CT Scan – Chest, Abdomen & Pelvis (CAP)

About a CT scan of the chest, abdomen and pelvis

A CT of the chest, abdomen and pelvis, often called a CAP or “CT CAP”, scans the body from the base of the neck down to the top of the legs in a single scan. It covers the lungs, heart and lymph nodes in the chest, the organs of the tummy such as the liver, pancreas, kidneys and bowel, and the bladder and reproductive organs in the pelvis. A CT (computed tomography) scan uses X-rays and a computer to make detailed cross-section pictures, which can be viewed from any angle.

The most common reason for a CAP scan is cancer:

• staging – finding out whether a cancer has spread to lymph nodes or other organs, which helps doctors plan treatment
• checking treatment – seeing how a cancer is responding to chemotherapy or other treatment
• follow-up – checking for any return of cancer after treatment

It may also be used to look for the cause of symptoms such as unexplained weight loss, fever or raised blood test markers, when the problem could be anywhere in the body. Your specialist will say whether you need the whole CAP or just part of it, such as a CT of the abdomen and pelvis. You can read more in our article on cancer detection using CT.

What happens during the scan

You may be asked to arrive up to an hour early to drink water or a contrast drink, which helps the bowel show up clearly. You then lie on your back on the scanner bed with your arms raised above your head. The bed moves through a short, open ring while you are scanned. The radiographer controls the scanner from the next room, but can see, hear and talk to you throughout. You will be asked to hold your breath for a few seconds. Most CAP scans use an injection of contrast dye.

For some CT scans, an injection of contrast dye is given through a small cannula in a vein, usually in your arm or hand, to make blood vessels and organs show up more clearly. CT contrast contains iodine. As it goes in you may feel warm and flushed, notice a metallic taste, or feel as if you are passing urine; these feelings pass within a minute or two. Allergic reactions are uncommon, and you may be asked to wait for up to 30 minutes afterwards. Where contrast is needed, it is charged separately.

Is CT safe?

CT uses X-rays, which are a type of ionising radiation. Because a CAP covers a large area, the dose is higher than for either a chest CT (about 8 mSv) or an abdomen and pelvis CT (about 10 mSv) alone. For people with cancer, the benefit of accurate staging and monitoring almost always far outweighs this small risk. The risk from a single scan is very small, and every CT scan is checked by a radiologist or radiographer to make sure the benefit of the scan outweighs the risk, as required by the Ionising Radiation (Medical Exposure) Regulations. If you have had other CT scans recently, tell us when you book.