Machine Learning in 4DCT Lung Stereotactic Body Radiotherapy (SBRT) Treatment Planning

Collaborator: Winship Cancer Institute, Emory University School of Medicine

The current project seeks to enhance current 4DCT lung cancer patient image processing, image guidance, and adaptive radiotherapy verification through the integration of machine learning (Artificial Intelligence – AI) methods in an existing clinical radiation oncology framework. The current state-of-the-art for Lung SBRT treatment planning begins with the accurate delineation of target organ volumes and their surrounding structures, which is usually done using semi- automatic methods, mixing computer-assisted tools, and dedicated physicians. When it comes to 4DCT scans, what is usually done is to compute a visual average of the images across the different respiratory phases and the contours for those organs (in one specific phase) are delineated. In the last few years, deformable image registration (DIR) techniques have been developed and used in this field to propagate the contour delineation from one specific phase to the rest of the respiratory phases in the CT. Results of the target region delineation are then used by physicians and clinicians to select an optimal treatment phase. Rather than the mostly manual and slow/iterative process introduced above, our current project seeks to create more accurate and more robust delineations through improved machine learning models, decreasing time spent per patient plan, and applying a more mathematically rigorous and objective manner of selecting the optimal radiation treatment gating window, while enhancing image resolution, enhancing target definition, and treatment delivery.

CT slice and contour reordering using advanced AI methods for lung SBRT segmentation.

Although other studies in the past have explored integrating AI for image segmentation for auto-contouring, our project’s novelty lies in the manner of initialized parameters and the specific operations performed. Our project furthers patient-specific treatment planning while adopting a more streamlined approach and helps make more informed decisions using AI, to arrive at improved radiation treatment plans for lung cancer patients undergoing SBRT. We have tested our algorithm in several patients and have seen encouraging improvements.