Nuclear medicine is special in medical imaging that uses radionucleides for diagnosis and treatment of disease. Radio nuclides are combined with other elements to form chemical compounds. These chemical compounds are again combined with existing pharmaceutical compounds to form radiopharmaceuticals. These radiopharmaceuticals are administered to the patients to localize a particular organ or cellular receptors. This allows the ability to image the disease-process in the body based on the cellular function and physiology. Nuclear medicine identifies diseases at an earlier stage then the other diagnostic procedures. Nuclear medicine is not only used for diagnosing but also for treating diseases.
In this imaging technology, radioactive substance is administered internally either orally or intravenously. External detectors like the gamma cameras capture and form images. Images are formed from the radiations emitted by the radiopharmaceuticals. This process is completely different from the other imaging technologies. There are several techniques in nuclear medicine. Scintigraphy is the process of creating 2 dimensional images by using internal radionucleides. SPECT is used for getting the images in different planes by using the gamma camera date from the projections. Positron Emission Tomography is another technique which uses coincidence detection to image functional process. Nuclear medicine imaging techniques are more organ specific. They are used for taking images of lungs, heart, bone and bran unlike the conventional technologies that focus only on the particular section of the body.
These diagnostic tests exploit the way the body handles substances in the presence of disease. The radionuclide introduced in the body will be bound chemically to a complex that acts characteristically within the body. This is known as tracer. A tracer will be processed and act differently in the presence of a disease. Increased concentration of the tracer means that there is a physiological problem in the particular organ. Many tracer complexes have been developed to image and treat different organs, glands and physiological process. Sometimes nuclear medicine scans are superimposed on images from CT or MRI to highlight the part of the body where the radiopharmaceutical is concentrated.
