Investigating the Influence of Minimum Segment Width in Volumetric-modulated Arc Planning of Prostate Cancer
Nidhi JAIN1,Alok KUMAR2,Ashok KUMAR1
1Department of Physics, Amity University, Noida-India
2Department of Radiation Oncology, Netaji Subhas Chandra Bose Cancer Hospital, Kolkata-India
DOI : 10.5505/tjo.2023.4137 OBJECTIVE
This study aims to investigate the impact of the minimum segment width on the planning outcomes of volumetric-modulated arc therapy (VMAT) in patients with prostate cancer and find the optimum value(s) for this parameter.

A retrospective analysis was conducted on 12 patients with prostate cancer who underwent VMAT treatment. For every patient, four treatment plans were created using different values of MSW (0.5 cm, 1.0 cm, 1.5 cm, and 2.0 cm). Other optimization parameters and objective constraints were kept the same across every case. Several dosimetric parameters were evaluated, including target coverage (Dmean - Mean dose to the planning target volumes [PTV], Dmax - Maximum dose to the PTV, conformity index, homogeneity index) and dose to the organ at risk. In addition, delivery efficiency metrics such as the number of control points, monitor units, and treatment time were assessed. Statistical analyses were performed using Wilcoxon signed-rank test.

Narrower segments (MSW0.5) yielded improved PTV coverage and conformity, while wider segments (MSW2.0) led to faster treatment delivery but compromised dosimetric parameters. There was no statistically significant difference between MSW0.5 and MSW1.0 (p>0.05) while the other MSW values showed statistically significant differences (p<0.05).

Based on the analysis of the plan quality and delivery efficiency, an MSW value of 1.0 cm exhibits optimal features in prostate cancer treatment plans. Further investigation with a larger number of patients and assessment of clinical outcomes is necessary to validate this conclusion. Keywords : Minimum segment width; MSW; prostate cancer; VMAT; volumetric-modulated arc planning