This is the sort of machine which is used to observe the interior of the human body using antimatter.
Yes, that’s right, antimatter. Organic compounds can be “tagged” with the radioactive isotopes fluorine-19 and carbon-11, which undergo positive beta decay, & the positrons rapidly strike electrons in the body, emitting gamma rays which are picked up by the detectors, showing where the compounds have concentrated. By the use of compounds with different metabolic roles, a variety of functions can be studied. These isotopes, and the rarely-used oxygen-15, are very short-lived, and are most commonly made in the hospital where they are used, by means of a particle accelerator.
A similar technique uses technetium-99m, which undergoes an isomeric transition, producing gamma radiation with no accompanying chemical change, with a half-life of six hours. That short half-life means that 99m-Tc is normally produced in the hospital from a parent isotope, molybdenum-99, which itself has a half-life of less than three days, and is obtained as a fission product by irradiating fully-enriched uranium targets in research reactors. (“Ordinary” technetium-99 has a half-life of 211 000 years!) Due partly to the insistence of the arms-control people on eliminating the civilian use of this fuel, there has been a worldwide shortage of this critical medical isotope for some years now.
Incidentally, AREVA, the French nuclear energy company, is opening a new medical isotope facility in Plano soon. Hopefully we can get a tour.