Interstitial injection of radioactive isotopes has provided the urologist with a new approach to the treatment of advanced urological tumors. Radioactive colloidal gold (Au198), reported by Flocks,* was the first isotope employed in far-advanced cancer of the prostate. Some investigators, using radioactive colloidal gold, have noted undesirable complications, such as radiation ulcer of the rectum or urinary bladder and depression of the hemopoietic system from the radiation of gold.198 Experience with x-ray, radium, or radon-seed gamma radiation has shown damage to adjacent benign tissues. The fact that gamma or x-ray radiation cannot be confined within the tumor area has made most radiation therapists reluctant to treat urological cancers by this means. Thus, the question naturally arises, would a pure beta-emitting isotope, interstitially injected, provide local tumorcidal radiation without serious widespread reaction in the normal tissue (Table 1).
Chromic phosphate (CrPO4) containing radioactive phosphorus32 was selected for