Modeling Acute Chemoradiotherapy (CRT) Diarrhea Severity Using Automatically Contoured Small Bowel.

We accurately modelled acute diarrhea (AUC = 0.90) for rectal cancer patients receiving CRT using AI-contoured small-bowel structures. The treatment arm and small-bowel dose were independently correlated to the diarrhea severity. The explainable model allowed us to quantify the impact of radiation dose, usage of irinotecan, and its combination, with a threshold of V = 160.93 cm yielding an equivalent impact. We will be extending the analysis to the whole trial cohort to improve the statistical power.