Experimental Evaluation of the Accuracy at the C-Arm Pose Estimation with X-Ray Images

abstract

C-arm X-ray systems need a high spatial accuracy for applications like cone beam computed tomography and 2D/3D overlay. One way to achieve the needed precision is a model-based calibration of the C-arm system. For such a calibration a kinematic and dynamic model of the system is constructed whose parameters are computed by pose measurements of the C-arm. Instead of common measurement systems used for a model-based calibration for robots like laser trackers, we use X-ray images of a calibration phantom to measure the C-arm pose. By the direct use of the imaging system, we overcome registration errors between the measurement device and the C-arm system. The C-arm pose measurement by X-ray imaging, the new measurement technique, has to be evaluated to check if the measurement accuracy is sufficient for the modelbased calibration regarding the two mentioned applications. The scope of this work is a real world evaluation of the C-arm pose measurement accuracy with X-ray images of a calibration phantom using relative phantom movements and a laser tracker as ground truth.