This isn't really a question; more like FYI.

I was reading Scantlings (May-June 2004) and saw that at TTRAG x-rays were used to investigate timber structures.

I have been using an ultrasonic probe to detect decay in older timber structures. Works quite well at finding those hidden soft spots and can also be used to grade timbers. Trade name is Sylvatest. We bought it from a company in Switzerland, and if you don't mind reading a little French, you can see it at
http://www.cbs-cbt.com/TECH/index_s.html

David