Safer CT scans

CT scanning—sometimes called CAT scanning—is one of the best and fastest noninvasive medical test that helps doctors diagnose and treat medical conditions. CT scanning combines special x-ray equipment with sophisticated computers to produce multiple images or pictures of the inside of the body. The scans are used to diagnose health problems such as cancers, cardiovascular disease, infectious disease, appendicitis, trauma and musculoskeletal disorders

The greatly increased availability of CT, together with its value for an increasing number of conditions, has been responsible for a large rise in popularity. However, the CT is regarded as a moderate to high radiation diagnostic technique. The radiation dose for a particular study depends on multiple factors such as volume scanned, patient build, number and type of scan sequences, and desired resolution and image quality. In United Kingdom, CT scans contributed 47% of the total collective dose from medical X-ray examinations in 2000/2001. World wide, including in developing countries, CT usage has increased considerably which led to an overall rise in the total amount of medical exposures.

The exposure of the patient, particularly children, has potential for induction of caner and hence, the probability of additional rise in fatality from the radiation induced cancer may increase marginally over the background rate. Numerous studies are being conducted on this aspect. Incidents of patients receiving radiation doses more-than-expected have been reported due to equipment failure and improper use of the equipments.

Typical scan doses in milli-Sievert, mSv (Sievert is the unit of radiation dose)

Chest X-ray - 0.1
Head CT - 1.5
Screening mammography - 3
Chest CT - 5.8
Cardiac CT angiogram - 6.7 – 13
Barium enema - 15

[For purposes of comparison, the average background exposure in India is around 2 mSv in one year].

There is a recent advice from the US Food and Drug Administration that the manufacturers, users and regulators should together arrive at an optimal solution to this problem so that over-exposures of the patients are avoided, and the CT scans should be made safer for the benefit of patients.