Inclusion Criteria:

          -  Participants who have histologically confirmed adenocarcinoma of the prostate.

          -  Participants with bone metastatic CRPC, progressing after 1 or 2 prior lines of
             systemic treatment for metastatic prostate cancer (including prior treatment for
             metastatic hormone sensitive prostate mHSPC or metastatic castration resistant
             prostate cancer mCRPC).

          -  Participants with at least 2 bone metastases on Tc 99m phosphonate whole body planar
             bone scans at Screening.

          -  Documented progression of mCRPC. Disease progression is defined by at least one of the
             following criteria: a. PCWG3 criteria (defined as 2 consecutive increases in PSA over
             a previous reference value measured at least one week prior, with a minimal start
             value of 1.0 ng/mL) or b. ≥2 new bone lesions (according to PCWG3 bone scan criteria)
             or c. Radiological progression according to RECIST, version 1.1.

          -  Ability to participate in the required study procedures including all scanning
             procedures and ability to control pain to ensure tolerance and completion of the
             necessary scanning procedures.

          -  Maintenance of medical castration or surgical castration with testosterone less than
             50 ng/dL (1.7 nmol/L). If the participant is being treated with luteinizing hormone
             releasing hormone (LHRH) agonists or antagonists (participant who has not undergone
             orchiectomy), this therapy must have been initiated at least 4 weeks prior to start of
             Screening and must be continued throughout the study.

          -  Participants must be on a bone health agent prior to the first dose of radium-223
             dichloride. Participants with at least 6 months of prior bone health agent (BHA)
             treatment are preferred.

          -  Eastern Cooperative Oncology Group performance status (ECOG PS) 0 or 1.

          -  Life expectancy ≥6 months.

        Exclusion Criteria:

          -  Any chronic medical condition requiring continuous systemic corticosteroid treatment
             at a higher dose than 5 mg prednisone / prednisolone twice daily.

          -  Pathological finding consistent with neuroendocrine features small cell carcinoma of
             the prostate.

          -  Metastatic bone deposits extend of disease (EOD) grades 0 or 4 (according to centrally
             assessed Tc 99m phosphonate planar bone scans during Screening).

          -  History of visceral metastasis, or presence of visceral metastasis detected by
             screening imaging examinations (according to central review at screening).

          -  Other malignancy treated within the last 5 years (except non-melanoma skin cancer or
             low-grade superficial bladder cancer).

          -  Imminent spinal cord compression based on clinical findings and / or magnetic
             resonance imaging (MRI). - Participants with history of spinal cord compression should
             have completely recovered.

          -  Active or symptomatic viral hepatitis

          -  Inability to tolerate any of the other imaging procedures in the study (ie, bone
             SPECT/CT and planar bone scans with a Tc 99m phosphonate radiotracer, DXA scan,
             radium-223 SPECT/CT scans).

          -  Any condition, which in the opinion of the investigator would preclude participation
             in this trial.

          -  Hypersensitivity to radium-223 dichloride.

          -  Blood transfusion or erythropoietin stimulating agents 4 weeks prior to start of
             Screening and during the whole Screening period before enrollment into the cohort.

          -  Prior administration of an investigational therapeutic for CRPC.