'Full-body' CT scans: Are they worth the cost in money and radiation exposure? (page 1 of 2)
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There has been an increasing trend in some countries, such as the US and Australia, for imaging centres to offer the general public ‘full-body’ computerised tomography (CT) scans to screen for possible disease. The individual undergoes scanning of the head and neck, thorax, abdomen and pelvis; the images are then reviewed and a report is produced within a matter of days. These scans are sold on the premise that a negative/normal result will reassure a concerned person; whereas a positive result might allow potentially serious disease to be diagnosed at an early stage allowing a better chance of effecting a cure. However, this procedure is not based on any meaningful evidence that it provides any worthwhile benefit for the individual. Indeed, apart from having to pay anything up to $1000 for the scan (in Australia), there are other disadvantages and risks to be considered. These include the radiation dose received by the patient, the costs of any further investigations arising from the result of the scan, especially if these are to exclude disease suggested but not confirmed on the original scan (false positive outcome) and a possible false sense of security instilled in those with negative/normal reports (false negative outcome). This practice has served to highlight concerns rising from the increasing use of CT scanning, the complexity of some of the new scanning techniques and the subsequent increase in the radiation dose to both the individual and the general population.
Computerised tomography technology has advanced dramatically in the last ten years. In particular the latest generation of multi-slice scanners can image the whole body in less than 30 seconds. With the production of impressive 3-D reconstructions and other fancy techniques it is easy to forget that relatively high doses of radiation are used in the production of these images. A chest X-ray typically delivers an effective dose of 0.02 mSv (millisieverts), equivalent to about three days’ exposure in the UK to natural sources of radiation in the environment. A CT scan of the abdomen or pelvis however delivers an effective dose of about 10 mSv to the patient, which is equivalent to 500 chest X-rays, or 4.5 years’ exposure to background radiation.1 The estimated risk of inducing fatal cancer is one in 2,000 at this level of dose.
