Hi,
u can check this one also
www.danb.org and look for RHS(radiation health and safety)
or call 1800 367 3262.they will give u the right info.
they will give u the state dental board numbers..u can call and find out abt texas..
i just gave my dental radiology exam 2 days ago from nj and i passed .its very simple
and easy....iam a dentist from india.hope this will help u.