Influence of Deviation in Absolute Dose on Verification Results of MatriXX
BAI Zhenglu1a, SHI Feiyue1b, QIN Wei1b, JIANG Hongbing1a,2
1.a.Department of Medical Equipment; b.Department of Radiation Oncology, Nanjing Medical University Affiliated Nanjing Hospital
(Nanjing First Hospital), Nanjing Jiangsu 210006, China; 2.Nanjing Health Information Center, Nanjing Jiangsu 210003, China
Abstract:Objective To discuss the influence of deviation in absolute dose on verification results of IMRT fields of MatriXX.
Methods Fields with gantry angle 180° (G180) were selected for 24 patients with cervical cancer, and corresponding verification
plans were created. The verification plans were implemented in the Varian Clinac iX linear accelerator, and the dose distributions
were measured by the two-dimensional ionization chamber array (MatriXX). OmniPro I’mRT software was used to simulate
the deviation in absolute dose (d), and d ranged from -10% to 10% with interval of 1%. Corresponding dose verification results
with different values of d were analyzed. Results By and large, gamma passing rate was decreased and value of average gamma
was increased when absolute dose deviated to positive or negative directions. The maximum gamma passing rate was not in the
position with d=0, but in the range of -3% to -1%, and the values of d were in the range of -3% to 0 when average gamma achieved
the minimum value. Conclusion Deviation in absolute dose has a significant influence on verification results of IMRT fields of
MatriXX. When analysing verification results, the factor of deviation in absolute dose should be taken into consideration. In routine
work of radiotherapy, the absolute dose of Clinac accelerator should be calibrated regularly.
柏正璐1a,时飞跃1b,秦伟1b,蒋红兵1a,2. 绝对剂量的偏移对MatriXX剂量验证结果的影响[J]. 中国医疗设备, 2017, 32(10): 48-51.
BAI Zhenglu1a, SHI Feiyue1b, QIN Wei1b, JIANG Hongbing1a,2. Influence of Deviation in Absolute Dose on Verification Results of MatriXX. China Medical Devices, 2017, 32(10): 48-51.