A PET scan uses radiation, or nuclear medicine imaging, to produce 3-dimensional, color images of the functional processes within the human body. PET stands for positron emission tomography. The machine detects pairs of gamma rays which are emitted indirectly by a tracer (positron-emitting radionuclide) which is placed in the body on a biologically active molecule. The images are reconstructed by computer analysis. Modern machines often use a CT X-ray scan which is performed on the patient at the same time in the same machine. PET scans can be used to diagnose a health condition, as well as for finding out how an existing condition is developing. PET scans are often used to see how effective an ongoing treatment is. How does a PET scan work? Radiotracer - Before carrying out a PET scan, a radioactive medicine is produced in a cyclotron (a type of machine). The radioactive medicine is then tagged to a natural chemical. This natural chemical could be glucose, water, or ammonia. The tagged natural chemical is known as a radiotracer. The radiotracer is then inserted into the human body. When it is inside the radiotracer will go to areas inside the body that use the natural chemical. For example, FDG (fluorodeoxyglucose - a radioactive drug) is tagged to glucose to make a radiotracer. The glucose goes into those parts of the body that use glucose for energy. Cancers, for example, use glucose differently from normal tissue - so, FDG can show up cancers. Detecting positrons - A PET scan detects the energy emitted by positively-charge particles (positrons). As the radiotracer is broken down inside the patients body positrons are made. This energy appears as a 3-dimensional image on a computer monitor. The image - The image reveals how parts of the patients body function by the way they break down the radiotracer. A PET image will display different levels of positrons according to brightness and color. When the image is complete it will be examined by a radiologist who reports his/her findings to a doctor. A radiologist is a doctor who specializes in interpreting these types of images, as well as MRI scan, CT scan, Ultrasound and X-ray images.
Posted on: Sun, 13 Apr 2014 14:35:24 +0000
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