Nuclear Medicine Introduced
Nuclear medicine is a familiar, albeit ominous, term not always understood. Nuclear medicine can be defined as a medical specialty which uses radioactive substances in a painless and cost-efficient way to detect and treat abnormalities and diseases of the body.
As a diagnostic tool, nuclear medicine can provide information about both physiology (function) and anatomy (structure) of the body in a non-invasive manner. The nuclear material is intravenously injected or introduced into the body by being swallowed or inhaled as a gas. Eventually the material accumulates in the expected part of the body giving off gamma rays. These gamma rays can then be detected from outside of the body, enabling a diagnose which will obtained earlier then by other methods and without the risks associated with surgery.
The radioactive materials which are used to detect problems within the body are referred to as radiopharmaceuticals or the simpler term, radiotracer. These radiopharmaceuticals are bound to substances which have a predictable behavior inside a healthy body but which behave differently when the body is under abnormal circumstances. An increase or decrease of expected radiotracer accumulation will produce "hot'' or "cold" spots on scans indicating a disease or other problem the body is attempting to cope with.
The materials are detected and tracked by special cameras which work in conjunction with a computer to build precise, accurate images of the part of the body being investigated. Both PET (positron emission tomography) and SPECT (Single photo emission computer tomography) are types of scans employed by nuclear medicine. Nuclear produced images when combined with CT or MRI images can give views with even more precise information. These images superimposed over each other are giving way to even newer technology where units able to perform more than one function such as a SPECT/CT or PET/CT units do the same thing simultaneously.
Among the abnormalities detectable with nuclear medical imaging: problems of the thyroid or kidneys as well as those of the pulmonary and cardio systems. Nuclear imaging is also useful for the detection of aneurysms and tumors as well as evaluating fractures, locating internal infections and inflammation and analyzing brain functions.
In nuclear therapy, radiation is delivered internally via radiopharmaceuticals, which move directly to the part of the body needing treatment. Usually diagnostic radiopharmaceuticals give off gamma rays; however, those used in therapy emit cell-damaging beta particles. In some cases implanted capsules containing isotopes are implanted to treat cancer; this is referred to as brachytherapy.
The amount of radiation delivered during a typical treatment is higher than the amount received in nuclear imaging which is comparable to that of an x-ray. However, radiation is kept to a safe amount by following the ALARA (As Low As Reasonably Achievable) principle. Due to the lack of side effects and radiation exposure to others, most nuclear medicine therapies can be performed as outpatient procedures.