Posts Tagged ‘CT’

Traumatic brain injury in children

March 16, 2008  |  General  |  2 Comments

Most children with significant brain injury spend time in a PICU. Like most experienced pediatric intensivists, I have seen hundreds of these children over the years, with dozens at least in the severe category. In one sense the term “traumatic brain injury” has limited usefulness because it covers such a wide range of injuries, from mild concussions to more extensive injury, to lethal damage. In another sense, however, it is a very useful diagnostic category because the brain responds to a wide variety of injuries in a very similar, stereotypic way.

Our understanding of the manifestations of TBI has grown over the years considerably. When head CT scans became available we could for the first time assess such things as bleeding inside the skull or swelling of the brain easily and safely. I remember how exciting it was in 1974 to see the first simple CT images taken on grainy Poloroid snapshots. Now we have sophisticated computer reconstructions of the brain. The technology represented such a breakthrough that its inventors received the Nobel Prize for it.

We soon realized, however, that some injuries to the brain, particularly what we call shear injury, are not well seen on CT — it takes an MRI scan to do that. We also came to realize that the most important thing we could do in the PICU for a child with severe TBI was to make sure the injury did not get worse: simple supportive measures like relieving pain and keeping the heart and lungs working well were key supportive measures to use while we waited for the child’s brain to heal.

Increasing understanding of milder forms of TBI have made us realize it is much more common than we once thought. For children, although the long-term outcome for mild to moderate TBI is good, persistent problems with such things as headache, mood changes, and difficulties in school are not uncommon, and these can last for months. There is a great deal of information available about TBI. There are many misconceptions about it, too. You can find authoritative, respected advice from the National Institutes of Health here and from the Brain Trauma Foundation here, and many more useful links here.

CT scans and radiation risk

December 1, 2007  |  General  |  No Comments

I’ve written before about the radiation risk of x-ray studies. Most of this risk is in the form of increased lifetime cancer risk. This is a particular concern for children because lifetime risk is cumulative, and children have much more of their life before them. Computed tomographic scans, or CT scans, use several hundred times the amount of radiation of ordinary x-rays.

A recent article in the New England Journal of Medicine estimated up to a third of all CT scans ordered in children are not really needed. Why all the unnecessary scans? One reason is poor communication between doctors when, for example, a child is transferred from one hospital to another. Another reason is “defensive medicine,” situations in which doctors order a scan because they fear missing something which, although highly unlikely, could get them sued.

The bottom line for parents? Ask your child’s doctor how crucial the CT scan is for your child’s care. From the article: “From an individual standpoint, when a CT scan is justified by medical need, the associated risk is small relative to the diagnostic information obtained.” The key is to make sure there is a good medical indication.

Are x-rays completely safe?

October 5, 2007  |  General

Doctors do a lot of x-rays on children. Is there a risk to that, or are x-rays completely safe? The answer, for chest, bone, and abdominal x-rays, is that they are very, very, very safe, but not totally risk-free. All of us are constantly exposed to radiation similar to x-rays. It comes primarily from naturally-occurring radioactive things around us, such as radon gas seeping up through the ground, or from outer space in the form of cosmic rays. People living at higher altitudes receive higher doses of such background radiation, amounting to about half again as much for someone living on the Colorado plateau compared with someone at sea level. To put things in perspective, the radiation dose in a single chest x-ray, on average, is similar to the background radiation most of us receive during a ten day time span living our normal lives.

There are several important things to remember about radiation risks. High radiation doses definitely cause death and disease (primarily cancer); the atomic bomb and the disaster at Chernobyl clearly showed this. A second key point is that radiation risk is cumulative over a lifetime. This is an important consideration for children, since they have most of their life ahead of them. Children are also more sensitive to the effects of x-rays than are adults. Still, it is logical to think of routine chest, arm and leg, and abdominal x-rays as being virtually without risk unless the child has already gotten for some reason a large radiation dose in the past.

Computed tomographic scans, CT scans, are another form of x-rays. We most commonly use CT scans to look at a child’s head, chest, or abdomen. The technology produces good images of the organs inside those body regions, and CT scanning has revolutionized how medicine and surgery are practiced. But CT must be used judiciously, particularly in children, because it subjects the child to much more radiation than does a simple chest or abdomen x-ray–200 to 300 times more, depending upon the particular technique used. So if a chest x-ray is the equivalent of ten days of background radiation exposure, a child getting a CT scan receives the same radiation dose as anywhere from five to ten years of normal living. I’ve written more about CT scan risk here.

The future cancer risk to a child from a single CT scan is still vanishingly small, and the benefits of getting the information the CT provides nearly always outweigh this tiny risk. However, this may not be the case for children who get many CT scans or have been exposed to other radiation in the past. Fortunately, this represents a relatively small number of children. There are ways of using reduced radiation doses in children, compared to the doses adults receive for CT. If you are concerned about this issue, ask your child’s doctor about it, or you can read more about it here.

I’ve also posted here about what medical risk means.