ARRS 2022 Abstracts

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1669. Comparing Intraoperative X-ray Imaging Systems in a Hybrid Operating Room: Investigations to Minimize Occupational Radiation Exposure
Authors * Denotes Presenting Author
  1. Paulina Cewe *; Karolinska Institute; Karolinska University Hospital
  2. Robert Vorbau; Karolinska University Hospital
  3. Artur Omar; Karolinska Institute; Karolinska University Hospital
  4. Adrian Elmi-Terander; Karolinska Institute; Karolinska University Hospital
  5. Erik Edström; Karolinska Institute; Karolinska University Hospital
Objective:
This study aims to reduce occupational radiation exposure in a hybrid operating room (OR) used for 3D image guided spine procedures. We hypothesized that the radiation environment in a hybrid operating room (OR) for 3D image-guided spine procedures varies depending on different imaging systems, staff position, and use of radiation protection shields (RPS). The effects of staff-positioning, different x-ray imaging systems and free-standing RPS are considered.

Materials and Methods:
The study was conducted in a 120 m2 hybrid OR with a ceiling height of 320 cm. Centered and fixed to the floor was a surgical table (Alphamaquet 1150, Maquet AG). An anthropomorphic whole-body phantom was positioned on the surgical OR table, representing a patient undergoing a spine procedure (PBU-60, Kyoto Kagaku). The phantom contains a synthetic skeleton embedded in a soft tissue substitute. In all measurements, the phantom was positioned on the surgical table in the supine position and examined at thoracic and lumbar spine levels, Th11- L4. Three commercially available devices were compared: the Allura Clarity image-guided therapy system (Philips Healthcare) the O-arm O2 image-guided CBCT (Medtronic) and the Veradius Unity Mobile C-arm (Philips Healthcare). The resulting scatter doses were measured at different positions in the hybrid OR using active personal dosimeters and an ionization chamber. Two types of RPS were evaluated, and the scattered radiation was investigated to evaluate the effectiveness of commonly used radiation protection equipment in the hybrid OR. The measurements were performed with the ionization chamber due to its high sensitivity to low fluence x-ray fields and its wide energy response, making it suitable for measuring the dose behind an RPS. Each RPS was positioned at different distances from the device isocenter (150-500 cm). In addition, the ionization chamber was positioned at different distances behind each RPS (30-240 cm).

Results:
Using the hCBCT system instead of the oCBCT system reduced the occupational radiation dose on average by 22%. At 200 cm from the phantom, the scatter doses from the hCBCT were 27% lower compared to the oCBCT. One rotational acquisition with hCBCT or oCBCT corresponded to 12 or 16 minutes of fluoroscopy with the C-arm, respectively. The scatter dose decreased by more than 90% behind an RPS; however, the protection was slightly less effective at 60 cm behind the RPS, due to tertiary scatter from the surroundings.

Conclusion:
For 3D image-guided spine procedures in the hybrid OR, occupational radiation exposure is lowered by using hCBCT rather than oCBCT. Radiation exposure can also be decreased by optimal staff positioning in the OR, considering distance to the source, and positioning relative to the walls, ceiling, and RPS. During intra-operative CBCT-imaging, staff can use RPS instead of heavy aprons to achieve effective whole-body dose reduction with improved comfort.