Decision-making processes in image guided radiotherapy: A think aloud study

3D Image Guided Radiotherapy (IGRT) using Cone Beam Computer Tomography (CBCT) has been implemented for a range of treatment sites across the UK in the last decade. A paucity of evidence exists to understand how radiation therapists (RTTs) make clinical decisions during image interpretation as part of the IGRT process. The aim of this study was to investigate the decision-making processes used by RTTs during image interpretation of IGRT.

Case study methodology was adopted utilising a think aloud observational method with follow-up interviews. 12 RTTs were observed and interviewed across three UK radiotherapy centres. Participants were observed reviewing and making clinical decisions in a simulated environment using clinical scenarios developed in partnership with each centres' Clinical Imaging Lead. Protocol analysis was used to analyse the observational data and thematic analysis was used to analyse the interview data.

A range of approaches to decision-making was observed which varied in length from nine phrases to 57 (mean 24) per case. Six themes emerged from the data: Set Sequence, Site Specific Clinical Priorities, Initial Gross Review, Decision to treat, Compromise and experience. In addition, three cognitive decision-making processes were identified: Simple linear, Linear repeating and Intuitive decision-making process. The findings of the study align with general principles of expert performance, whereby experience in a specific scope of practice is more beneficial in developing expertise than overall experience.

This study has provided new and original insight in the decision-making processes of RTTs. The study has highlighted three process models to explain how RTTs make decisions during IGRT: Simple linear, Linear repeating and Intuitive decision-making process. Intuitive processes are widely accepted to be error prone and linked to bias. When using this process, some RTTs followed this with a confirmation phase. This second phase of the process should be encouraged when teaching IGRT. The results of the study support the concept of expert performance, where performance and expertise are only improved by exposing individuals to specific types of experiences. RTTs, managers and Higher Education Institutions are encouraged to review these models and implement them into IGRT training. It is clear from the evidence base that understanding how we make decisions, enables us to develop expertise and reduce errors during the decision-making process.