Growth of CT scan use significant public health problem

Computed Tomography (CT) scans are an increasingly used X-ray-based tool for providing a three-dimensional view of a particular organ or tissue. The value of Computerized axial tomography scanning to diagnose injury, cancer and other health problems is undisputed. But are these scans being used too frequently, in some cases unnecessarily" What are the health consequences of having too a number of Computerized axial tomography scans over the course of a persons life".

In a Nov. 29, 2007 article in The New England Journal (NEJM), David J. Brenner, Ph.D., and Eric J. Hall, Ph.D., from the Center for Radiological Research at Columbia University Medical Center, argue that the potential carcinogenic effects from using Computerized axial tomography scans may be underestimated or overlooked. This is of particular concern, because perhaps one-third of all Computerized axial tomography scans performed in the United States may not be medically necessary, the radiation scientists say.

It is estimated that more than 62 million Computerized axial tomography scans per year are currently given in the United States, in comparison to three million 1980. Because Computerized axial tomography scans result in a far larger radiation exposure compared with conventional plain-film X-ray, this has resulted in a marked increase in the average personal radiation exposure in the United States, which has about doubled since 1980, largely because of the increased CT usage.

It used to be widely believed that all radiological examinations were essentially harmless, because of the small amounts of radiation involved, but Drs. Brenner and Hall show that this is unlikely to be true for Computerized axial tomography scans. In particular, Japanese atomic bomb survivors who were about two miles away from the explosions, actually received radiation doses quite similar to those from a Computerized axial tomography scan. Sixty years of study of these survivors have provided direct evidence that there will be an increased individual cancer risk, though small, for those who have this same dose of radiation from Computerized axial tomography scans. Eventhough the individual risk is small, the large number of Computerized axial tomography scans currently being given may result in a future public health problem. In particular, Drs. Brenner and Hall suggest that, in a few decades, about 1 to 2 percent of all cancers in the United States may be due to the radiation from Computerized axial tomography scans being done now.

Defensive Medicine Leads to Overuse
Drs. Brenner and Hall suggest that the rapid increase in CT usage represents a potential public health problem in the United States that should be proactively addressed. This is especially important for children, who are more sensitive than adults to radiation exposure. The issue arises, for example, when Computerized axial tomography scans are requested in the context of so-called defensive medicine, or when scans are repeated as a patient passes through different parts of the medical system. Compounding the issue, surveys suggest that the majority of radiologists and emergency-room physicians may not appreciate that Computerized axial tomography scans are likely to increase the lifetime risk of cancer. Ultimately, the health care system, the doctor, and the patient (who can perhaps best track of the number of Computerized axial tomography scans performed when dealing with multiple doctors) may have to share the burden of monitoring the appropriate dosage and number of scans.

Drs. Brenner and Hall suggest three strategies for proactively addressing the potential increased radiation risks linked to Computerized axial tomography scans:

1. Reduce the CT-related radiation dose in individual patients.

2. Replace CT use, when appropriate, with other options that have no radiation risk, such as ultrasound or magnetic resonance imaging (MRI).

3. Decrease the total number of Computerized axial tomography scans prescribed.

Drs. Brenner and Hall suggest in their papers conclusion that these strategies could potentially keep 20 million adults and, crucially, more than one million children annually in the United States from being irradiated unnecessarily. They stress, however, that in the majority of individual cases, the benefits linked to a correct diagnosis through CT will far outweigh the individual risk.


Posted by: Sean    Source