Types of Imaging

Diagnostic imaging has progressed enormously since X-rays were first discovered in 1895. Now diagnostic imaging encompasses a range of technologies, which can supply medical experts with an array of information which is used to diagnose, treat and monitor a vast range of clinical conditions.

The following list provides general information about the different types of imaging procedures carried out by ADIA members. If you would like more detailed information, please contact one of our member practices.



An X-ray image is produced by passing a very small amount of radiation through the body and onto a film or detector on the other side. Harder tissues, like bones, stop the X-rays more efficiently than soft tissues, so X-rays are often used to detect breaks or fractures. X-rays can also provide images of some soft tissues, particularly the lungs.



This is a widely used technique which produces detailed images of the body, using high frequency sound waves - much higher than human ears can hear. These sound waves go into the body and bounce back off different tissues. These reflected waves are then used to create a real-time image. The sound energy used is the scan has no know harmful effects, with the small amounts of energy being absorbed by the body as heat. Ultrasound is used to gain information about a variety of conditions, including pregnancy, gallstones and varicose veins.

Ultrasound can be capture images of the pelvis and abdomen, the musculo-skeletal system, breast abnormalities, the male reproduction system, the kidney, the thyroid, the gall bladder and pancreas and foetal development.  An Ultrasound which shows blood flow may also be called Colour Flow Doppler or Duplex Scan.



This procedure enables radiologists to view X-rays in real time on a television monitor. In most cases it involves giving the patient a contrast agent which helps distinguish between types of tissue in the body. The most common fluoroscopic procedures involve non-toxic barium sulphate as a contrast agent. For example, before a fluoroscopy of the upper part of the gastrointestinal tract (the oesophagus, stomach and duodenum) the patient will be asked to drink several cups of liquid containing barium sulphate.


CT (CAT scan) 

CT stands for Computed Tomography. A CT scan uses special X-ray equipment to obtain multiple images of the body from different angles. Special computer processing is then used to produce images of the body in cross-section, including bones and organs. CT provides better images of soft tissue than regular X-rays and is often used to look for cancer, pneumonia, abnormalities in the chest and bleeding in the brain.



MRI stands for Magnetic Resonance Imaging. This type of scan does not use X-rays, so no radiation is involved. Instead a very powerful magnet and radio-frequency pulses (similar to FM radio) collect information. A computer then uses this to form images. MRI gives a detailed view of the soft tissues, such as muscles, ligaments, brain tissue, discs and blood vessels.

While the magnet has no known side effects but it does interact with metal, so some patients with cardiac pacemakers, cerebral aneurysm clips, vascular stents, infusion pumps, neurostimulators and cochlear implants cannot be scanned. However, most metal implanted at surgery (e.g. hip and knee replacements and metal rods) is safe.



A mammogram is a low dose X-ray that provides detailed images of the internal structure of the breast. Mammograms are used to detect early breast cancer in women without symptoms, and to detect and diagnose breast disease in women experiencing symptoms such as a lump, pain or nipple discharge. Mammography plays a key role in the early detection of breast cancers because it can show changes in the breast tissue before a patient or doctor can feel them.


DEXA Scan (Bone Densitometry)

DEXA stands for Dual Energy X-ray Absorptiometry. This is a safe, painless and non-invasive scan used to measure the bone mineral content in various parts of the body, such as the spine, hip and wrist. DEXA is most often used to diagnose osteoporosis, a weakening of the bones, which  often affects women after menopause. DEXA is also effective in monitoring treatment for osteoporosis and other bone loss conditions.


Nuclear Medicine

Nuclear Medicine uses very small amounts of radioactive materials, or radiopharmaceuticals, to diagnose and sometimes treat disease. The radioactivity dose is very small, usually comparable to X-ray procedures. Radiopharmaceuticals are attracted to specific parts of the body and they emit gamma radiation which is detected by a gamma camera. Nuclear medicine is unique in that it records information on organ function and structure, as opposed to X-rays which only show structure. Nuclear medicine is usually able to detect conditions earlier than other tests allowing earlier treatment. Nuclear medicine can be used to investigate bones as well as all major organs including the lungs, kidneys, heart and brain.



PET stands for Positron Emission Tomography. This is a powerful diagnostic examination that uses small amounts of radioactive material administered to the patient. This material helps identify different structures within the body. It is often used to help in the diagnosis of certain cancers, brain disorders and heart conditions.

PET scans are very safe and there are no known side-effects from the substance.