Development and in-vivo testing of an MR-compatible biofeedback device for MR-guided radiotherapy simulation and treatment

Motivation: Biofeedback during radiotherapy simulation and treatment on conventional linacs improves the accuracy and reproducibility of patient alignment, especially those using breath-hold. However, commercial devices cannot operate in MR environments. Goal(s): The goal of this study was to develop an MR-compatible biofeedback device and test its utility in volunteer studies. Approach: The device consists of a single-board computer and addressable LED strip, which was automatically controlled by tracking anatomic motion in CINE MR images. Results: Initial volunteer studies using the device in an MR linac demonstrated that biofeedback-guided breath-hold resulted in more accurate and consistent target alignment compared to self-guided breath-hold. Impact: MR-compatible biofeedback devices can facilitate and improve breath-hold techniques for MR-guided radiotherapy simulation and treatment. Furthermore, incorporation of CINE MR images to measure changes in internal anatomy improves target alignment relative to existing devices that use surface imaging.