5. Physics heal thyself

Stable and radioactive isotopes are used extensively in diagnostic and therapeutic medical applications including studies of human body composition, energy balance, protein turnover, and metabolism. ‘Physics heal thyself: isotopes in medicine’ shows how ionizing radiation is key to a host of medical imaging techniques with radioactive isotopes widely used to target and kill cancer cells. Enriched isotopes are used as biological tracers; doubly labelled water in the diagnosis of type 2 diabetes; and 13C-labelled urea in diagnosing stomach and duodenal ulcers. Medical uses of ionizing radiation are manifold including X-ray imaging, radiotherapy with external X-ray beams, brachytherapy, targeted radionuclide therapy, single photon emission computed tomography, and positron emission tomography.