PET Scans Essay example

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Positron Emission Tomography

Positron Emission Tomography is a scanning technique that allows us to measure in detail the functioning of distinct areas of the human brain while the patient is comfortable, conscious and alert. PET represents a type of functional imaging, unlike X-rays or CT scans, which show only structural details within the brain. The differences between these types of imaging don’t end there.
In both X-rays and CT scans, a form of radiation is emitted and travels through the body, and a detector receives the unabsorbed rays and transmits them to a computer. The physics behind PET scanning is quite different. Basically, a person is injected with a radioactive substance. This substance begins the process of
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A line of response (LOR) indicates what two crystals detected the event. A unique line of response is identified by the angle and the radius of a perpendicular back to the center of the field of view. As additional events are detected, the lines of response are recorded. Each LOR is plotted using polar coordinates (angle vs. radius). The composite results in a sinusoidal plot of LORs through a single point and is referred to as a sinogram. The sinogram is comprised of numerous, overlapping single point plots. The matrix size of the sinogram is related to the size of the transverse field of view. Following acquisition, filtered back projection algorithms are applied to the data to produce the image.
The brain function being studied during a PET scan determines which positron-emitting radiopharmaceutical is used. Oxygen-15 can be used to label oxygen gas for the study of oxygen metabolism, carbon monoxide for the study of blood volume, or water for the study of blood flow in the brain. Similarly, fluorine-18 can be attached to a glucose molecule to produce 2-fluoro-2-deoxy-D-glucose (FDG) for use in the observation of the brain’s sugar metabolism.
PET is the only method that can detect and display metabolic changes in tissue, distinguish normal tissue from those that are diseased, such as in cancer, differentiate viable from dead or dying tissue, show regional blood flow, and determine the distribution and
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