Full body scan and virtual colonoscopy health risks

Last updated: 01 January 2004

Health Risks

Consumers should be aware of the risks associated with full body CT scans (also known as CAT scans) and virtual colonoscopy. Full body scans, promoted in NSW as a new preventative health screening service available to the public, involve doses of radiation that health experts do not consider to be justifiable in terms of a health check.

An investigation by NSW Health and the Environmental Protection Authority (EPA) found people can be exposed to dangerously high levels of radiation, sometimes up to 500 times more than a standard chest x-ray, for no gain at all.

It is important to distinguish between CT scanning as a screening tool, and CT scanning for diagnostic investigation. This warning applies to the use of CT scanning in people with no symptoms, or with symptoms that have not been assessed by a General Practitioner.

In other patients, CT scanning is one of many useful investigations available to explore symptoms or monitor the progress of significant diseases, with the radiation dose involved in a conventional diagnostic scan deemed to be justified by the health benefits that may arise from the diagnosis.

However full body CT scans as a health check up are unproven and no studies have been completed to support their use for this purpose.

Leading Australian and international authorities on radiation technology do not support CT body scans as a preventative screening tool.

Another recently developed application of the CT scanner is virtual colonoscopy. While this test has some use in the investigation of people with a risk of bowel cancer, it should only be undertaken after consulting with a general practitioner or gastroenterologist to consider the most appropriate method of investigation for an individual.

According to the International Commission on Radiological Protection, a full CT body scan examination with an effective dose of 10 millisieverts may be associated with an increase in the possibility of developing a fatal cancer of approximately 1 in 2,000.

This small increase in radiation-associated cancer risk for an individual can become a public health concern if large numbers of the population undergo increased numbers of CT scans of uncertain benefit.

The independent Radiation Advisory Council that advises the EPA and NSW Health on radiation matters, raised the following issues in relation to full body CT scans:

• The procedure has no proven benefit and has not been shown to identify small cancers.
• A medical practitioner should refer people for such a procedure if there is a real need.
• The results may be unreliable, especially if there has been no medical management prior to the scan.
• The potential radiation dose could be significant and pose long-term health risks.

CT scan operators who rely on advertising for business are subject to the following license conditions:

• Consumers will need an independent doctor's referral before undergoing a full body scan.
• Body scan operators must fully inform consumers about the risks of procedures, including the scale of the radiation dose, the inconclusive nature of the results and the risk for people under the age of 50 of developing cancer as a result of the procedure.
• Consumers are obliged to sign a declaration stating they have received such advice.

CT scans have an important role to play in the medical setting and should be used in accordance with professional medical advice. Consumers have a right to know that to use full body scans or virtual colonoscopy as a screening tool may increase their risk of cancer.