Implementation and validation of a commercial portal dosimetry software for intensity-modulated radiation therapy pre-treatment verification

Abstract

Electronic portal imaging devices (EPIDs) are extensively used for obtaining dosimetric information of pre-treatment field verification and in-vivo dosimetry for intensity-modulated radiotherapy (IMRT). In the present study, we have implemented the newly developed portal dosimetry software using independent dose prediction algorithm EPIDose TM and evaluated this new tool for the pre-treatment IMRT plan quality assurance of Whole Pelvis with Simultaneous Integrated Boost (WP-SIB-IMRT ) of prostate cases by comparing with routine two-dimensional (2D) array detector system (MapCHECK TM ). We have investigated 104 split fields using g-distributions in terms of predefined g frequency parameters. The mean γ values are found to be 0.42 (SD: 0.06) and 0.44 (SD: 0.06) for the EPIDose and MapCHECK TM , respectively. The average g∆ for EPIDose and MapCHECK TM are found as 0.51 (SD: 0.06) and 0.53 (SD: 0.07), respectively. Furthermore, the percentage of points with g < 1, γ < 1.5, and γ > 2 are 97.4%, 99.3%, and 0.56%, respectively for EPIDose and 96.4%, 99.0% and 0.62% for MapCHECK TM . Based on our results obtained with EPIDose and strong agreement with MapCHECK TM , we may conclude that the EPIDose portal dosimetry system has been successfully implemented and validated with our routine 2D array detector

Keywords

• 2D-array detector
• Electronic portal imaging device
• intensity-modulated radiotherapy
• portal dosimetry