Bone scans may be used to see if prostate, bladder, kidney , testicular or penile cancer has advanced. Although the number of bone scans has decreased over the years, these studies are helpful in assessing advanced urologic cancers. In these studies, a radionuclide is injected into the body. Over a period of hours, images are taken of the bones in the body. Absorption of the radionuclide in a specific area may indicate trauma or cancer in the bone. This test is generally safe. In rare cases, people have an allergic reaction to the liquid injected. Source: Urology Care Foundation