The calculation and comparison of integral dose for the rectum, bladder, right and left femur heads in two methods of prostate cancer radiotherapy: S.A.S IMRT vs. 3D CRT

Theaim of radiation therapy treatment planning is to achieve an optimal balancebetween delivering a high dose to target volume and a low dose to healthytissues. In order to refrain any complications resulting from the dose to the surroundingnormal organs, the role of treatment plan has been critically evaluated in termof how large the volume or mass of normal tissues exposed in the radiation. Theintegral dose, hence, is one of the important guidance for predicting the radiationeffects and choosing the treatment plan. The goal of this study is to compareand investigate the integral doses in conformal 3D vs. IMRT plan.Dosimetric data from five patients of prostate cancer, treated bysimultaneous integrated boost IMRT and 3D CRT were evaluated in thisprospective study. Target volume and organs at risk were contoured usingM.I.R.S Treatment Planning System (ModuleIntegrated Radiotherapy System version 5.0.00).A dose of 80 Gy to the PTV1, 57 Gy to RTV2 and 62 Gy to the PTV3 and 70Gy in 3DCRT and for PTV, was prescribed. For each patient IMRT plans using S.A.S(dynamic Step and Shoot) and 3D CRT with 6, 10 and 18MV energies, were done. Tocalculate the ID to the normal healthy tissue all the target volumes wereachieved. The Integral Dose was calculated as the mean- dose times the volumeof the structure. A total of thirty IMRT and 3D CRT plans were performed forevaluation. The mean ID received by rectum for 3D CRT was almost 1.04% greaterthan IMRT while in bladder mean value of ID for IMRT is also bigger than 3D CRTapproximately about 1.04%. In RFH and LFH the mean values of ID for 3D CRT werealmost 1.05% and 1.06% greater than IMRT, respectively. Due to the three PTVsin IMRT the integral dose in target volume has the biggest value comparing with3D CRT, considerably. Keywords: Integral dose, IMRT, 3D CRT,radiotherapy, SIB-IMRT