Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire; University of Texas Southwestern Medical Center, Dallas, Texas.
Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire; Department of Medicine, Radiation Oncology, Geisel School of Medicine, Dartmouth College Hanover, New Hampshire; Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire.
Pract Radiat Oncol. 2023 Mar-Apr;13(2):153-165. doi: 10.1016/j.prro.2022.10.011. Epub 2022 Nov 12.
The use of a linear accelerator (LINAC) in ultrahigh-dose-rate (UHDR) mode can provide a conduit for wider access to UHDR FLASH effects, sparing normal tissue, but care needs to be taken in the use of such systems to ensure errors are minimized. The failure mode and effects analysis was carried out in a team that has been involved in converting a LINAC between clinical use and UHDR experimental mode for more than 1 year after the proposed methods of TG100.
A team of 9 professionals with extensive experience were polled to outline the process map and workflow for analysis, and developed fault trees for potential errors, as well as failure modes that would result. The team scored the categories of severity magnitude, occurrence likelihood, and detectability potential in a scale of 1 to 10, so that a risk priority number (RPN = severity×occurrence×detectability) could be assessed for each.
A total of 46 potential failure modes were identified, including 5 with an RPN >100. These failure modes involved (1) patient set up, (2) gating mechanisms in delivery, and (3) detector in the beam stop mechanism. The identified methods to mitigate errors included the (1) use of a checklist post conversion, (2) use of robust radiation detectors, (3) automation of quality assurance and beam consistency checks, and (4) implementation of surface guidance during beam delivery.
The failure mode and effects analysis process was considered critically important in this setting of a new use of a LINAC, and the expert team developed a higher level of confidence in the ability to safely move UHDR LINAC use toward expanded research access.
使用直线加速器（LINAC）在超高剂量率（UHDR）模式下可以为更广泛地获得 UHDR FLASH 效应提供途径，同时保护正常组织，但在使用此类系统时需要小心谨慎，以确保最大限度地减少错误。该失效模式和影响分析是由一个团队进行的，该团队在 TG100 提出的方法之后，已经将一台 LINAC 从临床使用转换为 UHDR 实验模式超过 1 年，积累了丰富的经验。
团队由 9 名具有丰富经验的专业人员组成，对该过程图和分析工作流程进行了调查，并为潜在错误开发了故障树，以及可能导致的失效模式。团队对严重程度、发生可能性和可检测性这三个类别进行了 1 到 10 的评分，以便对每个类别进行风险优先数（RPN = 严重程度×发生可能性×可检测性）评估。
共确定了 46 种潜在失效模式，其中 5 种 RPN 值>100。这些失效模式涉及（1）患者摆位、（2）输送中的门控机制和（3）束流阻止器中的探测器。为减少错误而确定的方法包括（1）转换后使用检查表、（2）使用稳健的辐射探测器、（3）质量保证和束流一致性检查的自动化，以及（4）在束流输送期间实施表面引导。
在这种新用途的 LINAC 中，失效模式和影响分析过程被认为至关重要，专家组对安全地将 UHDR LINAC 应用扩展到更多研究的能力更具信心。
