When was pet imaging invented

Positron emission tomography PET builds images by detecting energy given off by decaying radioactive isotopes. Isotopes are atoms of an element with the same number of protons positively charged particles in the nucleus but a different number of neutrons neutral particles. Because radioactive isotopes are unstable, as they decay they throw off positrons that collide with electrons and produce gamma rays that shoot off in nearly opposite directions.

PET systems use the paths of the two detected gamma rays to determine the originating collision point, a process called electronic collimation. Anger, which became an essential component for nuclear medicine. Alternatives to the NaI detector were necessary since this detector had high scatter and low density which limited its resolution and efficiency, respectively.

An alternative was found in the s in bismuth germanite BGO which had a high density and a similar decay constant as NaI. With this crystal the first commercially available PET scanner was made. The s saw the technology improved by using ring geometry with 11, BGO crystals and a spatial resolution of 2. Another detector discovered was lutetium oxy-orthosilicate LSO which has an even higher density and a faster decay time than BGO and therefore has a higher sensitivity and lower random events, resulting in a resolution of 2.

A strong effort has been under place to improve PET technology. The search for better detectors and different radiotracers has and continue to be explored. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.

Further increasing the availability of PET imaging is a technology called gamma camera systems devices used to scan patients who have been injected with small amounts of radionuclides and currently in use with other nuclear medicine procedures. These systems have been adapted for use in PET scan procedures. The gamma camera system can complete a scan more quickly, and at less cost, than a traditional PET scan.

PET works by using a scanning device a machine with a large hole at its center to detect photons subatomic particles emitted by a radionuclide in the organ or tissue being examined. The radionuclides used in PET scans are made by attaching a radioactive atom to chemical substances that are used naturally by the particular organ or tissue during its metabolic process. For example, in PET scans of the brain, a radioactive atom is applied to glucose blood sugar to create a radionuclide called fluorodeoxyglucose FDG , because the brain uses glucose for its metabolism.

Other substances may be used for PET scanning, depending on the purpose of the scan. If blood flow and perfusion of an organ or tissue is of interest, the radionuclide may be a type of radioactive oxygen, carbon, nitrogen, or gallium. The radionuclide is administered into a vein through an intravenous IV line. Next, the PET scanner slowly moves over the part of the body being examined. Positrons are emitted by the breakdown of the radionuclide.

Gamma rays called annihilation photons are created when positrons collide with electrons near the decay event. The scanner then detects the annihilation photons, which arrive at the detectors in coincidence at degrees apart from one another. A computer analyzes those gamma rays and uses the information to create an image map of the organ or tissue being studied. The amount of the radionuclide collected in the tissue affects how brightly the tissue appears on the image, and indicates the level of organ or tissue function.

PET may also be used to evaluate the function of organs, such as the heart or brain. The most common use of PET is in the detection of cancer and the evaluation of cancer treatment. To diagnose dementias conditions that involve deterioration of mental function , such as Alzheimer's disease, as well as other neurological conditions such as:. Parkinson's disease. A progressive disease of the nervous system in which a fine tremor, muscle weakness, and a peculiar type of gait are seen.

Huntington's disease.