Evaluating dosimetric outcomes: a comparison of CyberKnife, VMAT FFF, and Helical Tomotherapy Radixact for treating localized prostate cancer.

Abstract

Prostate cancer (PCa) remains one of the most frequently diagnosed malignancies in men globally, ranking second in prevalence, with increasing incidence anticipated due to aging populations. Radiotherapy has emerged as a cornerstone treatment for localized PCa with stereotactic body radiation therapy (SBRT), and it offers a promising approach by delivering highly conformal high-dose radiation in fewer fractions. This study compares the dosimetric outcomes of three SBRT techniques-CyberKnife (CK), Volumetric Modulated Arc Therapy with flattening filter-free mode (VMAT FFF), and Helical Tomotherapy Radixact (HT)-for localized PCa. The investigation evaluates dose distribution characteristics, sparing of organs at risk (OARs), and treatment delivery efficiency. Two patient groups with low-to-intermediate-risk localized PCa treated at the Istituto Nazionale Tumori-IRCCS Fondazione G. Pascale were included. Treatment plans for CK, VMAT FFF, and HT were retrospectively generated and analyzed using dosimetric metrics such as Conformity Index (CI), Homogeneity Index (HI), Gradient Index, and dose-volume constraints for OARs. Results revealed comparable target coverage across all techniques, with CK demonstrating superior dose conformity and VMAT FFF achieving shorter treatment times. HT and VMAT FFF are effective alternatives, particularly for centers without access to CK systems, though CK offered advantages in challenging anatomical scenarios. Findings emphasize the feasibility of VMAT FFF and HT as viable options for expanding SBRT accessibility, enabling high-quality treatment delivery in diverse clinical settings.