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Journal of Applied Clinical Medical Physics

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https://www.readbyqxmd.com/read/28548315/aapm-medical-physics-practice-guideline-8-a-linear-accelerator-performance-tests
#1
Koren Smith, Peter Balter, John Duhon, Gerald A White, David L Vassy, Robin A Miller, Christopher F Serago, Lynne A Fairobent
PURPOSE: The purpose of this guideline is to provide a list of critical performance tests in order to assist the Qualified Medical Physicist (QMP) in establishing and maintaining a safe and effective quality assurance (QA) program. The performance tests on a linear accelerator (linac) should be selected to fit the clinical patterns of use of the accelerator and care should be given to perform tests which are relevant to detecting errors related to the specific use of the accelerator. METHODS: A risk assessment was performed on tests from current task group reports on linac QA to highlight those tests that are most effective at maintaining safety and quality for the patient...
May 26, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28517613/a-quantitative-method-to-the-analysis-of-mlc-leaf-position-and-speed-based-on-epid-and-ebt3-film-for-dynamic-imrt-treatment-with-different-types-of-mlc
#2
Yinghui Li, Lixin Chen, Jinhan Zhu, Bin Wang, Xiaowei Liu
A quantitative method based on the electronic portal imaging system (EPID) and film was developed for MLC position and speed testing; this method was used for three MLC types (Millennium, MLCi, and Agility MLC). To determine the leaf position, a picket fence designed by the dynamic (DMLC) model was used. The full-width half-maximum (FWHM) values of each gap measured by EPID and EBT3 were converted to the gap width using the FWHM versus nominal gap width relationship. The algorithm developed for the picket fence analysis was able to quantify the gap width, the distance between gaps, and each individual leaf position...
May 18, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28517492/practical-considerations-of-linear-accelerator-based-frameless-extracranial-radiosurgery-for-treatment-of-occipital-neuralgia-for-nonsurgical-candidates
#3
Travis R Denton, Lisa B E Shields, Jonathan N Howe, Todd S Shanks, Aaron C Spalding
Occipital neuralgia generally responds to medical or invasive procedures. Repeated invasive procedures generate increasing complications and are often contraindicated. Stereotactic radiosurgery (SRS) has not been reported as a treatment option largely due to the extracranial nature of the target as opposed to the similar, more established trigeminal neuralgia. A dedicated phantom study was conducted to determine the optimum imaging studies, fusion matrices, and treatment planning parameters to target the C2 dorsal root ganglion which forms the occipital nerve...
May 18, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28508491/implementation-of-absolute-quantification-in-small-animal-spect-imaging-phantom-and-animal-studies
#4
Shabnam Khorasani Gerdekoohi, Naser Vosoughi, Kaveh Tanha, Majid Assadi, Pardis Ghafarian, Arman Rahmim, Mohammad Reza Ay
PURPOSE: Presence of photon attenuation severely challenges quantitative accuracy in single-photon emission computed tomography (SPECT) imaging. Subsequently, various attenuation correction methods have been developed to compensate for this degradation. The present study aims to implement an attenuation correction method and then to evaluate quantification accuracy of attenuation correction in small-animal SPECT imaging. METHODS: Images were reconstructed using an iterative reconstruction method based on the maximum-likelihood expectation maximization (MLEM) algorithm including resolution recovery...
May 16, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28503916/exploratory-study-of-the-association-of-volumetric-modulated-arc-therapy-vmat-plan-robustness-with-local-failure-in-head-and-neck-cancer
#5
Wei Liu, Samir H Patel, Daniel P Harrington, Yanle Hu, Xiaoning Ding, Jiajian Shen, Michele Y Halyard, Steven E Schild, William W Wong, Gary E Ezzell, Martin Bues
This work is to show which is more relevant to cause local failures (LFs) due to patient setup uncertainty between the planning target volume (PTV) underdosage and the potential target underdosage subject to patient setup uncertainties in head and neck (H&N) cancer treated with volumetric-modulated arc therapy (VMAT). Thirteen LFs in 10 H&N patients treated by VMAT were analyzed. Measures have been taken to minimize the chances of insufficient target delineation for these patients and the patients were clinically determined to have LF based on the PET/CT scan results by an experienced radiologist and then reviewed by a second experienced radiation oncologist...
May 14, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28503898/evaluation-of-initial-setup-errors-of-two-immobilization-devices-for-lung-stereotactic-body-radiation-therapy-sbrt
#6
Yoshihiro Ueda, Teruki Teshima, Higinia Cárdenes, Indra J Das
The aim of this study was to investigate the accuracy and efficacy of two commonly used commercial immobilization systems for stereotactic body radiation therapy (SBRT) in lung cancer. This retrospective study assessed the efficacy and setup accuracy of two immobilization systems: the Elekta Body Frame (EBF) and the Civco Body Pro-Lok (CBP) in 80 patients evenly divided for each system. A cone beam CT (CBCT) was used before each treatment fraction for setup correction in both devices. Analyzed shifts were applied for setup correction and CBCT was repeated...
May 14, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28497529/aapm-medical-physics-practice-guideline-6-a-performance-characteristics-of-radiation-dose-index-monitoring-systems
#7
Dustin A Gress, Renee L Dickinson, William D Erwin, David W Jordan, Robert J Kobistek, Donna M Stevens, Mark P Supanich, Jia Wang, Lynne A Fairobent
The American Association of Physicists in Medicine (AAPM) is a nonprofit professional society whose primary purposes are to advance the science, education and professional practice of medical physics. The AAPM has more than 8,000 members and is the principal organization of medical physicists in the United States. The AAPM will periodically define new practice guidelines for medical physics practice to help advance the science of medical physics and to improve the quality of service to patients throughout the United States...
May 12, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28497476/optimization-of-a-novel-large-field-of-view-distortion-phantom-for-mr-only-treatment-planning
#8
Ryan G Price, Robert A Knight, Ken-Pin Hwang, Ersin Bayram, Siamak P Nejad-Davarani, Carri K Glide-Hurst
PURPOSE: MR-only treatment planning requires images of high geometric fidelity, particularly for large fields of view (FOV). However, the availability of large FOV distortion phantoms with analysis software is currently limited. This work sought to optimize a modular distortion phantom to accommodate multiple bore configurations and implement distortion characterization in a widely implementable solution. METHOD AND MATERIALS: To determine candidate materials, 1...
May 12, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28470956/mri-scanner-independent-specific-absorption-rate-measurements-using-diffusion-coefficients
#9
Youngseob Seo, Zhiyue J Wang
OBJECTIVE: The purpose of this study was to measure specific absorption rate (SAR) during MRI scanning using a human torso phantom through quantification of diffusion coefficients independently of those reported by the scanner software for five 1.5 and 3 T clinical MRI systems from different vendors. METHODS: A quadrature body coil transmitted the RF power and a body array coil received the signals. With diffusion tensor imaging, SAR values for three MRI sequences were measured on the five scanners and compared to the nominal values calculated by the scanners...
May 4, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28470819/tuning-of-acurosxb-source-size-setting-for-small-intracranial-targets
#10
Stephen J Gardner, Siming Lu, Chang Liu, Ning Wen, Indrin J Chetty
This study details a method to evaluate the source size selection for small field intracranial stereotactic radiosurgery (SRS) deliveries in Eclipse treatment planning system (TPS) for AcurosXB dose calculation algorithm. Our method uses end-to-end dosimetric data to evaluate a total of five source size selections (0.50 mm, 0.75 mm, 1.00 mm, 1.25 mm, and 1.50 mm). The dosimetric leaf gap (DLG) was varied in this analysis (three DLG values were tested for each scenario). We also tested two MLC leaf designs (standard and high-definition MLC) and two delivery types for intracranial SRS (volumetric modulated arc therapy [VMAT] and dynamic conformal arc [DCA])...
May 4, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28470816/patient-specific-methods-for-room-mounted-x-ray-imagers-for-monoscopic-stereoscopic-prostate-motion-monitoring
#11
M Tynan R Stevens, Dave D Parsons, James L Robar
PURPOSE: To investigate the improvement of combined monoscopic/stereoscopic prostate motion monitoring with room-mounted dual x-ray systems by adopting patient specific methods. METHODS: The linac couch was used as a motion stage to simulate 40 highly dynamic real patient prostate trajectories. For each trajectory, 40 s pretreatment and 120 s treatment periods were extracted to represent a typical treatment fraction. Motion was monitored via continuous stereoscopic x-ray imaging of a single gold fiducial and images were retrospectively divided into periods of stereoscopic and monoscopic imaging to simulate periodic blocking of the room-mounted system by the gantry during arc-based therapy...
May 4, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28464517/long-term-dosimetric-stability-of-multiple-tomotherapy-delivery-systems
#12
Jennifer B Smilowitz, David Dunkerley, Patrick M Hill, Poonam Yadav, Mark W Geurts
The dosimetric stability of six TomoTherapy units was analyzed to investigate changes in performance over time and with system upgrades. Energy and output were tracked using monitor chamber signal, onboard megavoltage computed tomography (MVCT) detector profile, and external ion chamber measurements. The systems (and monitoring periods) include three Hi-Art (67, 61, and 65 mos.), two TomoHDA (31 and 26 mos.), and one Radixact unit (11 mos.), representing approximately 10 years of clinical use. The four newest systems use the Dose Control Stability (DCS) system and Fixed Target Linear Accelerator (linac) (FTL)...
May 2, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28464490/the-geographic-penetration-of-the-jacmp-and-the-benefits-of-aapm-membership-for-clinical-medical-physicists-worldwide
#13
EDITORIAL
Michael D Mills
No abstract text is available yet for this article.
May 2, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28444840/topas-simulation-of-the-mevion-s250-compact-proton-therapy-unit
#14
Michael Prusator, Salahuddin Ahmad, Yong Chen
As proton therapy becomes increasingly popular, so does the need for Monte Carlo simulation studies involving accurate beam line modeling of proton treatment units. In this study, the 24 beam configurations of the Mevion S250 proton therapy system installed recently at our institution were modeled using the TOolkit for PArticle Simulation (TOPAS) code. Pristine Bragg peak, spread out Bragg peak (SOBP), and lateral beam profile dose distributions were simulated and matched to the measurements taken during commissioning of the unit...
April 26, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28444831/analysis-of-modulation-factor-to-shorten-the-delivery-time-in-helical-tomotherapy
#15
Hidetoshi Shimizu, Koji Sasaki, Hiroyuki Tachibana, Natsuo Tomita, Chiyoko Makita, Kuniyasu Nakashima, Kazushi Yokoi, Takashi Kubota, Manabu Yoshimoto, Tohru Iwata, Takeshi Kodaira
A low modulation factor (MF) maintaining a good dose distribution contributes to the shortening of the delivery time and efficiency of the treatment plan in helical tomotherapy. The purpose of this study was to reduce the delivery time using initial values and the upper limit values of MF. First, patients with head and neck cancer (293 cases) or prostate cancer (181 cases) treated between June 2011 and July 2015 were included in the analysis of MF values. The initial MF value (MFinitial ) was defined as the average MFactual value, and the upper limit of the MF value (MFUL ) was defined according the following equation: MFUL = 2 × standard deviation of MFactual value + the average MFactual Next, a treatment plan was designed for patients with head and neck cancer (62 cases) and prostate cancer (13 cases) treated between December 2015 and June 2016...
April 26, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28436155/the-mobius-airo-mobile-ct-for-image-guided-proton-therapy-characterization-commissioning
#16
Jasmine A Oliver, Omar A Zeidan, Sanford L Meeks, Amish P Shah, Jason Pukala, Patrick Kelly, Naren R Ramakrishna, Twyla R Willoughby
PURPOSE: The purpose of this study was to characterize the Mobius AIRO Mobile CT System for localization and image-guided proton therapy. This is the first known application of the AIRO for proton therapy. METHODS: Five CT images of a Catphan(®) 504 phantom were acquired on the AIRO Mobile CT System, Varian EDGE radiosurgery system cone beam CT (CBCT), Philips Brilliance Big Bore 16 slice CT simulator, and Siemens SOMATOM Definition AS 20 slice CT simulator. DoseLAB software v...
April 24, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28436134/measurement-of-skin-surface-dose-distributions-in-radiation-therapy-using-poly-vinyl-alcohol-cryogel-dosimeters
#17
Molham M Eyadeh, Marcin Wierzbicki, Kevin R Diamond
In external beam radiation therapy (EBRT), skin dose measurement is important to evaluate dose coverage of superficial target volumes. Treatment planning systems (TPSs) are often inaccurate in this region of the patient, so in vivo measurements are necessary for skin surface dose estimation. In this work, superficial dose distributions were measured using radiochromic translucent poly(vinyl alcohol) cryogels. The cryogels simultaneously served as bolus material, providing the necessary buildup to achieve the desired superficial dose...
April 24, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28436107/a-complete-4dct-ventilation-functional-avoidance-virtual-trial-developing-strategies-for-prospective-clinical-trials
#18
Timothy Waxweiler, Leah Schubert, Quentin Diot, Austin Faught, Kelly Stuhr, Richard Castillo, Edward Castillo, Thomas Guerrero, Chad Rusthoven, Laurie Gaspar, Brian Kavanagh, Moyed Miften, Yevgeniy Vinogradskiy
INTRODUCTION: 4DCT-ventilation is an exciting new imaging modality that uses 4DCT data to calculate lung-function maps. Because 4DCTs are acquired as standard of care for lung cancer patients undergoing radiotherapy, 4DCT-ventiltation provides functional information at no extra dosimetric or monetary cost to the patient. The development of clinical trials is underway to use 4DCT-ventilation imaging to spare functional lung in patients undergoing radiotherapy. The purpose of this work was to perform a virtual trial using retrospective data to develop the practical aspects of a 4DCT-ventilation functional avoidance clinical trial...
April 24, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28436094/dosimetric-validation-of-a-magnetic-resonance-image-gated-radiotherapy-system-using-a-motion-phantom-and-radiochromic-film
#19
James M Lamb, John S Ginn, Dylan P O'Connell, Nzhde Agazaryan, Minsong Cao, David H Thomas, Yingli Yang, Mircea Lazea, Percy Lee, Daniel A Low
PURPOSE: Magnetic resonance image (MRI) guided radiotherapy enables gating directly on the target position. We present an evaluation of an MRI-guided radiotherapy system's gating performance using an MRI-compatible respiratory motion phantom and radiochromic film. Our evaluation is geared toward validation of our institution's clinical gating protocol which involves planning to a target volume formed by expanding 5 mm about the gross tumor volume (GTV) and gating based on a 3 mm window about the GTV...
April 24, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28422430/aapm-spring-clinical-meeting-abstracts
#20
(no author information available yet)
No abstract text is available yet for this article.
April 19, 2017: Journal of Applied Clinical Medical Physics
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