Over 10,000 hospitals worldwide use radioisotopes in medicine, and about 90% of the procedures are for diagnosis.
The most common radioisotope used in diagnosis is technetium-99 (Tc-99), with some 35 million procedures per year, accounting for about 80% of all nuclear medicine procedures worldwide.
The radiation may be delivered by a machine outside the body (external-beam radiation therapy), or it may come from radioactive material placed in the body near cancer cells (internal radiation therapy, also called brachytherapy).
In some cases radiation can be used to treat diseased organs, or tumours.
Five Nobel Laureates have been closely involved with the use of radioactive tracers in medicine.
Wiens has a Ph D in Physics, with a minor in Geology.
His Ph D thesis was on isotope ratios in meteorites, including surface exposure dating.
Radiation therapy uses high-energy radiation to shrink tumors and kill cancer cells (1).