Objective. To demonstrate a novel approach of compensating overexposure artifacts in CT scans of the knees without attaching\nany supporting appliances to the patient. C-Arm CT systems offer the opportunity to perform weight-bearing knee scans on\nstanding patients to diagnose diseases like osteoarthritis. However, one serious issue is overexposure of the detector in regions\nclose to the patella, which can not be tackled with common techniques. Methods. A Kinect camera is used to algorithmically\nremove overexposure artifacts close to the knee surface. Overexposed near-surface knee regions are corrected by extrapolating\nthe absorption values from more reliable projection data. To achieve this, we develop a cross-calibration procedure to transform\nsurface points from the Kinect to CT voxel coordinates. Results. Artifacts at both knee phantoms are reduced significantly in\nthe reconstructed data and a major part of the truncated regions is restored. Conclusion. The results emphasize the feasibility of\nthe proposed approach. The accuracy of the cross-calibration procedure can be increased to further improve correction results.\nSignificance. The correction method can be extended to a multi-Kinect setup for use in real-world scenarios. Using depth cameras\ndoes not require prior scans and offers the possibility of a temporally synchronized correction of overexposure artifacts. To achieve\nthis, we develop a cross-calibration procedure to transform surface points from the Kinect to CT voxel coordinates.
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