Real‐time monitoring of seroma changes during breast cancer radiotherapy using Cherenkov imaging: A technical note

Abstract Background Seroma formation after breast‐conserving surgery is a common postoperative occurrence that can significantly affect the accuracy of radiation therapy. Variations in seroma size and shape during treatment introduce uncertainties in dose delivery, potentially compromising target coverage and increasing exposure to healthy tissue. Conventional monitoring relies on periodic imaging such as CT or MRI, which may not capture dynamic changes during the treatment course. Purpose This technical note investigates the feasibility of using Cherenkov imaging for real‐time monitoring of seroma evolution during breast cancer radiotherapy. The goal is to determine whether this approach can provide actionable information to improve treatment accuracy and support adaptive planning. Methods Breast cancer patients undergoing whole‐breast irradiation were treated using a TrueBeam linear accelerator (Varian, Palo Alto, CA) with surface guided radiation therapy (SGRT) for positioning and breath‐hold gating. Seromas were initially contoured during treatment planning and reassessed mid‐treatment using cone‐beam CT. Cherenkov imaging (DoseRT, VisionRT) was integrated into daily treatment sessions to visualize seroma changes in real time. Seroma size and shape were recorded for each fraction and compared with initial planning volumes and mid‐treatment imaging. Results Cherenkov imaging successfully identified and tracked seroma changes throughout the treatment course. Significant variability was observed among patients: some exhibited progressive enlargement, while others demonstrated resolution. For example, one patient's seroma increased from 24 cm 3 at planning to 29 cm 3 at completion, whereas another decreased from 12.5 to 5.8 cm 3 . Pixel‐based measurements from Cherenkov imaging correlated with volumetric changes observed on CT, confirming the reliability of this technique. These findings underscore the dynamic nature of seromas and the potential need for adaptive interventions during treatment. Conclusions Cherenkov imaging offers a practical, noninvasive solution for real‐time monitoring of seroma changes during breast cancer radiotherapy. By providing immediate feedback on anatomical variations, this technology can enhance treatment accuracy, reduce unnecessary radiation exposure to healthy tissues, and inform adaptive planning strategies. Further research is warranted to evaluate clinical outcomes, workflow integration, and cost‐effectiveness.