dosimetric and radiobiological comparison of three-dimensional conformal radiotherapy and helical tomotherapy in whole pelvic radiotherapy of prostate cancer patients

Background: modern radiotherapy techniques can destroy tumors with less harm to surrounding normal tissues. normal tissue complication probability (ntcp) models are useful to evaluate treatment plans.objective: this study aimed to use the quantitative analysis of normal tissue effects in the clinic (quantec) program to evaluate dose-volume indicators and radiobiological parameters for complications of the rectum and bladder in prostate cancer patients undergoing pelvic radiotherapy.material and methods: in this retrospective cross-sectional study, treatment planning information was gathered from 35 patients with pelvic lymph node involvement. of these, 17 and 18 were treated using the three-dimensional conformal radiotherapy technique (3d-crt) and the helical tomotherapy (ht) technique, respectively. the lyman-kutcher-burman and relative seriality models were used in conjunction with dose-volume histograms to calculate the ntcp values for the rectum and bladder.results: in the ht group compared to the 3d-crt group, the values of d-mean, v-40, v-50, v-60, and v-65 were lower for both the rectum and bladder. the ntcp values for grade 2 rectal bleeding, proctitis, and bladder toxicity were lower in the ht group. the dose-volume data of 67% of the ht patients satisfied all quantec criteria, while only 30% of the 3d-crt those met criteria. conclusion: the quantec criteria were satisfied for the rectum and bladder in the ht and 3d-crt groups, except for v-50, v-60, and v-65 of the rectum in 3d-crt patients. the ntcp values for both organs were lower in the ht group than in the 3d-crt group.