Dose Escalation Study Evaluating Safety of TheraSphere Prostate Cancer (PCa) Device

TheraSphere™ Y-90 Glass Microspheres are a targeted cancer therapy consisting of tiny glass beads containing radioactive Yttrium-90 (Y-90), which are injected directly into the blood vessel feeding the tumor through a microcatheter using advanced imaging guidance. The glass microspheres enter the tumor's blood supply, lodge within the blood vessels feeding the tumor, and release radiation to the tumor. The radiation works to destroy the tumor cells from within, thus limiting radiation exposure to surrounding normal tissues, a process referred to as selective internal radiation therapy (SIRT). This study aims to investigate the maximum safe radiation dose of TheraSphere Prostate Cancer (PCa) device that can be delivered in patients with clinically localized prostate cancer. The study will also evaluate the full safety profile, technical feasibility, efficacy, and quality of life metrics of the TheraSphere PCa device. Participants will be asked to complete the following: * At least two image-guided visits, including a mapping assessment (without Technetium Tc albumin aggregated \[Tc-MAA\]) prior to treatment * One treatment visit, including image-guided assessments * Fifteen post-treatment follow-up visits for a total of approximately 20 visits over the 5-year study period Note: the VOYAGER Study is a staged investigational device exemption (IDE) study; therefore, the full enrollment of 21 to 36 subjects is subject to FDA approval following safety review of the first 10 subjects enrolled.