Therapeutic Radionuclides: Production, Physical Characteristics, and Applications

This chapter will focus primarily on the selection criteria, production, and the nuclear, physical, and chemical properties of therapeutic radionuclides, including those that are currently being used, or studied and evaluated, and those that warrant future investigations. Various scientific and practical issues related to the production and availability of these radionuclides will also be addressed. It is expected that this chapter will form the basis for the other chapters in this volume that will in much greater detail deal with radiopharmaceuticals based on a number of these therapeutic radionuclides and their present and potential usefulness in the clinical setting for treating cancer and other disorders. We are also reintroducing and reinforcing our recently proposed paradigm that involves specific individual “dual-purpose” radionuclides or radionuclide pairs with emissions suitable for both imaging and therapy, and which when molecularly (selectively) targeted using appropriate carriers, would allow pre-therapy low-dose imaging plus higher dose therapy in the same patient. We have made an attempt to sort out and organize a number of such theragnostic radionuclides and radionuclide pairs that may thus potentially bring us closer to the age-long dream of personalized medicine for performing tailored low-dose molecular imaging (SPECT/CT or PET/CT) to provide the necessary pre-therapy information on biodistribution, dosimetry, the limiting or critical organ or tissue, and the maximum tolerated dose (MTD), etc., followed by performing higher dose targeted molecular therapy in the same patient with the same radiopharmaceutical. Beginning in the 1980s, our work at Brookhaven National Laboratory (BNL) with such a “dual-purpose” radionuclide, tin-117m, convinced us that it is arguably one of the most promising theragnostic radionuclides and we have continued to concentrate on this effort. Our results with this radionuclide are therefore covered in somewhat greater detail in this chapter. A major problem that continues to be addressed but remains yet to be fully resolved is the lack of availability, in sufficient quantities and at reasonable cost, of a majority of the best candidate radionuclides in a no-carrier-added (NCA) form. A brief description is provided of the recently developed new or modified methods at BNL for the production of five theragnostic radionuclide/radionuclide pair items, as well as some other therapeutic radionuclides which have become commercially available, whose nuclear, physical, and chemical characteristics seem to show promise for therapeutic oncology and for treating other disorders that respond to radionuclide therapy.