Dosimetry audits for passive motion management require dynamically-acquired measurements in a moving phantom to be compared to statically calculated planned doses. This study aimed to characterise the relationship between planning and delivery errors, and the measured dose in the Imaging and Radiation Oncology Core (IROC) thorax phantom, to assess different audit scoring approaches. Treatment plans were created using a 4DCT scan of the IROC phantom, equipped with film and thermoluminescent dosimeters (TLDs). Plans were created on the average intensity projection from all bins. Three levels of aperture complexity were explored: dynamic conformal arcs (DCAT), low-, and high-complexity volumetric modulated arcs (VMATLo, VMATHi). Simulated-measured doses were generated by modelling motion using isocenter shifts. Various errors were introduced including incorrect setup position and target delineation. Simulated-measured film doses were scored using gamma analysis and compared within specifi
Proton therapy enters a new era of efficiency with a software-driven QA solution – Physics World
physicsworld.com - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from physicsworld.com Daily Mail and Mail on Sunday newspapers.
Automated 3D Dose-volume Verification: Gearing Up for Complex Planning scenarios
LAP is prioritizing clinical awareness, uptake and application of the automated 3D dose-check functionality now incorporated into its RadCalc QA software
May 25, 2021 Independent verification always has been, and likely always will be, the core value proposition for RadCalc QA secondary check software. For more than two decades, this suite of widely deployed quality assurance (QA) tools has provided medical physicists and dosimetrists with fully automated and independent dosimetric verification of their radiotherapy treatment planning systems (TPS). What’s more, ongoing product innovation saw the RadCalc value proposition advance significantly last year with the clinical roll-out of automated 3-D dose-volume verification – a result of the successful integration of Monte Carlo and collapsed-cone convolution superposition algorithms into the platform.
Abstract
Purpose: To investigate intrinsic sensitivity of an electronic portal imaging device (EPID) and the ArcCHECK detector and to use this in assessing their performance in detecting delivery variations for lung SBRT VMAT. The effect of detector spatial resolution and dose matrix interpolation on the gamma pass rate was also considered. Materials and methods: Fifteen patients’ lung SBRT VMAT plans were used. Delivery variations (errors) were introduced by modifying collimator angles, multi-leaf collimator (MLC) field sizes and MLC field shifts by ±5, ±2, and ±1 degrees or mm (investigating 103 plans in total). EPID and ArcCHECK measured signals with introduced variations were compared to measured signals without variations (baseline), using OmniPro-I mRT software and gamma criteria of 3%/3 mm, 2%/2 mm, 2%/1 mm, and 1%/1 mm, to test each system s basic performance. The measurement sampling resolution for each was also changed to 1 mm and results compared to those with the de