Treffer: Clinical experience with a same-day simulation and treatment program for stereotactic radiation therapy on a C-arm linac.

Purpose: We report our experience with the implementation of a same-day simulation and treatment C-arm linear accelerator (linac)-based stereotactic program for patients with intracranial and extracranial metastatic disease.
Methods: Between May 2021 and October 2023, patients were treated in our same-day program with linac-based SRS/SBRT. Two slots per week were offered. Patients with expedited clinical needs, able to undergo SRS/SBRT simulation and treatment, were considered. Extracranial treatments were required to meet standards for automated intensity modulated radiation therapy (IMRT) optimization. Intracranial treatments were limited to 1-3 lesions and 1-2 isocenters. The day before treatment, the patient needed to be identified, and any diagnostic imaging had to be available for the physician and dosimetrist to discuss the plan. On the day of treatment, simulation was scheduled for 8 AM and treatment at 4 PM by default, with the goal to complete treatment by 6 PM. We analyzed information about each patient's treatment plan and time spent on each step of the workflow.
Results: Ninety-seven patients followed our same-day workflow and were included in the analysis. Seventy-five patients received intracranial SRS (57% to 1 lesion), while 22 patients received extracranial treatments (50% to the extremities). Simulation often required additional time to be completed, finishing a median 18 min (IQR 5-40) after the goal end time. The median time between simulation completion and end of the same-day treatment was 7.8 h (IQR 7.4-8.6). Treatment technique and the number of target volumes had a significant impact on planning time. The median treatment end time was 5:13 PM (IQR 4:46 PM-6:01 PM), with 74% ending by 6 PM.
Conclusions: A linac-based program to treat patients with SRS/SBRT in an expedited fashion was established and successfully treated patients in a same-day timeline. Careful selection of planning techniques to limit plan complexity and adding automation in time-consuming parts of the process are crucial when developing expedited workflows.
(© 2026 The Author(s). Journal of Applied Clinical Medical Physics published by Wiley Periodicals, LLC on behalf of The American Association of Physicists in Medicine.)