15th August 2014 – The number of CT scans carried out in the UK each year has risen 'dramatically' according to a report compiled by radiation experts for the Department of Health.
The Committee on Medical Aspects of Radiation in the Environment (COMARE) says there has been an increase in the number of CT scans conducted in hospitals in England from just over 1 million in 1996 to almost 5 million in 2013.
For the 10-year period from 1993 to 2002 a UK study found the number of CT examinations nearly doubled, from an estimated 25,000 to 48,000 scans per year in patients under 22 years of age.
CT scans, originally known as CAT scans (computed axial tomography) use specialised X-ray equipment to obtain images from different angles around the body to help diagnose injuries and diseases.
They can help determine if surgery is necessary; reduce the need for ‘exploratory’ surgery and improve diagnosis and treatment of cancer. They can also reduce the need for examination under sedation, especially in very young patients.
However, they also expose patients to radiation which can damage cells.
The NHS says that in most cases, the benefits outweigh any potential risks because a CT scan can provide a doctor with clearer images than those produced by a normal X-ray.
Children & CT scans
Children are more at risk of developing a build-up of radiation than adults. A CT scan will therefore only be recommended if a child has a serious condition.
A recent study in Australia considered the cancer risk from diagnostic CT scans carried out during childhood or adolescence between 1985 and 2005 in 680,000 people. It found a 24% increase in the incidence of all cancers was reported when compared with over 10 million unexposed people and the increase was greater for people exposed at younger ages.
A single abdominal CT examination on a 1-year-old child is estimated to give a lifetime cancer mortality risk of 1 in 550, far higher than for the equivalent examination on an adult.
For some time, medical X-rays have been the largest single artificial source of radiation exposure for the UK population.
The report by COMARE raises concerns about the radiation dose to patients from CT scans and especially in the increase in the number of younger patients undergoing them.
The experts say the potential benefit to a patient gained through a CT scan must be balanced against any potential harm which can be determined by three factors – the radiation dose, the age of the patient and the prognosis of the disease.
They want to reduce the likelihood of widely varying radiation exposures between different hospitals by encouraging them to share information and are recommending hospitals ensure any new CT scanners include a full range of dose reduction features.
The Royal College of Radiologists supports the recommendations. It says radiologists are more aware than most of the remarkable growth in the use of CT scans and have always accepted their responsibilities when it comes to radiation safety.
In a statement, Dr Peter Cavanagh, vice-president, clinical radiology, at the College says: "Understanding the key principles of justification and optimisation forms a core part of radiology training.
"Advising on imaging strategies for individual patients and recommending when CT and other high radiation dose examinations can be replaced by tests which involve less or no radiation is a central part of the role of a clinical radiologist."
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