Radiation Safety

Radiation safety includes a basic understanding of ionizing radiation and its use in diagnostic medicine. Radiation safety may also require formal instruction regarding X-rays and radiation issues. It is important for speech-language pathologists (SLPs) to have an understanding of radiation safety due to the SLP’s role in videofluoroscopic swallowing studies (VFSSs). Please direct your questions regarding specific protocols to the facility radiation safety officer (RSO).

Principles and Knowledge

X-rays are a form of radiant energy that enters matter (e.g., human tissue). Some X-rays are absorbed by and interact with matter partially or completely, whereas others will pass through. Denser tissues (e.g., teeth and bones) absorb more X-rays than softer tissues (e.g., muscles and digestive organs) when X-rays enter the body. Therefore, depending on the location of exposure, the associated risk may be affected (National Institute of Biomedical Imaging and Bioengineering, n.d.).

The majority of the radiation dose received by the SLP or others present (provided that the primary beam is avoided) comes from scattered radiation. Scatter is a group of X-rays that interact with matter and change direction. Radiation is scattered more or less uniformly in all directions as the X-ray beam interacts with the patient’s tissue. These X-rays may lose some of their energy but can still interact with and be absorbed by other tissues (U.S. Food and Drug Administration, 2020).

X-rays cannot be focused but do require collimation (restriction of X-ray beams) and filtration (removal of low-energy X-rays) to narrow the field of exposure. Tightly collimating the X-ray beam to the area of interest reduces the amount of scatter and the volume of tissue exposed, and it improves image quality (Lakhwani et al., 2019).

Considerations for VFSSs

Federal regulations mandate that all fluoroscopic equipment contain a 5-min timer (U.S. Food and Drug Administration, n.d.). Although the timer may sound during a VFSS, it is not an indication that the VFSS must stop. The timer is a reminder to the clinician(s) that 5 min of radiation have elapsed. The clinician takes care to reduce radiation beyond 5 min and ensures that additional swallow attempts beyond this point are well justified. Significant swallowing deficits or decreased clinician experience may lead to an increase in fluoroscopy times (Bonilha, Humphries, et al., 2013). A decreased fluoroscopic pulse rate reduces not only radiation exposure but also the number of available images used for assessment. A decreased pulse rate may influence clinician recommendations and judgment of swallowing impairment and findings during the assessment (Bonilha, Blair, et al., 2013).

SLP Responsibilities

1. Become familiar with the roles and responsibilities of the medical facility, radiologist, radiology technologist, and facility RSO in conducting safe, effective VFSSs for patients and workers, particularly to
• identify the RSO in the facility;
• identify the appropriate personnel who can confirm that the fluoroscopic system meets all federal and state radiation standards;
• confirm, in conjunction with the radiologist, that the fluoroscopic system has collimators to limit the radiated field to only the oropharyngeal region, trachea, and esophagus; and
• discuss the frame rate and/or pulse rate with the radiologist.
2. Identify local agencies/organizations that have regulatory authority concerning ionizing radiation and the recommended radiation dose limits for workers and the general public. Relevant organizations may include
• the Nuclear Regulatory Commission (see, e.g., U.S. Nuclear Regulatory Commission, 1998);
• the state Department of Health Bureau of Radiation Protection;
• the National Council on Radiation Protection and Measurements; and
• the American College of Radiology (see, e.g., American College of Radiology, 2017).
3. Apply knowledge of radiation safety through appropriate selection and referral recommendations for individuals to undergo videofluoroscopic procedures and be aware of duration of radiation exposure to individuals receiving a VFSS and frequency of follow-up studies.
4. Apply knowledge of radiation safety through well-planned, efficient VFSSs that keep radiation exposure as low as reasonably achievable—as recommended by the International Commission on Radiological Protection—while conducting a thorough exam in particular, to
• practice compensatory maneuvers, whenever possible, before using fluoroscopy or during breaks in fluoroscopy;
• position the patient via the guiding beam light before engaging fluoroscopy; and
• use appropriate barium (contrast) viscosity ranges for swallowing.
5. Use appropriate barium quantities.
6. Participate in annual radiation safety programs and radiation exposure monitoring offered by your medical facility and mandated by your state Department of Health’s Bureau of Radiation Protection.
7. Know and practice the fundamentals of dosimetry in the monitoring of radiation exposure, such as the wearing of a film badge (dosimetry badge) on the outside of the lead apron at the neck area. This badge will be reviewed periodically by the RSO. Some facilities may require additional badges to be worn at various locations on the body (e.g., exposure to the hand due to feeding patients).
8. Integrate the cardinal radiation safety factors, as follows (Hayes et al., 2009):
• Time: Whenever possible, reduce the duration of the study and rotate assignments between staff members.
• Distance and location: Remain as far from the patient and radiation equipment as practical; increasing distance is one of the most effective means of reducing exposure. The amount of radiation exposure that you receive is inversely related to your distance from the source. Location relative to the radiation equipment may also influence exposure (i.e., next to, in front of, behind).
• Shielding: During the study, wear protective apparel—such as lead aprons, eye shields, thyroid shields, and lead gloves—to decrease radiation exposure to vulnerable body organs. The amount of exposure decreased by shielding will vary with the energy of the X-ray and the thickness of the shield.
9. Know and practice special considerations and safety precautions given to individuals who are pregnant (radiation patients and workers), as follows:
• If the SLP participating in the VFSS is pregnant, that SLP should declare the pregnancy and contact the facility RSO for personal radiation safety management issues (e.g., dose rates, extra protection, exclusion from conducting studies, any previous exposure history).
• SLPs who are pregnant wear a lead wraparound apron of the highest lead content.
• SLPs who are pregnant may require more frequent dosimetry badge review. An additional dosimetry badge is worn at the waist under the apron.
• The first trimester is the time during which the embryo is most vulnerable to the potential biological effects of radiation. Normal protective measures typically keep the embryo/fetus of a pregnant worker well below dose limit recommendations.

References

American College of Radiology. (2017). ACR-SPR practice parameter for the performance of the modified barium swallow. https://www.acr.org/-/media/ACR/Files/Practice-Parameters/Modified-Ba-Swallow.pdf [PDF]

Bonilha, H. S., Blair, J., Carnes, B., Huda, W., Humphries, K., McGrattan, K., Michel, Y., & Martin-Harris, B. (2013). Preliminary investigation of the effect of pulse rate on judgments of swallowing impairment and treatment recommendations. Dysphagia, 28(4), 528–538. https://doi.org/10.1007/s00455-013-9463-z

Bonilha, H. S., Humphries, K., Blair, J., Hill, E. G., McGrattan, K., Carnes, B., Huda, W., & Martin-Harris, B. (2013). Radiation exposure time during MBSS: Influence of swallowing impairment severity, medical diagnosis, clinician experience, and standardized protocol use. Dysphagia, 28(1), 77–85. https://doi.org/10.1007/s00455-012-9415-z

Hayes, A., Alspaugh, J. M., Bartelt, D., Campion, M. B., Eng, J., Gayler, B. W., Henkel, S. E., Jones, B., Lingaraj, A., Mahesh, M., Rostkowski, M., Smith, C. P., & Haynos, J. (2009). Radiation safety for the speech-language pathologist. Dysphagia, 24(3), 274–279. https://doi.org/10.1007/s00455-008-9201-0

Lakhwani, O. P., Dalal, V., Jindal, M., & Nagala, A. (2019). Radiation protection and standardization. Journal of Clinical Orthopaedics and Trauma, 10(4), 738–743. https://doi.org/10.1016/j.jcot.2018.08.010

National Institute of Biomedical Imaging and Bioengineering. (n.d.). X-rays. https://www.nibib.nih.gov/science-education/science-topics/x-rays

U.S. Food and Drug Administration. (2020, September). Fluoroscopy. https://www.fda.gov/radiation-emitting-products/medical-x-ray-imaging/fluoroscopy

U.S. Nuclear Regulatory Commission. (1998). Dose equivalent to an embryo/fetus. http://www.nrc.gov/reading-rm/doc-collections/cfr/part020/part020-1208.html