Abhinay Ramachandran
Lesion Mapping, Dosimetry Calculation, and Treatment Implications in Hepatic Y-90 Microsphere Radioembolization

SchoolWestlake High School


ProgramRaiology


MentorShyam Srinivas, MD, PhD


DepartmentNuclear Medicine


Research
Lesion Mapping, Dosimetry Calculation, and Treatment Implications in Hepatic Y-90 Microsphere Radioembolization
Hypothesis
The dosage to tumors from a 3-compartment model is thought to be more accurate than the dosage to tumors from a 2-compartment model because the latter assumes homogeneous perfusion of the Y-90, which is contrary to the distribution seen on SPECT/CT MAA scans.
Methodology
Nine patients who had received Y-90 treatment had complete pre- and post-therapy PET/CT and CT imaging. The two largest lesions were contoured on the pre-CT and PET/CT scans and the post-CT and PET/CT scans. Knowing that the MAA scan models the distribution of Y-90, the lesion contours on the pre-CT and pre-PET scans were mapped onto MAA SPECT/CT scans. Dosages to tumors were obtained using specialized software. Dosages were compared to the calculated values based on a 3-compartment model versus a 2-compartment model.
Outcomes
A 3-compartment model more accurately determines the radiation dosage to lesions than a 2-compartment model because the 3-compartment model divides the injected dose into a healthy liver, tumor, and lung, and considers the tumor vascularity ratio (from MAA scan). Analysis of treatment success/failure may be more meaningful if the radiation dose to the lesions is known.