CT scans and Hiroshima
Today and Friday’s post are about radiation, the type your doctor orders for you. In medicine, it’s often good to be suspicious of the latest. If you’re quick to buy the very newest TV technology, the worst that can happen as an early adopter is that your format becomes obsolete. But as a medical early adopter, choosing wrongly, you could really suffer.
Last week there was a report about patients receiving too much radiation (excessive risk for the benefit received) from a new and already popular X-ray. That study is the subject of the next post. Today as background let’s just look at one article that appeared in late 2007 in a top medical journal, The New England Journal of Medicine titled “Computed Tomography — An Increasing Source of Radiation Exposure”.
In the future, if and when a doctor suggests to me some sort of CT (computed tomography) X-ray, I will say: Studies show that some CTs expose people to lots of radiation, so how does this CT rate, and how good is the CT facility you’re sending me to? If my doctor doesn’t know, I will question the radiologist at the X-ray facility before I schedule the test. I will want to know how their equipment rates with other institutions on radiation exposure, and what steps they take to protect patients from unnecessary exposure.
This might be shocking, but it’s true: from a single typical CT study you will receive about the same dose of radiation as an atomic bomb survivor who was one to two miles from ground zero at Hiroshima.
Those Japanese survivors received approximately a 3000 millirem radiation dose, and for a typical CT study—depending on where it is done, the type of scan, the age of the patient, and other factors—a person will receive from 1000 to 10,000 millirems of radiation. And here we are not talking about exotic scans, just normal CT studies ordered every day in emergency rooms and doctors’ offices by the thousands for complaints ranging from headache to chest pain to bellyache.
Excess radiation exposure—studied long-term in Hiroshima/Nagasaki survivors and radiation workers in the nuclear industry—has shown an increased risk for most types of cancer. Shockingly, a recent survey revealed that 53% of radiologists and 91% of emergency room doctors did not believe that CT scans increased the lifetime risk of cancer. But these scans can and they do. 75% of these doctors seriously underestimated the radiation dose from CT scanning. When I have spoken privately to radiologist friends about the issue of radiation from CT scans, they say yes, they are concerned, but seem to be hoping for the best; they really don’t want to think that their tests might increase anyone’s chance of cancer.
Despite that hope, it’s estimated up to 2% of cancers in the U.S. today are secondary to irradiation damage from CT scans, leading to 3 million excess cancer cases in the next 20 to 30 years in the U.S. alone. And while perhaps the increased risk from only one scan might be relatively small, many people undergo multiple scans over their lifetime, and the risk is cumulative. Disturbingly, children are much—up to 10 times—more sensitive to the cancer-inducing effects of radiation.
Next…ideas how to avoid unnecessary medical irradiation.
