Metabolic data

The metabolic data that describes the bio-chemical functioning (uptake of nutrients, etc) of the tumour is captured using the Positron Emission Tomography (PET) scanner inside the PET/CT machine. The way it captures the images is explained below:

The PET scans give information about the body's chemistry that is not available with other imaging techniques, revealing metabolic information providing the physician with extra insight.

The Positron Emission Tomography procedure works like a camera that produces detailed images of biological functions from inside the human body.

The Positron Emission Tomography scan is a unique, non-invasive diagnostic imaging tool that is a metabolic imaging tool. What this means is that a PET scan produces images detailing the biochemical functioning of an organ or tissue. In essence The PET scan visualizes biochemical changes caused by disease.

• In the PET scan procedure, a patient is given a substance that is tagged with a radiopharmaceutical. The radiopharmaceutical contains a radioactive that is used to help visualize metabolic changes in the body.

• This radioactive isotope is not dangerous to the person who take it as it has a short half-life, meaning that the radiation only last for a very short period of time, before which the isotope decays to become a stable element. The period is so brief that the radiation does no damage to the body, but can be used in helping to locate tumours

• Radio pharmaceuticals are given to a patient predominantly through an injection, but can also be given through an existing intravenous line or inhaled as a gas. The injection is usually given an hour before the scan to allow the tracer to move through the body and also allow uptake in the areas under investigation.

• The most common injection used in a PET scan is FDG. FDG is short for Fluorodeoxyglucose, a glucose-based radio pharmaceutical of Fluoride 18.

• In the scan the patient lies flat on a bed or table that moves steadily through the PET scanner.

• As FDG decays it emits protons (positively charged atoms). These positive protons collide with electrons (negatively charged atoms) from the scanner to produce gamma rays.

• The PET scanner has cameras that detect the gamma rays emitted from the patient, and turns these emissions into electrical signals.

• A computer generates the medical images by processing the gamma ray signals that are collected by the scanner.

• If an area is cancerous, the signals will be stronger there than in surrounding tissue as more of the radio pharmaceutical (FDG) is being absorbed in those areas, due to cancerous tumours absorbing more glucose than non-cancerous areas.

• This finite procedure produces clear digital images, which are assembled by the computer into a 3-D image of the patient's body. In the PET/CT scanner the images from the PET are combined with the CT scan results to gather more detailed information on the tumour