Results of a Comparative Study on Fast Superposition, Superposition Algorithm in Intensity Modulated Radiotherapy Techniques for Prostate Cancer

This study aims to compare the dosimetric coverage of the Planning Target Volume (PTV) and the dose to main organs at risk (OARs) between two dif-ferent algorithms fast superposition (FSUP), superposition (SUP) using in-tensity-modulated radiotherapy (IMRT) techniques for prostate cancer. Ten patients with prostate cancer were selected for this study. For each patient, IMRT plans were created with 6 MV photon beam quality using CMS XiO treatment planning system. The delivery of IMRT was carried out using the step and shoot techniques. The dose coverage for each patient was designated to an ICRU report 62 reference point in the PTV, medium coverage of the planned target volume to be 95% of the prescribed dose while the maximum dose in the target volume to be not greater than 107% of the prescribed dose. A hypofractionated prescription dose of 70 Gy/28# at 2.5 Gy per fraction was used. For target, this evalua-tion was made with comparing the conformity index (CI) and homogeneity index (HI). The results of the present study showed the OARs got less dose from the SUP algorithm compared to FSUP algorithms. Statistically not significant difference was observed in V107% of PTV, MU/CC, conformity Index (p = 0.057, p = 0.215, p = 0.370) and 95% PTV Volume received prescription dose from both Plans. For prostate cancer, the superposition algorithm showed better results in the IMRT plan compared to the fast superposition algorithm.