Retrospective Evaluation of an Always-on Cherenkov Imaging System for Radiotherapy Quality Improvement

Purpose: Cherenkov imaging is now clinically available to track the course of radiation therapy as a treatment verification tool. The aim of this work was to discover the benefits of always-on Cherenkov images as a novel incident detection and quality improvement system through retrospective review of imaging in our center. Methods: Continuous imaging of all patients was attempted during a 12-month period by automating the acquisition of Cherenkov imaging using an always-on commercial system. Multi-camera systems were installed in two treatment bunkers in the radiation oncology clinic at our center and one bunker in an affiliated satellite clinic. Images were acquired as part of normal treatment procedure and reviewed retrospectively with potential incidents flagged for evaluation by the physician and medical physics teams. Results: In total, 622 patients were imaged as part of this study. In this summary, 9 patients were identified with incidents occurring during their course of treatment that were detected only with Cherenkov imaging. Incidents were found relating to issues during simulation, planning, pre-treatment review, and treatment delivery, however none of the incidents were detected prior to treatment delivery. Primary areas of improvement identified in this study are dose to unintended areas in planning, dose to unintended areas due to positioning, and non-ideal bolus placement during setup. Case studies are presented highlighting the detection of these issues using Cherenkov imaging. Conclusions: All detected events were deemed below the threshold for reporting, but their observation could lead to quality improvement in practice. Perhaps most importantly, the imaging was seamless with no effort required by the radiotherapy team and provided both real-time and permanent records of what was delivered in each fraction.