For most of the century and a bit more of radiology, it has been possible to claim that radiation exposures have gotten safer for both patients and radiation workers. William Coolidge’s hot cathode x-ray tubes starting in 1913 blocked most of the scattered rays from the original gas tubes and had an adjusted aperture for the part of anatomy to be studied. Some years later, the Geiger counter and other measurement tools allowed the recording of exposures. The first international efforts to define exposures came in the late 1920s and have grown ever since.
When computed tomography (CT) scanners became available in the 1970s, they were regarded immediately as the most dynamic imaging advance since x-ray discovery itself. Their obvious value resulted in the growth of CT studies to 60 million a year in 2006 and increasing every year. CT exams use more radiation than conventional x-ray techniques. A report from the National Council for Radiation Protection and Measurement in 2008 (NCRP 160) contained that estimate and the observation that CT scans, at 17% of diagnostic studies, accounted for 48% of medical exposures. And, in the past three decades, medical exposures had increased to about the same volume as natural background radiation received by all of us.
The NCRP report asserted the increased volume and exposures to patients, but it offered no conclusions about the effects of cumulative population exposures. Twice the average background is not necessarily harmful. But in recent years, a growing number of doctors other than radiologists have performed x-ray imaging exams and few of them have any grasp of radiation protection.
In the same last few years, there has emerged a new concern about reducing patient exposures. One of the more remarkable efforts is known cleverly as “Image Gently,” a slogan adopted by pediatric radiologists and spread from the United States to most parts of the world. A rash of articles asserting that radiation exposures cause cancers has appeared in medical publications other than radiology journals.
All of this has resulted in revived proposals that the patient x-ray doses received in all medical procedures should be captured, recorded, and furnished to each patient, as well as to medical facilities. In earlier years, the NCRP, the American College of Radiology, and most government agencies opposed the need, as well as the potential procedure. It was and still is possible for a radiologic physicist to determine estimated doses in the rare instances where such information is needed for medical, scientific, or legal purposes.
One of the major proponents of current dose recording is the International Atomic Energy Agency. The IAEA’s major focus has been on nuclear sources for atomic weapons and electric power sources. In the past decade, it has gotten active in medical radiation functions, producing basic instructions for medical uses. And now, the IAEA is proposing a requirement for checking patient doses and recording each one for each patient on an electronic “smart card,” which would be given to every patient to carry around and proffer with updating for every future x-ray imaging study.
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