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Editorials |
1 From the Department of Radiology, University of Texas–Houston Medical School, 6431 Fannin St, Houston, TX 77030. Received March 29, 2004; accepted March 30. Address correspondence to the author (e-mail: louis.k.wagner@uth.tmc.edu).
Index terms: Editorials • Radiations, exposure to patients and personnel • Radiations, injurious effects, neoplastic • Radiology and radiologists
In this month’s issue of Radiology, Yoshinaga et al (1) review the world literature on carcinogenic risk in medical radiation workers. This review serves as a long-overdue and very welcome assessment of how we, as a profession, manage our risks of exposure to the ionizing ingredient of what we do. Concisely, here is what they conclude: Medical radiation workers who were exposed during a time when exposures were often very high by today’s standards experienced increases in cancer incidence and cancer mortality when compared with unexposed populations. The cancers most prevalent were leukemia, breast cancer (in women), and skin cancers. Those who worked during a time when substantial protection measures and practices were in place were not measurably at risk.
Yoshinaga et al point out the limitations of their conclusions, perhaps the most important of which is that the follow-up period for workers in the more recently exposed groups has been insufficient to assess the lifetime risks in those workers. There also exists some evidence that skin cancers may have been caused in the later groups presumably because of high cumulative exposure to the hands or other body parts. For example, dentists who held bitewing films in place during radiography clearly had enormous exposures to their hands. Nevertheless, the data clearly show that we made important strides over the years in protecting ourselves.
While the focus of the Yoshinaga et al was to understand the risks of radiation and to enlighten us with information on the dose-response effects for those exposed in the medical profession, we as practitioners must focus on the ramifications of these findings on our practices.
All the detectable risk occurred in those who practiced at a time when radiation protection was either an uncoined term or during a period of our profession’s growing pains. Methods to monitor personal radiation exposure were either not developed or not well used. Standards for exposure were far more lax than in today’s practice. The use of personal protection devices, such as lead aprons, was not always rigorously employed by staff. That some were dying of radiation-induced cancer became an obvious fact. Slowly, over decades, we refined and matured our practices because we were motivated to avoid the same fate. Indeed, it was our predecessors in the medical profession who held the first international conference on what to do about radiation hazards.
The review by Yoshinaga et al informs us that those who learned the lesson did well. Cancer risk was reduced to literally unmeasurable levels in medical populations who lowered their exposure. But, in addition to the limited follow-up for more recently exposed workers, there are other pitfalls that might allow us to interpret these data with overconfidence about our current practices. On the other hand, there are also other challenges that might lead us to believe that we are overprotected for radiation and underprotected for other hazards.
The information provided by Yoshinaga et al, with the assessment of populations of workers, teaches us about our behavior as a group. But the data also clearly indicate that those at serious risk are those for whom exposures are comparatively very high (eg, cumulative doses, 200 mGy). There are many individuals in our profession who receive relatively high cumulative exposures, but they are in the minority and their risks are statistically diluted when they are examined in a study of effects in populations. Perhaps more important, however, our profession has changed from that of the study groups in the review by Yoshinaga et al.
Fluoroscopy has been a well-established modality for about 100 years. But during the time of the review data, its use was primarily confined to short diagnostic examinations. In the past few decades the role of fluoroscopy has greatly expanded, and it has emerged as a primary tool in new types of intermediate and complex interventions. Its use spans multiple disciplines including radiology, cardiology, pulmonology, orthopedics, pain management, and others. Unfortunately, few medical professionals in disciplines outside of radiology are well trained in radiation protection and management. Indeed, many radiologists may have outdated training or may have become complacent and might do well to reassess their skills.
Radiation protection in the interventional environment offers unusual challenges that are sometimes overlooked. For example, hand and leg exposures are often unmonitored for many procedures for which dose accumulation can be very high. None of the populations in the review studies on radiation effects cover this modern era because it is too recent. So, do not allow the results of the review to lure you into that proverbial pit of overconfidence. We have some big challenges ahead for us, and we must work hard to avoid surprises that await us if we let down our guard.
But on the other side of the coin, with these new interventional practices physicians are hanging about 10 lb (4
kg) or more of lead over their bodies while they stand and lean over the patient. The ergonomics of this practice is questionable, and some have suspected that this increases the risk for back problems later in life. So, the question might arise as to whether some of us wear too much lead to protect our torsos from x-rays while we pay too little attention to unshielded body parts. The challenge for the interventional radiology suite is to get the lead, or at least some of it, off our backs and to put it where it will do the most good.
Here is what I think we learn from this review. (a) As a profession we must maintain vigilance and not allow ourselves to be lured into a false sense of security about the need for good radiation management practices. (b) Since we know that high cumulative exposures result in measurable risks, we must identify those practices and populations that fit into this category and do something about them before high doses are allowed to accumulate. (c) We must maintain safe practices by keeping doses well managed for those who are in the low-exposure group, so that their risks never increase.
Here are some questions that might prove useful:
1. In your hospital, how many different specialties use fluoroscopy and are they all trained in radiation management? For example, do fluoroscopists know about and use the various dose-reduction features of your fluoroscopy equipment?
2. How many interventionalists in your facility are careless about monitoring their exposure to radiation?
3. Do your physicians know how best to protect their hands from fluoroscopic radiation?
4. Have you ever checked the exposures to the legs of your fluoroscopists who use C-arm fluoroscopy to see just how high those exposures are?
5. Is your staff trained in the proper use of protective shields, including lead aprons?
6. Is there adequate shielding in the floors and ceilings of your computed tomography (CT) suites or your interventional fluoroscopy suites? Have you checked?
7. Does your facility perform CT fluoroscopy and do you know what the radiation levels are for this type of use?
8. Is your nuclear medicine department adequately designed to protect clerical staff from modern day use of penetrating radiations?
Radiation management requires more than just use of a radiation badge and lead apron. The lessons in the review by Yoshinaga et al are clear—the workers at the greatest risk are those who allow themselves to be chronically exposed at low rates to high cumulative levels of radiation. Properly protecting ourselves while not increasing other long-term risks is our challenge. We must actively make an effort to identify areas at risk in our ever-changing environment of medical radiation use and appropriately design our protection to meet those challenges; otherwise, we run the risk of being unfortunately surprised by our lack of diligence.
ACKNOWLEDGMENTS
Many thanks to Benjamin R. Archer, PhD, Stephen F. Balter, PhD, and Donald L. Miller, MD, for their thoughtful suggestions.
FOOTNOTES
Author stated no financial relationship to disclose.
See also the article by Yoshinaga et al in this issue.
REFERENCES
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