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Journal of Applied Clinical Medical Physics

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https://www.readbyqxmd.com/read/28594085/preliminary-study-of-clinical-application-on-imrt-three-dimensional-dose-verification-based-epid-system
#1
Miaoyun Huang, David Huang, Jianping Zhang, Yuangui Chen, Benhua Xu, Lixin Chen
The three-dimensional dose (3D) distribution of intensity-modulated radiation therapy (IMRT) was verified based on electronic portal imaging devices (EPIDs), and the results were analyzed. Thirty IMRT plans of different lesions were selected for 3D EPID-based dose verification. The gamma passing rates of the 3D dose verification-based EPID system (Edose, Version 3.01, Raydose, Guangdong, China) and Delta4 measurements were then compared with treatment planning system (TPS) calculations using global gamma criteria of 5%/3 mm, 3%/3 mm, and 2%/2 mm...
June 8, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28594079/development-of-the-breast-immobilization-system-in-prone-setup-the-effect-of-bra-in-prone-position-to-improve-the-breast-setup-error
#2
Mariko Kawamura, Yoshikazu Maeda, Kazutaka Yamamoto, Shigeyuki Takamatsu, Yoshitaka Sato, Hiroki Minami, Yusuke Saga, Kyo Kume, Yuji Tameshige, Makoto Sasaki, Hiroyasu Tamamura, Kouji Ohta, Yoshiyuki Itoh, Shinji Naganawa
PURPOSE/OBJECTIVE(S): Accurate and reproducible positioning of the breast is difficult due to its deformability and softness; thus, targeting a breast tumor or tumor bed with fractionated radiotherapy using external beam radiation is difficult. The aim of this study was to develop a novel bra to aid in breast immobilization in the prone position. MATERIALS & METHODS: To assess the accuracy of prone position fixation of breast tumors, 33 breast cancer patients with 34 lesions were recruited...
June 8, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28585732/cost-effective-immobilization-for-whole-brain-radiation-therapy
#3
Ashley E Rubinstein, W Scott Ingram, Brian M Anderson, Skylar S Gay, Xenia J Fave, Rachel B Ger, Rachel E McCarroll, Constance A Owens, Tucker J Netherton, Kelly D Kisling, Laurence E Court, Jinzhong Yang, Yuting Li, Joonsang Lee, Dennis S Mackin, Carlos E Cardenas
To investigate the inter- and intra-fraction motion associated with the use of a low-cost tape immobilization technique as an alternative to thermoplastic immobilization masks for whole-brain treatments. The results of this study may be of interest to clinical staff with severely limited resources (e.g., in low-income countries) and also when treating patients who cannot tolerate standard immobilization masks. Setup reproducibility of eight healthy volunteers was assessed for two different immobilization techniques...
June 6, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28585724/assessment-of-volumetric-absorbed-dose-for-mobile-fluoroscopic-3d-image-acquisition
#4
Stephanie Leon
Mobile fluoroscopy (c-arm) units offering 3D image reconstruction are becoming more common in surgical settings. Although these images are "CT-like" and sometimes replace the postoperative CT, the acquisition is technically very different from a traditional CT acquisition. Dose assessment is complicated by a large beam width, automatic exposure rate control, and a rotation of less than 360°. The purpose of this work was to explore the impact of these factors on the volumetric dose calculation and to provide practical recommendations for clinical physicists assessing dose from these units using commonly available equipment...
June 6, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28585715/does-liver-resection-transplantation-affect-respiratory-induced-liver-motion-in-patients-with-hepatocellular-carcinoma
#5
Yong Hu, Yong-Kang Zhou, Yi-Xing Chen, Lu-Xi Ye, Zhao-Chong Zeng
The purpose of this study was to evaluate the changes in magnitude of three-dimensional (3D) liver motion after liver resection/transplantation in patients with hepatocellular carcinoma (HCC) using four-dimensional (4D)-computed tomography (CT) images. From January 2012 to April 2016, 74 HCC patients underwent 4D-CT scans under a free-breathing state to assess respiratory liver motion. Of the 74 patients, 40 did not have a liver resection/transplantation (Group A), 34 with liver resection/transplantation. 15 underwent major or minor resection in the right liver lobe (Group B), 14 underwent major or minor resection in the left liver lobe (Group C), and five underwent liver transplantation (Group D)...
June 6, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28585406/mr-safe-personal-radiation-dosimeters
#6
E Tchistiakova, A Kim, W Y Song, G Pang
Magnetic resonance imaging (MRI) is being rapidly integrated for cancer treatments-such systems are referred to as MRI-guided radiation therapy (MRIgRT). As the magnet of an MRI scanner is always on, the presence of a strong static magnetic field from the MRI scanner during radiotherapy delivery presents new challenges. One of the challenges is that a personal radiation dosimeter used to estimate the radiation dose deposited in an individual wearing the device must be MR-safe. No such devices, however, are currently available...
June 6, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28585300/investigation-of-error-detection-capabilities-of-phantom-epid-and-mlc-log-file-based-imrt-qa-methods
#7
Dewayne L Defoor, Sotirios Stathakis, Joseph E Roring, Neil A Kirby, Panayiotis Mavroidis, Mohammad Obeidat, Nikos Papanikolaou
A patient specific quality assurance (QA) should detect errors that originate anywhere in the treatment planning process. However, the increasing complexity of treatment plans has increased the need for improvements in the accuracy of the patient specific pretreatment verification process. This has led to the utilization of higher resolution QA methods such as the electronic portal imaging device (EPID) as well as MLC log files and it is important to know the types of errors that can be detected with these methods...
June 6, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28585287/effect-of-vero-pan-tilt-motion-on-the-dose-distribution
#8
Heru Prasetio, Indra Yohannes, Christoph Bert
Tumor tracking is an option for intra-fractional motion management in radiotherapy. The VERO gimbal tracking system creates a unique beam geometry and understanding the effect of the gimbal motion in terms of dose distribution is important to assess the dose deviation from the reference conditions. Beam profiles, output factors (OF) and percentage depth doses (PDD) were measured and evaluated to investigate this effect. In order to find regions affected by the pan-tilt motion, synthesized 2D dose distributions were generated...
June 6, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28585277/technical-note-monte-carlo-calculations-of-the-aapm-tg-43-brachytherapy-dosimetry-parameters-for-a-new-titanium-encapsulated-yb-169-source
#9
Francisco J Reynoso, John J Munro Iii, Sang Hyun Cho
Due to a number of distinct advantages resulting from the relatively low energy gamma ray spectrum of Yb-169, various designs of Yb-169 sources have been developed over the years for brachytherapy applications. Lately, Yb-169 has also been suggested as an effective and practical radioisotope option for a novel radiation treatment approach often known as gold nanoparticle-aided radiation therapy (GNRT). In a recently published study, the current investigators used the Monte Carlo N-Particle Version 5 (MCNP5) code to design a novel titanium-encapsulated Yb-169 source optimized for GNRT applications...
June 6, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28574221/validation-of-a-method-for-in%C3%A2-vivo-3d-dose-reconstruction-in-sbrt-using-a-new-transmission-detector
#10
Yuji Nakaguchi, Takeshi Ono, Masato Maruyama, Yoshinobu Shimohigashi, Yudai Kai
Stereotactic body radiation therapy (SBRT) involves the delivery of substantially larger doses over fewer fractions than conventional therapy. Therefore, SBRT treatments will strongly benefit patients using vivo patient dose verification, because the impact of the fraction is large. For in vivo measurements, a commercially available quality assurance (QA) system is the COMPASS system (IBA Dosimetry, Germany). For measurements, the system uses a new transmission detector (Dolphin, IBA Dosimetry). In this study, we evaluated the method for in vivo 3D dose reconstruction for SBRT using this new transmission detector...
June 2, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28574219/optimization-of-the-dosimetric-leaf-gap-for-use-in-planning-vmat-treatments-of-spine-sabr-cases
#11
Nigel D Middlebrook, Bess Sutherland, Tanya Kairn
The dosimetric leaf gap (DLG) is a beam configuration parameter used in the Varian Eclipse treatment planning system, to model the effects of rounded MLC leaf ends. Measuring the DLG using the conventional sliding-slit technique has been shown to be produce questionable results for some volumetric modulated arc therapy (VMAT) treatments. This study therefore investigated the use of radiochromic film measurements to optimize the DLG specifically for the purpose of producing accurate VMAT plans using a flattening-filter-free (FFF) beam, for use in treating vertebral targets using a stereotactic (SABR, also known as SBRT) fractionation schedule...
June 2, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28574211/comparison-of-the-recommendations-of-the-aapm-tg-51-and-tg-51-addendum-reference-dosimetry-protocols
#12
Travis J McCaw, Min-Sig Hwang, Si Young Jang, M Saiful Huq
This work quantified differences between recommendations of the TG-51 and TG-51 addendum reference dosimetry protocols. Reference dosimetry was performed for flattened photon beams with nominal energies of 6, 10, 15, and 23 MV, as well as flattening-filter free (FFF) beam energies of 6 and 10 MV, following the recommendations of both the TG-51 and TG-51 addendum protocols using both a Farmer(®) ionization chamber and a scanning ionization chamber with calibration coefficients traceable to absorbed dose-to-water (Dw ) standards...
June 2, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28574192/feasibility-study-of-ultrasound-imaging-for-stereotactic-body-radiation-therapy-with-active-breathing-coordinator-in-pancreatic-cancer
#13
Lin Su, Iulian Iordachita, Yin Zhang, Junghoon Lee, Sook Kien Ng, Juan Jackson, Ted Hooker, John Wong, Joseph M Herman, H Tutkun Sen, Peter Kazanzides, Muyinatu A Lediju Bell, Chen Yang, Kai Ding
PURPOSE: Stereotactic body radiation therapy (SBRT) allows for high radiation doses to be delivered to the pancreatic tumors with limited toxicity. Nevertheless, the respiratory motion of the pancreas introduces major uncertainty during SBRT. Ultrasound imaging is a non-ionizing, non-invasive, and real-time technique for intrafraction monitoring. A configuration is not available to place the ultrasound probe during pancreas SBRT for monitoring. METHODS AND MATERIALS: An arm-bridge system was designed and built...
June 2, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28548315/aapm-medical-physics-practice-guideline-8-a-linear-accelerator-performance-tests
#14
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
#15
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
#16
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
#17
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
#18
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
#19
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
#20
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
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