Better way to view cancer

The two types of scan show different details of the area

Tumours could be pinpointed more accurately than ever using a new technique to look inside the body, say cancer experts.

The Cancer Research Campaign (CRC), which funded research into the new high-tech system, says it could lead to life-saving improvements in radiotherapy.

Doctors at the Mount Vernon Hospital in London have combined two existing methods for taking images of the body to get the clearer picture of where tumours are.

This will mean radiotherapy can be tailored to the shape of tumours, though it could be several years before the technique is widely used in hospitals.

Our research should help us to mould radiation dosages to fit a tumour's shape, improving the effectiveness of radiotherapy

Dr Peter Hoskin,
Clinical consultant oncologist

Doctors want to ensure all the cancerous tissue is treated, but that healthy tissue, which can be damaged by radiotherapy, is not.

Initially doctors are planning to use the technique in the treatment of prostate cancer, the second most common cancer in men, but it could also be used in the treatment of other cancers, such as brain and head and neck.

In 1997 there were 21,800 new cases of prostate cancer diagnosed in the UK. In 1999, 9,500 men died.

Dr Peter Hoskin, the Mount Vernon doctor who led the study, told BBC News Online: "It will make the treatment we can give more accurate."

Imaging

The two scanning techniques used are computed tomography (CT) and magnetic resonance imaging (MRI).

CT scanning is a special X-ray technique which takes images from different angles around the body.

A computer then processes the images to show a cross-section of tissues and organs.

Dr Peter Hoskin: says the technique will help plan treatment

It clearly shows the position of the tumour in relation to the outside of the body, but does not show enough detail to allow doctors to judge the tumour's size, shape or surrounding tissues.

MRI scanning is a modern alternative to CT scanning.

It gives good internal detail, but does not give an accurate outline of the patient's body.

MRI works by using radio waves and a very strong magnetic field to give detailed pictures of internal organs and tissues.

This makes it difficult for doctors to pinpoint the exact location of the tumour.

But by using the two together, doctors trained to read the unique and clear images, will see extra detail and be able to make precise judgements about the amount of radiation to be given, and how it should be directed.

To get the enhanced image, researchers have had to develop special software, which has been designed by researchers at Kings College Hospital, London, which can overlay the two types of scan.

Fixed points, usually bone, are used to line the two images up.

Precise treatment

A treatment called brachytherapy, which involves radiation being given directly into the gland through the insertion of very fine radioactive needles, is often used to treat prostate cancer.

It is very efficient, but doctors rely on accurate location of the tumour

CT scanning, which does not provide as much detail on the shape and size of a tumour as MRI, is currently used to locate the tumour. Using both together could help, say the researchers.

Dr Hoskin added: "The principal of what we've been doing is enabling us to use these much more detailed MRI imaging with CT to point radiation does and see where the radiation dose is going.

"Our research should help us to mould radiation dosages to fit a tumour's shape, improving the effectiveness of radiotherapy.

"By avoiding damage to normal tissues we could provide patients with a safer form of treatment."

The system should mean doctors will be better able to check at the edges of a tumour to make sure nothing is missed.

It should help doctors treating prostate tumours to prevent radiation hitting the rectum, which currently leads to long term bowel problems for a third of patients

Dr Lesley Walker, CRC's director of cancer information, said: "For certain cancers, doctors often have to take a broad brush approach to radiotherapy, because imaging techniques aren't good enough for them to plan radiotherapy on an individual patient basis."

Work to check the new technique is accurate should be completed by the end of the year, when it will be introduced in the treatment of patients.