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Journal of Applied Clinical Medical Physics

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https://www.readbyqxmd.com/read/30221462/development-of-a-dedicated-phantom-for-multi-target-single-isocentre-stereotactic-radiosurgery-end-to-end-testing
#1
Joel Poder, Ryan Brown, Harry Porter, Rashmi Gupta, Anna Ralston
PURPOSE: The aim of this project was to design and manufacture a cost-effective end-to-end (E2E) phantom for quantifying the geometric and dosimetric accuracy of a linear accelerator based, multi-target single-isocenter (MTSI) frameless stereotactic radiosurgery (SRS) technique. METHOD: A prespex Multi-Plug device from a Sun Nuclear ArcCheck phantom (Sun Nuclear, Melbourne, FL) was enhanced to make it more applicable for MTSI SRS E2E testing. The following steps in the SRS chain were then analysed using the phantom: magnetic resonance imaging (MRI) distortion, planning computed tomography (CT) scan and MRI image registration accuracy, phantom setup accuracy using CBCT, dosimetric accuracy using ion chamber, planar film dose measurements and coincidence of linear accelerator mega-voltage (MV), and kilo-voltage (kV) isocenters using Winston-Lutz testing (WLT)...
September 16, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/30220111/partially-ablative-radiotherapy-par-for-large-mass-tumors-using-simultaneous-integrated-boost-a-dose-escalation-feasibility-study
#2
Savino Cilla, Francesco Deodato, Anna Ianiro, Gabriella Macchia, Vincenzo Picardi, Milly Buwenge, Silvia Cammelli, Alice Zamagni, Vincenzo Valentini, Alessio G Morganti
PURPOSE: This study aimed to assess the feasibility to plan and deliver highly heterogeneous doses to symptomatic large tumors using volumetric modulated arc therapy (VMAT) and simultaneous integrated boost (SIB) during a short course palliative accelerated radiotherapy. METHODS: A patient with a large symptomatic chordoma infiltrating the right gluteal region was selected. A modified SIB treatment was implemented to irradiate the central volume of the tumor (boost target volume, BTV) up to 10 Gy/fraction in a dose escalation trial while maintaining the remaining tumor volume (planning target volume, PTV) and the surrounding healthy tissues within 5 Gy/fraction in twice daily fractions for two consecutive days...
September 15, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/30216702/detectors-assessment-for-stereotactic-radiosurgery-with-cones
#3
Nicolas Garnier, Régis Amblard, Rémy Villeneuve, Rodolphe Haykal, Cécile Ortholan, Philippe Colin, Anaïs Gérard, Sarah Belhomme, Franck Mady, Mourad Benabdesselam, Benjamin Serrano
The purpose of this work is to assess eight detectors performance for output factor (OF), percent depth dose (PDD), and beam profiles in a 6-MV Clinac stereotactic radiosurgery mode for cone irradiation using Monte Carlo simulation as reference. Cones with diameters comprised between 30 and 4 mm have been studied. The evaluated detectors were ionization chambers: pinpoint and pinpoint 3D, diodes: SRS, P and E, Edge, MicroDiamond and EBT3 radiochromic films. The results showed that pinpoints underestimate OF up to -2...
September 14, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/30216639/using-max-standardized-uptake-value-from-positron-emission-tomography-to-assess-tumor-responses-after-lung-stereotactic-body-radiotherapy-for-different-prescriptions
#4
Meisong Ding, William Zollinger, Robert Ebeling, David Heard, Ryan Posey
PURPOSE: To retrospectively investigate tumor responses of lung SBRT patients for different prescriptions. To analyze the relation between optimal biologically equivalent dose (BED) and tumor responses. METHODS AND MATERIALS: Tumor responses after lung SBRT were compared by examining 48 treatments used four prescriptions. This study used simplified tumor response criteria: (a) Complete Response (CR) - post max SUV (SUVpost ) after SBRT in the treated tumor region was almost the same as the SUVs in the surrounding regions; (b) Partial Response (PR) - SUVpost was smaller than previous max SUV (SUVpre ), but was greater than the SUVs in the surrounding regions; (c) No Response (NR) - SUVpost was the same as or greater than SUVpre ...
September 14, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/30207053/impact-of-a-novel-exponential-weighted-4dct-reconstruction-algorithm
#5
Eric D Morris, Joshua P Kim, Paul Klahr, Carri K Glide-Hurst
PURPOSE: This work characterizes a novel exponential 4DCT reconstruction algorithm (EXPO), in phantom and patient, to determine its impact on image quality as compared to the standard cosine-squared weighted 4DCT reconstruction. METHODS: A motion platform translated objects in the superior-inferior (S-I) direction at varied breathing rates (8-20 bpm) and couch pitches (0.06-0.1) to evaluate interplay between parameters. Ten-phase 4DCTs were acquired and data were reconstructed with cosine squared and EXPO weighting...
September 11, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/30199127/the-dosimetric-effect-of-electron-density-overrides-in-3dcrt-lung-sbrt-for-a-range-of-lung-tumor-dimensions
#6
Grace E A Healy, Steven H Marsh, Andrew T Cousins
The combined effects of lung tumor motion and limitations of treatment planning system dose calculations in lung regions increases uncertainty in dose delivered to the tumor and surrounding normal tissues in lung stereotactic body radiotherapy (SBRT). This study investigated the effect on plan quality and accuracy when overriding treatment volume electron density values. The QUASAR phantom with modified cork cylindrical inserts, each containing a simulated spherical tumor of 15-mm, 22-mm, or 30-mm diameter, was used to simulate lung tumor motion...
September 10, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/30188009/equivalency-of-beam-scan-data-collection-using-a-1d-tank-and-automated-couch-movements-to-traditional-3d-tank-measurements
#7
Nels C Knutson, Matthew C Schmidt, Matthew D Belley, Ngoc Nguyen, Michael Price, Sasa Mutic, Erno Sajo, H Harold Li
This work shows the feasibility of collecting linear accelerator beam data using just a 1-D water tank and automated couch movements with the goal to maximize the cost effectiveness in resource-limited clinical settings. Two commissioning datasets were acquired: (a) using a standard of practice 3D water tank scanning system (3DS) and (b) using a novel technique to translate a commercial TG-51 complaint 1D water tank via automated couch movements (1DS). The Extensible Markup Language (XML) was used to dynamically move the linear accelerator couch position (and thus the 1D tank) during radiation delivery for the acquisition of inline, crossline, and diagonal profiles...
September 6, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/30187997/regarding-the-parallel-opposed-editorial-about-3d-printing-technology-will-eventually-eliminate-the-need-of-purchasing-commercial-phantoms-for-clinical-medical-physics-qa-procedures
#8
LETTER
Marius Treutwein
No abstract text is available yet for this article.
September 6, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/30182461/cone-beam-ct-for-qa-of-synthetic-ct-in-mri-only-for-prostate-patients
#9
Emilia Palmér, Emilia Persson, Petra Ambolt, Christian Gustafsson, Adalsteinn Gunnlaugsson, Lars E Olsson
PURPOSE: Magnetic resonance imaging (MRI)-only radiotherapy is performed without computed tomography (CT). A synthetic CT (sCT) is used for treatment planning. The aim of this study was to develop a clinically feasible quality assurance (QA) procedure for sCT using the kV-cone beam CT (CBCT), in an MRI-only workflow for prostate cancer patients. MATERIAL AND METHOD: Three criteria were addressed; stability in Hounsfield Units (HUs), deviations in HUs between the CT and CBCT, and validation of the QA procedure...
September 4, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/30178521/evaluation-of-the-truebeam-machine-performance-check-mpc-obi-x-ray-tube-alignment-procedure
#10
Michael P Barnes, Dennis Pomare, Frederick W Menk, Buiron Moraro, Peter B Greer
Alignment of the On-Board Imager (OBI) X-ray tube is important for ensuring imaging to treatment isocenter coincidence, which in turn is important for accurate Image Guided Radiotherapy (IGRT). Varian introduced a new X-ray tube alignment procedure for the TrueBeam linac in software version 2.5 MR2 as part of the machine performance check (MPC) application. This study evaluated the new procedure against conventional methods and examined the clinical significance of X-ray tube misalignment. Long term stability and short term repeatability of MPC tube alignment was assessed as well as sensitivity of the method to setup error...
September 3, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/30160025/framework-for-the-quantitative-assessment-of-adaptive-radiation-therapy-protocols
#11
Sarah Weppler, Harvey Quon, Robyn Banerjee, Colleen Schinkel, Wendy Smith
BACKGROUND: Adaptive radiation therapy (ART) "flags," such as change in external body contour or relative weight loss, are widely used to identify which head and neck cancer (HNC) patients may benefit from replanned treatment. Despite the popularity of ART, few published quantitative approaches verify the accuracy of replan candidate identification, especially with regards to the simple flagging approaches that are considered current standard of practice. We propose a quantitative evaluation framework, demonstrated through the assessment of a single institution's clinical ART flag: change in body contour exceeding 1...
August 29, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/30141230/contour-based-lung-dose-prediction-for-breast-proton-therapy
#12
Chuan Zeng, Kevin Sine, Dennis Mah
PURPOSE: This study evaluates the feasibility of lung dose prediction based on target contour and patient anatomy for breast patients treated with proton therapy. METHODS: Fifty-two randomly selected patients were included in the cohort, who were treated to 50.4-66.4 Gy(RBE) to the left (36), right (15), or bilateral (1) breast with uniform scanning (32) or pencil beam scanning (20). Anterior-oblique beams were used for each patient. The prescription doses were all scaled to 50...
August 23, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/30058170/validation-and-clinical-implementation-of-an-accurate-monte-carlo-code-for-pencil-beam-scanning-proton-therapy
#13
Sheng Huang, Minglei Kang, Kevin Souris, Christopher Ainsley, Timothy D Solberg, James E McDonough, Charles B Simone, Liyong Lin
Monte Carlo (MC)-based dose calculations are generally superior to analytical dose calculations (ADC) in modeling the dose distribution for proton pencil beam scanning (PBS) treatments. The purpose of this paper is to present a methodology for commissioning and validating an accurate MC code for PBS utilizing a parameterized source model, including an implementation of a range shifter, that can independently check the ADC in commercial treatment planning system (TPS) and fast Monte Carlo dose calculation in opensource platform (MCsquare)...
July 30, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/29984464/an-interactive-plan-and-model-evolution-method-for-knowledge-based-pelvic-vmat-planning
#14
Meijiao Wang, Sha Li, Yuliang Huang, Haizhen Yue, Tian Li, Hao Wu, Song Gao, Yibao Zhang
PURPOSE: To test if a RapidPlan DVH estimation model and its training plans can be improved interactively through a closed-loop evolution process. METHODS AND MATERIALS: Eighty-one manual plans (P0 ) that were used to configure an initial rectal RapidPlan model (M0 ) were reoptimized using M0 (closed-loop), yielding 81 P1 plans. The 75 improved P1 (P1+ ) and the remaining 6 P0 were used to configure model M1 . The 81 training plans were reoptimized again using M1 , producing 23 P2 plans that were superior to both their P0 and P1 forms (P2+ )...
July 8, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/29935001/single-institution-report-of-setup-margins-of-voluntary-deep-inspiration-breath-hold-dibh-whole-breast-radiotherapy-implemented-with-real-time-surface-imaging
#15
Annie Xiao, Jennie Crosby, Martha Malin, Hyejoo Kang, Maxine Washington, Yasmin Hasan, Steven J Chmura, Hania A Al-Hallaq
PURPOSE: We calculated setup margins for whole breast radiotherapy during voluntary deep-inspiration breath-hold (vDIBH) using real-time surface imaging (SI). METHODS AND MATERIALS: Patients (n = 58) with a 27-to-31 split between right- and left-sided cancers were analyzed. Treatment beams were gated using AlignRT by registering the whole breast region-of-interest to the surface generated from the simulation CT scan. AlignRT recorded (three-dimensional) 3D displacements and the beam-on-state every 0...
June 22, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/29934993/a-simple-method-to-account-for-skin-dose-enhancement-during-treatment-planning-of-vmat-treatments-of-patients-in-contact-with-immobilization-equipment
#16
James Rijken, Tanya Kairn, Scott Crowe, Luis Muñoz, Jamie Trapp
PURPOSE: The ability to accurately predict skin doses and thereby design radiotherapy treatments that balance the likelihood of skin reactions against other treatment objectives is especially important when hypofractionated prescription regimes are used. However, calculations of skin dose provided by many commercial radiotherapy treatment planning systems are known to be inaccurate, especially if the presence of immobilization equipment is not accurately taken into account. This study proposes a simple method by which the accuracy of skin dose calculations can be substantially improved, to allow informed evaluation of volumetric modulated arc therapy (VMAT) treatment plans...
June 22, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/30125454/comparison-of-semiautomated-tangential-vmat-with-3dcrt-for-breast-or-chest-wall-and-regional-nodes
#17
Mikel Byrne, Ben Archibald-Heeren, Yunfei Hu, Andrew Fong, Leena Chong, Amy Teh
Radiotherapy to the breast after surgery sometimes requires adjoining nodes to be included in the treatment volume. In these cases, the traditional approach has been a complex 3-Dimensional Conformal Radiotherapy (3DCRT) beam arrangement which can result in significant dose heterogeneity at the beam junctions. A Volumetric Modulated Arc Therapy (VMAT) beam arrangement has previously been proposed for breast cases, where the chest wall/breast is treated with a limited angle (partial arc) tangential VMAT technique (Virén et al...
September 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/30125453/second-cancer-risk-after-radiation-therapy-of-ependymoma-using-the-flattening-filter-free-irradiation-mode-of-a-linear-accelerator
#18
Judit Alvarez Moret, Tina Obermeier, Fabian Pohl, Rainer Loeschel, Oliver Koelbl, Barbara Dobler
Pediatric patients suffering from ependymoma are usually treated with cranial or craniospinal three-dimensional (3D) conformal radiotherapy (3DCRT). Intensity-modulated techniques spare dose to the surrounding tissue, but the risk for second malignancies may be increased due to the increase in low-dose volume. The aim of this study is to investigate if the flattening filter free (FFF) mode allows reducing the risk for second malignancies compared to the mode with flattening filter (FF) for intensity-modulated techniques and to 3DCRT...
September 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/30117641/investigating-a-novel-split-filter-dual-energy-ct-technique-for-improving-pancreas-tumor-visibility-for-radiation-therapy
#19
Lianna D Di Maso, Jessie Huang, Michael F Bassetti, Larry A DeWerd, Jessica R Miller
PURPOSE: Tumor delineation using conventional CT images can be a challenge for pancreatic adenocarcinoma where contrast between the tumor and surrounding healthy tissue is low. This work investigates the ability of a split-filter dual-energy CT (DECT) system to improve pancreatic tumor contrast and contrast-to-noise ratio (CNR) for radiation therapy treatment planning. MATERIALS AND METHODS: Multiphasic scans of 20 pancreatic tumors were acquired using a split-filter DECT technique with iodinated contrast medium, OMNIPAQUETM ...
September 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/30117273/medical-physics-3-0-versus-1-0-a-case-study-in-digital-radiography-quality-control
#20
Diana E Carver, Charles E Willis, Paul J Stauduhar, Thomas K Nishino, Jered R Wells, Ehsan Samei
PURPOSE: The study illustrates how a renewed approach to medical physics, Medical Physics 3.0 (MP3.0), can identify performance decrement of digital radiography (DR) systems when conventional Medical Physics 1.0 (MP1.0) methods fail. METHODS: MP1.0 tests included traditional annual tests plus the manufacturer's automated Quality Assurance Procedures (QAP) of a DR system before and after a radiologist's image quality (IQ) complaint repeated after service intervention...
September 2018: Journal of Applied Clinical Medical Physics
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