Jackie-
I know it's not the protocol, why not call where she is supposed to have ct scan and see if they've heard anything from the office? Maybe they have an inside number they could call and ask about helping you schedule for your mom.
I know it sounds crazy to do, you wouldn't believe how many times one office mom was dealing with dropped the ball. You have to be the strongest advocate you can be, and sometimes they don't make it easy for us. When you went to the appt, can you recall the nurses name who was with your mom's doctor? If so, maybe call and ask for her, maybe she can respond to a call.
Good luck.

Donna
CG to Mom, dx 4/25/07 with tongue cancer,T3N0,tx began 7/6/07, 31 tx's of IMRT, 8 cycles of Erbitux. Brachytherapy, surgery, left neck dissection and temp trach placed all on 9/17/07, trach removed 10/17/07. ORN of jaw, late effect of radiation symptoms. **lost my beautiful mother on 5/5/11.