Answer to Question #15455 Submitted to "Ask the Experts"

As first-time parents, we were uncertain about many things. Recently, we noticed a dent at the back center of our baby's head when he was only one month old. Although he seemed fine and was feeding normally, we decided to go to the emergency room to check if this was normal. At the hospital, they ordered a skull x ray. We were somewhat hesitant, as we didn't think it was something serious, but proceeded just in case. The results came back normal, and we were referred to a specialist for a follow-up.

The specialist reassured us that the dent we felt was normal for our baby. Since then, I've struggled with feelings of guilt, questioning if the x ray was even necessary. The thought that our love and concern for him resulted in radiation exposure, especially when he is so small, has been weighing heavily on me. I'm aware that there is always an increased risk of cancer from radiation exposure, and this makes me feel down and guilty.

My questions are:

1. The specialist mentioned that a single x ray is nothing to worry about. However, my baby underwent AP, lateral, and Towne's views. Does this mean he was exposed to three x-ray procedures? What is his future risk of cancer from these x rays?
2. I've read that one of the risk factors for thyroid cancer is radiation exposure to the head and neck area, especially during childhood. What is the likelihood of him developing thyroid cancer in the future? Additionally, is there any risk of brain tumors?
3. At such a young age (one month old), will this skull x ray cause autism? Also, will there be any impact on his brain or learning development?
4. Could this radiation exposure affect his future children, potentially increasing the chances of having children with health issues?

I can hear the despair in your questions, and I hope that I can ease your concerns. First and foremost, it is important to remember that a physician ordered x rays because there was a reasonable belief that x rays would be useful in deciding what care to provide for your son. It is great news that the x rays did not show anything suspicious, but that does not mean that you should not have gotten him the x rays. The consequences of not having x rays when a physician orders them can be very serious. You did the right thing by following the doctor's orders.

I want to first address the idea "that there is always an increased risk of cancer from radiation exposure." Unfortunately, there is a lot of misinformation about radiation and radiation risks in the media and available online. There is not always an increased risk of cancer from radiation exposure. At very high exposures, this is true, but at low exposures this is not the case. Low exposures include x-ray imaging of the skull like your son had.

Let's talk about cancer risk in general. Some children do unfortunately develop cancer due to genetic, environmental, or unknown causes. Based on a study by Siegel et al. published in 2023, the overall incidence of childhood cancer in the United States between 2003 and 2019 was 178.3 per one million. This result means that in a population of one million children, we would expect 178 children to develop cancer, or less than 0.02% of children, from all causes. A study by Earl et al. in 2022 estimated 26 excess cancers per million babies receiving AP, lateral, Townes and SMV skull imaging. If we add in that theoretical population risk study of the earlier estimate, the total population risk now becomes 204.3 children per million, or still about 0.02%. Remember that means in a million children, 99.98% do NOT develop cancer. Odds are far more in your favor that your child will NOT develop cancer. 

Now to address your specific questions. Having AP, lateral, and Towne's views does mean that three separate images were obtained. However, the total dose is still very low. As stated above, the Earl et al. reference puts the risk at 26 excess cancers per million, which means that there is a 99.99% probability that there will be no cancer. 

Regarding thyroid or brain cancer as a result of his radiation exposure, the population risk is not stratified into particular cancer type, the risk is still just 0.02% of developing any cancer for any reason. Which again is the same as the normal incidence of cancer in children.

There is not any scientific link between autism and radiation. In fact, the cause of autism is still not understood. One of my own children, a twin, is high-functioning autistic while his twin is neurotypical. Cognitive abilities could be impacted if your son needed to receive therapeutic doses of radiation for cancer, which are far higher doses. However, diagnostic x rays will not impact cognitive ability, even though he's so young; the exposure is simply too small.

Lastly, the exposures will not impact his ability to have children and there will be no genetic changes passed on to his offspring. Your son would have needed a very high radiation exposure to his reproductive organs to induce sterility. His reproductive organs were not in the field of view for skull imaging.

I know you are scared and only want the best for your son. I hope you take the information I've provided to heart and can relax in the knowledge that you did the right thing by having the x rays taken and there will be no lingering radiation exposure effects as a result. If your son ends up anything like my boys, you'll have more x rays in your future. It seemed that I was in urgent care getting x rays every six months or so with one of my boys because they injured something. X rays are a great diagnostic tool that may well become your friend when patching up your son. My boys are now 21, 21, and 23, none of them have cancer, and I never hesitated to have x rays when they were needed. You are doing the right thing! You got this. I hope radiation drops to the very least of your worries. 

Kendall Berry, MSPH, CMLSO