- With Mayo Clinic medical oncologist
Timothy Moynihan, M.D.
read biographyclose windowBiography of
Timothy Moynihan, M.D.
Timothy Moynihan, M.D.
"As a practicing medical oncologist, I meet with patients and families every day to help manage their course through this disease called cancer. This experience provides unique insight into the needs of cancer patients, their families and loved ones and brings into sharp focus the need for reliable information to be readily available in terms that can be easily understood." — Dr. Timothy Moynihan
Dr. Timothy Moynihan believes that providing consumers accurate, timely information on the broad, complex topic of cancer is the biggest challenge facing medical Web sites. As the guiding force behind our cancer coverage, he makes sure Mayo Clinic meets the test.
Dr. Moynihan, born in Las Vegas, N.M., but raised in Denver, is a consultant in medical oncology at Mayo Clinic and an associate professor at Mayo Clinic College of Medicine. He is board certified in internal medicine, medical oncology, and hospice and palliative care medicine. He did his medical oncology training at Johns Hopkins Hospital in Baltimore, and then went on to the University of Minnesota and St. Paul Regions Medical Center in St. Paul, Minn., for seven years before moving to Mayo Clinic in 1999. Dr. Moynihan is director of the palliative care program at Mayo Clinic and associate medical director of the Mayo Clinic hospice.
Dr. Moynihan currently serves as the education chair for the Department of Medical Oncology and fellowship program director. Four times he has been selected as Teacher of the Year in medical oncology and elected to the Teacher of the Year Hall of Fame. Past honors include distinguished clinical teacher at the University of Minnesota Medical School, best internist at the Medical College of Wisconsin and recipient of The Upjohn Achievement Award for Excellence in Medicine. He serves on several national committees for the American Society of Clinical Oncology.
"The Internet provides a ready source of information on a wide range of topics of interest to those affected by cancer," Dr. Moynihan says. "The difficulty is trying to decide which sites provide reputable information and which information is relevant to each individual patient. The long history and tradition of excellence associated with Mayo Clinic assures you that information provided will be reliable, up-to-date and comprehensive."
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Question
CT scans: Are they safe?
Are CT scans safe? I read an article that said CT scans may increase my risk of cancer. Is this true?
Answer
from Timothy Moynihan, M.D.
CT scans are very safe. Since its invention in 1971, the computerized tomography (CT) scan has been used in hundreds of millions of people to diagnose disease and guide treatment. It is one of the most trusted diagnostic tools available to doctors.
Like other X-ray imaging exams, CT scans involve a brief, targeted exposure to a small amount of ionizing radiation, which is used to create an image of your internal organs. No radiation remains in your body after the scan is over. Although CT scans expose you to more radiation than traditional X-ray exams do, they also provide much more detailed images, which allows your doctor to detect and precisely locate a vast array of medical conditions.
Since the 1980s, CT scans have become faster, cheaper and more widely available. As a result, the use of CT scans has greatly expanded. In addition, the level of detail provided by CT scans has increased and the radiation dose required has decreased. For example, after a motor vehicle accident, your entire body could be scanned by CT in 30 seconds or less and the "slices" represented by each image could be made to be as thin as 0.5 millimeters. Such a detailed look into your body could pinpoint severe injuries within minutes, allowing doctors to quickly begin necessary treatments.
In spite of the undisputed medical benefits of CT, some scientists are alarmed by the increasing use of CT scans. According to a 2007 report published in the New England Journal of Medicine, this benefit might carry an unforeseen cost — namely, an increase in cancer rates in the coming years.
Scientists have known for at least 50 years that high doses of radiation can cause cancer to occur — often decades after the radiation exposure. So the concern about overuse of CT scans isn't completely unfounded.
However, the medical and scientific communities remain sharply divided over whether the small amount of radiation you get from medical imaging is enough to cause cancer. In fact, the doses from medical imaging are so much lower than those that have clearly been linked to cancer that many scientists believe that it's impossible to study enough people to ever prove that CT scans actually do cause cancer.
It's important to note that no cases of cancer have ever been specifically linked to CT scans. In nearly all cases, the benefits of CT scans in diagnosing and treating troubling or severe symptoms outweigh the very small theoretical risk of CT scans causing cancer.
Still, it's a bad idea to request a CT scan or any imaging study unless you have symptoms that require one. No matter how small the risk, any exposure to radiation without a defined medical purpose just isn't appropriate.
Also, CT results aren't always clear-cut. There are medical conditions, such as diabetes, that can't be seen on a CT image. If a CT scan finds something unusual, you could subject yourself to additional medical tests and needless worry — only to find that you're in good health. For these reasons, most professional medical societies and the Food and Drug Administration advise against CT screening exams in otherwise healthy people.
If you're scheduled to have a CT scan and have concerns, ask your doctor to explain why he or she feels that a CT scan is necessary. If you and your doctor conclude that the CT might help with your medical problem, don't worry about the safety of the exam.
