“I will do no harm or injustice to them.”1 The phrase is at the heart of the Hippocratic Oath. Whether or not radiologic technologists swear to Greek gods and goddesses, a genuine desire to help others is generally a strong motivating factor in entering the field of medical imaging. That includes taking prudent precautions to safeguard the patient’s wellbeing. Should this include shielding? While it has been part of radiology training and protocol for some four decades, recent thinking indicates that shielding has a negligible benefit and may increase patient risk.
A legacy practice
In the early days of medical imaging, there was naturally concern about the consequences of radiation dose for the patient; primarily increased risk of cancer. We further understood very high radiation exposure to be harmful to sperm and eggs, so the impact of imaging on future generations was also a source of uneasiness. We knew X-rays used lower levels of radiation that were not destructive to reproduction. However, CT diagnostic imaging was just emerging in the mid- to late-1970s. In 1976, patient shielding became part of the U.S. Code of Federal Regulations2 – citing that hereditary issues and gonadal shielding were of concern. It is worth noting that no genetic defects in human offspring have ever been correlated to diagnostic radiation.3
Yet the practice of shielding persists, firmly entrenched in the role of the radiologic technologist. Advanced Health Education Center (AHEC) is a provider of continuing education for healthcare professionals. In a survey4 of their blog readership, published in January 2018, 86% of respondents said, even if the organization they work for changed its policy, they would continue to shield patients. Nine percent indicated they would selectively shield, and one percent would quit their jobs rather than stop shielding.
One reader supported that position by commenting, “I preferred (retired now) to practice ALARA and excellent shielding protocols for all ionizing imaging studies. Most patients do not see or know radiation safety protocols (tight collimation, reduced fluoro time, correct exposure index, number of repeats, proper histogram, etc.), but they do know if you placed shields on them prior to exposure. Shielding helps demonstrate to patients that we pay attention to ALL the details of medical imaging and we care about their safety. I would continue the shielding even if hospital practices change.”4
While another countered with, “As scientists, and medical professionals, we should be guided by science rather than a fear of lawyers trying to use misinformation against us. The bottom line is that the risk to patients created by patient shielding (increased patient dose from any ABC/AEC/ADC system trying to ‘see through’ a lead shield, obscured anatomy, etc.) FAR outweighs any theoretical benefit the shielding may provide to the patient.”4
The argument for not shielding
A lot has changed in medical imaging technology since 1976. Advances in instrumentation, automatic exposure techniques, and image reconstruction have dramatically reduced dose and examination time. The overall shift from conventional radiographs to digital image receptors and processing further reduced the need for shielding.
The real controversy, though, is not whether shielding is beneficial. It revolves around shielding potentially increasing radiation dose, as the above AHEC Online blog commenter indicated.
The American Association of Physicians in Medicine (AAMP) has taken a stance against shielding.5 Their position is based on four primary points, with the last two directly related to increased risk:
- “Radiation doses used in diagnostic imaging are not associated with measurable harm to gonads or fetus.”5
- “Patient shielding is ineffective in reducing internal scatter.”5
- Shielding may compromise the exam, requiring re-takes. Shielding that extends or moves into the field of view can block observation of critical anatomy or pathology. It may also cause artifacts. Dose from repeating the exam may be greater than exposure from not shielding. More importantly, obstruction or image degradation may keep vital information from the scrutiny of the interpreting physician.
- The lead shield may undermine the automatic exposure control of the device. Lead reduces the force and effect of radiation in imaging – precisely why it is used for shielding aprons. When the material enters the field of view of the imaging device, the automated system compensates by significantly upping X-ray output in an attempt to penetrate the shield. The patient receives a higher radiation dose, and image quality is corrupted.
Is informed consent the answer?
Possibly, depending on the policies of the facility. A cursory explanation that shielding has been discontinued is likely to raise questions with the potential to derail appointment scheduling and generate anxiety for the patient.
If a medical facility determines that shielding should be an option for the patient, it becomes the technologist’s responsibility to succinctly explain benefits and risks. It is a dialogue that calls for a measure of scientific fact, balanced with compassion – an understanding that fear of radiation has long been ingrained into the public’s mindset. The few moments that conversation takes, however, could be instrumental in the patient’s diagnosis and outcome.
- Greek Medicine. History of Medicine Division, National Library of Medicine, National Institutes of Health. https://www.nlm.nih.gov/hmd/greek/greek_oath.html June 15, 2019.
- Patient Shielding In Diagnostic Imaging: Discontinuing a Legacy Practice. American Journal of Roentgenology. https://www.ajronline.org/doi/full/10.2214/AJR.18.20508 June 15, 2019.
- Health Risks From Exposure to Low Levels of Ionizing Radiation. National Research Council. https://books.google.com/books?hl=en&lr=&id=H4J3Ns_3lUIC&oi=fnd&pg=PR1&ots=mFFV2wr7NT&sig=CMvGtoLKcbhmAhoV-P7eyi-ki-4#v=onepage&q&f=false June 15, 2019.
- What Would You Do? Stop Shielding Your Patients? AHEConline. https://aheconline.blog/2018/01/15/what-would-you-do-stop-shielding-your-patients/ June 15, 2019.
- AAPM Position Statement on the Use of Patient Gonadal and Fetal Shielding. American Association of Physicists in Medicine. https://www.aapm.org/org/policies/details.asp?id=468&type=PP¤t=true. June 15, 2019.