A Windows GUI application for real-time image guidance during motion-managed proton beam therapy

Abstract

Respiratory motion-management is crucial for maintaining robustness of the delivered dose in radiotherapy. This is particularly relevant for spot-scanned proton therapy, where motion-induced dosimetric “interplay” effects can severely perturb the planned dose distribution. Our proton therapy vendor developed a stereoscopic kV X-ray image-guidance platform along with a 3D/2D image matching algorithm for 6 degree-of-freedom patient positioning with a robotic couch. However, this vendor-provided solution lacks the capability to process and display X-ray fluoroscopic imaging, which is crucial for aspects of motion management. To address this clinical gap, we developed a Windows-based software tool in .NET/C# to passively acquire the vendor’s flat-panel detector (FPD) data stream (CameraLink) and handle fluoroscopic images in real time. We developed a novel calibration phantom and the accompanying room-geometry-specific calibration routine for projective overlay of DICOM-RT structures onto the 2D FPD images. Because our calibration routine has been developed independently this tool serves as an independent means to test and validate the vendor’s imaging geometry calibration. Having DICOM integration with our treatment planning infrastructure, this therapy tool automatically archives clinical X-ray data to a HIPAA-compliant cloud, and therefore serves as a data interface to retrieve previously recorded X-ray images and cine video streams. This functions as a platform for image guidance research in the future. The next goal on our roadmap is to develop computer-vision/deep-learning methods for real-time soft-tissue based tumor tracking.