Atoms in medicine and health

The introduction of radiation into biomedicine occurred in 1923 when Hevesy tried to study lead metabolism in plants using its radioisotope. Nuclear medicine is a clinical specialty devoted to the diagnotic, therapeutic and research applications of radionuclides. Imaging however constitutes the main bulk of this specialty and is mostly for diagnostic reasons. The first time a radiotracer was used in humans was in 1925 when investigators tried to measure the velocity of blood flow using radon. Worth mentioning is the use of radionuclides for immunoassays which had been introduced by Berson and Yalow in 1959. Besides their diagnostic utilities, radionuclides offer tremendous therapeutic possibilities. In 1936, John Lawrence used phosphorous-32 to treat leukemia. This inaugurated the therapeutic usage of radioisotopes. The first ever recorded use of radioiodine for the treatment of hyperthyroidism was in 1936 at the Massachusetts General Hospital in Boston. It was then used for thyroid cancer treatment in New York sometime between 1943 to 1946. Today, several radioisotopes have already achieved important therapeutic applications. Strontium-89 and Samarium-153 are of value for relief of pain due to bone metastasis. Phosphorous-32 has been used as an adjunct in the treatment of polycythemia vera. More recently, therapeutic recognition site ligands which holds promise in the future presents a more specific approach to radiotherapy. The gamma camera was invented in 1958 by Hal Anger, a great leap from the primordial cloud chamber. Multiheaded cameras were introduced with the aim of better sensitivity and faster acquisition times. Single photon emission computed tomography (SPECT) was incorporated into the system in 1976 for better delineation of structures. Improvements in this technology eventually paved the way for dedicated instruments. Moreover, improvements in instrumentation have now made possible to do 'SPECT' imaging using 'PET' tracers using dual headed cameras operating in coincidence mode