Camera-augmented mobile C-arm (CAMC) application:: 3D reconstruction using a low-cost mobile C-arm

High-end X-ray C-arm gantries have recently been used for 3D reconstruction. Low-cost mobile C-arms enjoy the advantage of being readily available and are often used as interventional imaging device, but do not guarantee the reproducibility of their motion. The calibration and reconstruction process used for high-end C-arms cannot be applied to them. Camera-Augmented Mobile C-arm (CAMC) is the solution we propose. A CCD camera is attached to the (motorized) mobile C-arm in order to calibrate the C-arm's projection geometry on-line. The relationship between X-ray and camera projection geometry is characterized in an off-line calibration process. We propose the notion of Virtual Detector (VD), which enables us to describe both optical and X-ray geometry as pinhole cameras with fixed intrinsic parameters. We have conducted experiments in order to compare the results of CAMC calibration with the calibration method used for high-end C-arms and using an optical tracking system (Polaris from Northern Digital, Inc.).