Quality assurance for on‐table adaptive magnetic resonance guided radiation therapy: A software tool to complement secondary dose calculation and failure modes discovered in clinical routine

Abstract

Online adaption of treatment plans on a magnetic resonance (MR)‐Linac enables the daily creation of new (adapted) treatment plans using current anatomical information of the patient as seen on MR images. Plan quality assurance (QA) relies on a secondary dose calculation (SDC) that is required because a pretreatment measurement is impossible during the adaptive workflow. However, failure mode and effect analysis of the adaptive planning process shows a large number of error sources, and not all of them are covered by SDC. As the complex multidisciplinary adaption process takes place under time pressure, additional software solutions for pretreatment per‐fraction QA need to be used. It is essential to double‐check SDC input to ensure a safe treatment delivery. Here, we present an automated treatment plan check tool for adaptive radiotherapy (APART) at a 0.35 T MR‐Linac. It is designed to complement the manufacturer‐provided adaptive QA tool comprising SDC. Checks performed by APART include contour analysis, electron density map examinations, and fluence modulation complexity controls. For nine of 362 adapted fractions (2.5%), irregularities regarding missing slices in target volumes and organs at risks as well as in margin expansion of target volumes have been found. This demonstrates that mistakes occur and can be detected by additional QA measures, especially contour analysis. Therefore, it is recommended to implement further QA tools additional to what the manufacturer provides to facilitate an informed decision about the quality of the treatment plan.

Risk management patterns in radiation oncology—results of a national survey within the framework of the Patient Safety in German Radiation Oncology (PaSaGeRO) project

“…It was designed using LimeSurvey (LimeSurvey GmbH, Hamburg, Germany) containing 18 questions in multiplechoice style. Self-assessment concerning knowledge on RM was answered using a 5-point Likert scale: very good (1)-good (2)-satisfying (3)-bad (4)-very bad (5). Process steps as mentioned in the questionnaire were aligned to the WHO radiotherapy risk profile [3].…”

“…Radiation oncology (RO) plays a vital role in cancer management with almost half of all patients undergoing radiation therapy (RT) during their course of disease [1]. Modern leading to a devastating impact in terms of side-effects and therapy success [2][3][4][5]. In recent years, several organizations have focused on patient safety during RT, providing recommendations for radiation oncology professionals [3,[6][7][8].…”

Clinical rationale for in vivo portal dosimetry in magnetic resonance guided online adaptive radiotherapy

“…Simpler non-dosimetric solutions have also been proposed to check irregularities during the plan adaptation and patient model creation processes including contour analysis, electron density map examinations, and fluence modulation complexity controls. In a recent study [33] , irregularities were found in 9 out 362 adapted fractions.…”

ICRU REPORT 97: MRI-Guided Radiation Therapy Using MRI-Linear Accelerators

“…This kind of contouring issue is not easily caught by the secondary absorbed-dose calculation QA because contour and electron density are direct inputs to it, indicating the necessity to develop additional automated plan check tools to identify the issues associated with contouring and electron density mapping. Based on the potential risks identified in the FMEA of the adaptive planning process, several in-house tools for automated contour analysis, electron density examination, and additional plan checks have been reported as complementary plan QA to the secondary absorbed-dose calculation (Cai et al , 2018; Rippke et al , 2022).…”

“…Mitigation strategies such as standardized workflow, clearly-defined protocols, and checklists to ensure protocol adherence were implemented to minimize all the high risks that were classified based on the combination of probability and severity levels to an acceptable level (Klüter et al, 2021). Contouring and electron density assignment were also reported to be the highest risk priority categories by different institutions (Garcia Schüler et al, 2021;Rippke et al, 2022). The quality of the contour directly impacts the quality of the treatment plan as shown by an example in Fig.…”