Download or read book A study on the dosimetric properties of an epid dosimetry system for pre-treatment dynamic IMRT quality assurance written by Sandy D. Villaruz and published by . This book was released on 2017 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: Portal dosimetry offers a convenient assessment tool for patient-specific quality assurance (QA) of Intensity Modulated Radiation Therapy (IMRT) treatment plans. However, the criteria for acceptability of each test as part of the QA process for IMRT plans have not yet been established. This study, therefore, aimed to investigate the dosimetric properties of the aS1000 portal dosimetry system and to come up with specific equipment parameters for routine IMRT pretreatment QA in our institution. This study intended to establish a protocol to serve as a sound basis for setting clinical action levels in standardizing the evaluation of Electronic Portal Imaging Device (EPID)-based pre-treatment IMRT QA. It focused on the calibration and characterization of an in-house portal dosimetry system as well as the comparison of Eclipse treatment planning system (TPS) predicted portal dose image to EPID measured dose image. A 6 MV Varian Unique Linear Accelerator equipped with an amorphous silicon (a-Si) flat panel imager was used in this study. The dosimetric characteristics which include reproducibility, dose-response behavior, dose rate dependence, field size dependence, gantry angle dependence, inverse square law agreement, and pixel uniformity of the PortalVision as1000 EPID for verification of pre-treatment dynamic IMRT delivery were investigated. Portal dose image measurements were then compared with the Eclipse predicted dose images. Planar dose comparison was carried out with gamma criteria of 3% for dose difference and a distance-toagreement of 3mm. The use of EPID for treatment verification is less time consuming, easier to set-up and is fully automated. Basing from the results, portal dosimetry is a promising tool for pre-treatment dynamic IMRT QA in our institution.