A simple and interpretable method to predict head and neck offline adaptation needs based on anatomical changes

Background

Modern radiotherapy techniques do not automatically account for anatomical changes during treatment, which can lead to reduced target coverage, hotspots, or increased dose to healthy tissues. Adaptive Radiotherapy (ART) addresses this by updating the treatment plan based on the patient's current anatomy. In routine clinical practice, the decision to replan is often triggered by a suboptimal fit of the immobilization mask, identified by the radiation therapy technologist. Because this process is operator dependent and lacks methodological rigor, a quantitative decision-support method could substantially improve the replanning decision. Daily image-guided radiotherapy (IGRT) images provide valuable clinical information but often lack sufficient quality for accurate target contouring or reliable dose calculation to support straightforward clinical decision-making. This limitation motivates the need for a simpler, more practical, and scalable alternative.