Patient-specific quality assurance for non-normal radiotherapy plans based on statistical process control
10.3760/cma.j.cn112271-20240304-00083
- VernacularTitle:基于统计过程控制的非正态放疗计划个体化质量保证
- Author:
Juan DENG
1
;
Gaoyuan LIU
;
Chuou YIN
;
Jiang LIU
;
Guojian MEI
;
Ling HUA
;
Shutong YU
;
Xinhui FU
;
Chen LIN
;
Tian LI
;
Yibao ZHANG
Author Information
1. 德阳市人民医院肿瘤科，德阳 618000
- Publication Type:Journal Article
- Keywords:
Radiotherapy;
Statistical process control;
Non-normal distribution;
Patient-specific quality assurance
- From:
Chinese Journal of Radiological Medicine and Protection
2025;45(4):296-301
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To apply statistical process control (SPC) techniques to the quality assurance of non-normal radiotherapy plans through Johnson transformation, establishing patient-specific tolerance and action limits based on treatment sites and dose/distance assessment criteria, thereby enhancing the intensity-modulated radiation therapy (IMRT) verification accuracy and dose delivery precision.Methods:In this study, 951 gamma analysis data of patient-specific quality assurance (PSQA) executed on the Halcyon accelerator platform were selected and categorized into six groups based on treatment sites, including brain (102 cases), head and neck (100 cases), breast (229 cases), lung (154 cases), esophagus (223 cases), and pelvic (143 cases) groups. The six groups of data were statistically analyzed through Anderson-Darling normality tests ( α = 0.05) using Minitab 21 software. Non-normal data were transformed into normal data through Johnson transformation and then were used to establish treatment site-specific tolerance and action limits, which were compared with the Shewhart control charts based on normal distributions. Results:The PSQA result of the six groups all exhibited non-normal distributions ( P < 0.05). Through Johnson transformation, the tolerance and action limits for the head and neck, breast, lung, esophagus, and pelvic areas under the 3%/2 mm criterion ranged from 95.13% to 96.16% and 94.19% to 95.91%, respectively. In contrast, the tolerance and action limits ranged from 91.15% to 94.86% and 89.94% to 94.78% under the 2%/2 mm criterion. Directly applying Shewhart control charts without normality assumptions yielded higher tolerance limits compared to the application of Johnson transformation, increasing the false positive rate in the non-normal PSQA process. Conclusions:Applying the SPC techniques directly to a non-normal process can lead to an increased false alarm rate and wrong process interpretation. The SPC techniques combined with Johnson transformation enable more effective monitoring of a non-normal PSQA process, facilitating timely identification of potential factors that may lead to an out-of-control process based on the treatment site-specific limits.
