Abstract: Current protocols in surface and interstitial HDR brachytherapy require CT imaging to visualize and digitize catheters for treatment planning. For interstitial HDR brachytherapy, MRI is routinely acquired for tissue segmentation, owing to its superior soft tissue contrast. However, MRI often does not provide sufficient contrast visualize catheters, hence, CT is still relied upon for catheter digitization process. The purpose of this study was to investigate the implementation of an MRI-only treatment planning (MRTP) approach that can potentially eliminate CT and improve the clinical treatment planning process for HDR brachytherapy. We have optimized ‘Pointwise Encoding Time Reduction with Radial Acquisition’ (PETRA) MRI sequence and examined the feasibility of implementing MRTP in phantoms and clinical data for:

a) Surface HDR brachytherapy using a flexible mesh-style Freiburg Flap applicator
b) Interstitial HDR brachytherapy using the Syed-Neblett template

About the speaker: Casey Lee is a 2nd year medical physics resident in the Harvard Medical Physics Residency Program. She received her Ph.D. in Medical Biophysics from the University of Toronto in 2020. Her thesis examined lactate levels in intracranial metastases using Hyperpolarized 13C MRI. During the 1st year of the residency program, she worked on a research project exploring MRI-only treatment planning in high-dose-rate brachytherapy under the supervision of Drs. Ivan Buzurovic and Robert Cormack at Brigham and Women’s Hospital.