Patients with castrate resistant prostate cancer (CRPCA) with osseous metastatic disease planning to undergo Ra-223 therapy may be eligible for this study. Positron emission tomography (PET/CT) imaging will use the investigational radiotracer [11C]acetate. Imaging will occur prior to Ra-223 therapy and after 2 cycles, in addition to standard of care 99mTcMDP bone scan at baseline and a research 99mTc-MDP bone scan post-therapy