Correct way to use Hausdorff Distance

Question

I am looking for some guidance here. I am trying to compare two x-rays of jaw bones. The x-rays show trabecula bone, which is bone that contains lots of holes. I am hoping to show that trabecular bone patterns, like fingerprints, can be used to identify an individual. I want to use the Hausdorff distance to compare how similar (or different) two x-rays are. I take the x-rays and threshold them to become black/white images, then use an edge detection filter. I wrote a C# program to compute the Hausdorff distance of the two images. Can I identify the points in both images as starting at the origin (0,0) or do they need to be spaced at some distance from each other? Thanks in advance for your help. Jim