STORY BYHow many x-rays can you receive before that becomes a bigger problem than the one you’re trying to find? How much radiation is too much in a single diagnostic procedure?
Every time you get a bone, dental or chest x-ray, a mammogram or a CT-scan (computerized tomography), you’re subjected to radiation. (In fact, every time you walk outside and greet the atmosphere, you’re subjected, as well.)
But, following the death of news anchor Peter Jennings of lung cancer, smokers and former smokers are asking their doctors about an expensive and relatively untested x-ray procedure called a helical CT scan that may employ potentially dangerous levels of radiation.
No one questions the superiority of a CT scan to detect far more lung tumors than conventional chest x-rays or to find lung tumors long before they cause symptoms or show up on a chest x-ray. But, many authorities believe the risk of such a procedure outweighs the benefit and cost, which can run as much as $1,300.
“The biggest contributor to radiation in the population for medical x-rays is CT, or computed tomography,” says Louis K. Wagner, PhD, and a medical physicist and professor in the Department of Diagnostic and Interventional Imaging at The University of Texas Medical School at Houston.
The CT scan has a much higher degree of radiation exposure than routine chest x-rays, says Richard Castriotta, MD and professor of medicine and division director for pulmonary, critical care and sleep medicine at the UT Medical School at Houston.
One problem with CT screening for lung cancer in non-symptomatic individuals is that “we don’t have any experience with it yet,” explains Wagner. Mammography, on the other hand, “has been well-studied. There was a lot of investigation about potential risks of radiation exposure. The question came up: Would we be doing more harm than good? Could we possibly be inducing more cancer than we’re finding and curing?”
After long study, mammograms were recommended for women beginning at about age 40, when the risk of developing breast cancer starts to rise and the risk of radiation exposure begins to fall, Wagner explains. Before age 40, few women develop breast cancer, and the density of a young woman’s breast makes mammography impractical. As a woman ages, the composition of the breast changes, and x-rays are better able to penetrate it.
It is “notoriously difficult” to assess the risks of low levels of radiation exposure, notes Robert Emery, assistant vice president for environmental health and safety at the UT Health Science Center at Houston. “People are bombarded every day by normal sources, from the environment, the atmosphere, the water we drink, our food sources. The general consensus is that we know what the dangers are to high levels, just not the danger to low levels.”
Any level of radiation you receive carries incremental risks, according to safety experts and the Nuclear Regulatory Commission. But that doesn’t mean you should avoid medical exams. Instead, Emery says, “talk to your provider to assess the safest way to proceed. It means, when you have dental exams, make sure you’re using a lead apron to cover your body. It means, if you switch dentists, ask if you can have the previous records sent over that would have prior x-rays.”
But, back to that question of CT scans for lung cancer. The American Cancer Society estimates that an estimated 172,570 cases will be diagnosed and 163,510 people will die of lung cancer this year, making it the leading cause of cancer-related deaths in American men and women. Research shows that smoking is the main cause, and that people remain at risk many years after they quit. So doesn’t it make sense that those at risk should consider a CT scan?
“At this point, it’s up to the individual and his doctor as to whether he should undergo screenings without symptoms of disease,” Wagner says. “If a person is really concerned because of a history of smoking, and maybe a history of cancer in the family, see a physician. Talk about it and don’t worry about the radiation. Go get it done.
“But if a person is perfectly healthy, even though he had smoked earlier, I’d say, what would be a better way to spend your money for your health? Taking a trip for some rest and relaxation in the Bahamas or getting a screening CT scan? You decide that. For me, I’d go to the Bahamas.”
Castriotta agrees. He recommends a CT scan for a patient only if “we’re suspicious of something on the chest x-ray, we believe that the CT scan can offer more vital information or if we are looking for something that will not be seen on a routine x-ray. At the present we’re not recommending CT scanning for asymptomatic individuals with normal chest x-rays and no symptoms. The risk doesn’t warrant the benefit and cost.”
An eventual alternative for high-risk patients may be fluorescence bronchoscopy techniques “in which just a few cells of cancer in the major airways can be detected,” Castriotta says. Fluorescence bronschoscopy does not employ radiation.
Do not be afraid to ask your health provider to explain the risks and benefits of the myriad diagnostic imaging techniques available.
For more information on general diagnostic imaging techniques:
The Radiological Society of North America
http://www.radiologyinfo.org/content/safety/rad_safety.htm
UPDATED: 1-20-2006
Editorial Board | Legal Disclaimer | Privacy & Security | Contact Us
©2000-2006 Office of Institutional Advancement, UT-Houston
Dr. Richard Castriotta is director of the Division of Pulmonary, Critical Care and Sleep Medicine at UT Medical School.
See Dr. Castriotta also at:
Men: Pay Attention
to Your Bicycle Seat
Men who bike more than three hours a week should be aware that standard bicycle seats, ridden for extended periods, can cause temporary numbness and, in some, more serious problems, such as erectile dysfunction.
Such problems are caused by compression of an artery and a nerve connected to the penis. New seat designs to minimize compression are now available.
Other preventive measures you can incorporate:
