This paper presents the first design of a mirror based RGBD X-ray imaging system and includes an evaluation study of the depth errors induced by the mirror when used in combination with an infrared pattern-emission RGBD camera. Our evaluation consisted of three experiments. The first demonstrated almost no difference in depth measurements of the camera with and without the use of the mirror. The final two experiments demonstrated that there were no relative and location-specific errors induced by the mirror showing the feasibility of the RGBDX-ray imaging system. Lastly, we showcase the potential of the RGBDX-ray system towards a visualization application in which an X-ray image is fused to the 3D reconstruction of the surgical scene via the RGBD camera, using automatic C-arm pose estimation.

Electromagnetic (EM) tracking is highly relevant for many computer assisted interventions. This is in particular due to the fact that the scientific community has not yet developed a general solution for tracking of flexible instruments within the human body. Electromagnetic tracking solutions are highly attractive for minimally invasive procedures, since they do not require line of sight. However, a major problem with EM tracking solutions is that they do not provide uniform accuracy throughout the tracking volume and the desired, highest accuracy is often only achieved close to the center of tracking volume. In this paper, we present a solution to the tracking problem, by mounting an EM field generator onto a robot arm. Proposing a new tracking paradigm, we take advantage of the electromagnetic tracking to detect the sensor within a specific sub-volume, with known and optimal accuracy. We then use the more accurate and robust robot positioning for obtaining uniform accuracy throughout the tracking volume. Such an EM servoing methodology guarantees optimal and uniform accuracy, by allowing us to always keep the tracked sensor close to the center of the tracking volume. In this paper, both dynamic accuracy and accuracy distribution within the tracking volume are evaluated using optical tracking as ground truth. In repeated evaluations, the proposed method was able to reduce the overall error from 6.64±7.86 mm to a significantly improved accuracy of 3.83±6.43 mm. In addition, the combined system provides a larger tracking volume, which is only limited by the reach of the robot and not the much smaller tracking volume defined by the magnetic field generator.