Radioisotopes are chemical entities that have the potential to emit radiation which can be detected through specific methods. Although such radiation is considered bad to the human body, these isotopes are selected according to its usefulness as well as its minimum harm to the patient. When considering them in relation to medicine, these chemical agents are used either in diagnostic procedures or else in the treatment of certain conditions.
Radioisotopes used for diagnostic procedures:
In the body, certain chemical agents or trace elements will show high affinity to specific tissues such as in the case of iodine to the thyroid. In such instances, if these elements can be labeled with a radioisotope, it can be detected in the target organ and a specialized camera will be able to produce an image depicting the structure as well as functionality of the said tissues.
In another instances, radioisotope Tc-99m, which probably is the most widely used radioisotope of all, will concentrate in the heart, liver, kidneys and in the brain and therefore will be useful in detecting certain defects in relation to these organs. For example, when this chemical agent is injected in to the blood stream while a patient does an exercise test, it can be detected on its passage through the vessels in the heart and will illustrate the patency of the same and any defects or blockages can be identified by the physician.
Apart from these uses, nuclear brain imaging and radio-immuno assays will also make use of these radioisotopes in performing their function.
Use in relation to treatment:
Radioisotopes will have an important place in treating conditions such as cancers and many research and clinical trials are underway to harness this potential. But, being harmful to living tissues, the use of such agents needs to be strictly controlled and tight regulations when considering its many other potentially deadly uses.
Among the treatment modalities that are used, teletherapy and brachytherapy is considered the most effective. In telethrapy, a gamma ray emitting device would be used to direct these high energy rays in to the cancer cells from outside. Co-60, which is a strictly regulated radioisotope, is being used for this process and the authorities have imposed strict guidelines to follow when using this technique.
In contrast to teletherpay, brachytherapy will direct radiation towards the cancer cells by being present within the tissues and this would be achieved through implanting devices which emits these rays to the surroundings. Iridium-192 and Iodine-125 are both used in such therapeutic uses and in case the isotope device exerts radiation even after the cancerous tissues have been eliminated, it may have to be removed in order to prevent any harmful side effects.
Reference : http://www.northland.cc.mn.us/biology/biology1111/Bioreadings/radioisotopes.htm