Three-Dimensional Visualization of Scattered Radiation Sources with a Scintillator-Coupled CMOS Camera in C-Arm-Guided Thoracolumbar Spine Surgery

Surgeons performing thoracolumbar spine surgery under mobile C-arm fluoroscopy receive scattered radiation whose spatial distribution cannot be seen. A visualization system combining a pinhole collimator, a cesium iodide scintillator, a high-sensitivity complementary metal-oxide-semiconductor (CMOS) camera and a depth camera was placed at the surgeon’s position, and its images were composed on a three-dimensional point cloud of the operating room. A torso phantom was irradiated once per condition in the lateral (LR) and under-table (AP) projections, without a movable lead-glass plate and with it at two heights. Sources appeared on the beam-entrance surface and the operating table. At the pinhole, 140 cm above the floor, the dose rate without the plate was 29.7 mSv/h (LR) and 15.6 mSv/h (AP), 9.6 and 5.0 µSv per exposure, a ratio of 1.9; a lower edge at 135 cm gave no measurable reduction, and at 120 cm the dose rate fell by 20% (LR) and 6% (AP). Monte Carlo simulation with a validated model of the same tube head gave a ratio of 1.90 at the measurement position and reproduced the null at 135 cm. Projection choice mattered more than plate position.