Obesity, Medical Imaging and Radiation

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As a result of many comorbidities (type II diabetes, cardiovascular disease, hypertension, and other diseases including cancer), patients with obesity are more likely to present for health assessment than their normal weight peers and are more likely, and more often, to require medical imaging.

Exams considered simple to perform on average sized patients bring challenges to radiologists for obese patients. Those exams need to be adapted to obtain quality images of obese individuals. With difficulty and precision, medical imaging specialists must position the patient so the thinnest fat layer is closest to the image receptor. The increased subcutaneous fat thickness always makes the treatments less accurate. This can lead to the requirement for repeated images and frustrations for radiographers when trying to achieve an image of sufficient quality to make a diagnosis. This is why patients with obesity experience a greater radiation burden for radiographic imaging compared to their optimal weight counterparts

A few years ago, researchers at the Rensselaer Polytechnic Institute were the first to calculate exactly how much additional radiation obese patients receive when undergoing a routine CT scan.

Thick layers of fat like this:

. . . make it difficult for the x-ray beam to penetrate the patient. When regular settings on the scanners were set, blurry images were produced. To ensure there were enough x-ray photons passing through the body to form a good image, the power (technically referred to as ‘tube potential’) had to be turned up.

The Rensselaer study showed that the internal organs of obese men receive 62% more radiation during a CT scan than those of normal weight men. For obese women, it was an increase of 59%.

The risk associated with a radiation dose from a single CT scan or X-ray is small. However, if you are over-fat, you’re at a greater risk for a long list of medical diagnoses, requiring more imaging . . . and radiation exposure is cumulative over your lifetime.