Could the Fluence Smoothing Parameter Impact the VMAT Planning for Cervical Cancer?

Background/Objectives Optimizing Volumetric Modulated Arc Therapy (VMAT) for cervical cancer is crucial in modern radiation therapy. This study examines the impact of the fluence smoothing parameter. This key factor significantly influences the quality and efficiency of VMAT plans, which allow precise dose delivery while sparing healthy tissues. Material & Methods A retrospective analysis of 15 cervical cancer patients treated with VMAT was conducted. For each patient, four treatment plans with varying fluence levels (low, medium, high, off) were created, keeping other parameters constant. Dosimetric parameters, including target coverage (Dmean, Dmax, conformity index, homogeneity index) and organ-at-risk dosing, were evaluated. Treatment efficiency metrics, such as control points, monitor units, and plan calculation time, were also assessed. Statistical analyses were performed using the Wilcoxon signed-rank test. Result The findings of this study indicate that selecting different fluence smoothing levels had no statistically significant effect on the PTV and OAR doses. However, there was a statistically significant impact on the monitor units (MU) and control points of the VMAT plans. Specifically, as smoothness increased, the MU, control points, and plan complexity (PCT) decreased. Conclusion Upon analyzing the quality of the treatment plans and their delivery efficiency, it is evident that higher fluence smoothing values demonstrate better characteristics for cervical cancer treatment plans.