PET Scans Essay -- essays research papers fc

Positron Emission TomographyPositron Emission Tomography is a scanning technique that allows us to measure in detail the military operation 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 nevertheless structural details within the brain. The differences between these types of imaging dont end there. In both X-rays and CT scans, a form of radiation is emitted and travels done 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 radioactive decay inside of the person and interacts with the tissue to produce gamma radiation. These gamma rays are detected by scintillation crystals and transmitted to a computer, where images are produced. just how does this all take place?The d escription of PET scans in detail requires the understanding of the radioactive substance injected into the subject. First, a small amount of a biochemical substance is tagged with a antielectron-emitting radioisotope. A positron is an anti-electron. Positrons are given off during the decay of the nuclei of the radioisotope. When the positron emitted collides with an electron in the tissue of the subject, both the positron and the electron are annihilated. When this happens, the collision produces two gamma rays having the same energy (511 KeV), but going in opposite directions. These gamma rays, produced by the annihilation of a positron and an electron, leave the patients body and are detected by the PET scanner. The detection of positron-annihilation events forms the heart of any PET scanner. In closely systems, the Gamma detector is a BGO (bismuth germinate oxide) crystal, a high-density scintillator. When it is combined with high performance photomultiplier tubes (PMTs), the detection of 511 KeV gamma rays is possible. These BGO crystals are arranged into 64 distinct segments so that the scintillation light from each of the segments can be distributed onto the photocathodes of four photomultiplier tubes to be amplified. These block detectors are placed into modules of four arranged as eight columns of 32 rows of crystals each. A ring of these detectors surrounds the patient during... ...kinsons disease, or schizophrenia. Recently, new advances have been made in PET technology. A pair of American scientists working in Switzerland came up with a combination PET/CT scanner, which effectively pairs the two techniques. This new combination will be very useful in crabmeat diagnosis. With the PET/CT, both anatomical and functional imaging can be done and reproduced on the same image. This will be helpful in pinpointing the localisation principle of tumors, and also for the early identification of tumors too small to be of concern in CT scanning. Works Cited Jaroff, Leon. A Winning Combination. Time 15623 4 Dec 2000. Mullen, Robyn J. Positron Emission Tomography. 5 Dec 1995. http//www.bae.ncsu.edu/bae/courses/bae590F/1995/mullen/. Yahoo. 25 Mar 2001. PET Scans. 15 Jan 2001. http//www.lifeimage.com/techdata.htm. Yahoo. 25 Mar 2001.UIHC Positron Emission Tomography imagination Center. 14 Aug 2000. http//www.pet.radiology.uiowa.edu/. Yahoo. 25 Mar 2001.