Before the end of 2011 it is expected that over 1000 new scanners will be installed in airports around the United States. These scanners use extremely low energy "backscatter" X-rays that bounce off of our bodies to look under our clothing to check for concealed weapons. The X-rays used are so weak they are unable to penetrate the skin and soft tissue like a diagnostic medical X-ray, and that is why they are referred to as "backscatter" X-rays. These machines have caused concern by some of our patients that they are being endangered, and they wonder how to put this type of exposure into perspective.
According to the website (www.radiologyInfo.org) sponsored by the American College of Radiology (ACR) and the Radiological Society of North America (RSNA), the radiation dose from these scanners is measured at 0.02 microsieverts. A microsievert (μSv)is one millionth of a sievert (Sv), the standard international unit of radiation dose. Microsieverts, (μSv ) measure the effective dose of radiation in a medical procedure. For example, the dose of a chest X-ray's is approximately 100 μSv, a mammogram is 400 μSv and a CT scan of the abdomen and pelvis is about 15,000 μSv.
In addition to medical tests, all of us are exposed to natural radiation from the earth's natural radioactive materials and also from natural cosmic radiation from the atmosphere. According to ACR and RSNA, the average person is exposed to about 3000 μSv of natural radiation per year! This varies somewhat depending on where we live. People in Denver receive 1500 μSv more per year than those of us who live at sea level. The increased elevation we experience while flying also exposes us to more of this natural radiation, about 30μSv on every transcontinental flight.
Bottom line, the exposure from these scanners seems truly trivial when you consider the tiny exposure of 0.02 μSv. Using the numbers already discussed, a traveler would have to have 5,000 backscatter scans to reach the low dose of a standard chest X-ray.
My advice - have your scan when traveling and don't worry! What is important is to take action to reduce proven cancer risks. For example, smoking causes 30 percent of all cancer deaths and about 80-90 precent of death from lung cancer, yet over one fifth of American adults smoke.
The National Cancer Institute (NCI) tells us that obesity and physical inactivity account for about 30 percent of several major cancers, such as colon, breast, uterine, kidney and esophageal cancer, and 1/3 of us are obese. Skin cancer, the most common type of cancer in the United States, is known to be related to excess sun exposure. These are some of the real things we need to worry about, and they are in our control.