Daily quality control data analysis and process evaluation of linear accelerator
Jin Xiaoli1, Lu Ying1, Shi Qinying1, Hao Lin1, Xing Xiaofen2
1Department of Radiation Oncology,Shanxi Bethune Hospital (Shanxi Academy of Medical Sciences),Tai Yuan 030031,China; 2Center of Radiation Oncology,Shanxi Cancer Hospital,Tai Yuan 030031,China
Abstract：Objective To analyze the quality control data of linear accelerator detected by Daily QA3 and to evaluate this quality control process using statistical process control.Methods After the calibrations of the accelerator and Daily QA3,Daily QA3 device was used to perform daily quality control by technicians and physicists and 100 groups and 30 groups of daily quality control data were collected. After the accelerator and Daily QA3 were re-calibrated,Daily QA3 device was utilized to perform daily quality control by technicians and 100 groups of the daily quality control data were repeatedly collected. The variations of normalized signal-to-noise ratio of quality control data collected after two calibrations were analyzed. The first 30 groups of daily quality control data measured by technicians and physicists were adopted to calculate the I-MR control chartsand compare the location of CL and the range of UCL and LCL. The process capability indices were calculated for three different quality control processes bytechnicians and physicists, respectively.Results For twice calibrations,normalized signal-to-noise ratio of quality control data significantly changed before 6 weeks, became stable between 6 and 8 weeks,and the changes became smaller after 8 weeks. For dose output measured by physicists,the rang of UCL and LCL was more narrow. In terms of flatness and symmetry,the location of CL was closer to zero. Regarding dose output and flatness,the process capability indices of three different quality control process were all satisfied ≥1,whereas unsatisfied for transverse symmetry. Conclusions The first 30–40 data points should be adopted to delineate I-MR control chart of the linear accelerator in daily quality control process. The quality control process should be completed by a fixed and small group of personnel and an optimal tolerance level should be customized.
Jin Xiaoli,Lu Ying,Shi Qinying et al. Daily quality control data analysis and process evaluation of linear accelerator[J]. Chinese Journal of Radiation Oncology, 2020, 29(3): 220-224.
[1] Shalek RJ. Determination of absorbed dose in a patient irradiated by beams of X or gamma rays in radiotherapy procedures[J]. Med Phys,1977,4(5):461.
[2] Klein EE,Hanley J,Bayouth J,et al. Task Group 142 report:quality assurance of medical accelerators[J]. Med Phys,2009,36(9):4197-4212. DOI:10.1118/1.3190392.
[3] Binny D,Lancaster CM,Kairn T,et al. Monitoring Daily QA3 constancy for routine quality assurance on linear accelerators[J]. Eur Med Phys,2016,32(11):1479-1487. DOI:10.1016/j.ejmp.2016.10.021.
[4] 胡俏俏,张艺宝,刘卓伦,等. 四种常见加速器晨检仪的性能比较[J]. 中华放射医学与防护杂志,2015,35(7):532-535. DOI:10.3760/cma.j.issn.0254-5098.2015.07.012.
Hu QQ,Zhang YB,Liu ZL,et al. Performance comparison of four common LINAC daily QA instruments[J]. Chin J Radiol Med Prot,2015,35(7):532-535. DOI:10.3760/cma.j.issn.0254-5098.2015.07.012.
[5] Pawlicki T,Chera B,Ning T,et al. The systematic application of quality measures and process control in clinical radiation oncology[J]. Semin Radiat Oncol,2012,22(1):70-76. DOI:10.1016/j.semradonc.2011.09.006.
[6] Pawlicki T,Whitaker M,Boyer AL. Statistical process control for radiotherapy quality assurance[J]. Med Phys,2005,32(9):2777-2786. DOI:10.1118/1.2001209.
[7] 李定宇,戴建荣. 统计过程控制方法在加速器质量保证中的应用[J]. 国际放射医学核医学杂志,2009,33(1):54-58. DOI:10.3760/cma.j.issn.1673-4114.2009.01.054.
Li DY,Dai JR. The application of statistical process control in linac quality assurance[J]. Int J Radiat Med Nucl Med,2009, 33(1):54-58. DOI:10.3760/cma.j.issn.1673-4114.2009.01.054.
[8] 李光俊,李衍龙,肖江洪,等. VMAT加速器日常运行分析及过程质量控制[J]. 中华放射肿瘤学杂志,2015,24(2):200-204. DOI:10.3760/cma.j.issn.1004-4221.2015.02.023.
Li GJ,Li YL,Xiao JH,et al. Quality control of linac in daily volumetric-modulated arc therapy[J]. Chin J Radiat Oncol,2015,24(2):200-204. DOI:10.3760/cma.j.issn.1004-4221.2015.02.023.
[9] Binny D,Mezzenga E,Lancaster CM,et al. Investigating output and energy variations and their relationship to delivery QA results using statistical process control for helical tomotherapy[J]. Phys Med,2017,38(6):105-110. DOI:10.1016/j.ejmp.2017.05.052.
[10] Rah JE,Shin D,Oh DH,et al. Feasibility study of using statistical process control to customized quality assurance in proton therapy[J]. Med Phys,2014,41(9):092105. DOI:10.1118/1.4893916.
[11] Sanghangthum T,Suriyapee S,Srisatit S,et al. Retrospective analysis of linear accelerator output constancy checks using process control techniques[J]. J Appl Clin Med Phys,2013,14(1):4032. DOI:10.1120/jacmp.v14i1.4032.
2020, Vol. 29 
