Abstract
This study reports on our experience with the in-vivo dose verification software, EPIgray® (DOSIsoft, Cachan, France). After the initial commissioning process, clinical experiments on phantom treatments were evaluated to assess the level of accuracy of the electronic portal imaging device (EPID) based in-vivo dose verification.EPIgray was commissioned based on the company’s instructions. This involved ion chamber measurements and portal imaging of solid water blocks of various thicknesses between 5 and 35 cm. Field sizes varied between 2 x 2 cm2 and 20 x 20 cm2. The determined conversion factors were adjusted through an additional iterative process using treatment planning system calculations. Subsequently, evaluation was performed using treatment plans of single and opposed beams, as well as intensity modulated radiotherapy (IMRT) plans, based on recommendations from the task group report TG-119 to test for dose reconstruction accuracy. All tests were performed using blocks of solid water slabs as a phantom.For single square fields, the dose at isocenter was reconstructed within 3% accuracy in EPIgray compared to the treatment planning system dose. Similarly, the relative deviation of the total dose was accurately reconstructed within 3% for all IMRT plans with points placed inside a high-dose region near the isocenter. Predictions became less accurate than < 5% when the evaluation point was outside the treatment target. Dose at points 5 cm or more away from the isocenter or within an avoidance structure was reconstructed less reliably.EPIgray formalism accuracy is adequate for an efficient error detection system with verifications performed in high-dose volumes. It provides immediate intra-fractional feedback on the delivery of treatment plans without affecting the treatment beam. Besides the EPID, no additional hardware is required. The software evaluates local point dose measurements to verify treatment plan delivery and patient positioning within 5% accuracy, depending on the placement of evaluation points.
Highlights
Electronic portal imaging has been established since the 1950s; modern electronic portal imaging devices (EPIDs), which led to a wider spread of commercialization of
Extensive research has focused on amorphous silicon detectors, which led to Varian Medical Systems, Elekta Oncology Systems, and Siemens Medical Systems each integrating EPIDs on their linear accelerators with indirect-detection, active matrix, flat-panels
This study reports on the commissioning and evaluation of a commercially available software product that uses the EPID for in-vivo dosimetry (IVD) during external beam radiotherapy (EBRT)
Summary
Electronic portal imaging has been established since the 1950s; modern electronic portal imaging devices (EPIDs), which led to a wider spread of commercialization of. How to cite this article Held M, Cheung J, Perez Andujar A, et al (February 02, 2018) Commissioning and Evaluation of an Electronic Portal Imaging Device-Based In-Vivo Dosimetry Software. In radiation oncology, their main purpose was to facilitate patient setup on the treatment machine and to monitor the patient alignment during treatment. Compared to portal films, using EPIDs saved time; image quality was considered to be inferior [3]. Extensive research has focused on amorphous silicon (aSi) detectors, which led to Varian Medical Systems, Elekta Oncology Systems, and Siemens Medical Systems each integrating EPIDs on their linear accelerators with indirect-detection, active matrix, flat-panels
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