How to protect yourself from excessive radiation

X-rays have been used for almost 120 years, but the introduction of computed tomography, or CT scans, in the 1970s was revolutionary, says Consumer Reports. The new tests, which use multiple X-ray images, allowed doctors to see with unprecedented precision the inner workings of the human body.

Use of the tests grew quickly, rising from fewer than 3 million per year in 1980 to more than 80 million now. But recent research shows that about one-third of those scans serve little, if any, medical purpose. And even when CT scans or other radiology tests are necessary, doctors and technicians don’t always take steps to limit radiation exposure.

All of that exposure poses serious health threats. Researchers estimate that at least 2 percent of all future cancers in the United States — approximately 29,000 cases and 15,000 deaths per year — will stem from CT scans alone. Even some standard X-rays, which expose you to much smaller amounts of radiation, can pose risks if you undergo multiple ones.

WHERE THE RAYS ARE — AND AREN’T

Consumer Reports ranks tests in order of radiation exposure:

Ultrasound. High-frequency sound waves sent through the body create echoes as they bounce off organs and tissues. Echoes are then turned into real-time images called sonograms. Produces fairly good images of soft-tissue disease. Radiation exposure: none.

MRI. Magnetic resonance imaging uses magnets and radio waves to create detailed images that can help spot cancers and soft-tissue problems. Radiation exposure: none.

Mammogram. Uses low-dose X-rays to spot masses and mineral deposits that could indicate breast cancer. Radiation exposure: low.

X-ray. The standard scan emits a broad beam that passes through the body before landing on film, casting shadowlike images. Fluoroscopy produces a continuous image, or X-ray movie. Radiation exposure: minimal to medium.

CT. Computed tomography uses a pencil-thin X-ray beam to create a series of images from multiple angles, which are then transferred to a computer, creating a 3-D image that can be enlarged and rotated onscreen. Excellent for looking at soft tissue. Radiation exposure: minimal to high.

PET. Positron emission tomography requires the patient to ingest a radioactive tracer that lands in cells, especially cancer cells. Some machines that are used combine PET and CT scans. Radiation exposure: medium to high.

4 SCANS YOU CAN USUALLY SKIP

These imaging tests were culled from the Choosing Wisely campaign, an initiative of more than 60 professional medical organizations, to identify tests or treatments that are done too often.

X-rays for back pain. Getting an X-ray or CT scan to find the cause of back pain would seem to be a good idea. But the pain usually stems from muscle damage and clears up on its own within a month or so. Getting a test sooner than that won’t speed your recovery.

Chest X-rays before surgery. Many people automatically receive a chest X-ray to “clear” them for surgery. (Some hospitals even require the test for almost all patients who are admitted.) That’s unnecessary, according to the American College of Radiology. According to Consumer Reports, you generally need the test only if you have lung or heart disease, you have signs or symptoms of a heart or lung condition or you’re scheduled for surgery that will involve the heart, lungs or part of the chest.

CT scans to screen for lung cancer. The American College of Chest Physicians, among other groups, says that the test is worthwhile only for people at the highest risk of developing lung cancer: current or former smokers between the ages of 55 and 80 who smoked the equivalent of a pack a day for 30 years.

CT scans for headaches. Many people who experience severe headaches want a CT scan to see whether they’re caused by a brain tumor or other serious problem. But the American Headache Society says that’s necessary only if your doctor can’t diagnose your problem based on a physical exam.

2015 Consumers Union Inc.