Nuclear Medicine is the specialty branch of medicine in which radioactive materials are used to diagnose and treat diseases. It is also sometimes referred to as molecular imaging.
Nuclear Medicine refers to the use of radioisotopes and radiopharmaceuticals for the diagnosis of disease through organ imaging and functional assessment, and emphasized the functional and physiological changes associated to diseases rather than anatomy.
Anatomic detail is best provided by x-ray procedures such as CT and MRI. The combination of the anatomic information from x-rays and the physiologic information generated from the Nuclear Medicine gamma cameras, either through planar and/or SPECT techniques, and PET cameras enhance diagnostic accuracy thereby assisting the referring physician to better manage the patient’s medical condition.
Radioactive drugs called radiopharmaceuticals are compounds administered to the patient based upon physiological function of the target organ. There are many different types of radiopharmaceutcals, each used for a specific test or treatment.
A radionuclide is the radioactive portion of the radiopharmaceutical. A radionuclide is an atom with an unstable nucleus. The radionuclide undergoes radioactive decay by emitting a gamma ray (s) and/or subatomic particles. Each radiopharmaceutical has a radionuclide component.
- Examples of radionuclides: Iodine-123 (I-123), Technetium- 99m (Tc-99m)
- Examples of radiopharmaceuticals: I-123 mIBG (metaiodobenzylguanidine)
- Technetium-99m MDP (methylene-diphosphonate)
A radioisotope is a version of a chemical element that has an unstable nucleus and emits radiation during its decay to a stable form. A radioisotope is so-named because it is a radioactive isotope, an isotope being an alternate version of a chemical element that has a different atomic mass. Examples are Iodine-123, Iodine-131, and Iodine-125, all the same element (iodine) but each having different atomic masses.
Gamma camera – A gamma camera is a system of detectors, photo sensors and computers used in the recording of gamma ray emissions emanating from radioisotopes present in the body.
Planar imaging – A technique where a two-dimensional image of an organ is produced on a gamma camera.
SPECT – An acronym that stands for Single Photon Emission Computed Tomography, a nuclear medicine imaging technique in which a gamma camera rotates around the patient and takes pictures from many angles, after which a computer then forms a tomographic (cross-sectional – three-dimensional) image.
PET – An acronym that stands for Positron Emission Tomography. PET is a unique Nuclear Medicine imaging technique that uses short-lived radionuclides (less than 2 hours) to produce three-dimensional images of those substances functioning within the body. PET scans are performed on a specialized unit called a PET camera.
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