Nuclear Medicine

Nuclear Medicine branch of medicine connected with the use of radioactive substances for diagnosis, therapy, and research. Use of ionising radiation such as X-rays in the diagnosis of defects in organs has been in practice since long, but in this case one uses radiant energy from exogenous sources such as the X-ray machine and analyses the image produced on a photographic film - the technique is called radiology. Nuclear medicine, on the other hand, uses radioactive atoms that are relevant to human body functions. The radioactive molecules are used in two ways: in vivo (in the body) and in vitro (outside the body). In the former technique, the radioactive substance is introduced into the body in diagnostic and therapeutic procedures, while in the latter case body fluid such as blood is drawn and used externally by mixing it with the radioactive substance. The technology of nuclear medicine is thus distinct from radiology, although in nuclear medicine also image analysis is an integral part.

In therapy, as opposed to diagnosis, for instance in the treatment of cancer, use of X-rays is an area that falls under nuclear medicine. An example familiar in nuclear medicine is the use of radioactive iodine I131 in the diagnosis and treatment of thyroid malfunction. The thyroid gland located in the throat is the centre of iodine metabolism. Rate of iodine uptake by the thyroid gland is used as a measure of thyroid function. This is done by feeding the subject a small dose of radioactive iodine and monitoring its accumulation rate in the thyroid gland. Radioactive iodine at a much larger dose can also be used for treatment of a hyperactive thyroid gland. Radiation emitted from the radioactive iodine atoms destroys part of the gland so that the symptoms of hyperthyroidism largely disappear.

Advances in computer technology have added new dimensions to nuclear medicine. After administration of a radioactive substance to a patient, sophisticated computer software is now used to develop images that are then processed by a computer and the investigator readily gets the time activity curve using suitable computer software.

The history of nuclear medicine in Bangladesh dates back to the early 1960s (when Bangladesh was a part of Pakistan). Since 1961, nuclear medicine techniques are in use here in the treatment of goiter and other thyroid diseases. At present there is one Institute of Nuclear Medicine located at the Bangabandhu Sheikh Mujib Medical University, and one at the Dhaka Medical College premises run by the Bangladesh Atomic Energy Commission. Besides, about a dozen Nuclear Medicine Centres are attached to government medical colleges of the country. The technology deserves to be expanded to serve 130 million people of Bangladesh and in some selected areas the private sector is interested to participate. In this connection, of course, regulatory control must be properly applied since the technology is complicated and involves not only physicians, but also nuclear physicist, electronic engineer, chemist and trained technologists.

Bangladesh is an iodine deficient area and nearly half of the population suffers from varying degrees of iodine deficiency and thyroid dysfunction, and as such the technology of nuclear medicine in this case can be adopted some day as a public health tool. Radioactive atoms commonly used in the different centres of nuclear medicine are I131 and Tc 99m MDP, for thyroid and related bone diagnosis and research. [Zia Uddin Ahmed]

See also radiotherapy.