Image Comparison for Visual Basic in VS2013

I am making a Computer-Aided Diagnostic Tool for Chest X-ray Diagnostic; I tried researching for techniques to do this and for now the best I've come-up with is by stocking a healthy Chest X-ray in my system's database (image1) then compare it to the Chest X-ray (image2) that the user will input for analysis.

I also researched that you can compare 2 image in VS2013 by comparing pixels 1 by 1 (image1_px1 = image2_px1, image1_px2 = image2_px2... and so on).

Now my question is how to make an image comparison (code) in VS2013 using VB?

I researched that I can use (get.pixel, etc.) and that there is also a much more better way, though, I just don't know what, when and how to begin.

In advance, thank you to everyone for the help.