Formulation of objective indices to quantify machine failure risk analysis for interruptions in radiotherapy.

Daisuke Kawahara,Yusuke Ochi,Yasushi Nagata,Hisashi Nakano,Akito Saito

doi:10.1002/acm2.13126

Abstract

ObjectivesTo evaluate the effect of interruption in radiotherapy due to machine failure in patients and medical institutions using machine failure risk analysis (MFRA).Material and methodsThe risk of machine failure during treatment is assigned to three scores (biological effect, B; occurrence, O; and cost of labor and repair parts, C) for each type of machine failure. The biological patient risk (BPR) and the economic institution risk (EIR) are calculated as the product of B and O (B×O) and C and O (C×O), respectively. The MFRA is performed in two linear accelerators (linacs).ResultThe multileaf collimator (MLC) fault has the highest BPR and second highest EIR. In particular, TrueBeam has a higher BPR and EIR for MLC failures. The total EIR in TrueBeam was significantly higher than that in Clinac iX. The minor interlock had the second highest BPR, whereas a smaller EIR. Meanwhile, the EIR for the LaserGuard fault was the highest, and that for the monitor chamber fault was the second highest. These machine failures occurred in TrueBeam. The BPR and EIR should be evaluated for each linac. Further, the sensitivity of the BPR, it decreased with higher T1/2 and α/β values. No relative difference is observed in the BPR for each machine failure when T1/2 and α/β were varied.ConclusionThe risk faced by patients and institutions in machine failure may be reduced using MFRA.Advances in knowledgeFor clinical radiotherapy, interruption can occur from unscheduled downtime with machine failures. Interruption causes sublethal damage repair. The current study evaluated the effect of interruption in radiotherapy owing to machine failure on patients and medical institutions using a new method, that is, machine failure risk analysis.

Highlights

A linear accelerator that facilitates the treatment of cancer comprises complex hardware and software
The current study proposes a new machine failure risk analysis (MFRA) method that involves calculating the cost of replacement of linac parts and the biological effect of DT on patients
Based on the 60 failure modes identified, the machine failures were broadly classified into the following categories: multileaf collimator (MLC), potentiometer, radio frequency (RF) driver, minor interlock, water temperature and quantity, monitor chamber and LaserGuard

Summary

Introduction

A linear accelerator (linac) that facilitates the treatment of cancer comprises complex hardware and software. Component dysfunction or failure calls for service engineering and immediate on-site repair, resulting in the disruption of clinical services and unscheduled machine downtime (DT) 1,2. This presents a strain on the patients and involves a cost for the institution. Linac interlocks prevent grave failures by ensuring that the operation of the system is discontinued when the operating parameters exceed the specified limits of the system. Such interlocks can cause DT, thereby affecting clinical operations

Objectives

Methods

Discussion

Conclusion