X4D Overview

X4D tracks 3D objects (bones, implants, etc.) in X-ray images by generating digitally reconstructed radiographs (DRRs) of the objects and matching them to the X-ray images. It requires that the 3D X-ray configuration parameters be defined in the subject file and that the X-ray images be corrected.

To match DRR images to X-ray images, both sets of images are processed first. X-ray images are smoothed with a convolution filter, and then an edge detection algorithm is performed on them. The final processed X-ray image that is used for tracking is the edge detection image times a weighting factor, plus the smoothed intensity image. DRR images are not smoothed, but are input to the edge detection algorithm. The final processed DRR image is the edge detection image time a weighting factor, plus the original DRR image.

X4D has a job batch option, enabling multiple tracking optimizations to be run without user intervention.

Tutorials

Getting Started Tracking Bones

How To: Track Multiple Bones

How To: Optimize Xray/DRR Settings

How To: Calculate Bone Poses from Mocap Data

Image Metrics

The measurement used by the optimization algorithm to compare the X-ray and DRR images during object tracking.