Group VIA radiopharmaceuticals
The elements of group VIA which have useful radionuclides for nuclear medicine studies are oxygen, selenium and tellurium. They have two electrons in their outermost shells and in general form covalent bonds. The useful radionuclides are oxygen-15, selenium-75 and tellurium-123m. The radiopharmaceuticals of oxygen-15 are described in Chapter 14 (positron emitters); selenium-75 taura-23-selena-25-homocholic acid (75Se-HCAT) is described in Chapter 15 (non-imaging). There are no available radiopharmaceuticals containing tellurium-123m. Selenium-75 /-selenomethionine was evaluated for pancreas imaging but because of high background radioactivity it is seldom used. Only selenium-75 selenomethyl norcholesterol is described in this chapter.