Initial Clinical Experience Using Daily Artificial Intelligence-Assisted Adaptive Radiotherapy on Cone-Beam CT for Cancer of the Head and Neck

Abstract

Adaptive radiation therapy (ART) has emerged as a promising method to modify treatment plans in response to structural and spatial changes that occur during a treatment course. In particular, patients with locally advanced Head and Neck (HN) Cancers often experience changes in target volumes and organs-at risk requiring replanning throughout treatment. The implementation of daily ART using daily cone-beam Cone-Beam CT (CBCT) imaging is a solution that may improve the therapeutic ratio by accounting for intra-fractional changes throughout the patient's treatment course. We evaluated the initial clinical experience of daily ART for patients with locally advanced HN cancer using a commercially available, online adaptive platform with AI-assisted workflows on daily CBCT. For treatment, AI-based auto-contour and structure deformation of OARs and Targets were reviewed and edited by the treating physician. Two plans were generated including, a CT sim-based plan with deformed structures (scheduled) and a re-optimized plan (adaptive) of which both plans evaluated and the best one approved and delivered. Clinical outcomes and dosimetric parameters were reviewed. A total of 23 patients with locally advanced HN cancers (7 Nasopharynx, 6 Oropharynx, 2 oral cavity, 8 larynx) were treated with daily ART from December 2020 until November 2022. 655 adaptive and scheduled radiotherapy plans were generated of which 95.7% of the adaptive plans were chosen. Adaptive plans demonstrated superior V95 PTV70, PTV60, PTV56 mean coverage by 1.02%, 8.14%, and 7.2%, respectively. At a median follow up of 10.1 months, the local control was 91.3%. The 1-year actuarial PFS was 86.9% and 1 year actuarial OS was 82.6%. Two patients required prophylactic g-tube. 30% and 21% of patients had acute grade 3 dysphagia and odynophagia, respectively; 13% with chronic grade 2 xerostomia. There were no grade 4 or grade 5 toxicities. These findings provide evidence for the feasibility and potential clinical benefit of incorporating daily adaptive AI radiotherapy on CBCT in the treatment of locally advanced HN cancer. Further prospective studies are needed to confirm these findings and determine the optimal clinical applications of this approach.