Are We Overusing CT Scans? Not Necessarily

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´╗┐Are We Overusing CT Scans? Not Necessarily

Robert Glatter, MD: Hi. I am Dr. Robert Glatter, editorial board member of Medscape Emergency Medicine. Welcome to AAEM 2014 (the American Academy of Emergency Medicine Annual Scientific Assembly) in New York City.

With me today is Dr. David Schwartz, Professor of Emergency Medicine at New York University School of Medicine. Dr. Schwartz also is a specialist in diagnostic imaging and emergency radiology.

Today, we are discussing the use of CT in the emergency department (ED), and specifically the issue of radiation -- with reference to a January 30, 2014, op-ed in the New York Times titled, "We Are Giving Ourselves Cancer."

David T. Schwartz, MD: Nice to be here.

Dr. Glatter: Thank you so much for doing this. What are your thoughts about this issue? Are too many CT scans giving us cancer?

Dr. Schwartz: There has been a lot of talk these days about overuse of CT scanning in the ED and in medicine in general, and quite a few papers have documented an astronomical increase in the use of CT scanning. The problem with some of those articles is that they go back to the introduction of CT scanning.

If you look back to 20 years ago, CT scanning was just being introduced; to say that the use of CT has increased tremendously since it was first introduced is unfair because it did not exist that many years ago. Thus, there has been a well-documented increase in the use of CT scanning, but this is because CT is such a potent diagnostic test that helps in many different areas in medicine.

Dr. Glatter: What are the main indications that show CT as superior in the practice of emergency medicine?

Dr. Schwartz: CT has revolutionized emergency diagnosis of many different disorders -- all sorts of traumatic injuries (head injury, for example), as well as other major traumatic injuries. Many patients with abdominal pain, for example, can receive a precise diagnosis without going to the operating room, which was a big problem before the use of CT. Patients would undergo exploratory laparotomy for suspected appendicitis. There are many other uses: pulmonary embolism or chest pain diagnosis.

Dr. Glatter: So CT is a very useful tool for the practicing emergency physician.

Dr. Schwartz: Right.

Dr. Glatter: What is the basis of this evolving public perception that we are radiating ourselves to death?

Dr. Schwartz: The title of the op-ed is, "We Are Giving Ourselves Cancer," which focuses on only one part of the equation. It certainly is true that compared with conventional radiography, CT scanning gives a much higher radiation dose, and that there is a small but theoretically detectable risk that CT scanning may induce cancer in patients.

The risk, however, is very small -- a risk that accumulates over a 20- or 30-year period. A CT scan confers a 1 in 2000 risk of developing cancer over the course of a patient's lifetime. But that risk, which sounds substantial, must be balanced against the health benefits of receiving a precise diagnosis of that person's disorder.

Thus, you are seeing only part of the equation. I would think many more lives have been saved by the rapid diagnostic information you get from CT scanning, compared with lives lost or cancers caused by the radiation dose.

Dr. Glatter: What kinds of cancers would develop 20 to 30 years down the line?

Dr. Schwartz: We do not know specifically, but it probably depends on the part of the body that is being irradiated.

Dr. Glatter: With children, obviously, we are more concerned.

Dr. Schwartz: Right. The potential for radiation to induce cancer is very age-dependent. If a very young child undergoes CT scanning or irradiation, they have a longer lifespan to run into these problems, and their tissues are more radiation-sensitive, so much of the equation when thinking of CT scanning depends on the age of the patient. In young children, you would want to be more selective, whereas in someone aged 45 years or older, the risk is infinitesimal compared with the benefits that patient would receive.

Dr. Glatter: Do you find that the public is asking questions when you order a CT scan? Are they less inclined to have the scan?

Dr. Schwartz: I have not encountered that, although as people hear about this op-ed, there is a possibility that they will question it. This is really a bigger issue for parents of young children, and if they have not heard about it and you explain it to them, I think their concerns are much more understandable.

Dr. Glatter: What alternatives to CT do you see for imaging for pulmonary emboli or trauma, for example; do you see any reasonable alternatives?

Dr. Schwartz: In some instances, alternatives are available, and many of these articles make a lot out of that, but these alternatives are not always useful. Ultrasonography may be an alternative diagnostic test for some problems and sometimes MRI, but this is expensive and not so readily available. CT scanning is widely used because it is such a beneficial and good test for many disorders.

Dr. Glatter: The use of low-dose CT scan has been evolving. Could you discuss that?

Dr. Schwartz: The issue of the relatively large amount of radiation with CT scanning was identified in 2001, in the context of radiation dosage for children. As a consequence of that, the radiation physicist David Brenner realized that you could reduce the radiation dose to children because their bodies are so much smaller. Thus, reducing the radiation dose can be done relatively easily, and that has been accomplished in diagnostic imaging in children.

They also realized that other things could be done with the technology and the generation of CT images that could reduce the radiation dose. I believe that until this became a prominent issue, many radiologists and radiation equipment manufacturing companies really did not keep track of the radiation dose. Now they are much more aware of that. They can keep track of the radiation dose and do everything possible to reduce the dose now.

Dr. Glatter: Do you have any thoughts about focused CT scanning? We talk about right lower quadrant CT or isolated CT by the regions of the body. Do you think that is possible?

Dr. Schwartz: That would be a mixed bag. For example, you mentioned lower abdominal pain that could be due to appendicitis. Why is it important to scan the entire abdomen in that case? People have advocated a focused scan for that. The problem is that although you think it may be appendicitis, it could be some other disorder, and it is possible you could miss other things if you become too focused on your testing.

Dr. Glatter: Right. That is a technical limitation and a medicolegal problem, as well. Thank you so much for joining us.

Dr. Schwartz: It has been a pleasure.

Dr. Glatter: Thank you for joining us at AAEM 2014.

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