This morning I heard CNN's medical correspondent Dr. Sanjay Gupta discussing the unfortunate untimely death of Ohio Congresswoman Stephanie Tubbs Jones. During his discussion he mentioned CT scans as a routine scanning tool for brain aneurysm, which to his credit he dismissed. It has not been very long since there was a fad to obtain routine total body scans. The CT scan has been used in my career with gradually increasing frequency until recently when new research and heightened awareness of the increased risk has come to fore, particularly in regard to children. A recent article in the New England Journal of Medicine by Brenner, et al, has alerted the public as well as physicians about the possible dangers of radiation exposure with increased use of the CT scan.
In my profession as an ER physician a frantic mother brings in her 18-month-old girl who fell out of the shopping cart at the supermarket and landed on her head. She had an apparent momentary loss of consciousness, her eyes were open but she didn't immediately cry. The lights were on but nobody was home. Then she whimpered, then she howled, then she was gradually consoled and by the time she arrived at the ER she is playful and happy with a goose egg on her forehead. Do I get the CT? If she has a bleed in her brain intervention by a brain surgeon could save her life. What if she had suffered seizures as an infant and had already had two CT scans as part of the routine workup for unexplained seizures? I think the standard of care in the absence of rapid MRI availability would be to get the scan. She would probably have to be sedated to get the CT but she would certainly require sedation to get an MRI which is slower not mention more expensive. Sedation, of course, carries its own risks. Now the little girl is playing in her bed, bright eyed and happy as a lark. And now I'm about to expose her to radiation equivalent to the proximal suburbs of Hiroshima, perhaps about to lower her IQ forever. It's a lot to think about and the decision should be shared with the parents.
This risk is still technically theoretical since this exposure to ionizing radiation takes many years to present as cancer.The importance of CT scans as a diagnostic tool is incredible. For the detection of brain bleeds, early appendicitis, kidney stones, tumors, internal abscess, and many other life threatening conditions it gives quick and statistically reliable information. It has given medicine a huge leg up. However, no one has ever claimed that it is a substitute for clinical judgment.
Much of the data we have concerning radiation exposure comes from that gathered on the survivors of the atomic bombs we dropped on Japan in 1945. It has been suggested that the median dose of radiation in these studies that has shown an increase in cancer risk is the equivalent of 2-3 CT scans. It is worth noting that the type of radiation emitted by a bomb is different than that used in scanning, but it is still ionizing radiation. In a Swedish study by Hall,et al, looking at infants who had received radiation treatments for cutaneous hemangiomas, such as wine-stain birthmarks, showed some decrease in cognitive abilities in their teenage years and early adulthood. It is well known that children are more sensitive to ionizing radiation than adults. It has been suggested that after the age of 50 the increased risk of cancer is not statistically relevant if the patient has not received CT scans in the past.
Everything in medicine is risk versus benefit. The most important thing for a lay person to know is that there are indications for CT scans, but you should discuss just what your doctor is looking for and if there are alternative imaging exams or strategies for evaluation. Many times the benefit outweighs the risk which is rather small especially in the older the patient is and the fewer CT's they have already received.
The best way to avoid the dilemma of the little girl who fell out of the shopping cart is to prevent it. Fasten seat-belts, make sure that skaters, cyclists and skate boarders are wearing helmets. Preventative medicine is the cheapest most effective medicine available. How many CT scans have you had?