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| Positron Emission Tomography (PET) |
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| PET is a sophisticated version of radio isotope scanning. |
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| The principle behind PET scanning is as follows. Short - lived radio isotopes such as 11C, 13N or 15O are produced and incorporated into a solution (of glucose) that can be injected into the body. As the radio isotope circulates through the body, it emits positively charge electrons called Positrons. Positrons collide with negatively charge electrons in body tissues, causing their annihilation and the release of gamma rays (g-rays). The gamma rays travel in opposite directions and are detected and recorded by PET receptors. A computer then takes the information and constructs a coloured PET scan (a 3D image) that shows where the radioisotopes are being used in the body. For e.g., a metabiolically active tissue will get more blood supply and a greater supply of radioactive glucose and would appear as a brighter area in the PET image. Metabiolically inactive tissue would appear as a darker area comparatively. |
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| In a PET scan of human brain, the darkened area indicates damage, may be from a stoke. Bright areas show normal blood flow and normal activity. Thus the doctor can pinpoint the areas of greater brain activity and impaired activity. |
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| Using PET |
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| 1) Physicians can study the effect of drugs in body organs. |
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| 2) Measure blood flow through organs like brain and heart |
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| 3) Identify the extent of damage due to stroke or heart attack. |
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| 4) detect cancer, study epilepsy, schizophrenia, Parkinson's disease and drug addiction. |
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