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.