Analysis and Comparison of Portal Dosimetry Dose Verification Results of Split Field
and Large Field for IMRT Plans of Nasopharyngeal Carcinoma
SHI Feiyue1a, 2,WANG Min1a,ZHAO Ziting1b,QIN Wei1a,ZHAO Huanyu1a,WEI Xiaowei1a
1. a. Radiation Therapy Center丨 b. Department of Medical Equipment, Nanjing First Hospital, Nanjing Medical University,
Nanjing Jiangsu 210006, China丨 2. Center of Medical Physics, Nanjing Medical University, Nanjing Jiangsu 210029, China
Abstract:Objective To study the portal dosimetry (PD) dose verification of intensity modulated radiotherapy (IMRT) plan for
nasopharyngeal carcinoma (NPC), and compare the values of gamma passing rate (G) between split field and large field, so as to
provide valuable reference for evaluating the PD dose verification results of IMRT plan for NPC. Methods The IMRT plans for 11
patients with NPC were chosen for this study. Firstly, the PD dose verification plans with only split fields were created by using the
Eclipse treatment planning system. The PD plans were performed by Clinac iX linear accelerator. Then, the value of G for each split
field was obtained by PD software module. The value of G for each large field was obtained by matrix addition. Finally, statistical
analysis and comparison were applied to the data of G for split field and large field. Results For 11 cases of PD dose verification
plans, the statistical values of G for all split fields and large fields were 98.08%±1.80% and 97.81%±1.96% respectively. The
results of comparison between 198 split fields and corresponding large fields by paired t-test showed that, there was no statistical
difference between the two groups (P>0.05). The symbol ΔG represented the difference in values of G between split field and
large field. The statistical value and absolute value of ΔG were 0.26%±2.21% and 1.38%±1.75% respectively. For each PD dose
verification plan, the maximum, minimum, mean and standard deviation of G values for all the split fields and large fields were
calculated respectively. The paired t-test was applied to the two types of field with the above four parameters. The results showed that,
there was no significant difference for the three parameters of minimum, mean and standard deviation (P>0.05). Conclusion By and
large, there is small difference in gamma passing rate between split field and large field for the PD verification plans of NPC. There is
no statistical difference in values of mean and standard deviation of gamma passing rate of all the fields for each PD verification plan
between split field and large field.
时飞跃1a, 2,王敏1a,赵紫婷1b,秦伟1a,赵环宇1a,魏晓为1a. 鼻咽癌调强计划分野和大野Portal Dosimetry剂量验证的分析比较[J]. 中国医疗设备, 2021, 36(4): 9-12.
SHI Feiyue1a, 2,WANG Min1a,ZHAO Ziting1b,QIN Wei1a,ZHAO Huanyu1a,WEI Xiaowei1a. Analysis and Comparison of Portal Dosimetry Dose Verification Results of Split Field
and Large Field for IMRT Plans of Nasopharyngeal Carcinoma. China Medical Devices, 2021, 36(4): 9-12.