Workflow and dosimetric results for direct-to-unit single-fraction adaptive lung SBRT delivered on the ONE-STOP prospective pilot clinical trial.

Abstract

BackgroundDirect-to-unit (DTU) workflows coupled with online adaptive radiation therapy can streamline stereotactic body radiation therapy (SBRT) by eliminating conventional simulation and prolonged treatment planning, thereby reducing treatment burden while maintaining high dosimetric quality.AimTo evaluate the feasibility and dosimetric robustness of a CBCT-guided DTU workflow for single-fraction lung SBRT.MethodsPatients with early-stage non-small cell lung cancer or oligometastatic lung disease were enrolled in this prospective pilot clinical trial. Patients received single-fraction SBRT (30-34 Gy) using a DTU workflow on a ring-gantry and CBCT-guided adaptive platform. Dosimetric quality was assessed by comparing target volumes and dosimetric indices between DTU plans generated on treatment CBCT and backup plans derived from 4DCT imaging.ResultsEight of ten patients (80%) were successfully treated using the DTU workflow, meeting the predefined feasibility endpoint. One patient was screen failed due to respiratory motion exceeding trial criteria. All DTU plans adhered to protocol requirements, meeting P1 organ-at-risk constraints and target coverage objectives when achievable, with plan quality comparable to simulation-based workflows. Treatment sessions were completed within 1.5 h. Two patients were triaged to conventional workflows due to excessive tumor motion in one case and unacceptable online dosimetry related to atypical setup, anatomical factors and plan normalization in the other.ConclusionCBCT-guided DTU single-fraction lung SBRT is feasible and dosimetrically similar to conventional workflows, enabling high-quality treatment in a single clinical visit. These findings motivate expanded application of DTU workflows within our clinic and expansion to other anatomical sites to reduce time toxicity and improve patient access to care.