.com/index.php?rid=5018294&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fh174x37274162061%2F Abstract  In order to evaluate the usefulness of a metal oxide-silicon field-effect transistor (MOSFET) detector as a in vivo dosimeter, we performed in vivo dosimetry using the MOSFET detector with an anthropomorphic phantom. We used the RANDO phantom as an anthropomorphic phantom, and dose measurements were carried out in the abdominal, thoracic, and head and neck regions for simple square field sizes of 10 × 10, 5 × 5, and 3 × 3 cm2 with a 6-MV photon beam. The dose measured by the MOSFET detector was verified by the dose calculations of the superposition (SP) algorithm in the XiO radiotherapy treatment-planning system. In most cases, the measured doses agreed with the results of the SP algorithm within ±3%. Our results demonstrated ... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018294 Wed, 03 Feb 2010 06:56:13 +0100 5018294 http://www.medworm.com/index.php?rid=5018295&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fp3724g1n419x7551%2F Abstract  A nationwide survey was conducted on electron accelerators for radiation therapy in Japan for obtaining fundamental data on the actual operational situation of these accelerators. The research subjects were all medical institutions equipped with electron accelerators for radiation therapy (874 accelerators) in Japan. Postcards explaining the purpose and procedure of the survey were sent to each institution. Each institution was requested to download a questionnaire from the website and return it by e-mail. We obtained the following results. Energy: about 90% of the accelerators did not exceed 10 MeV as the permitted maximum energy. Beam intensity: a total of 94% of the accelerators did not exceed 4 Gy/min as the mean exposure dose rate. Beam time: a tota... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018295 Fri, 22 Jan 2010 02:11:23 +0100 5018295 http://www.medworm.com/index.php?rid=5018296&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2F937l4g48914l58u0%2F In this study, we investigated the processes of energy deposition by considering interactions including the nuclear reactions between protons and water molecules by a Monte Carlo simulation for proton therapy. We estimated the number of particles produced by a variety of nuclear reactions, and we focused on the interaction in the low-energy region (below 1 MeV). Furthermore, we considered the charge-changing processes in the low-energy region (less than a few hundred keV). Finally, we evaluated the total dose and the contribution of primary protons and secondary particles through nuclear reactions to the absorbed dose. The results showed that the protons generate numerous neutrons via nuclear reactions. Particularly, neutrons with relatively low energies produce recoil protons b... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018296 Mon, 28 Dec 2009 07:12:47 +0100 5018296 http://www.medworm.com/index.php?rid=5018297&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fn06673j012353967%2F Abstract  Our purpose in this study was to evaluate the preliminary clinical efficacy of soft-copy reading of digital mammography, for a 15-mega-sub-pixel (MsP) and a 9-MsP super-high-resolution liquid-crystal display (SHR-LCD) by use of an independent sub-pixel driving technology. We performed three kinds of phantom observation studies by six radiological technologists. Detectability of a contrast-detail phantom and simulated small objects (SSOs) resembling microcalcifications (MCLs), and shape discrimination ability of SSOs with round and square shapes, were examined and compared with a 5-MP conventional LCD (5-MP LCD). In each study, four types of display magnification ratio were used. The detectability and the shape discrimination ability of the 15-MsP SHR-LCD were high... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018297 Fri, 25 Dec 2009 00:23:22 +0100 5018297 http://www.medworm.com/index.php?rid=5018298&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fbm49552371712584%2F Abstract  We evaluated patients with atrial fibrillation (Af) to define the optimal phase for ECG-gated image reconstruction for multi-slice CT (MSCT) of the left atrial appendage (LAA). We performed MSCT scans in 37 patients with Af, and we reconstructed multi-planar reformation images of the LAA, defined by the absolute delay (ms) immediately after the T wave, and by the relative delay (%). For visual analysis of the image quality for each image, a four-grade scoring system (poor to excellent) was used by two blinded, independent reviewers. Images obtained by absolute delay and by relative delay were classified as being of poor, fair, good, or excellent quality in 2, 2, 8, and 25 cases, and in 18, 11, 8, and 0 cases, respectively. This phase-definition strategy in Af pati... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018298 Fri, 18 Dec 2009 07:17:36 +0100 5018298 http://www.medworm.com/index.php?rid=5018299&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2F86n2421260182504%2F Abstract  The quality control of liquid-crystal display (LCD) monitors has become one of the important topics for maintaining reliable soft-copy readings in the interpretation of diagnostic images. In this paper, the effects of correction in the luminance measurement of an LCD monitor by use of a telescopic-type luminance meter were investigated. The luminance of the LCD monitor in different ambient-lighting conditions was measured and compared to the results obtained with no ambient lighting (0 lux). The reproducibility of luminance measurements and luminance ratios without a baffled tube was lower than those measured with the baffled tube due to the effect of ambient light. These tendencies were obvious at a relatively low luminance. The correction method by subtract... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018299 Thu, 10 Dec 2009 15:29:41 +0100 5018299 http://www.medworm.com/index.php?rid=5018300&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fwww.springerlink.com%2Fcontent%2F0515440214462q27%2F Abstract  To design a range-compensating bolus for heavy-charged-particle radiotherapy of lung cancer, we propose an image-processing method that uses CT projection data for treatment planning. We studied six lung cancer patients in 4DCT mode. Three types of range-compensating bolus were designed with use of (1) each bolus for 4DCT images, (2) image-based maximum-intensity projection data (4DIM), and (3) CT images reconstructed by the use of maximum-attenuation projection data (4DPM) along the time axis around exhale (=respiratory-gated treatment). Carbon-ion dose distributions were calculated by the use of these designed range-compensating boluses and were compared. The dose distribution with 4DIM caused overdosing beyond the target. However, the dose distribution with 4DP... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=5018300 Thu, 10 Dec 2009 15:29:40 +0100 5018300 http://www.medworm.com/index.php?rid=3066577&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Ft52018731937v316%2F In this study, the nuclear medicine staff wore one finger dosimeter placed at the base of the index finger of the working hand. When a physician injected radioisotope drugs, the finger dose was 22.4 µSv, that for radiological technologists handling 99mTc was 29.6 µSv/day (consultation period 20 days), that for a physician injecting 18F-FDG-PET drugs was 51.3 µSv (right finger 53.9 µSv, left finger 47.2 µSv), that for pharmacists’ assay of FDG was 31.5 µSv, and that for radiological technologists positioning patients was 1.9 µSv. The largest value (94.1 µSv) was observed in physicians in the case of aspiration of a delivered drug. The finger dosimeter provides an effective solution for radiation protection procedures and follow-up.... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=3066577 Thu, 03 Dec 2009 12:54:08 +0100 3066577 http://www.medworm.com/index.php?rid=3016908&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fl27t42q10u274106%2F Abstract  In our conventional visual inspection for setup verification, we have routinely used a console monitor of a CR system and a monitor of a treatment-planning system (i.e., the separate-monitor method) in order to avoid the need for CR portal-film generation. However, the separate-monitor method provided insufficient precision in detecting setup errors. We devised a setup verification procedure that uses a high-resolution liquid-crystal display monitor (i.e., the single-monitor method). Our objective in the present study was to evaluate the precision of the single-monitor method. These two methods were compared in terms of the precision of visual inspection. The single-monitor method was significantly superior to the separate-monitor method in sensitivity and in the ... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=3016908 Thu, 19 Nov 2009 20:02:56 +0100 3016908 http://www.medworm.com/index.php?rid=2971829&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fn418188v26560175%2F Abstract  Pulmonary blood flow is reflected in dynamic chest radiographs as changes in X-ray translucency, i.e., pixel values. Thus, decreased blood flow should be observed as a reduction of the variation of X-ray translucency. We performed the present study to investigate the feasibility of pulmonary blood flow evaluation with a dynamic flat-panel detector (FPD). Sequential chest radiographs of 14 subjects were obtained with a dynamic FPD system. The changes in pixel value in each local area were measured and mapped on the original image by use of a gray scale in which small and large changes were shown in white and black, respectively. The resulting images were compared to the findings in perfusion scans. The cross-correlation coefficients of the changes in pixel value an... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2971829 Fri, 06 Nov 2009 09:53:28 +0100 2971829 http://www.medworm.com/index.php?rid=2962800&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fp3h1662328608728%2F In this study, the organ doses were measured using a human- body phantom simulating a medical staff member, and we considered an effective method for decreasing exposure to staff in positron emission tomography examinations. A fluorescence glass dosimeter was arranged for measurements in various organs. Regarding exposure, the average ratio of the dose at 100 cm from the source to the dose at 30 cm was 0.35. The ratio of the dose at 100 cm with a 3 cm lead shield to the dose at 100 cm with no shielding device was 0.01. To reduce the radiation exposure effectively, medical staff members should inform the patient of the details of the examination in advance, reduce the contact time with the patient during the examination, and maximize their distance from the pa... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2962800 Tue, 03 Nov 2009 07:03:49 +0100 2962800 http://www.medworm.com/index.php?rid=2898348&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fy5814p81168861k3%2F Abstract  We have developed new design algorithms for compensating boli to facilitate the implementation of four-dimensional charged-particle lung therapy in clinical applications. Four-dimensional CT (4DCT) data for eight lung cancer patients were acquired with a 16-slice CT under free breathing. Six compensating boli were developed that may be categorized into three classes: (1) boli-based on contoured gross tumor volumes (GTV) from a 4DCT data set during each respiratory phase, subsequently combined into one (GTV-4DCT bolus); (2) boli-based on contoured internal target volume (ITV) from image-processed 3DCT data only [temporal-maximum-intensity-projection (TMIP)/temporal-average-intensity-projection (TAIP)] with calculated boli (ITV-TMIP and ITV-TAIP boli); and (3) boli-b... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2898348 Tue, 13 Oct 2009 10:54:37 +0100 2898348 http://www.medworm.com/index.php?rid=2812221&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fr24n217392120631%2F Abstract  The results of Monte Carlo calculated dose distributions of proton treatment of ocular melanoma are presented. An efficient spot scanning method utilizing active energy modulation, which also minimizes the number of target spots was developed. We simulated various parameter values for the particle energy spread and the pencil beam diameter in order to determine values suitable for medical treatment. We found that a 2.5-mm-diameter proton beam with a 5% Gaussian energy spread was suitable for treatment of ocular melanoma while preserving vision for the typical case that we simulated. The energy spectra and the required proton current were also calculated and are reported. The results are intended to serve as a guideline for a new class of low-cost, compact accelera... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2812221 Fri, 18 Sep 2009 16:24:05 +0100 2812221 http://www.medworm.com/index.php?rid=2768432&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fv7486775383483x3%2F Abstract  Our purpose in this study was to examine the detectability of a lung nodule at different maximum luminance settings of a liquid-crystal display (LCD) monitor by utilizing receiver operating characteristic (ROC) analysis. The LCD monitor used in this study was calibrated to the grayscale standard display function with different maximum luminance settings (670, 450, and 170 cd/m2). The average area under the ROC curve (AUC) and the standard deviation for all observers at 670, 450, and 170 cd/m2 were 0.837 ± 0.076, 0.832 ± 0.051, and 0.830 ± 0.078, respectively. There was no statistically significant difference in AUC as a function of the maximum luminance setting of the LCD monitor. Considering the results, setting the maximum... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2768432 Thu, 03 Sep 2009 06:11:47 +0100 2768432 http://www.medworm.com/index.php?rid=2653373&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fq6545x1071533075%2F Abstract  Physics-related subjects are important in the educational fields of radiological physics and technology. However, conventional teaching tools, for example texts, equations, and two-dimensional figures, are not very effective in attracting the interest of students. Therefore, we have created several multimedia educational materials covering radiological physics and technology. Each educational presentation includes several segments of high-quality computer-graphic animations designed to attract students’ interest. We used personal computers (PCs) and commercial software to create and compile these. Undergraduate and graduate students and teachers and related professionals contributed to the design and creation of the educational materials as part of student resea... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2653373 Mon, 27 Jul 2009 22:38:26 +0100 2653373 http://www.medworm.com/index.php?rid=2610565&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2F818646w13340739g%2F Content Type Journal ArticleDOI 10.1007/s12194-009-0064-3 Journal Radiological Physics and TechnologyOnline ISSN 1865-0341Print ISSN 1865-0333 (Source: Radiological Physics and Technology) Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2610565 Wed, 15 Jul 2009 13:49:34 +0100 2610565 http://www.medworm.com/index.php?rid=2597832&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2F5312476843772628%2F Abstract  Titanium-encapsulated 125I brachytherapy sources are in use for treatment of the eye, brain, and head and neck region, and for early stage prostate cancer. The photoelectric interaction of 125I photons with titanium encapsulation generates Ti K X-rays (~5 keV). According to the National Institute of Standards and Technology (NIST) 1999 air-kerma strength, S k, standard, these X-rays should be excluded from S k. We used the EGSnrc Monte Carlo code system to calculate the S k (including the contribution of ~5-keV X-rays), dose rate constant, and radial dose function for five different 125I source models. Depending upon the source model, the contribution of 5-keV Ti X-rays to S k varies between 17.1 and 18.7%. Including these X-rays as part of S k would result in un... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2597832 Sat, 11 Jul 2009 06:53:21 +0100 2597832 http://www.medworm.com/index.php?rid=2579922&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2F984330120415351t%2F Abstract  Electron applicators and cut-outs have been used for some time in the delivery of electron beam therapy. A dual electron multileaf collimator (eMLC) consisting of upper and lower eMLCs was designed, and dose distributions of electron beams delivered by it were evaluated by Monte Carlo simulations by use of the EGSnrc Monte Carlo code. The percentage depth dose (PDD), dose profiles, dose gradient falloff (G), depth of maximum dose (R 100), surface dose, bremsstrahlung background, beam flatness, and penumbra of the dual eMLC were evaluated and compared with those simulated and measured with the standard applicators inserted into the treatment head of the medical linear accelerator (linac). The results showed good agreement in most cases. Specifically, the flatness a... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2579922 Mon, 06 Jul 2009 16:53:49 +0100 2579922 http://www.medworm.com/index.php?rid=2569586&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Ft6k32228q2620k62%2F Abstract  To assess the relationship between intra-abdominal fat and sigmoid colon cancer, we investigated the intra-abdominal fat distribution in 172 examples of sigmoid colon cancer and 767 examples of various other pathologies by using data from multidetector-row computed tomography. One significant finding was that the intra-abdominal fat area in sigmoid colon cancer presents a small secondary peak in the pelvis on the profile of the intra-abdominal fat, which we called the pelvic sub-peak. The presence or absence of the pelvic sub-peak was determined based on the sub-peak ratio, which was calculated by dividing the maximum peak by the sub-peak value on the profile of the intra-abdominal fat area. The pelvic sub-peak was defined as having a sub-peak ratio ≥0.1. The pe... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2569586 Wed, 01 Jul 2009 06:24:56 +0100 2569586 http://www.medworm.com/index.php?rid=2569587&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2F34206j0n5271w8q1%2F In this study, we demonstrate the feasibility of 3D NIR fluorescence tomography imaging by employing DOI-PET detectors in computer simulations. In the simulations, we used a 40 mm × 40 mm × 40 mm cubic phantom, a square detector geometry, and an optical diffusion equation to approximate the light propagation. We then evaluated imaging systems for 3D fluorescence tomography with different detector resolutions and excitation light arrangements using singular-value analysis and imaging simulation. We confirmed that the reconstructed images from low-resolution detectors (8 × 8 pixels for an area of 40 mm × 40 mm) are the same as those from high-resolution detectors (16 × 16 pixels for the same area). Conten... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2569587 Tue, 30 Jun 2009 15:43:58 +0100 2569587 http://www.medworm.com/index.php?rid=2462819&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2F216418483483726r%2F Abstract  Our purpose in this study was to investigate the optimal position for the quantification of hepatic perfusion by using a dual-input, single-compartment model and dynamic contrast-enhanced computed tomography (DCE-CT) in rats. The DCE-CT studies were performed with the animals in the supine and prone position, with an interval of 1 day, on six male Sprague–Dawley rats. The distance between the inferior vena cava (IVC) and portal vein was calculated. The arterial hepatic blood flow (AHBF) and portal hepatic blood flow (PHBF) were also estimated by use of time–density curves (TDCs) in the aorta, portal vein, and liver. The distance between the IVC and portal vein in the supine position (3.68 ± 0.22 mm) was significantly greater than that in th... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2462819 Fri, 05 Jun 2009 08:56:17 +0100 2462819 http://www.medworm.com/index.php?rid=2423106&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2F9100347704k5q657%2F Abstract  A medical compact cyclotron produces about 1015 neutrons per day along with 100 GBq of 18F. Therefore, it is important to establish radiation safety guidelines on residual radioactivity for routine operation, maintenance work, and decommissioning. Thus, we developed a simple method for measuring the thermal neutrons in a cyclotron room. In order to verify the feasibility of our proposed method, we measured the thermal neutron distribution around a cyclotron by using the activation of 23Na in salt. We installed 78 salt dosimeters in the cyclotron room with a 50 cm mesh. The photopeak of 24Na was measured, and the neutron flux distribution was estimated. Monitoring the neutron flux distribution in a cyclotron room appears to be useful for not only obtaining ... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2423106 Sat, 16 May 2009 05:57:51 +0100 2423106 http://www.medworm.com/index.php?rid=2423107&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fr0w8562663280428%2F Abstract  The differentiation of focal liver lesions in magnetic resonance (MR) imaging is primarily based on the intensity and homogeneity of lesions with different imaging sequences. However, these imaging findings are falsely interpreted in some patients because of the complexities involved. Our aim is to establish a computer-aided diagnosis system named LiverANN for classifying the pathologies of focal liver lesions into five categories using the artificial neural network (ANN) technique. On each MR image, a region of interest (ROI) in the focal liver lesion was delineated by a radiologist. The intensity and homogeneity within the ROI were calculated automatically, producing numerical data that were analyzed by feeding them into the LiverANN as inputs. Outputs were the ... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2423107 Thu, 14 May 2009 06:47:22 +0100 2423107 http://www.medworm.com/index.php?rid=2423108&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fh77m022765756042%2F Abstract  It is known that the performance of liquid-crystal display (LCD) monitors, such as the luminance and contrast ratio, is dependent on the viewing angle. Our purpose in this study was to compare the angular performance and the effect on observer performance of different types of LCD monitors. The luminance performance and contrast ratio as a function of viewing angle (−60° to 60°) in each direction for two types of LCD monitors, namely, a general-purpose LCD monitor and one especially designed for medical use, were measured in this study. Furthermore, the observer performance at various viewing angles in the horizontal direction for a medical-grade LCD monitor was investigated by eight observers based on a contrast-detail diagram. The two types of LCD monitors s... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2423108 Thu, 14 May 2009 06:47:21 +0100 2423108 http://www.medworm.com/index.php?rid=2387456&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Ff7j570462x9n2562%2F Abstract  Recent linear accelerators can perform cone-beam computed tomography to correct setup errors immediately before dose delivery. We calculated the dose distribution with setup errors acquired from cone-beam computed tomography to determine a more realistic and individual effect of setup errors. The differences in dose distribution were analyzed. The setup errors of three patients who were irradiated in the neck, esophagus, and pelvic area were obtained retrospectively. We found that the maximum dose variances for the three cases were 19.9–35.9%. The maximum dose variance points were relatively far from the isocenter. The volume of the 10% dose difference had widths of 1.3–1.85 cm around the beam edges. The V95 and mean doses at the clinical target volume we... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2387456 Fri, 01 May 2009 06:31:58 +0100 2387456 http://www.medworm.com/index.php?rid=2367181&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fv10p881414751186%2F Abstract  We evaluated dynamic changes in water diffusion in the brain during the cardiac cycle by using cine diffusion MRI. On a 1.5-T MRI, ECG-triggered single-shot diffusion echo planar imaging was used with sensitivity encoding, halfscan, and rectangular field of view techniques for minimizing bulk motion effects such as brain pulsation, with a data-sampling window of 3 ms. The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) in the white matter zone were determined in ten healthy volunteers and then compared with the intracranial volume change (ICVC) revealed by phase-contrast cine MRI during the cardiac cycle. In addition, a frequency analysis of these waveforms was performed. ADC and FA values changed significantly during the cardiac cycle, de... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2367181 Thu, 23 Apr 2009 07:54:06 +0100 2367181 http://www.medworm.com/index.php?rid=2363965&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Ft41k31l7544145h5%2F Abstract  We propose a new method for diagnostic assistance in oncology, [fluorine-18]-2-fluoro-2-deoxy-d-glucose (FDG)-positron emission tomography (PET). Early and delayed scans were performed on 10 patients with lung cancer by use of an ECAT EXACT 47 PET scanner, and standardized-uptake-value (SUV) images were created. Three segmentation (S1, S2, and S3) maps were created from the early and delayed SUV images according to various thresholds (SUVthreshold = 2.0, 2.5, and 3.0) based on the early image and the percentage change defined as (SUVdelayed − SUVearly) × 100/SUVearly. Voxels that had larger voxel values in their early images than the SUVthreshold were clustered into three classes: S1 if the percentage change was larger than 10, S2 if t... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2363965 Tue, 21 Apr 2009 11:19:36 +0100 2363965 http://www.medworm.com/index.php?rid=2340921&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fp83107v838747k73%2F Content Type Journal ArticleDOI 10.1007/s12194-009-0055-4Authors Kunio Doi, The University of Chicago Department of Radiology Chicago IL USA Journal Radiological Physics and TechnologyOnline ISSN 1865-0341Print ISSN 1865-0333 (Source: Radiological Physics and Technology) Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2340921 Tue, 14 Apr 2009 05:51:46 +0100 2340921 http://www.medworm.com/index.php?rid=2328712&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fx7255723j5053553%2F Abstract  It is essential to make accurate estimates of the scatter of radiation from the human body when calculating the leakage dose in medical X-ray imaging facilities. The scatter fraction varies with the size and shape of the radiation field in a way that is not exactly proportional to the area of the field. Japanese law quotes values for the scatter fraction that are provided by the National Council on Radiation Protection and Measurements, but these data were obtained 30 years ago, using equipment that differed considerably from that employed nowadays. To date, no attempt has been made to confirm whether these data accurately describe current Japanese equipment. In the present study, we used an ion chamber dosimeter to measure scattered radiation fractions, and ... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2328712 Wed, 08 Apr 2009 08:26:44 +0100 2328712 http://www.medworm.com/index.php?rid=2297368&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fc32v150675488356%2F Abstract  The management of induced radioactivity of the cyclotron itself and structures is an important issue in decommissioning of medical compact cyclotrons. To obtain basic data on the actual operational conditions of cyclotrons, we performed nationwide survey. The actual beam current was about half of the maximum beam current indicated in the official permits for cyclotron operation. The actual operating time was about 10% of the maximum operating time indicated in the official permits. The average daily radioactive-nuclide (18F) production was only 10% of the allowed maximum quantity. From these results, it became clear that the induced radioactivity of a cyclotron and its concrete structures based on the maximum beam current and the maximum operating time may be overe... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2297368 Fri, 27 Mar 2009 06:49:55 +0100 2297368 http://www.medworm.com/index.php?rid=2284059&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Ff1603074quj47962%2F Abstract  Neurosurgeons sometimes find it difficult to locate tumors precisely during microsurgery, particularly tumors located in the brain parenchyma because of the absence of boundaries in this region. Image-guided neurosurgical techniques conducted with the help of neuronavigation systems have been developed and have gained importance recently. Accuracy is vital during image-guided neurosurgery. We used a phantom to evaluate the errors introduced during navigation. The three errors evaluated were skin-shift, marker-gap, and table-rotation errors. The skin-shift error occurs if the fiducial markers positioned on the scalp move when the head is fixed to a head holder with head pins. The marker-gap error occurs when the marker ball is positioned incorrectly in the marker s... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2284059 Tue, 17 Mar 2009 06:48:00 +0100 2284059 http://www.medworm.com/index.php?rid=2076205&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Ft1371666782l32m2%2F Abstract  We have developed a practical dose verification method for radiotherapy treatment planning systems by using only a Farmer ionization chamber in inhomogeneous phantoms. In particular, we compared experimental dose verifications of multi-layer phantom geometries and laterally inhomogeneous phantom geometries for homogeneous and inhomogenous dose calculations by using the fast-Fourier-transform convolution, fast-superposition, and superposition in the XiO radiotherapy treatment-planning system. We applied the dose verification method to three kernel-based algorithms in various phantom geometries with water-, lung- and bone-equivalent media of different field sizes. These calculations were then compared with experimental measurements by use of the Farmer ionization ch... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2076205 Tue, 30 Dec 2008 06:58:18 +0100 2076205 http://www.medworm.com/index.php?rid=2068130&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fk13471661415u652%2F Abstract  We evaluated the water-equivalent length (WEL) reproducibility due to variation in the external respiratory marker position when using a 4DCT scan in respiratory-gated charged-particle treatment. Two sets of pancreatic 4DCT data from two patients were acquired under free breathing conditions with 256-slice CT. The 4DCT data included two exhalation phases and the respiratory patterns in each patient differed, one being regular and the other irregular. The WEL calculation region is defined in the first respiratory cycle by two planes, one at the patient entrance surface and the other behind the target in the anterior–posterior (AP) and posterior–anterior (PA) directions. In the regular respiratory pattern, the WEL variation within the target region was less than... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2068130 Thu, 25 Dec 2008 06:55:20 +0100 2068130 http://www.medworm.com/index.php?rid=2054184&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fk874xv4p25282424%2F This study concentrated on measuring the dependence of the polarity effect at various energies, and for various field size, ionization chamber, and electrometer combinations. Of the seven chambers, CC01, PTW23323, and PTW31006 had the largest polarity effect for small field sizes. The materials of the central electrode of these three chambers were steel or air-equivalent plastic C-552. The magnitude of the polarity effect was shown to be strongly dependent on the material of the collecting electrode. This polarity effect dependence was observed for the ionization chambers and small field sizes studied. Content Type Journal ArticleDOI 10.1007/s12194-008-0050-1Authors Tetsunori Shimono, Hoshigaoka Koseinenkin Hospital Department of Radiology 4-8-1 Hoshigaoka Hirakata Osaka 573-0013 ... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2054184 Thu, 18 Dec 2008 09:34:25 +0100 2054184 http://www.medworm.com/index.php?rid=2054183&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2F443u4g07v703541v%2F Abstract  Currently, it is difficult to carry out refraction-contrast radiography by using a conventional X-ray generator. Thus, we developed an embossed radiography system utilizing dual-energy subtraction for decreasing the absorption contrast in unnecessary regions, and the contrast resolution of a target region was increased by use of image-shifting subtraction and a linear-contrast system in a flat panel detector (FPD). The X-ray generator had a 100-μm-focus tube. Energy subtraction was performed at tube voltages of 45 and 65 kV, a tube current of 0.50 mA, and an X-ray exposure time of 5.0 s. A 1.0-mm-thick aluminum filter was used for absorbing low-photon-energy bremsstrahlung X-rays. Embossed radiography was achieved with cohesion imaging by use of th... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2054183 Thu, 18 Dec 2008 09:34:25 +0100 2054183 http://www.medworm.com/index.php?rid=2048514&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fkp418h625192100n%2F Abstract  Our purpose in this study was to examine the potential usefulness of liquid–crystal display (LCD) monitors having the capability of rendering higher than 8 bits in display-bit depth. An LCD monitor having the capability of rendering 8, 10, and 12 bits was used. It was calibrated to the grayscale standard display function with a maximum luminance of 450 cd/m2 and a minimum of 0.75 cd/m2. For examining the grayscale resolution reported by ten observers, various simple test patterns having two different combinations of luminance in 8, 10, and 12 bits were randomly displayed on the LCD monitor. These patterns were placed on different uniform background luminance levels, such as 0, 50, and 100%, for maximum luminance. All observers participating in this study... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2048514 Tue, 16 Dec 2008 07:57:52 +0100 2048514 http://www.medworm.com/index.php?rid=2041722&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fg6h6t724l32g0451%2F We present a review of the rationale, technology, and methodology of image guidance, as well as an overview of current work in IGRT at the Massachusetts General Hospital. The technology is rapidly evolving, and synergisms between the various acquisition approaches are converging to provide unparalleled information on target and normal tissue location and motion. With these new approaches to patient localization, we expect improved clinical results to be forthcoming. Content Type Journal ArticleDOI 10.1007/s12194-008-0045-yAuthors George T. Y. Chen, Massachusetts General Hospital Department of Radiation Oncology 100 Blossom Street Boston MA 02114 USAGregory C. Sharp, Massachusetts General Hospital Department of Radiation Oncology 100 Blossom Street Boston MA 02114 USAShinichiro Mori... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2041722 Mon, 15 Dec 2008 06:54:57 +0100 2041722 http://www.medworm.com/index.php?rid=2034390&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fp061327146w44227%2F Abstract  We have developed a new protocol of myocardial perfusion-gated single-photon emission computed tomography (SPECT), by use of technetium-99m sestamibi (MIBI), in which SPECT imaging at rest followed by SPECT imaging after adenosine with low level ergometer stress can be conducted by use of the Monzen position within a shortened total testing time of 1 h or less. The study group consisted of 137 patients who underwent this new imaging protocol. The diagnostic quality of the images was as good as that of images obtained with the conventional method (30–60 min after the injection of MIBI). The SPECT image quality for the 137 patients was evaluated, and the percentages of images rated as excellent, good, fair, and poor were 65.3, 27.4, 5.8, and 1.5% for the... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2034390 Thu, 11 Dec 2008 11:59:43 +0100 2034390 http://www.medworm.com/index.php?rid=2034391&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fp03269017585671m%2F Abstract  We have proposed a new “OpenPET” geometry consisting of two detector rings of axial length W each separated by a gap G. For obtaining an axially continuous field of view (FOV) of 2W + G, the maximum limit for G must be W. However, two valleys of sensitivity appear on both sides of the gap. Setting a more limited range for the gap as G < W, which is desirable for filling in the sensitivity valleys, results in not only a shortened gap, but also a shortened axial FOV. In this paper, we propose an alternative method for improving the uniformity of sensitivity by shifting two detector rings axially closer or further apart at the same velocity to each other. In addition, image reconstruction of the OpenPET is an incomplete problem, and low-freque... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=2034391 Wed, 10 Dec 2008 07:23:43 +0100 2034391 http://www.medworm.com/index.php?rid=1976695&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2F8383mg1013212030%2F Abstract  Monte Carlo numerical simulations were conducted to evaluate the effectiveness of colloidal gold as a contrast agent. The simulations were conducted using a simple configuration, modeling a phantom to maintain the generality of the results, and the effects of the mass percentage of gold accumulated inside the tumor and the energy of the irradiating X-rays were evaluated, as well as other information, such as the energy spectrum of the photons reaching the detector and the change in the energy deposited inside the phantom. The contrast of the X-ray image due to the layer is calculated from the total energy of photons transmitted to the back surface of the phantom. The simulation revealed that colloidal gold with a mass percentage of 1.0% provided an image for which... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=1976695 Tue, 18 Nov 2008 08:10:25 +0100 1976695 http://www.medworm.com/index.php?rid=1964790&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fj6238x20n3633382%2F Abstract  For reducing the risk of skin injury during interventional radiology (IR) procedures, it has been suggested that physicians track patients’ exposure doses. The metal-oxide semiconductor field effect transistor (MOSFET) dosimeter is designed to measure patient exposure dose during radiotherapy applications at megavoltage photon energies. Our purpose in this study was to evaluate the feasibility of using a MOSFET dosimeter (OneDose system) to measure patients’ skin dose during exposure to diagnostic X-ray energies used in IR. The response of the OneDose system was almost constant at diagnostic X-ray energies, although the sensitivity was higher than that at megavoltage photon energies. We found that the angular dependence was minimal at diagnostic X-ray energies... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=1964790 Fri, 14 Nov 2008 08:41:54 +0100 1964790 http://www.medworm.com/index.php?rid=1953184&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2F0332m73tj22w532n%2F In conclusion, the quantitative analysis of hepatic tumors was able to differentiate among these lesions by use of the T2-shine ratio. Content Type Journal ArticleDOI 10.1007/s12194-008-0043-0Authors Akio Ogura, Kyoto City Hospital Department of Radiology 1-2, Higashitakada-cho, Mibu, Nakagyo-ku Kyoto JapanKatsumi Hayakawa, Kyoto City Hospital Department of Radiology 1-2, Higashitakada-cho, Mibu, Nakagyo-ku Kyoto JapanTosiaki Miyati, Kanazawa University Graduate School of Medical Science Kanazawa JapanFumie Maeda, Kyoto City Hospital Department of Radiology 1-2, Higashitakada-cho, Mibu, Nakagyo-ku Kyoto JapanAkira Miyai, Kyoto City Hospital Department of Radiology 1-2, Higashitakada-cho, Mibu, Nakagyo-ku Kyoto JapanFumito Saeki, Kyoto City Hospital Department of Radiology 1-2, Higash... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=1953184 Mon, 10 Nov 2008 08:15:58 +0100 1953184 http://www.medworm.com/index.php?rid=1953185&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fp4328p1456858j04%2F Abstract  X-ray fluorescence (XRF) analysis is useful for measuring density distributions of contrast media in vivo. An XRF camera was developed for carrying out mapping for iodine-based contrast media used in medical angiography. Objects are exposed by an X-ray beam from a cerium target. Cerium K-series X-rays are absorbed effectively by iodine media in objects, and iodine fluorescence is produced from the objects. Next, iodine Kα fluorescence is selected out by use of a 58-µm-thick stannum filter and is detected by a cadmium telluride (CdTe) detector. The Kα rays are discriminated out by a multichannel analyzer, and the number of photons is counted by a counter card. The objects are moved and scanned by an x–y stage in conjunction with a two-stage controller, and X-r... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=1953185 Mon, 10 Nov 2008 08:15:57 +0100 1953185 http://www.medworm.com/index.php?rid=1945633&cid=s_37299_75_f&fid=37299&url=http%3A%2F%2Fspringerlink.com%2Fcontent%2Fv57t4uj446138427%2F Abstract  To provide faster calculation of digitally reconstructed radiographs (DRRs) in patient-positioning verification, we developed and evaluated a graphic processing unit (GPU)-based DRR software application and compared it with a central processing unit (CPU)-based application. The evaluation metrics were calculation speed and image quality for various slice thicknesses. The results showed that the GPU-based DRR computation was an average of 50 times faster than the CPU-based methodology, whereas the image quality was very similar. This excellent performance may increase the accuracy of patient positioning and improve the patient treatment throughput time. Content Type Journal ArticleDOI 10.1007/s12194-008-0040-3Authors Shinichiro Mori, National Institute of Radio... Radiological Physics and Technology journals http://www.medworm.com/rss/comments.php?id=1945633 Fri, 07 Nov 2008 08:13:58 +0100 1945633