Radioisotope thermoelectric generators (RTGs) The radioactive decay of<unk>  generates a significant amount of heat, 0.95 W/g in the form of pure<unk>  metal or approximately 0.460 W/g as<unk>  titanate and is cheaper than the alternative 238Pu. It is used as a heat source in many Russian/Soviet radioisotope thermoelectric generators, usually in the form of<unk>  titanate. It was also used in the US "Sentinel" series of RTGs. Industrial applications<unk>  finds use in industry as a radioactive source for thickness gauges. Medical applications<unk>  finds extensive use in medicine as a radioactive source for superficial radiotherapy of some cancers. Controlled amounts of<unk>  and 89Sr can be used in treatment of bone cancer, and to treat coronary restenosis via vascular brachytherapy. It is also used as a radioactive tracer in medicine and agriculture. Aerospace applications<unk>  is used as a blade inspection method in some helicopters with hollow blade spars to indicate if a crack has formed. Radiological warfare In April 1943, Enrico Fermi suggested to Robert Oppenheimer the possibility of using the radioactive byproducts from enrichment to contaminate the German food supply. The background was fear that the German atomic bomb project was already at an advanced stage, and Fermi was also skeptical at the time that an atomic bomb could be developed quickly enough. Oppenheimer discussed the proposal with Edward Teller, who suggested the use of<unk> . James Bryant Conant and Leslie R. Groves were also briefed, but Oppenheimer wanted to proceed with the plan only if enough food could be contaminated with the weapon to kill half a million people.
Strontium-90
Technetium 
Radium-223
Iodine 
Iodine
Rubidium-82 chloride
Technetium-99m
Dotinurad