Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA.
IROC Houston QA Center, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA.
Med Phys. 2017 Nov;44(11):5575-5583. doi: 10.1002/mp.12551. Epub 2017 Oct 19.
The objective of this work was to assess both the perception of failure modes in Intensity Modulated Radiation Therapy (IMRT) when the linac is operated at the edge of tolerances given in AAPM TG-40 (Kutcher et al.) and TG-142 (Klein et al.) as well as the application of FMEA to this specific section of the IMRT process.
An online survey was distributed to approximately 2000 physicists worldwide that participate in quality services provided by the Imaging and Radiation Oncology Core - Houston (IROC-H). The survey briefly described eleven different failure modes covered by basic quality assurance in step-and-shoot IMRT at or near TG-40 (Kutcher et al.) and TG-142 (Klein et al.) tolerance criteria levels. Respondents were asked to estimate the worst case scenario percent dose error that could be caused by each of these failure modes in a head and neck patient as well as the FMEA scores: Occurrence, Detectability, and Severity. Risk probability number (RPN) scores were calculated as the product of these scores. Demographic data were also collected.
A total of 181 individual and three group responses were submitted. 84% were from North America. Most (76%) individual respondents performed at least 80% clinical work and 92% were nationally certified. Respondent medical physics experience ranged from 2.5 to 45 yr (average 18 yr). A total of 52% of individual respondents were at least somewhat familiar with FMEA, while 17% were not familiar. Several IMRT techniques, treatment planning systems, and linear accelerator manufacturers were represented. All failure modes received widely varying scores ranging from 1 to 10 for occurrence, at least 1-9 for detectability, and at least 1-7 for severity. Ranking failure modes by RPN scores also resulted in large variability, with each failure mode being ranked both most risky (1st) and least risky (11th) by different respondents. On average MLC modeling had the highest RPN scores. Individual estimated percent dose errors and severity scores positively correlated (P < 0.01) for each FM as expected. No universal correlations were found between the demographic information collected and scoring, percent dose errors or ranking.
Failure modes investigated overall were evaluated as low to medium risk, with average RPNs less than 110. The ranking of 11 failure modes was not agreed upon by the community. Large variability in FMEA scoring may be caused by individual interpretation and/or experience, reflecting the subjective nature of the FMEA tool.
本研究旨在评估调强放射治疗（IMRT）在 AAPM TG-40（Kutcher 等人）和 TG-142（Klein 等人）规定的容差边缘运行时失败模式的感知，以及将 FMEA 应用于 IMRT 过程的这一特定部分。
向全球约 2000 名参与成像和放射肿瘤学核心-休斯顿（IROC-H）质量服务的物理学家分发了在线调查。该调查简要描述了 11 种不同的失败模式，这些失败模式涵盖了基本质量保证范围内的分步 IMRT，其剂量误差接近 TG-40（Kutcher 等人）和 TG-142（Klein 等人）的容差标准。要求受访者估计每个失败模式在头颈部患者中可能导致的最坏情况百分剂量误差，以及 FMEA 评分：发生、可检测性和严重性。风险概率数（RPN）评分是这些评分的乘积。还收集了人口统计学数据。
共提交了 181 份个人和 3 份小组回复。84%来自北美。大多数（76%）个人回复者进行了至少 80%的临床工作，92%的人获得了国家认证。受访者的医学物理经验从 2.5 年到 45 年不等（平均 18 年）。共有 52%的个人回复者对 FMEA 至少有些熟悉，而 17%的人不熟悉。代表了多种 IMRT 技术、治疗计划系统和直线加速器制造商。所有失败模式的评分从 1 到 10（发生）、至少 1 到 9（可检测性）和至少 1 到 7（严重性）不等。按 RPN 评分对失败模式进行排序也会导致很大的差异，不同的回复者将每种失败模式都排在最危险（第 1 位）和最不危险（第 11 位）。平均而言，MLC 建模的 RPN 评分最高。如预期的那样，个体估计的百分剂量误差和严重程度评分之间呈正相关（P<0.01）。在收集的人口统计学信息与评分、百分剂量误差或排名之间未发现普遍相关性。
总体而言，调查的失败模式被评估为低到中等风险，平均 RPN 值低于 110。11 种失败模式的排名未得到社区的一致认可。FMEA 评分的较大差异可能是由个体解释和/或经验引起的，反映了 FMEA 工具的主观性。
