The New England Journal of Medicine has recently published an informative article on this subject, including risks and benefits of CT scans. It can be found here:

http://content.nejm.org.libproxy.unm.edu/cgi/reprint/357/22/2277.pdf

I think many of the commenters will find that the increase in cancer risk from a single CT is fairly small.

A few comments on the main article:

1) Did anyone seriously believe that patients who undergo a CT receive as much radiation as the people who were at ground zero in Hiroshima? The people at the edges of the town suffered no ill effects, so what does the statement about Hiroshima mean, exactly?

2) The annual exposure of people to background radiation - what you get just walking around - is about 2.4 mSv ("milliSieverts") per year. An abdominal CT exposes the patient to between 10 and 13 mSv. It often helps to put these exposures in perspective.

3) It is one thing to look back on a "bump on the head" that came to nothing and regret the exposure of a head CT, and quite another to carry a dazed little girl to the ER and not know if she is bleeding into her brain or not. Doctors may not place as much importance on preventing radiation exposure as they should, but considering the amount of damage a subdural bleed can do, a wise doctor and parent will err on the side of getting the CT.

Thus: avoid a CT if you are sure you don't need it, but if you are not sure, a CT is really, really unlikely to have any negative effects, and can provide critical information fast - often saving lives.

I am looking for concrete answers concerning the dangers of ct scans on small children.
my son was recently given a brain ct scan in a emergency room, thankfully they found nothing other than a sinus infection. It was a while later that I was curious about the radiation dose and looked on-line to find to my horror that he has a definite increase cancer risk now from that CT scan. My son also had a barium swallow as a infant a chest x-ray and a leg x-ray, nobody asked me about previous radiation exposure which makes his risk even greater. I really feel there should be a change in policy, parents should be verbally told that they are increasing the child's risk of cancer. We parents are not doctors or radiologist and to assume we know this is criminal. I believe in the importance of CT scans as a life saving tool but for my son if I would have been clearly informed of the risk I would of opted for observation or an MRI. I fear for my child everyday and worry that my uninformed decision could cost him his life. I have spoken to the hospital where my son was treated and they explained to me that he has received his lifetime dose of radiation and I should avoid any further exposure. Considering that my son is only 7 I worry that he might need a ct scan in the future. I have read that a ct scan gives you the same dose of radiation that people received from the Hiroshima bombing. Since we have not been using ct scans that long is it known what number of children truly develop cancer from the scan? I am looking for concrete answers on this subject and everything I read frightens me further. I hope someone can answer some of these questions.

"...I know that there is nothing that I can do now. I have been searching the web for the last 3 days to learn everything I can about what damage has been done to him and what his chances are of developing cancer down the road."
I recommend Dr. Joel Fuhrman's book, "Eat to Live," in which he presents evidence that a plant-based (vegetarian/vegan) diet substantially reduces the chances of cancers. He is an M.D. and I especially liked his comment that perhaps many cancers are the result of a deficiency of the kinds of anti-cancer chemicals that occur naturally in plants (pigments, flavonoids, etc.). Also, the correlations between cancers and consumption of meat and/or dairy is stunning.

I took my 22 month old son to the emergency room 3 days ago after a fall. He had a bump on his head with a scrape. The doctor recommended a CT scan, and it ended up that he had 2 because the first one didn't come out clearly because he moved his head during the procedure. I had no idea until doing some research on the web that the CT scans involved such large doses of ionizing radiation. I would NEVER have agreed to these tests had I known. I am totally sick over this, but I know that there is nothing that I can do now. I have been searching the web for the last 3 days to learn everything I can about what damage has been done to him and what his chances are of developing cancer down the road. I cannot find clear answers. I suppose there are no clear answers and I will never know what harm these tests might have caused him. I just don't know how to move on--I keep replaying the events in my head and wishing I had made different decisions.

My 20 month old son also had a unnecessary CT head scan after a minor fall from his crib. The ER doctor ordered it causally and only spent less then 5 minutes observing him. He was fully conscious and interactive after the fall. After reading about head injuries, I found out that the CT head scan really wasn't necessary for him and observation should have been the course of action. I asked the radiologist about the radiation prior too the scan and was told that it was lower then a regular chest x-ray. Wow, did I find out differently. It was the equivalent of about 40 adult chest x-rays. I feel betrayed by people that I trusted. The risk outweighted the benefit. Was it defense medicine? I am so fearful of what his future holds for him as now he has a significant increased lifetime risk of radiation-induced cancer. Also, what has this done to his IQ? Pediatric CT scans are increasing and every parent needs to be educated of the risks vs benefits involved before they decide to subject their child to the radiation involved in a CT scan. I am also grieving.
Karen

We are the grieving parents of a three month old son. He had an unnecessary CT head scan. We were told the radiation he would be receiving was "equivilient to one modern day x-ray". We have now learned the truth. We are horrified. Cancer risk seem small compared to the BMJ Swedish study by Hall showing low radiation exposure causing learning and cognitive disorders. We are so sickened. We have to sign for vaccines and anesthesia however not be informed of a blast of low level radiation?!! This is so BARBARIC!!!
We are heavy hearted parents. We have no recourse only the goal to have every person in America informed of the level of radiation a CT scan and the insuing known and unknown risks.
Our son's CT scan was ordered so causally. It was if a temperature was been ordered. Low level radiation is standard care in some clinics.
This is once again BARBARIC. In our day and age of MedicaL Care.
Heavy hearted parents,
Andrea