Pal Bipasha, Pal Angshuman, Das Suresh, Palit Soura, Sarkar Papai, Mondal Subhayan, Mallik Suman, Goswami Jyotirup, Das Sayan, Sen Arijit, Mondol Monidipa
Narayana Superspeciality Hospital, 120/1 Andul Road, Howrah 711103, West Bengal, India.
Department of Mechanical Engineering, Jadavpur University, 188 Raja SC Mallick Road, Kolkata 700032, West Bengal, India.
Rep Pract Oncol Radiother. 2020 Jan-Feb;25(1):91-99. doi: 10.1016/j.rpor.2019.12.004. Epub 2019 Dec 10.
To examine the application of Statistical Process Control (SPC) and Ishikawa diagrams for retrospective evaluation of machine Quality Assurance (QA) performance in radiotherapy.
SPC is a popular method for supplementing the performance of QA techniques in healthcare. This work investigates the applicability of SPC techniques and Ishikawa charts in machine QA.
SPC has been applied to recommend QA limits on the particular beam parameters using the QUICKCHECK QA portable constancy check device for 6 MV and 10 MV flattened photon beams from the Elekta Versa HD linear accelerator (Linac). Four machine QA parameters - beam flatness, beam symmetry along gun target direction and left-right direction, and beam quality factor (BQF) - were selected for retrospective analysis. Shewhart charts, Exponentially Weighted Moving Average (EWMA) charts and Cumulative Sum (CUSUM) charts were obtained for each parameter. The root causes for a failure in machine QA were broken down into an Ishikawa diagram enabling the user to identify the root cause of error and rectify the problem subsequently.
Shewhart charts and EWMA charts applied could detect loss in control in one variable in the 6 MV beams and in all four variables in 10 MV beams. CUSUM charts detected offsets in the readings. The Ishikawa chart exhaustively included the possible errors that lead to loss of control.
SPC is proven to be effective for detection of loss in control in machine QA. The Ishikawa chart provides the set of probable root causes of machine error useful while troubleshooting.
研究统计过程控制（SPC）和石川图在放射治疗中机器质量保证（QA）性能回顾性评估中的应用。
SPC是一种用于补充医疗保健中QA技术性能的常用方法。本研究探讨SPC技术和石川图在机器QA中的适用性。
使用QUICKCHECK QA便携式稳定性检测设备，对医科达Versa HD直线加速器（直线加速器）的6MV和10MV扁平光子束的特定射束参数应用SPC，以推荐QA限值。选择四个机器QA参数——射束平坦度、沿枪靶方向和左右方向的射束对称性以及射束质量因子（BQF）——进行回顾性分析。为每个参数获取了休哈特图、指数加权移动平均（EWMA）图和累积和（CUSUM）图。将机器QA失败的根本原因分解到石川图中，以便用户识别错误的根本原因并随后纠正问题。
应用的休哈特图和EWMA图能够检测到6MV射束中一个变量以及10MV射束中所有四个变量的失控情况。CUSUM图检测到读数中的偏移。石川图详尽地列出了导致失控的可能误差。
事实证明，SPC对于检测机器QA中的失控情况是有效的。石川图提供了在故障排除时有用的机器错误可能根本原因集。
