A PET-CT scan uses acronyms for much longer terms: Positron Emission Tomography (PET) and Computerized Tomography (CT). They are both imaging tools that are used in hospitals throughout the world to help doctors locate cancerous cells and tumors in the body, in order to enable better and more accurate diagnosis. Each scan brings something to the process - the PET scan detects the metabolic signal of any growing cancer cells and the CT scan provides a very detailed image of the inside of the body which helps provide information about the location and quantity of any cancerous tumors. Used together these two scans are extremely powerful in terms of providing medical data and provide much information about the severity of any cancerous activity. This is the reason they are usually carried out at the same time. These scans use non-surgical processes and take very little time to carry out. They can be carried out on an outpatient basis and are completely painless tests

A PET scan is a type of nuclear medicine imaging and is carried out by exposing the body to some radioactive material. This is usually administered via an injection into the vein, a pill of some type or inhaled as a gas. The amount the body is exposed to is very small so there are no long term side effects. The radioactive material accumulates in the area of the body that is being investigated and by doing so, energy (gamma) rays are given off. These rays are picked up by a special probe and scanner. Working together, the probe and the scanner can detect how much of the radioactive material has been absorbed by the body and turn this into an image that provides intricate details of the structure and function of the organs, cells and tissue in that particular area.

Image fusion or co-registration refers to the practice of superimposing these images with the images produced by a computerized topography scan (CT scan) or even with a magnetic resonance image (MRI scan). By correlating images in this way even more accurate and more precise information can be gleaned which makes for better diagnosing of patients.

Whilst a PET scan is useful for measuring functions such as blood flow, oxygen use and a person’s glucose metabolism in order to see how particular organs are working, a CT scan is useful for providing internal images with anatomic information. When combined in the way described above doctors have access to a wealth of information that enables them to "see" exactly what is wrong with a person and how serious the condition is. When used together these two scans (or modalities) create synergy - they can provide much more detailed information and prove to be far more valuable than when used separately.

PET-CT scans are in particular used to detect cancer in the body. Not only can tumors be found but the rate of growth of cancerous cells and the extent to which they have spread can be seen. These types of scan can be given at regular intervals throughout the treatment of cancer to see how effective it has been and if the cancer is returning or being kept at bay. Aside from oncology, these scans are also useful for determining blood flow to the heart and assessing the damage after a heart attack to see what treatment or surgery would be appropriate. PET-CT scans are also useful for mapping brain function and detecting abnormalities such as tumors, disorders and problems with the nervous system.

The medical world benefits greatly from the use of PET-CT scans in their methods for diagnosis. Medical image processing is a powerful tool in the fight against many serious illnesses and disorders, but when used together in particular a PET scan and CT scan provide a wealth of information. It works particularly well with oncology software, enabling cancerous growth to be detected and monitored continuously.