For the practice lifetime of any radiologist reading this essay, it has been axiomatic to say that modern radiology is safe and effective. Modern equipment, when used by qualified people, produces vital diagnostic images with no danger of harmful radiation exposure to patients or to those performing the examination.
Unfortunately, it turns out in recent years that our comfortable assertion is no longer true. Two decades ago, estimates were that diagnostic x-ray procedures accounted for some 15% of the radiation exposure of Americans and that natural background accounted for more than half of the total amount. Current preliminary estimates from the National Council on Radiation Protection and Measurements attribute more than half of all ionizing radiation exposures to medical imaging.
The causes of this are a mixture of the good and bad. Medical imaging is better than ever, thus stimulating the demand for more procedures. These improved procedures provide more significant medical information and, in some instances, provide treatment as well as diagnosis. The shift from old-style x-rays and fluoroscopy to CT scans and more sophisticated nuclear studies have led to a 600% increase in medical radiation exposures in the United States.
The current estimate is that the number of CT scans performed increased from 3 million a year in 1980 to 60 million in 2005. Isotope imaging procedures increased from 7 million in 1980 to 20 million at present. The increase in image-guided therapy (or interventional radiology) has increased greatly the exposure of a smaller group of patients and has subjected some of them to radiation exposures at levels thought to be cancer inductive. Most of us have seen photographs of radiation burns on patients subjected to these procedures.
Other elements pertain. It is precautionary and profitable as well to perform CT scans on any patient presenting to a hospital emergency department. Saturation of the market for CT scanners in hospitals and other facilities operated by radiologists has prompted some manufacturers to peddle their CT scanners to any other physician or other health professional who will ante up the money for a down payment. Referring physicians do not refer if they have their own CT scanners or isotope labs. What does this mean to patient selection for imaging procedures? It is not likely to restrain the number of patients sent down the hall instead of away to the nearest radiologist.
A well-collimated x-ray procedure limited exposure to the area of immediate clinical interest. A spiral CT scanner with 64 or 128 or 256 slices simultaneously exposes most of the whole body. Some interventional procedures may take an hour or more, during which the “other” physician never removes his foot from the pedal. Many of those other physicians have no training in imaging procedures and even less understanding of the need for good radiation hygiene.
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