What Do Breast Imaging and Mammography Have in Common with Airport Baggage Screening?

Have you heard the one about the TSA employee and the radiologist? No really, it’s not a joke. It turns out that airport baggage screening staff and radiologists who specialize in breast imaging have something in common — and studies prove it.

Let’s start with familiarity of targets. Most people are not familiar with looking for guns, bombs and knives, so they are less likely to perceive them. Consequently, airport screeners have to be trained to look for weapons. Not surprisingly, the most experienced screeners do the best job of detection.

It’s the same for radiologists. The more time we spend doing breast imaging and reading mammograms, the better we become at spotting what is troubling, and staying away from what is not.

But it’s not all that simple. In addition to the familiarity of the target, there is the issue of frequency of the target.

When airport screeners are training, and a gun is concealed in every fourth or fifth bag, there is a high level of detection. But when a gun is hidden in only one of 300 bags, detection can be trickier and less accurate. When airport screeners experience either long periods of calm, or distractions, they suffer from subsequent losses of concentration, and thus diminished weapons detection.

Similarly, for radiologists doing breast imaging and reading mammograms, repetition, tedium, fatigue and distractions can all contribute to a loss of concentration and diminished cancer detection accuracy.

Radiologists can expect to see three to six cancers per thousand images. It’s a relatively infrequent event, and that leads to one of the biggest problems with doing breast imaging and reading mammograms: missed lesions. Lack of detection is a function of the overall infrequency of findings.

An additional issue is partial identification — being able to pick out an object or a sign of cancer when looking at only part of the lesion.

Breast imaging research studies indicate that when looking at overlapping structures, it is much more difficult to distinguish different, isolated findings. In these instances, computer-aided detection can help by picking out a part of the feature that might not otherwise be perceived.

Another aspect of the problem is identifying parts of objects with underlying clutter. When there are a lot of objects in one place on an image, the result can be partial visualization, which makes accurate breast imaging and mammography difficult. No matter how accurate the breast imaging technology, some lesions are going to be obscured by overlying breast tissue density.

The more time we radiologists spend doing breast imaging and reading mammograms, the better we will become at spotting what is troubling, and staying away from what is not.

Remember this the next time you are in a long airport security line and wondering what is taking so long.

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Author: Jessica W. T. Leung, MD