Explain the principle involved in PET scan.

Explanation

Positron Emission Tomographic Scanning (PET ) :
1. PET is also computerized imaging technique unlike CT.
2. Positron emission tomography (PET ) is a nuclear medicine procedure based on the measurement of positrone emission from radiolabelled tracer molecules.
3. These radiotracers allow biologic processes to be measured and whole body images to be obtained which demostrates sites of radiotracer accumulation.
4. A PET image gives quantitative regional information on the metabolic and physiological processes
5. PET uses positron emitting radio isotopes ` (""^(11)C ""^(13)N ""^(15)O ""^(18)F ) ` which are generated by the cyclotron.
6. The most common radiotracer in use today is 18F - fluorodeoxglucose (18F - FDG ) which is a radio labelled sugar (glucose ) molecule.
7. These atoms are then incorporated by chemical methods into biological molecules like glucose, amino acids and ammonia.
8. These positron emitting compounds are then injected in very small amounts into or inhaled by experimental animals or human sugjects.
9. The three dimensional distribution of the labeled trace is then probed by powerful PET cameras and the images are reconstructed by a computer.
10. The quantitative interpretation of the image is done by varying mathematical models.
11. They deal with the process of uptake and metabolism of the radioisotope.