ARRS 2022 Abstracts

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1334. Portable Chest Radiographs Through Glass Barriers: A Multi-Institute Investigation
Authors * Denotes Presenting Author
  1. Sarah McKenney; Stanford University
  2. John Wait *; Southern California Permanente Medical Group
  3. Virgil Cooper; Kaiser Permanente Northern California
  4. Amirh Johnson; Kaiser Permanente Northern California
  5. Jia Wang; Stanford University
  6. Ann Leung; Stanford University
  7. Jessica Clements; Southern California Permanente Medical Group
Objective:
To conserve personal protective equipment (PPE) and reduce exposure to patients who are potentially infected COVID-19, several Californian facilities independently implemented a method of acquiring portable chest radiographs through glass barriers that was originally developed by the University of Washington.

Materials and Methods:
This work quantifies the transmission of radiation through a glass barrier using six radiographic systems at five facilities. Patient entrance air kerma (EAK) and effective dose were estimated both with and without the glass barrier. Beam penetrability and resulting exposure index (EI) and deviation index (DI) were measured and used to adjust the tube current-time product (mAs) for glass barriers. Because of beam hardening, the contrast-to-noise ratio (CNR) was measured with image quality phantoms to ensure diagnostic integrity. Finally, scatter surveys were performed to assess staff radiation exposure both inside and outside the exam room.

Results:
The glass barriers attenuated a mean of 61% of the normal x-ray beams. When the mAs was increased to match EI values, there was no discernible degradation of image quality as determined by the CNR. This was corroborated with subjective assessments of image quality by chest radiologists. The glass-hardened beams acted as a filter for low energy x-rays and some facilities observed slight changes in patient effective doses. There was scattering from both the phantoms and the glass barriers within the room.

Conclusion:
Glass barriers require an approximate 2.5-times increase in beam intensity, with all other technique factors held constant. Further refinements are necessary for increased source-to-image distance and beam quality to adequately match EI values. This does not result in a significant increase in the radiation dose delivered to the patient. The use of lead aprons, mobile shields, and increased distance from scattering sources should be employed where practicable to keep staff radiation doses as low as reasonably achievable.