Dosimetric effects related to collimator angle optimization in intensity‐modulated radiotherapy planning for gastric cancer

Abstract

AbstractObjectiveTo investigate the dosimetric impact of different collimator angle optimization methods in intensity‐modulated radiotherapy of gastric cancer.MethodsA total of 10 gastric cases were retrospectively selected in this study. Three sets of plans were generated with different collimator angle optimization: setting the collimator angle to 0° (CL0), applying Eclipse automatic collimator angle optimization (CLA), and setting the collimator angle corresponding to the minimum X‐jaw gap (CLX). Different dosimetric metrics were applied in comparison of the target volume and normal tissues. Delivery efficiency was accessed in terms of control points, split fields, monitor units, and treatment time. All plans were verified using the 2‐D array MatriXX, and the γ‐index analysis was carried out by using different criteria.ResultsThere was no significant difference in dosimetric comparison of planning target volume and organs at risk. Compared with CL0, Both CLA and CLX can significantly reduce control points, split fields, and monitor units, except that CLA increased treatment time. For dose verification, the γ passing rate showed a tendency of CLx > CLA > CL0.ConclusionFor intensity‐modulated radiotherapy for gastric cancer, CLA and CLX can obtain comparable dosimetry distribution in respect to CL0. However, CLX can significantly increase the dose delivery efficiency and verification passing rates. It was suggested that CLx was beneficial in intensity‐modulated radiotherapy for gastric cancer.