October 1, 2010 - “First, do no harm” is a principle taught early in medical training. Making sure benefits outweigh risks is a fundamental tenet in caring for patients. Recently, the concern that diagnostic radiation, namely the amount of radiation which we are receiving with various x-ray tests,
may actually be causing problems.
Every day more than 19,500 computed tomography (CT) scans are performed in the United States, according to a recent Archives of Internal Medicine study. Each scan equals from 30 to 442 chest x-rays.
Before anyone gets too paranoid, please understand that each year we all receive the equivalent of multiple chest x-rays from radiation found within our normal environment. The National Council on Radiation Protection (NCRP) says that the average resident of the U.S. receives radiation from outer space, radioactive materials in the earth, and small amounts of radioactive material in most foods we consume.
It is becoming increasingly evident, however, that large doses of radiation from scans will translate, statistically, into additional cases of cancer. Nearly 70% of non-elderly adults receive at least one scan every three years. Most patients receive low doses of radiation but small minorities receive “high” and “very high” doses due to the type of study or equipment used.
In the same issue of the Archives, a different study noted a 13-fold variation in radiation exposure with the same test performed in different locations. According to the NCH diagnostic radiology department and Jim Bates, Director of the Naples Diagnostic Imaging Center, we have been monitoring and recording our exposures for the past seven years. NCH uses Alliance Medical Physics which carefully monitors and audits our radiation exposures. Their observations indicate that we provide some of the lowest radiation exposures they have seen. So we have been minimizing exposure while still collecting a good image.
Certain tests are particularly alarming: the average dosage of radiation in a CT coronary angiogram, for example, is equivalent to 309 chest x-rays. One in every 270 patients having this study will develop cancer from the diagnostic procedure. Another, parallel study estimated that there will be 15,000 unnecessary deaths annually due to imprudent use of radiology tests.
The effort to avoid unnecessary radiation should be multifaceted. All scans should be done using the least amount of radiation and not all tests need to use radiation. Magnetic resonance imaging (MRI) and ECHO technology do not expose people to radiation. Therefore, whenever possible, these safer procedures should be prescribed.
Equally important in promoting good health is the avoidance of unnecessary tests. Currently, there is an eight-fold variation among states which allow in-office diagnostic testing versus those states which prohibit such tests, according to the Government Accountability Office.
“As scans become more sensitive, incidental findings lead to additional testing (and often more radiation), biopsies, and anxiety” according to the editor of the Archives of Internal Medicine. We are discovering that more is not always better. However, having the right diagnostic test at the right time, after presenting an appropriate medical history, physical examination, and simple blood tests, is the best way to care for oneself. Seeking out the lowest radiation exposure test is also worth pursuing. Ask if there are other ways to image, such as MRI or ECHO. By making your physicians aware of your concerns everyone can participate in avoiding unnecessary radiation exposure.
Everyone—patients and physicians—want to add value by providing the most cost effective plan with the least risk for future side effects. Please do understand, diagnostic radiology has revolutionized modern medicine but nothing is without some side effects.