But they rely on dangerous radiation to get the job done and the harms may be greater than previously thought, reports CBS News medical correspondent Dr. Jon LaPook.
After Alabama school teacher Becky Coudert had a brain CT scan in September her hair started to fall out and, according to a lawyer, "She developed a broad band of baldness from one temple to the other, from around the back of the head."
Her lawyer says she received a higher than normal radiation dose. Two other patients have come forward with similar stories. In Los Angeles, for giving excess radiation to more than 250 patients during their CT scans.
Read more about CT scans from WebMD
The problem of too much radiation during CT scans may be more widespread than anyone thought.
"The doses are actually higher than are generally reported," said Rebecca Smith-Bindman, a professor of radiology and biomedical imaging at the University of California San Francisco
New research out today found a wide variation in radiation dose for the most common CT scans, like abdomen, pelvis and chest. A survey of four hospitals found some patients received 13 times more radiation than others for the same type of scan.
"Depending on where a particular patient is sent - hospital one or hospital two - or if he goes in the evening, the dose that the patient received would have been profoundly different and that degree of variation is what was so surprising," Smith-Bindman said.
And just how dangerous is the extra radiation?
"The risk is not huge but it's definitely real," she said.
Radiation is a known carcinogen, even in the relatively small amounts used with most CT's. There are a number of uncertainties involved in predicting cancer risk. But a second study today estimates that about 29,000 future cancers might be caused by the 72 million CT scans done in 2007.
"If a ct scan is truly indicated, patients should proceed with that scan," said Dr. Jim Brink. "But be sure to choose an accredited facility that could be relied upon to control dose and make it as low as possible."
The FDA is investigating the type of brain scan that went wrong in California and Alabama hospitals. Experts are calling for regulations to standardize how all CT scans are performed.
Lawsuits involving CT radiation