Comparison of dose distribution between intensity modulated radiation therapy and dynamic arc therapy in and out-of-field for prostate cancer treatment plan

Abstract

Introduction The aim of this study is to compare intensity modulated radiation therapy (IMRT) and dynamic conformal arc therapy (DAT) for prostate cancer treatments. Doses received by in-field and out-of-field organs were estimated for both techniques. Materials and methods We selected five patients with a prostate cancer and we simulated their treatment by IMRT and DAT A 6-beam (6MV) ballistic was used for the IMRT treatment whereas a 4-arc (6MV) ballistic was used for the DAT. Dose volume histograms (DVHs), were computed OARs and Remaining Volume at Risk (RVR) for both techniques, and estimates of the dose out-of-field for twelve anatomical sites were analyzed and compared between the two techniques. The out-of-field dose was performed using experimental data from previous work. Results The mean increase for the RVR included between 2–45 Gy for IMRT was about 1434 cm 3 as compared to DAT. On the other hand, IMRT significantly increased the irradiated volume of the rectum wall in the dose range of 2–60 Gy and also significantly increased the irradiated volume of bladder wall. However the IMRT significantly reduced the dose to the femoral heads compared to the DAT. For both techniques, the dose to the PTV remained similar. For the twelve out-of-field anatomical sites evaluated, ratio between the estimated doses for both techniques varies between 1.01 and 1.1, DAT leading to the lower doses. Conclusion DAT improves the treatment of the prostate cancer by reducing the doses not only to the OARs but also to the RVR.