NM is a branch of medicine that uses radiation to provide information about the functioning of a person's specific organs or to treat disease. In most cases, the information is used by physicians to make a quick, accurate diagnosis of the patient's illness. The thyroid, bones, heart, liver and many other organs can be easily imaged, and disorders in their function revealed. In some cases radiation can be used to treat diseased organs, or tumors. The most common radioisotope used in diagnosis is technetium-99 with six hours half life producing 140 Kev. For daily quality control, they use cobalt 57, called sheet source, which has one year half time producing 120 Kev which is close to technetium. For the daily quality control, we started at 7 am and counted four million of sources. Old sheets may produce five Thousand counts per second and new sheets 15,000 counts per second. Then we do the error table using the water and plastic phantom to set the machine's baseline. These daily quality controls is meant to make event and consistent signals. When the crystal get the radiation, emits photon, the detector generate analog current based on photon, and machine transfer the analog signal as digital signal to be stored.For the first scan be used GE nuclear medicine/CT 640 Machine which does nuclear medicine plus CT scan.
A more recent development is Positron Emission Tomography (PET) which is a more precise and sophisticated technique using isotopes produced in a cyclotron. A positron-emitting radionuclide is introduced, usually by injection, and accumulates in the target tissue. As it decays it emits a positron, which promptly combines with a nearby electron resulting in the simultaneous emission of two identifiable gamma rays in opposite directions. These are detected by a PET camera and give very precise indication of their origin. PET's most important clinical role is in oncology, with fluorine-18 as the tracer, since it has proven to be the most accurate non-invasive method of detecting and evaluating most cancers. It is also well used in cardiac and brain imaging.New procedures combine PET with computed X-ray tomography (CT) scans to give co-registration of the two images (PETCT), enabling 30% better diagnosis than with traditional gamma camera alone. It is a very powerful and significant tool which provides unique information on a wide variety of diseases from dementia to cardiovascular disease and cancer (oncology).Positioning of the radiation source within the body makes the fundamental difference between nuclear medicine imaging and other imaging techniques such as x-rays. Gamma imaging by either method described provides a view of the position and concentration of the radioisotope within the body. Organ malfunction can be indicated if the isotope is either partially taken up in the organ (cold spot), or taken up in excess (hot spot). If a series of images is taken over a period of time, an unusual pattern or rate of isotope movement could indicate malfunction in the organ.
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