ESTRO 2025 - Abstract Book

S4062

RTT - Patient care, preparation, immobilisation and IGRT verification protocols

ESTRO 2025

1267

Digital Poster Clinical use of a cost-effective breath hold monitoring system based on depth cameras Jochem Kaas Radiotherapie, Radiotherapiegroep, Arnhem, Netherlands

Purpose/Objective:

Radiotherapy of left-sided breast cancer typically involves a deep inspiration breath hold technique to reduce heart dose and toxicity. A stable breath hold is required for successful irradiation, since an unstable breath hold position and variations between individual breath holds can cause a misposition of the target. The stability and reproducibility of breath holds is difficult to judge on normal room-monitoring camera systems. This has prompted radiotherapy clinics to introduce various systems to monitor and improve breath hold, including EPID-based systems, physical breath guides, and full SGRT based systems. We introduce a cost-effective depth camera system, recently implemented in our institute. We monitored at least 3 fractions of 43 distinct patients treated, and present the results. Material/Methods: The breath hold monitoring system (CNERGY Breath Hold, Cablon Medical) consists of a single camera unit containing two infrared stereo cameras for depth measurement. Depth is measured at the tip of the sternum of the patient, converted to a height in patient coordinates, and this is tracked during the fraction at 15 fps. The average height measured during the CBCT is taken as the reference height, which is compared to the height measured during the MV beams. For analysis, we present box plots of all height differences measured during MV beams for each patient. Additionally we estimate the measurement stability of the camera system itself in a real-world scenario using the most stable looking observed MV beams, under the assumption that the most stable looking MV beams were cases where the surface of the patient was actually stationary.