Obese Get Higher Doses of Radiation for X-Rays

July 1 -- TUESDAY, June 30 (HealthDay News) -- People who are overweight and obese are usually given higher-than-normal doses of radiation in order to obtain usable X-ray images, even though the long-term effects are unknown, new research contends.

"You need to get a certain amount of X-rays to go through the body in order to get an informative image, and excess weight impedes that," explained the study's lead author, Jacquelyn C. Yanch, a professor at the Massachusetts Institute of Technology in Boston. "And there are very few ways around that problem, other than increasing an overweight patient's exposure to radiation to improve the image quality."

"Americans have gotten larger on average over the last half-century, and so as a result, our radiation dosages have gone up," she added. "Exposure can be sometimes 20, 30, even 40 times as much for an overweight patient as for a lean person. And in general, we're also getting more exams and more intensive exams."

"But even so, we don't actually know the impact of such high doses over time, or whether they're dangerous, because we simply haven't tracked the effect," Yanch said. "So, it's very important for us to start monitoring this exposure for each individual patient so we can get a handle on it."

X-rays account for the lion's share of people's exposure to radiation, the researchers note.

To gauge how high radiation doses must be to get effective X-rays for overweight and obese people, the researchers used computer simulations that delivered X-ray beams at various strength levels to so-called "phantom" patients representing five different fat tissue levels, from lean to obese. Different body areas, including the chest and abdominal regions, were X-rayed to see which entry points were most effective in rendering high-quality images.

The researchers then compared the dosage levels, body position options and body mass distribution numbers with the amount of radiation the computer software indicated that each imaginary patient would have had to absorb to get the desired image.