Augmented Reality Surgical Navigation in Spine Surgery to Minimize Staff Radiation Exposure

Erik Edström, MD, PhD; Gustav Burström, MD; Artur Omar, PhD; Rami Nachabe, PhD; Michael Söderman, MD, PhD; Oscar Persson, MD; Paul Gerdhem, MD, PhD; Adrian Elmi-Terander, MD, PhD

Disclosures

Spine. 2020;45(1):E45-E53. 

In This Article

Abstract and Introduction

Abstract

Study Design: Prospective observational study.

Objective: To assess staff and patient radiation exposure during augmented reality surgical navigation in spine surgery.

Summary of Background Data: Surgical navigation in combination with intraoperative three-dimensional imaging has been shown to significantly increase the clinical accuracy of pedicle screw placement. Although this technique may increase the total radiation exposure compared with fluoroscopy, the occupational exposure can be minimized, as navigation is radiation free and staff can be positioned behind protective shielding during three-dimensional imaging. The patient radiation exposure during treatment and verification of pedicle screw positions can also be reduced.

Methods: Twenty patients undergoing spine surgery with pedicle screw placement were included in the study. The staff radiation exposure was measured using real-time active personnel dosimeters and was further compared with measurements using a reference dosimeter attached to the C-arm (i.e., a worst-case staff exposure situation). The patient radiation exposures were recorded, and effective doses (ED) were determined.

Results: The average staff exposure per procedure was 0.21 ± 0.06 μSv. The average staff-to-reference dose ratio per procedure was 0.05% and decreased to less than 0.01% after a few procedures had been performed. The average patient ED was 15.8 ± 1.8 mSv which mainly correlated with the number of vertebrae treated and the number of cone-beam computed tomography acquisitions performed. A low-dose protocol used for the final 10 procedures yielded a 32% ED reduction per spinal level treated.

Conclusion: This study demonstrated significantly lower occupational doses compared with values reported in the literature. Real-time active personnel dosimeters contributed to a fast optimization and adoption of protective measures throughout the study. Even though our data include both cone-beam computed tomography for navigation planning and intraoperative screw placement verification, we find low patient radiation exposure levels compared with published data.

Level of Evidence: 3

Introduction

In spine surgery pedicle screw placement and instrumentation is used in a wide spectrum of clinical indications. Screw placement is more challenging in the thoracic spine, due to the smaller pedicle widths, as compared with the lumbar spine.[1,2] In scoliosis cases, where the pedicles are often dysplastic and thinner on the concave side of the deformity, the misplacement rate might be as high as 35%.[3]

In recent years, the use of three-dimensional (3D) imaging, obtained by a C-arm or a computed tomography (CT) system, for spine surgery has rapidly increased. These systems are used for intraoperative pedicle screw planning, placement, assessment, and revision.[4] The use of 3D imaging has, in conjunction with computer-assisted navigation, been shown to significantly reduce the risk of screw misplacement.[5] Although the clinical benefits associated with 3D imaging are substantial, it is important to consider that this technique may potentially subject both patients and operative staff to increased radiation exposure. Although the patient exposure is inevitable and should adhere to the As Low As Reasonably Achievable principle, it is nonetheless justified by higher accuracy and reduced intraoperative risk. Furthermore, it can be considered a "once in a life time" exposure. The staff exposure, on the other hand, cannot be justified. Long-term occupational exposure is associated with a risk of radiation-induced cancer[6] and radiation-induced tissue effects (such as cataract) if certain dose limits are exceeded.[7] The occupational exposure of spine surgeons is of particular concern. Within the orthopedic specialty their exposure levels are second only to that of trauma/limb deformity surgeons.[8]

The hybrid operating room (OR) is a modern concept of surgical theater integrating a motorized C-am with intraoperative 3D imaging capability, well suited for spine surgery.[9–11] The purpose of this study was to quantify the radiation exposure to surgical staff and patients in a hybrid OR when using Augmented Reality Surgical Navigation (ARSN) for pedicle screw placement.

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