Comparison of two pre-treatment verification methods for arc – IMRT plans

Abstract

In radiotherapy, the application of the IMRT arc technique, a special technique of external beam irradiation, while providing greater ballistic accuracy and personalization of treatment, as well as better speed of execution, requires special attention to the development of the treatment plan and its verification.Therefore, tools and methods of physical-health analysis that allow verification of the accuracy of the delivery of the radiant beam in the stages prior to treatment are essential. At the unit of Medical Physics at Dimiccoli Hospital Barletta, a prospective experimental study was conducted based on the comparison of two different methods of pre-treatment verification in patients treated for prostate cancer with the aim of increasing the performance of the treatment workflow.A comparative evaluation of gamma analysis results on images acquired with a 2D flat panel detector EPID (Electronic Portal Imaging Device) on the one hand and a 2D ionizing chambers detector on the other hand was conducted. The study sample included 38 patients undergoing radiotherapy with IMRT between December 2021 and October 2022, and each subject was studied and verified with both methods.The results of gamma analysis conducted with the two methods of pre-treatment verification of patients with prostate cancer are superimposable. In addition, with EPID we have a significant saving of machine time and thus allows an increase in the number of patients undergoing daily radiotherapy.In light of internationally accepted dosimetric and radiation protection accuracy standards according to Decree 101/2020, pre-treatment verification of dose distributions, using a 2D flat panel detection system (EPID), was found to be in line with waiting list reduction goals.