Erik,
I don’t know if the hole can be cut without compromising the slab’s structural integrity, but I doubt they “x-rayed” the slab. Last time I knew, X-Rays required a source on one side and film on the other. I doubt they put one under the slab. There are certainly other ways of determining tendon locations, but I get nervous when someone is imprecise.
Jim Getaz
Winchester, Va.