Enhancing Treatment Efficiency: Investigating the Optimal Segment Width in Volumetric Modulated Arc Therapy for Prostate Cancer Management

Context: The minimum segment width (MSW) is a critical element in designing optimal apertures and creating segments of various sizes and shapes in radiation treatment planning. Aims: This study utilized dose-volume histogram analysis to evaluate the effect of MSW on dose distribution in patients undergoing volumetric modulated arc therapy (VMAT) for prostate cancer. Settings and Design: VMAT plans were generated for 13 prostate cancer patients using 6MV photons in the Monaco treatment planning system. The plans were designed with three different MSW: 0.5 cm, 1.0 cm, and 1.5 cm while keeping all remaining factors constant. Subjects and Methods: The plans for each MSW group were compared based on several criteria: conformity index, homogeneity index, dose to organs at risk, control points, monitor units (MUs), plan execution time, and gamma passing rates (GPRs). Results: Comparing the plans with different MSWs revealed that treatment plans using MSWs of 0.5 cm and 1.0 cm were of higher standard compared to those with an MSW of 1.5 cm. Specifically, planning target volume coverage (V95) significantly decreased with the increase to a 1.5 cm MSW. It was also noted that with an increase in MSW, the overall MUs decreased and the GPR improved. Conclusions: The 0.5 cm and 1.0 cm MSW sets demonstrated superior VMAT plan merit compared to the 1.5 cm MSW set. VMAT plans with a 1.0 cm MSW can be considered the optimal choice, ensuring both high-plan quality and efficient treatment for prostate cases.