Radionuclide and PET scan

A radionuclide is a radioactive form of common elements known as isotopes. They are chemicals which emit a radioactivity called gamma rays. Examples of these isotopes are carbon, oxygen and nitrogen, they are used because they decay quickly and are therefore less harmful to the environment.

The radionuclide is then combined with other elements to create radioactive a version of substances that are found in or absorbed by the body, for example glucose.  This is then introduced into the body either through a drip or injection into the vein. It then accumulates in the target organ.

The computer then builds up a picture by converting the different intensities of radioactivity emitted into different colours or shades of grey. Areas of the target organ or tissue which emit lots of gamma rays because they are more active, may be shown as red spots also known as “hot spots” on the picture or monitor.

The computer then builds up a picture by converting the different intensities of radioactivity emitted into different colours or shades of grey. Areas of the target organ or tissue which emit lots of gamma rays because they are more active, may be shown as red spots also known as “hot spots” on the picture or monitor.

PET scan stands for Positron Emission Tomography. It is one of the techniques that uses radionuclide to collect radiation from the organ by gamma rays. They create images which show where cells are particularly active in the body. It is most commonly used to diagnose cancer; however, it can be used to diagnose other conditions such as Alzheimer’s, epilepsy and heart disease.

A PET scan works by detecting the energy released by positrons which are tiny particles which are made when radioactive medicine in broken down inside the body. As these particles are broken down they create gamma rays, which are detected by the scanner which creates a 3D image. The image can show how parts of the body works by the way it breaks down the radio tracer.

Different positrons are show as different colours and brightness. Bright colours show high radiation which means it is active functioning. Dark colours are areas that are not functioning properly. A radiologist who is trained in interpreting pictures of inside the body, will look at the images and report the results to the patient’s doctor.

During a PET scan the patient is placed on a table and slides into the scanner, the gamma camera detects emitted gamma radiation, the computer then processes cross sectional information. After this a coloured image is produced, the brightest colours indicating the most radiation which means that they are active and dark areas meaning there is little activity. Where most of the substance is being used, it means that it is functioning normally.