  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.
