Dosimetric and Radiobiological Comparison of Three-Dimensional Conformal Radiotherapy and Helical Tomotherapy in...

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.

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.

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.

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.

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.