Preliminary study on dosimetry characteristics of a novel cylindrical dose verification system.

Abstract

To develop a novel ionization chamber array dosimetry system, study its dosimetry characteristics, and perform preliminary tests for plan dose verification. The dosimetry characteristics of this new array were tested, including short-term and long-term reproducibility, dose linearity, dose rate dependence, field size dependence, and angular dependence. The open field and MLC field plans were designed for dose testing. Randomly select 30 patient treatment plans (10 intensity-modulated radiation therapy [IMRT] plans and 20 volumetric modulated arc therapy [VMAT] plans) that have undergone dose verification using Portal Dosimetry to perform verification measurement and evaluate dose verification test results. The dosimetry characteristics of the arrays all performed well. The gamma passing rates (3%/2mm) were more than 96% for the combined open field and MLC field plans. The average gamma pass rates were (99.54±0.58)% and (96.70±3.41)% for the 10 IMRT plans and (99.32±0.89)% and (94.91±6.01)% for the 20 VMAT plans at the 3%/2mm and 2%/2mm criteria, respectively, which is similar to the Portal Dosimetry's measurement results. This novel ionization chamber array demonstrates good dosimetry characteristics and is suitable for clinical IMRT and VMAT plan verifications.