Obese Patients Get Blasted With Higher Levels of Radiation During X-ray and CT Scans

Posted on April 5, 2012

Obese People CT Scan

Researchers from the Rensselaer Polytechnic Institute (RPI) note that most medical imaging equipment is not designed with overweight and obese patients in mind. As a result, these individuals are exposed to higher levels of radiation during routine X-ray and CT scans. The RPI researchers calculated 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%.

Currently, if technicians use normal equipment settings to perform a CT scan on an obese patient, the resulting images are blurry as the X-ray photons have to travel further and make their way through layers of fat. As a result, technicians generally adjust the equipment to a more powerful setting, which produces a better image but exposes the patient to more radiation.

X. George Xu, head of the Nuclear Engineering Program at Rensselaer, has developed technology that could help solve the problem and reduce obese patient's radiation exposure during scans. Xu's research team created detailed 3-D computer models of overweight and obese men and women, and used computer simulations to determine how X-rays interact with the different body types. These models, known as "phantoms," can help physicians configure and optimize CT scanning devices in such a way that minimizes how much radiation a patient receives.

Xu says, "Radiation exposure is cumulative over a patient's lifetime. The risk associated with a radiation dose from a single CT scan is relatively small when compared with the clinical benefit of the procedure. But patients are increasingly undergoing multiple CT scans and other radiation-based procedures, which can lead to unnecessary radiation risk. Regretfully, our study shows that obese and overweight patients can be exposed to an even greater level of radiation. Our new study brings us one step closer to minimizing radiation exposure and mitigating this risk to patients."

These new phantoms for overweight and obese patients will be part of an new software package, VirtualDose, developed by Xu and his team. VirtualDose aims to enable the creation of a personalized, ultra-realistic phantom of any patient undergoing a CT scan. The program takes into consideration a patient's individual characteristics, including age, sex, height, weight, and even if a woman is pregnant. By entering these data into the software, VirtualDose creates a phantom that accurately models the patient's internal organs. These phantoms will allow physicians and researchers to compare the radiation doses a patient will get from different CT scanner settings, and then choose the most appropriate configuration.

Results of the study were published here in the journal, Physics in Medicine & Biology.

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