Published October 9, 2020
Rebecca M. Marsh
Associate Professor & Medical Physicist
University of Colorado School of Medicine
Associate Professor, Department of Radiology
University of Colorado School of Medicine
In mid-2018, we wrote and submitted a manuscript, “Patient Shielding in Diagnostic Imaging: Discontinuing a Legacy Practice,” to AJR. In it, we discussed the practice of shielding patients during medical imaging exams within the context of current technology and scientific knowledge. We proposed that the benefits to patients are negligible, while the associated risks can be substantial, and that the “legacy” practice should be abandoned. Our article was accepted by AJR and set aside for the April issue that would have a special focus on medical physics.
We were certainly not the first to question the continued use of patient gonadal shielding, but its print publication ended up coinciding with two other pertinent announcements. On April 1, 2019, the Food and Drug Administration announced a proposal to remove the portions of the Code of Federal Regulations that recommended the use of gonadal shielding. The next day, following the spring meeting of their board of directors, the American Association of Physicists in Medicine (AAPM) released a position statement that outlined the scientific justification for removing patient gonadal and fetal shielding from routine clinical use. This confluence of events firmly established April 2019 as the unofficial “Month of Patient Shielding” and revealed that the time had come for the imaging community to fully address this topic.
What followed has been an animated debate about the role of patient gonadal and fetal shielding. We had written our article to advocate for science-based clinical practice but were unprepared for what the surrounding discussion would reveal—a broad spectrum in perceived effectiveness of patient shielding and awareness and interpretation of available scientific evidence. We will highlight some of this by looking at the response to the “Month of Patient Shielding” and provide some thoughts about a path forward.
Several professional organizations have joined efforts to reconsider patient shielding practices through their endorsement of the AAPM position statement. These include American organizations such as the American College of Radiology (ACR), Health Physics Society, Image Gently Alliance and international organizations both near and far. In March 2020, the British Institute of Radiology (BIR) released an extensive guidance document that, like the AAPM position statement, states that current radiography technology and scientific evidence supports the removal of patient gonadal and fetal shielding from all radiograph-based imaging, including fluoroscopy, computed tomography (CT), and mammography. Notably, the BIR document expands this stance to include dental radiography.
Responses from state regulatory bodies have been mixed—some have removed the patient shielding requirements from their regulations (Oregon), while others have doubled down on their gonadal shielding requirements (Ohio). In some states, regulatory changes are in progress. For example, in California, the Radiologic Technology Certification Committee has voted to remove the section of state regulations that had previously required gonadal shielding. Other states have decided to delay consideration of changing state regulations until the release of a pending statement from the National Council on Radiation Protection and Measurements.
Conversations have also revealed misconceptions about regulatory and accreditation bodies’ positions on patient shielding. Neither the Joint Commission nor the ACR accreditation programs even mention patient shielding. And although gonadal shielding is often seen as a federal requirement or law (21 CFR), it is not. The section about gonadal shielding that appears in 21 CFR, added in 1976, is a recommendation. While it is not, nor has it ever been, a requirement, the addition in 21 CFR led almost every state to introduce gonadal shielding into their local regulations. Interestingly, the most recent version of the Suggested State Regulations prepared by the Conference of Radiation Control Program Directors in 2015 makes no statement about patient shielding. Further, every state that has (or had) a regulation about gonadal shielding contained language that allowed not shielding a patient, if it could compromise the diagnostic quality of the exam. We posit that this condition is met for every exam where the gonads are within or near the imaging field of view—the presence of patient gonadal shielding greatly increases the risk of degrading image quality.
While many professional organizations and individuals united in efforts to redefine the role of patient shielding, this support was not universal. Some comments brought our professional and personal competence into question. On social media, our article was described as “a fluff article” and “very irresponsible and ill-informed.” We were deemed suitable recipients of the “Idiot of the Year Award,” accused of lacking a basic understanding of science. Importantly, these comments often revealed misconceptions about patient shielding and x-ray physics in general, including the idea that shielding increases patient dose by reflecting x-rays back towards the patient (it doesn’t) or that off-axis radiation contributes substantially to patient dose (also not true). This discussion highlighted differences in definitions of “common knowledge” within and between medical imaging subspecialists, including physicists, radiologic technologists, radiologists, and regulators.
Perhaps most importantly, the responses to our article revealed where we had failed to communicate effectively. Some interpreted the article as an accusation that radiologic technologists are incompetent, despite our intention to point out that even under ideal circumstances, it is nearly impossible for shields to fully cover the gonads (or fetus) without also obscuring adjacent anatomy, increasing x-ray tube output, or negatively affecting image quality. We were highlighting a deficiency in patient shielding policies, not in radiologic technologists’ skill.
Overall, there was substantial concern that if gonadal and fetal shielding were removed from the clinic, patients and parents would be up in arms, fating facilities that made this change to become outcasts of the medical imaging world, disgraced and destitute. Some argued that the perceived safety provided by shielding outweighs any potential negative effects on image quality or dose. While these are legitimate concerns, and they ought to be considered and addressed, we maintain that it is insufficient reason to abandon the overarching goal of advocating for science-driven clinical care. (As an aside, patients’ response to the discontinuation of patient shielding in the facility where we work—first implemented in the fall of 2018—has been remarkably mild.)
Further Research Developments
As mentioned, recognition of the problems associated with patient shielding was not novel. Our paper was based on the work of others, accompanied by a logical discussion of the associated science. However, one criticism that was levied in response to our paper was, “Where’s the science to support this?” We encourage anyone seeking more information to review the reference list included in the initial article. Further, we direct them to more recent articles that address various relevant topics, including measurement of the increase in female gonadal dose when shielding is used in conjunction with automatic exposure control; a review of gonadal doses in radiography and the effect on patient shielding guidelines; and quantification of fetal dose with and without patient shielding. Notably, all of this research reinforces the existing evidence that the benefits of patient gonadal and fetal shielding are negligible, especially when compared with the associated risks.
It has become apparent that while physics can (and in our opinion should) lay the foundation for clinical practice, any real change must address the less tangible aspects of patient care and professionalism. How will patients and parents respond to such a change? How will the imaging community communicate this change with other medical professionals, including referring physicians? What are the regulatory and legal ramifications? What effect will there be on certification exams and educational programs? Does not providing patient shielding conflict with certifying bodies’ codes of ethics?
Luckily, when the position statement was formally released, AAPM had the foresight to form a multi-society committee that would focus on communication and educational efforts across subspecialties, including radiologic technologists, educators, regulators, physicians, and physicists. One of us (RM) was asked to chair this committee, which also has representation from more than a dozen professional organizations. The Communicating Advances in Radiation Education for Shielding (CARES) committee represents the creation of a virtual table where these discussions can take place. To date, this has resulted in a strong social medial presence, inter-society dialogue, and an FAQs document. Further educational materials are under development.
We were not the first, nor will this article be the last, to question whether patient gonadal and fetal shielding improves patient safety. However, developments over the past 18 months leave us confident that there are many people who care deeply about patient safety and are committed to finding a reasonable path forward. We are also hopeful that this multi-society cooperation in addressing a clinical problem is representative of how the medical imaging community can approach similar topics in the future. While we each view the practice of medical imaging through the lens our own subspecialty, patients are best served when our clinical practice is formed from our collective knowledge, skills, and experience.
The opinions expressed in InPractice magazine are those of the author(s); they do not necessarily reflect the viewpoint or position of the editors, reviewers, or publisher.