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Journal of Applied Clinical Medical Physics

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https://www.readbyqxmd.com/read/29024297/reducing-dose-to-the-lungs-through-loosing-target-dose-homogeneity-requirement-for-radiotherapy-of-non-small-cell-lung-cancer
#1
Junjie Miao, Hui Yan, Yuan Tian, Pan Ma, Zhiqiang Liu, Minghui Li, Wenting Ren, Jiayun Chen, Ye Zhang, Jianrong Dai
It is important to minimize lung dose during intensity-modulated radiation therapy (IMRT) of nonsmall cell lung cancer (NSCLC). In this study, an approach was proposed to reduce lung dose by relaxing the constraint of target dose homogeneity during treatment planning of IMRT. Ten NSCLC patients with lung tumor on the right side were selected. The total dose for planning target volume (PTV) was 60 Gy (2 Gy/fraction). For each patient, two IMRT plans with six beams were created in Pinnacle treatment planning system...
October 11, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28984069/assessment-of-radiopharmaceutical-retention-for-vascular-access-ports-using-positron-emission-tomography-imaging
#2
Michael S Gossman, Huaiyu Zheng, John G Evans, Junling Li, Chin K Ng
PURPOSE: The purpose of this study was to resolve the issue of whether various generations of CR Bard peripheral vascular access ports and catheters are prone to retain PET radiopharmaceuticals. The study evaluates the residual radioactivity remaining following injection for two PET radiopharmaceuticals currently used extensively in the clinic, FDG and Na(18) F. METHODS: FDG was purchased from a local cyclotron facility and Na(18) F was prepared in-house. Three generations of currently marketed vascular access ports were tested...
October 5, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28984023/relationship-between-the-radiation-doses-at-nonenhanced-ct-studies-using-different-tube-voltages-and-automatic-tube-current-modulation-during-anthropomorphic-phantoms-of-young-children
#3
Takanori Masuda, Yoshinori Funama, Masao Kiguchi, Kazuaki Osawa, Syouichi Suzuki, Takayuki Oku, Koichi Sugisawa, Tomokazu Shouji, Kazuo Awai
To compare the radiation dose and image noise of nonenhanced CT scans performed at 80, 100, and 120 kVp with tube current modulation (TCM) we used anthropomorphic phantoms of newborn, 1-year-old, and 5-year-old children. The noise index was set at 12. The image noise in the center of the phantoms at the level of the chest and abdomen was measured within a circumscribed region of interest. We measured the doses in individual tissues or organs with radio-photoluminescence glass dosimeters for each phantom. Various tissues or organs were assigned and the radiation dose was calculated based on the international commission on radiological protection definition...
October 5, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28980445/dosimetric-effects-of-anatomical-changes-during-fractionated-photon-radiation-therapy-in-pancreatic-cancer-patients
#4
Astrid van der Horst, Antonetta C Houweling, Geertjan van Tienhoven, Jorrit Visser, Arjan Bel
Pancreatic tumors show large interfractional position variation. In addition, changes in gastrointestinal gas volumes and body contour take place over the course of radiation therapy. We aimed to quantify the effect of these anatomical changes on target dose coverage, for the clinically used fiducial marker-based patient position verification and, for comparison, also for simulated bony anatomy-based position verification. Nine consecutive patients were included in this retrospective study. To enable fraction dose calculations on cone-beam CT (CBCT), the planning CT was deformably registered to each CBCT (13-15 per patient); gas volumes visible on CBCT were copied to the deformed CT...
October 4, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28980442/automated-prediction-of-dosimetric-eligibility-for-hypofractionated-prostate-radiotherapy
#5
Anthony Lausch, Michael Lamey, Grace G Zeng
Clinical implementation of hypofractionated prostate radiotherapy (PROFIT trial, NCT003046759) represents an opportunity to significantly reduce the burden of treatment on the patient and clinic. However, efficacy was only demonstrated among the patient demographic who could meet the trial dose constraints and so it is necessary to emulate this triage step in clinical practice. The purpose of this study was to build a convenient tool to address the challenge of determining patient eligibility for hypofractionated treatment within the clinic...
October 4, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28980432/commissioning-of-a-ptw-34070-large-area-plane-parallel-ionization-chamber-for-small-field-megavoltage-photon-dosimetry
#6
Tom Kupfer, Joerg Lehmann, Duncan J Butler, Ganesan Ramanathan, Tracy E Bailey, Rick D Franich
PURPOSE: This study investigates a large-area plane-parallel ionization chamber (LAC) for measurements of dose-area product in water (DAPw ) in megavoltage (MV) photon fields. METHODS: Uniformity of electrode separation of the LAC (PTW34070 Bragg Peak Chamber, sensitive volume diameter: 8.16 cm) was measured using high-resolution microCT. Signal dependence on angle α of beam incidence for square 6 MV fields of side length s = 20 cm and 1 cm was measured in air...
October 4, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28980395/improved-vessel-tissue-contrast-and-image-quality-in-3d-radial-sampling-based-4d-mri
#7
Zixin Deng, Wensha Yang, Jianing Pang, Xiaoming Bi, Richard Tuli, Debiao Li, Zhaoyang Fan
PURPOSE: In radiation treatment planning for thoracic and abdominal tumors, 4D-MRI has shown promise in respiratory motion characterization with improved soft-tissue contrast compared to clinical standard, 4D computed tomography (4D-CT). This study aimed to further improve vessel-tissue contrast and overall image quality in 3D radial sampling-based 4D-MRI using a slab-selective (SS) excitation approach. METHODS: The technique was implemented in a 3D radial sampling with self-gating-based k-space sorting sequence...
October 4, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28960753/the-impact-of-a-high-definition-multileaf-collimator-for-spine-sbrt
#8
Kelly C Younge, John R Kuchta, Justin K Mikell, Benjamin Rosen, Jeremy S Bredfeldt, Martha M Matuszak
PURPOSE: Advanced radiotherapy delivery systems designed for high-dose, high-precision treatments often come equipped with high-definition multi-leaf collimators (HD-MLC) aimed at more finely shaping radiation dose to the target. In this work, we study the effect of a high definition MLC on spine stereotactic body radiation therapy (SBRT) treatment plan quality and plan deliverability. METHODS AND MATERIALS: Seventeen spine SBRT cases were planned with VMAT using a standard definition MLC (M120), HD-MLC, and HD-MLC with an added objective to reduce monitor units (MU)...
September 27, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28960724/forward-treatment-planning-techniques-to-reduce-the-normalization-effect-in-gamma-knife-radiosurgery
#9
Hao-Wen Cheng, Wei-Lun Lo, Chun-Yuan Kuo, Yu-Kai Su, Jo-Ting Tsai, Jia-Wei Lin, Yu-Jen Wang, David Hung-Chi Pan
In Gamma Knife forward treatment planning, normalization effect may be observed when multiple shots are used for treating large lesions. This effect can reduce the proportion of coverage of high-value isodose lines within targets. The aim of this study was to evaluate the performance of forward treatment planning techniques using the Leksell Gamma Knife for the normalization effect reduction. We adjusted the shot positions and weightings to optimize the dose distribution and reduce the overlap of high-value isodose lines from each shot, thereby mitigating the normalization effect during treatment planning...
September 27, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28960696/real-time-intrafraction-prostate-motion-during-linac-based-stereotactic-radiotherapy-with-rectal-displacement
#10
Kimberley Legge, Doan Nguyen, Jin Aun Ng, Lee Wilton, Matthew Richardson, Jeremy Booth, Paul Keall, Darryl J O'Connor, Peter Greer, Jarad Martin
BACKGROUND: Kilovoltage Intrafraction Monitoring (KIM) is a method which determines the three-dimensional position of the prostate from two-dimensional kilovoltage (kV) projections taken during linac based radiotherapy treatment with real-time feedback. Rectal displacement devices (RDDs) allow for improved rectal dosimetry during prostate cancer treatment. This study used KIM to perform a preliminary investigation of prostate intrafraction motion observed in patients with an RDD in place...
September 27, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28944980/failure-mode-and-effects-analysis-a-community-practice-perspective
#11
Bradley W Schuller, Angi Burns, Elizabeth A Ceilley, Alan King, Joan LeTourneau, Alexander Markovic, Lynda Sterkel, Brigid Taplin, Jennifer Wanner, Jeffrey M Albert
PURPOSE: To report our early experiences with failure mode and effects analysis (FMEA) in a community practice setting. METHODS: The FMEA facilitator received extensive training at the AAPM Summer School. Early efforts focused on department education and emphasized the need for process evaluation in the context of high profile radiation therapy accidents. A multidisciplinary team was assembled with representation from each of the major department disciplines. Stereotactic radiosurgery (SRS) was identified as the most appropriate treatment technique for the first FMEA evaluation, as it is largely self-contained and has the potential to produce high impact failure modes...
September 25, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28944979/dosimetric-validation-of-monaco-treatment-planning-system-on-an-elekta-versahd-linear-accelerator
#12
Ganesh Narayanasamy, Daniel L Saenz, Dewayne Defoor, Niko Papanikolaou, Sotirios Stathakis
The purpose of this study is to perform dosimetric validation of Monaco treatment planning system version 5.1. The Elekta VersaHD linear accelerator with high dose rate flattening filter-free photon modes and electron energies was used in this study. The dosimetric output of the new Agility head combined with the FFF photon modes warranted this investigation into the dosimetric accuracy prior to clinical usage. A model of the VersaHD linac was created in Monaco TPS by Elekta using commissioned beam data including percent depth dose curves, beam profiles, and output factors...
September 25, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28921910/100-days-with-scans-of-the-same-catphan-phantom-on-the-same-ct-scanner
#13
Ellen Husby, Elisabeth D Svendsen, Hilde K Andersen, Anne Catrine T Martinsen
Quality control (QC) of CT scanners is important to evaluate image quality and radiation dose. Different QC phantoms for testing image quality parameters on CT are commercially available, and Catphan phantoms are widely used for this purpose. More data from measured image quality parameters on CT are necessary to assess test methods, tolerance levels, and test frequencies. The aim of this study was to evaluate the stability of essential image quality parameters for axial and helical scans on one CT scanner over time...
September 18, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28921881/use-of-a-radial-projection-to-reduce-the-statistical-uncertainty-of-spot-lateral-profiles-generated-by-monte-carlo-simulation
#14
Xiaoning Ding, Wei Liu, Jiajian Shen, Aman Anand, Joshua B Stoker, Yanle Hu, Martin Bues
Monte Carlo (MC) simulation has been used to generate commissioning data for the beam modeling of treatment planning system (TPS). We have developed a method called radial projection (RP) for postprocessing of MC-simulation-generated data. We used the RP method to reduce the statistical uncertainty of the lateral profile of proton pencil beams with axial symmetry. The RP method takes advantage of the axial symmetry of dose distribution to use the mean value of multiple independent scores as the representative score...
September 18, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28921843/potential-proton-and-photon-dose-degradation-in-advanced-head-and-neck-cancer-patients-by-intratherapy-changes
#15
Kristin Stützer, Annika Jakobi, Anna Bandurska-Luque, Steffen Barczyk, Carolin Arnsmeyer, Steffen Löck, Christian Richter
PURPOSE: Evaluation of dose degradation by anatomic changes for head-and-neck cancer (HNC) intensity-modulated proton therapy (IMPT) relative to intensity-modulated photon therapy (IMRT) and identification of potential indicators for IMPT treatment plan adaptation. METHODS: For 31 advanced HNC datasets, IMPT and IMRT plans were recalculated on a computed tomography scan (CT) taken after about 4 weeks of therapy. Dose parameter changes were determined for the organs at risk (OARs) spinal cord, brain stem, parotid glands, brachial plexus, and mandible, for the clinical target volume (CTV) and the healthy tissue outside planning target volume (PTV)...
September 18, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28905514/dosimetric-characterization-of-gms-bt-125-1-125-i-radioactive-seed-with-monte-carlo-simulations-and-experimental-measurement
#16
Nan Zhao, Ruijie Yang, Li Ren, Yi Fan, Junli Li, Jianguo Zhang
PURPOSE: To investigate the dosimetric characteristics of the new GMS BT-125-1 (125) I radioactive seed, including dose rate constant, radial dose functions, and anisotropy functions. METHODS: Dosimetric parameters of GMS BT-125-1 (125) I seed including dose rate constant, radial dose functions, and anisotropy functions were calculated using the Monte Carlo code of MCNP5, and measured with thermoluminescent dosimeters (TLDs). The results were compared with those of PharmaSeed BT-125-1, PharmaSeed BT-125-2 (125) I, and model 6711 (125) I seeds...
September 14, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28901729/magnetic-field-dose-effects-on-different-radiation-beam-geometries-for-hypofractionated-partial-breast-irradiation
#17
Anthony Kim, Stephanie Lim-Reinders, Claire McCann, Syed Bilal Ahmad, Arjun Sahgal, Justin Lee, Brian M Keller
PURPOSE: Hypofractionated partial breast irradiation (HPBI) involves treatment to the breast tumor using high doses per fraction. Recent advances in MRI-Linac solutions have potential in being applied to HPBI due to gains in the soft tissue contrast of MRI; however, there are potentially deleterious effects of the magnetic field on the dose distribution. The purpose of this work is to determine the effects of the magnetic field on the dose distribution for HPBI tumors using a tangential beam arrangement (TAN), 5-beam intensity-modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT)...
September 13, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28901684/comparison-of-initial-patient-setup-accuracy-between-surface-imaging-and-three-point-localization-a-retrospective-analysis
#18
Dennis N Stanley, Kristen A McConnell, Neil Kirby, Alonso N Gutiérrez, Nikos Papanikolaou, Karl Rasmussen
PURPOSE: Historically, the process of positioning a patient prior to imaging verification used a set of permanent patient marks, or tattoos, placed subcutaneously. After aligning to these tattoos, plan specific shifts are applied and the position is verified with imaging, such as cone-beam computed tomography (CBCT). Due to a variety of factors, these marks may deviate from the desired position or it may be hard to align the patient to these marks. Surface-based imaging systems are an alternative method of verifying initial positioning with the entire skin surface instead of tattoos...
September 13, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28901659/using-gamma-index-to-flag-changes-in-anatomy-during-image-guided-radiation-therapy-of-head-and-neck-cancer
#19
Bryan Schaly, Jeff Kempe, Varagur Venkatesan, Sylvia Mitchell, Jerry J Battista
During radiation therapy of head and neck cancer, the decision to consider replanning a treatment because of anatomical changes has significant resource implications. We developed an algorithm that compares cone-beam computed tomography (CBCT) image pairs and provides an automatic alert as to when remedial action may be required. Retrospective CBCT data from ten head and neck cancer patients that were replanned during their treatment was used to train the algorithm on when to recommend a repeat CT simulation (re-CT)...
September 13, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28895282/a-patient-safety-education-program-in-a-medical-physics-residency
#20
Eric C Ford, Matthew Nyflot, Matthew B Spraker, Gabrielle Kane, Kristi R G Hendrickson
Education in patient safety and quality of care is a requirement for radiation oncology residency programs according to accrediting agencies. However, recent surveys indicate that most programs lack a formal program to support this learning. The aim of this report was to address this gap and share experiences with a structured educational program on quality and safety designed specifically for medical physics therapy residencies. Five key topic areas were identified, drawn from published recommendations on safety and quality...
September 12, 2017: Journal of Applied Clinical Medical Physics
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