Posted November 11, 2012
By RICHARD A. SZUCS-Commonwealth Radiology, P.C.
RICHMOND —Sometimes I'll hear patients ask about the risk of radiation from a diagnostic test.
It's a good question. As a radiologist, I've certainly thought about it a lot myself.
Advances in medical imaging over the past several decades have improved our ability to diagnose diseases and monitor response to therapy. Medical imaging examinations are generally less expensive than the invasive procedures they replace and are linked to greater life expectancy and decreased cancer mortality rates. Some of these tests involve the use of ionizing radiation.
Many people are understandably concerned about radiation. The increasing use of these examinations has resulted in increased radiation exposure to the American population.
But is it dangerous?
It could be. Ionizing radiation in high doses is a proven human carcinogen; we've seen this in studies of Japanese atomic bomb survivors, people exposed during the Chernobyl nuclear reactor accident, cancer patients treated with high doses of radiation and workers with high levels of occupational exposure. Even with exposure to high doses, not everyone will develop cancer.
Some experts believe that there is potential risk from exposure to lower doses of ionizing radiation. However, this has not been proven. In fact, people who live at high altitudes, airline pilots and flight attendants exposed to higher background radiation do not have higher cancer rates.
Nevertheless, many experts believe there is no threshold below which ionizing radiation is totally safe. Ionizing radiation, by the way, comes from natural materials and cosmic rays and is found everywhere – and therefore everyone is exposed to a level of background radiation. Radiation has many practical uses in medicine both for diagnosis and treatment.
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In 2009, the National Council on Radiation Protection published "Ionizing Radiation Exposure of the Population of the United States." According to the report, the largest increase in radiation exposure to the U.S. population is from patient exposure to diagnostic, nuclear and interventional medical procedures. Since the early 1980s, there has been a 600 percent increase in radiation exposure from diagnostic medical procedures, particularly CT imaging and cardiac nuclear medicine imaging.
That same year, another article, in the Archives of Internal Medicine, predicted a large number of cancers resulting from CT scans performed in 2007. The article led to a number of alarmist reports in the media of the cancer risk from CT scans, which raised concerns among patients and physicians.
Although we do not know the precise cancer risk from exposure to the lower doses of radiation received from medical imaging examinations, I do believe it's prudent to minimize exposure to ionizing radiation. This can be accomplished by controlling the radiation dose from each examination and controlling the number of examinations performed. The greatest concern is for children who are growing rapidly and are believed to be more susceptible to the effects of radiation.
So how do we control the exposure?
Physicians who perform radiologic examinations seek to keep the radiation dose "as low as reasonably achievable" while obtaining the necessary diagnostic information. The American College of Radiology accreditation program requires that radiation doses be within an acceptable range in order for a facility to be accredited.
Newer technology permitting imaging with less radiation is continually being developed. The Image Gently campaign raises awareness of the need to adjust the radiation dose when imaging children. Parents should ask if their child is receiving a "kid-size" radiation dose. I would encourage patients to look for facilities that are accredited and that participate in programs such as Image Gently.
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In order to control the number of examinations performed, physicians need to carefully consider the need for each examination and the alternatives available before ordering a study which involves ionizing radiation. I urge physicians to consider the appropriateness criteria developed by national specialty societies such as the American College of Radiology and the American College of Cardiology when ordering examinations.
Some institutions have incorporated appropriateness criteria into their computerized physician order entry pathways to make that easier. The American Board of Internal Medicine Foundation has started a Choosing Wisely campaign to help physicians and patients choose medical imaging studies that are evidence-based, not duplicative, free from harm and truly necessary.
As a patient, what else can you do? You should keep a record of your X-ray history and before undergoing a scan ask why the examination is necessary, how it will improve your health care and whether alternative studies can provide the same diagnostic information. CT is often the best test but sometimes ultrasound or MRI can provide the same information without ionizing radiation. Give careful consideration to the frequency of follow-up examinations, especially if the information obtained will not change the way you are treated.
The benefits of properly performed and clinically justified CT examinations should always outweigh the risks for an individual patient. Physicians and patients should work together to determine that the benefit of a given test is greater than the risk.
I encourage my colleagues not to hesitate to order a study that will significantly impact patient care. I also encourage patients not refuse an indicated study because of excessive fear of the consequences of radiation.