Some 70 million CT scans are performed in the US every year. That's up from 3 million in the early 1980s.
Some government scientists say the FDA has ignored warnings about the radiation risk, especially when screening for colon cancer.
Scientists contend CT scans expose patients to the equivalent of 400 chest x-rays. They also say thousands of people die of radiation-induced cancer every year.
Scientists plan to discuss their concerns during a meeting called by the FDA Tuesday.
