Low energy X and Gammaray sources such as Cs 13 (9.7 Days Tl/2, 30 keV) are extremely useful in cancer therapy with obvious advantages such as ease of shielding, useful range in tissue. Since Cs 131 is capable of forming insoluble metal complexes with metal salts such as Ammonium Molybdophosphate, it is intended to exploit this property of Cesium in this study. The purpose of the present study is to explore the feasibility of commercially manufacturing radioactive sources of Cs 131 technologically superior and better capable than existing ones, of providing uniform distribution of radioactivity and desirable safety characteristics.We plan to accomplish this project in several steps: a. complex formation with a suitable metal as a substrate, from which Cesium does not dissociate, b. seed manufacture, consisting of central tunrsten core coated with a suitable metal complex, film manufacture, consisting of suitable membrane coated with a suitable metal complex, c. evaluation of radioactive source integrity against leakage using conventional procedures, and d. evaluation of uniformity of dose distribution in the radioactive source and clinical potential by dose and dose rate measurements.Commercial Applications:This research will result in commercial development of Cs 131 seeds and films for cancer therapy. These sources offer considerable advantage in terms of ease of handling, shielding, and treatment of tumors. Best Industries, with its 1.5 million dollar state of the art automated, computerized manufacturing facility is ideally suited for manufacturing and commercializing to hospitals internationally.National Cancer Institute (NCI)