I've always called my Ts by their first name, even the ones who have their doctorate. It would bother me to have to call any of them Dr. X. It's like putting up a wall. I wouldn't be able to connect on a deep level with someone who elevates themselves by title.

Btw, my Pdoc lets me call her by her first name too! That I find weird. First medical doctor that has allowed that. I still call her doctor