Abstract Background: Radiotherapy is an essential component of definitive treatment for many patients with breast cancer. Cherenkov imaging is an emerging optical imaging technology that enables visualization of radiotherapy beams on the patient’s surface in real-time. The anatomy and treatment setup of breast radiotherapy make it particularly well suited for evaluation with this technique. While Cherenkov imaging typically confirms accurate treatment delivery, it has also revealed instances of irradiation to unintended tissues. We hypothesized that Cherenkov imaging could be used as a quality improvement tool to identify and minimize radiation dose to normal tissues among patients receiving radiotherapy for breast cancer. Methods: As part of a prospective clinical trial, Cherenkov images were reviewed daily for all patients receiving breast radiotherapy at 1 academic and 1 community medical center. When dose to anatomical regions outside the treated breast was identified on Cherenkov images, a root cause analysis was performed to determine contributing factors. Treatment plans were re-evaluated using the treatment planning system (TPS), and modifications were made when clinically appropriate. Results: •Case 1: Cherenkov imaging identified unexpected dose on the ipsilateral back of a patient treated in the prone position. TPS review revealed an anterior-posterior (AP) beam exiting through the heart. The plan was revised to eliminate the AP field, and institutional practice was updated to minimize heart and lung exposure in similar cases.•Case 2: Excess dose to the left arm was identified in a prone left breast treatment. Review suggested that adjusting the multi-leaf collimators (MLCs) could reduce exposure. A revised plan was implemented, resulting in reduced arm dose on subsequent fractions.•Case 3: Cherenkov imaging showed signal on the chin and neck of a young patient receiving supraclavicular irradiation. A more optimal setup was identified, the patient was re-simulated with modified positioning, and a new plan was created. Subsequent imaging confirmed reduced unintended exposure in the revised plan.•Case 4: A patient noted a sore throat 2 weeks into a course of breast and supraclavicular irradiation. Review of Cherenkov images and the TPS suggested contralateral extension of the right supraclavicular field due to a setup issue during treatment delivery, as breast anatomy and the supraclavicular field did not correlate well. MLCs were adjusted to minimize esophagus dose. •Case 5: Cherenkov imaging showed unexpected contralateral breast dose. Review of on-treatment imaging and the TPS suggested this was due to patient setup, and modifications were made in to setup in future treatments to minimize contralateral breast dose. Conclusions: Cherenkov imaging provides real-time visual feedback on beam delivery during breast radiotherapy and is a valuable tool for identifying and improving suboptimal deliveries. By increasing the salience of treatment plan features that may be overlooked with traditional plan evaluation strategies and enabling timely plan adjustments, this methodology has the potential to improve patient safety. Incorporating Cherenkov imaging into routine clinical workflows may enhance the quality of breast radiotherapy by minimizing the irradiation of off-target tissues. Citation Format: A. L. Matous, E. Chen, L. Jarvis. Cherenkov Imaging as a Real-Time Quality Improvement Tool in Breast Radiotherapy: A Case Series abstract. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS1-07-30.
Matous et al. (Tue,) studied this question.