When they shoot dye into the joint,it is called a arthrogram. They hurt like $$$$ and it is a good thing they only wanted to do it on my right tmj because I would have NEVER let them touch the other side. It felt like a hot nail being drilled into my joint. Then once they get inside the joint, they move the needle around to get different picures. I had a discogram on my back and it is pretty much the same horrendous pain.
Tomograms are nothing to worry about.