You may be asked not to eat and drink for a few hours before the scan. When you arrive, you will be given an injection of a dye. This helps the specialist see the prostate and surrounding organs on the scan. It is not radioactive. You may also be asked to remove any metal jewellery.

The CT scanner is shaped like a large doughnut. You will lie on a sliding table, which moves through the hole in the middle of the machine. You will need to keep still and you may be asked to hold your breath for short periods of time. You will be able to speak to the staff through an intercom.

The scanner takes X-rays of your pelvis. These are fed into a computer to create an image of the prostate and the surrounding tissues, including the lymph nodes. The scan takes 10-20 minutes and you will be able to go home afterwards. The pictures taken by the scanner are put together and looked at by your specialist team for possible signs that the cancer has spread. This can take up to two weeks.

You may be asked to remove any jewellery or metal items, and to leave credit cards or similar items at home, or with a friend or relative. The specialist will ask you questions about your health and whether you have any implants, such as a pacemaker for your heart. This is to make sure the scan does not harm you.

Some MRI scanners are doughnut-shaped, like a CT scanner, but others are shaped like a long tunnel. You will lie on a table which passes into the scanner. Some people find this frightening, but staff are aware of this and will help you if you become uncomfortable. If you suffer from a fear of enclosed spaces (claustrophobia), you should let the scanning department know before your scan.

The scan takes between 30 and 40 minutes. The machine is very noisy but you will not feel anything. You can speak to the staff through a microphone and you may be able to listen to music.

You may be given an injection of a special dye during the scan if the radiographer thinks it will help improve the pictures taken by the scanner.

A small amount of a safe radioactive dye is injected into a vein in your arm. This travels around your body in your bloodstream and collects in areas where bone cells are active.

After two to three hours, you will have your scan. You will lie on a table while the machine moves down your body, taking pictures. This takes around half an hour. The camera will pick up any 'hot spots' where the radioactive substance has collected. These hot spots can show where the cancer has spread to the bone. They also show any areas of arthritis and other bone damage. You should tell the specialist if you have any arthritis or have had a previous bone injury, surgery, or fracture, as it will help them to interpret the scan results.

The specialist will look at the results to see whether any cancer is present. You may need to have X-rays of any 'hot spots' to help work out whether changes to the bone are due to cancer or other damage. If there is still doubt, you may need to have an MRIscan of these areas of the bone. Occasionally some men have a bone biopsy.

You may be asked to avoid contact with pregnant women and children for up to 24 hours after the scan. You may be asked to drink plenty of fluids before and after the scan.