"Patient dose concerns loom larger: need, education, licensure, is our answer" - 3rd of June 2010, R. Maroszek
Diagnostic Imaging, USA
A physician, who at the time was the principal doctor of a major medical clinic, once approached me about radiation dose issues and asked me to compare a chest x-ray to a chest and abdomen CT scan. I was prepared, having dealt with similar concerns expressed by other medical practitioners, and explained briefly how it can vary greatly and how the potential health hazards are weighed against the benefits. It was not the first time I had an inquiry about dose-saving techniques from the medical community or from patients. I started realizing how more and more the general public is being affected by media coverage and how the medical community should be able to react.
I have had numerous discussions with radiologists and technicians on this topic. When considering the health risk of ionizing radiation due to exposure to imaging devices such as x-ray or CT scanners, we need to take multiple factors into account. Age of tissue, patient weight, area of the body being scanned, prior accumulated dose, and distance from the device producing radiation are just a few.
Different sources quote different averages, and different scanners have different specifications, capabilities, and software. There is also the question of admitted radiation vs. absorbed radiation (the biological effect). Altogether, the issue is not as straightforward as some media sources portray it.
Radiation protection bodies and agencies, such as the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) in Australia or appropriate departments of the Environmental Protection Agency (EPA) or Nuclear Regulatory Commission (NRC) in the U.S. (there are actually more agencies involved), have established quality assurance programs and licensing regimens. There is also a general movement to create transparency and patient education, including informational materials in such media as television, newspapers, and the Internet.
Standards vary by nation and, try as they might to comply with other countries’ standards, there is no single golden rule for radiation dosage or radiation protection that exists across all nations. This would be an almost impossible task.
There is the ALARA (as low as reasonable achievable) principle used by the operators of equipment. Additionally, many specialist practices, including radiology centers, form groups and have their own internal quality assurance programs; e.g., the “Image Gently” campaign for pediatric imaging.
There still is room for improvement and standardization of dose-saving techniques and procedures across practices, regions, and nations. Employing highly skilled and trained technicians who have a deep understanding of the latest techniques is definitely one of the key steps to achieving the best care and lowest dose.
If we were to actually compare an x-ray to other modalities, we would come up with inconclusive results that would depend on the source of information and each individual patient’s case. Taking into account the effective (absorbed) radiation dose, a chest x-ray is 0.02 mSv according to the U.S. Food and Drug Administration (FDA), ARPANSA, and the Health Physics Society (HPS). CT abdomen is 8 mSv as measured by the FDA, which is about 400 x-rays, and 10.6 mSv (530 x-rays) as measured by the HPS. According to ARPANSA, a CT scan of the entire body is 10.6 mSv. Some other modalities used or procedures performed can generate radiation doses as high as 40 mSv. All this can be compared with an average annual exposure to radiatio
n in our regular lives of 3.6 mSv, according to HPS.]]>
But ultimately we need to realize that those CT procedures are many times more accurate and appropriate nowadays than the x-ray for precise and effective diagnostic imaging. The early detection made possible by many procedures saves lives, so we need to weigh the enormous advantages against the potential risk of cancer due to radiation.
There is medical research showing that for a man over the age of 30, cancer due to medical imaging radiation would be highly unlikely because he would not live long enough to experience it. For those at the other end of the scale, children, radiation dose-saving techniques should be especially sophisticated.
But as much as there is a need for continuous improvement and training for the radiology staff to learn new dose-saving techniques, as well as a need to use up-to-date equipment with the latest software to assist the technician and minimize exposure times, patients need to put a higher level of trust in the radiology community.
Operators of x-ray machines, CT scanners, and other equipment in Australia are required by law to be highly trained and educated, and they have to renew their license every few years. Patients should also remember that there was a good reason the general practitioner or specialist referred them for a particular imaging procedure: it is a valuable and sometimes life-saving diagnostic tool.
Mr. Maroszek is an executive of Melbourne Specialist Imaging and Director of MGCW, a consulting practice specializing in medical policy advice and ethical marketing. He can be reached at [email protected] Special thanks to Dr. Mark Scott, director of radiology at the Royal Victorian Eye and Ear Hospital and founder of Melbourne Specialist Imaging