Cancer risks from CT scans

RADIATION from CT scans done in 2007 will cause 29,000 cancers and kill nearly 15,000 Americans, researchers said on Monday.

The findings, published in the Archives of Internal Medicine, add to mounting evidence that Americans are overexposed to radiation from diagnostic tests, especially from a specialised kind of X-ray called a computed tomography, or CT, scan.

'What we learned is there is a significant amount of radiation with these CT scans, more than what we thought, and there is a significant number of cancers,' said Dr Rita Redberg, editor of the Archives of Internal Medicine, where the studies were published.

'It's estimated that just from the CT scans done in one year, just in 2007, there will be 15,000 excess deaths,' she said in a telephone interview. 'We're doing millions of CT scans every year and the numbers are increasing. That is a lot of excess deaths.'

CT scans give doctors a view inside the body, often eliminating the need for exploratory surgery. But CT scans involve much higher radiation dose than conventional X-rays. A chest CT scan exposes the patient to more than 100 times the radiation dose of a chest X-ray. About 70 million CT scans were done on Americans in 2007, up from 3 million in 1980. Amy Berrington de Gonzalez of the National Cancer Institute and colleagues developed a computer model to estimate the impact of so many scans.

They estimated the scans done in 2007 will cause 29,000 cancers. A third of the projected cancers will occur in people who were ages 35 to 54 when they got their CT, two-thirds will occur in women and 15 per cent will arise from scans done in children or teens. The researchers estimated there will be an extra 2,000 excess breast cancers just from CT scans done in 2007