There is evidence that Actinium-225 Prostate-Specific Membrane Antigen (225Ac-PSMA) has a potentially higher level of efficacy than 177 Lutetium Prostate-Specific Membrane Antigen (177Lu-PSMA) as a radioligand therapy. This single center, pilot study will compare differences in the mechanisms of actinium-225 and lutetium-177 radioligand therapies (RLT) in participants with high or very high risk localized or locoregional prostate cancer planning on undergoing a prostatectomy.