Author: Jia Wang, Vani Yadav 👨🔬
Affiliation: Stanford University 🌍
Purpose: To evaluate the radiation dose and imaging quality of two novel CBCT X-Ray imaging systems used in spine surgeries.
Methods: CBCT scan of ACR CT and CTDI phantoms was performed to acquire axial images from a commercial CBCT imaging system with radiographic, fluoroscopic and CT imaging capabilities (Loop-X, Brainlab) utilizing a spine protocol (120 kV, 8 mA). Axial images of ACR CT and CIRS body phantoms were acquired with a cone beam tomosynthesis C-arm (nView S1) utilizing clinical abdomen protocol (60 kV, 4 mA). ACR CT, CTDI and CIRS body phantoms were imaged to acquire axial images with Medtronic O-Arm utilizing clinical abdomen protocol (120 kV, 16 mA). CTDIvol were compared for the Loop-X and O-Arm. Point dose measurements at five different locations in CIRS phantoms were compared for nView S1 and O-Arm. Spatial resolution of all three imaging systems was evaluated using the high contrast module of ACR CT phantom.
Results: Volumetric imaging from Loop-X resulted in slightly lower CTDIvol (9.99 mGy) than O-Arm (12.48 mGy) but both systems showed similar spatial resolution (8lp/cm) measured in axial images of ACR CT phantom. Volumetric imaging from nView S1 resulted in greater than 60% reduction in point doses at each phantom location compared to O-Arm but the spatial resolution (7lp/cm) was comparable to images from Loop-X and O-Arm.
Conclusion: Compared to O-Arm and Loop-X, nView S1 offers significant dose reduction due to its unique imaging geometry. However, the images from nView S1 suffer from artifacts (metal artifacts, geometric artifacts) which may not significantly impact surgical guidance. The high contrast spatial resolution was found similar among the three imaging systems.