PET scans are similar to Nuclear Scanning. They combine Nuclear Scanning with chemical analysis to enable physicians to observe how organs work.
PET scans use the opposite approach from conventional X-ray and CT scans, where the radiation comes out of a machine and then passes through the patient’s body. During a PET scan, a radioactive material is introduced into the patient's body (usually by injection), and is detected by a sophisticated camera.
The abbreviation PET stands for positron emission tomography. Positrons are positively charged electrons that are produced spontaneously as certain radioactive substances (for example, radioactive glucose) decompose. These radioactive substances, or tracers, are created in special facilities called medical cyclotrons. The type of tracer used for a particular PET scan varies, based on the medical condition for which a patient is being tested. The tracers have very short half-lives, which means that they decay rapidly into non-radioactive form. Thus, radioactive material is inside the patient for only a very short time, and the total dose of radiation is equal to and sometimes even less than many other kinds of X-ray procedures. A tomograph is an imaging device, or camera, that obtains sectional views through a patient's body.
During a PET scan, the patient receives an injection of a radioactive substance through a vein in the arm. This substance travels through the bloodstream, into the soft tissue, and eventually reaches the areas that are being scanned. This process takes about 90 minutes. The technologist may take some images during the injection to evaluate the blood flow to a particular area where there may be pain.
PET scans are extremely safe because the radioactive material is quickly cleared from the body.
Last updated: 01-Jan-09