If your child suffers a bad blow to the head or experiences severe unexplained stomach pain, landing you in the emergency department, it can be scary. The sooner you can get answers, the sooner your fears can be allayed, your child can get treatment and start feeling better.

As a pediatric radiologist, I use imaging scans to get those answers quickly, which can make all the difference in the middle of a life-threatening emergency. But I recognize that the benefits of these tests, some of which use radiation, must be balanced with potential risks for children. Exposure to ionizing radiation is a risk factor for developing cancer later in life. The effects of radiation are cumulative, so the radiation a child receives today will be with him or her forever. Moreover, it's important to remember that with diagnostic testing, as well as with treatment, kids are growing and their tissue is more sensitive.

The most common imaging scan that uses radiation is digital radiography, more commonly known as an X-ray. Radiography uses X-rays, radiant energy beams like light or radio waves that pass through the body, to produce images of the body's internal structures, such as bones, organs and teeth. A single X-ray, such as one used to image a child's fractured ankle, uses very little radiation, and the benefits of the test typically far outweigh the risks. We also use lead aprons to cover the parts of the body not being imaged to further limit the child's exposure.

For more detailed imaging, computed tomography (CT) has proven to be a useful tool. First developed in the 1970s, CT combines hundreds of X-rays taken from many angles to produce detailed cross-sectional images of one part of the body. Largely because these scans are fast, accurate and non-invasive, they are used 10 times more now than they were in 1980. In the United States alone, between 5 and 9 million CT scans are performed annually on children.

CT scans are often used to evaluate a head injury or abdominal pain in children, but CT scans can also help us diagnose fractures and internal injuries, as well as cancers, infections and blood clots. There are clear benefits to CT scans: When we find a cancerous tumor early before it's had time to spread, for example, the scan can be lifesaving.

However, because CT scans expose patients to several hundred times more radiation than an X-ray, those benefits must be weighed very carefully against the risk of exposure. Nearly half of children in emergency departments with a head injury end up getting a CT scan, according to the American Academy of Pediatrics, and one-third of these scans are not necessary. For children with mild concussions, CT scans usually come back normal exposing the child to radiation while providing no clinical benefit. These scans are much more useful for bleeding in the brain and skull fractures.

This is why it's important for a physician to ask detailed questions about the injury and symptoms before considering what tests to run. Whenever possible, I always first try to find answers with an MRI or an ultrasound - neither of which produce radiation (MRIs use radio waves and ultrasound uses sound waves to create an image). Yet, CT scans are sometimes the best modality of imaging in certain conditions, so much depends on the child and his or her condition.

There are ways to minimize a child's exposure to radiation without forgoing the benefit of this powerful tool when it's truly needed.

First, I recommend that before consenting to a CT scan for a child, parents should ask their doctor about using alternative forms of imaging that do not involve radiation.

Second, it's wise to confirm that the facility's CT scan settings can be adjusted for the child's size, so that your child does not receive a higher radiation dose than is truly necessary. Fortunately, it's common for emergency departments, as well as most other imaging centers, to be equipped with pediatric dose protocols for CT scans.

Many facilities, like the ones we use at Kaiser Permanente, have specific protocols for children, including equipment capable of low-dose CT scanning. Our scanners have built-in protocols with a type of software that allows us to make adjustments to the scanner according to the size and age of the child. Depending on the test being performed, these scanners can reduce the dose for a baby or child by as much as half of what an adult would receive.

Third, ask if the CT technologist can scan only the part of the body that needs to be examined. If your child has abdominal pain and doctors suspect appendicitis, for example, the radiologist can scan only the lower abdomen and pelvis, excluding the lower chest and upper abdomen. Limiting the scan to the affected area lowers the overall radiation dose.

Finally, confirm that the radiologist has saved the dose information for each scan, so that the amount of radiation your child has been exposed to is documented and can be used when considering future scans. Information on radiation dose is often automatically saved by the equipment into the imaging database.

Taking these simple steps can reduce the risk of radiation exposure in your child - which also reduces the possible slight risk of your child developing a future radiation-related cancer. But parents should also keep in mind that, while no amount of radiation is considered absolutely safe, the cancer risks associated with imaging scans are small. We just need to minimize the risks for kids whenever possible.

For more guidance on safe and effective medical imaging for children, visit the Parent section of imagegently.org. For information about dental imaging, visit the American Academy of Pediatric Dentistry site.


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Shashi Ranganath, MD, is a board-certified pediatric radiologist and Assistant Regional Medical Director of Imaging Services at Mid-Atlantic Permanente Medical Group (MAPMG).