Leveraging CT-based online adaptive radiotherapy for dose escalation in hypofractionated radiotherapy for locally advanced unresectable lung cancer

Standard treatment for locally advanced (LA) lung cancer is surgery or concurrent chemoradiotherapy (CRT), but many patients are ineligible due to comorbidities. Sequential radiation (RT) and chemotherapy offer lower local control (LC) rates. Dose escalation and hypofractionation are emerging options for locally advanced (LA) NSCLC patients ineligible for surgery or chemoradiotherapy. However, toxicity rates remain unacceptable (G3-esophagitis up to 24%, G3-pneumonitis up to 12%). We have developed a novel approach that leverages CT-based online adaptive radiotherapy (oART) to deliver a simultaneously integrated boost while respecting OAR constraints. The oART workflow consists of image acquisition, patient modeling/contouring, plan generation/selection, verification image match (CBCT-to-CBCT), and treatment delivery. Targets were rigidly propagated and aligned daily; critical OARs were recontoured to account for inter-fraction variability and ensure OAR tolerances were not exceeded for daily treatment. Here, we outline our technical approach.