Abstract
Yttrium-90 (Y-90) therapy has become an important component to the care of patients with primary hepatic malignancies and lesions that have metastasized to the liver. Therapy is administered through an intra-arterial procedure after an interventional procedure is performed using an albumin labeled product to ensure therapy will be delivered to the target volume of interest with minimal migration from the target of choice. In the past, dose to target has been measured by activity delivered and qualitative deposition of dose on metabolic imaging post application. Imaging tools such as single positron emission computer tomography (SPECT) and digital positron emission tomography have given us insight into quantitative dose to volumetric tumor target and dose to normal tissue. Recent validation of computational software has provided voxel-based dosimetry similar to applied processes established in radiation oncology planning systems. This development presents an opportunity to create dose volume analysis similar to teletherapy and brachytherapy dose delivery for Y-90 therapy. In this case report, we review Y-90 dosimetry on a patient with dual diagnosis of a locally advanced high-risk adenocarcinoma of the prostate which required treatment to the para-aortic lymph nodes located in the same axial plane with renal parenchyma. Although not clinically anticipated, hepatocellular carcinoma was serendipitously discovered at the time of staging for prostate cancer. Treatment dosimetry of the hepatocellular carcinoma is reviewed in retrospect with voxel-based commercial software. Same day SPECT study suggested dose localized to the liver, however voxel planning software confirmed unintentional dose to additional structures including the right kidney and uninvolved liver which influenced radiation therapy treatment planning for prostate carcinoma. With modern available tools, post therapy dosimetry for Y-90 can be performed in a manner similar to volumetric dosimetry used in radiation oncology and provide valuable dose volume analysis of dose delivered to target and additional tissue.
