Radiopharmaceuticals
Small quantities of radioactive pharmaceuticals minimize risk while creating invaluable opportunities for physicians to image and evaluate the body without surgery.
Credit: Brookhaven National Laboratory
One of the most significant ways in which chemistry has had an impact on society is through the field of nuclear medicine. By using compounds classified as “radiopharmaceuticals” or radioactive pharmaceuticals, doctors and scientists have dramatically improved their ability to image the body so they can diagnose medical conditions without invasive surgery.
Technetium-99m is one such radiopharmaceutical. Its unique properties make it ideal for taking medical images and creating functional studies of the brain, thyroid, kidneys, lungs, bones, blood, gallbladder, heart, and of various types of tumors. It is used in over 80 percent of all medical procedures involving radiopharmaceuticals. It has a short half-life of six hours, which means that technetium’s radioactivity dissipates rapidly. To obtain the isotope, it is “milked” as needed from a radioactive molybdenum source that has a much longer half-life. The technetium-99m is then added to a pre-made chemical kit to form a compound appropriate for the body part to be studied. Once the agent has reached the site that is to be imaged, medical technicians use specialized equipment to see how the organ is functioning and/or to detect cancers.
Although the idea of having a radioactive substance in a human body may be initially alarming, only tiny quantities of radiopharmaceuticals are used because the imaging techniques and technology are so highly sensitive. The chemical agents are also designed for the specific organ or type of tumor cell in question. For example, iodine is used specifically for thyroid studies. Thus, the radioactive agent remains localized rather than diffusing randomly throughout the body.
Radioactive elements are selected from among those with very short half-lives so the amounts that the body does not excrete directly decay rapidly to background levels. Likewise, many of the elements used for these methods have nuclei that are gamma emitters, which are among the least damaging since the radiation can completely exit the body.
Radiopharmaceuticals provide a swift means for doctors to evaluate internal symptoms. These chemical compounds save patients enormous amounts of time and are much less invasive than surgical evaluations.
More information about uses of radiopharmaceuticals may be found at http://www.mayoclinic.com/health/drug-information/DR602307