Sherry -
Your fear is understandable -- many of us have been there, too, and the prospect of doing radiation IS scary. As Karen says, though, once you've done one treatment, you'll see how it works and will devise your own way of handling the mask and everything. I used to count the number of times the radiation machine moved from one side to the other, to keep myself distracted. After only a few treatments, the mask became bearable; I saw it as my savior, tried to befriend it in a way. After several treatments, it all became a routine that -- believe it or not -- I looked forward to, just because I knew it was zapping away that nasty cancer!
So hang in there, eat what you can now so that you bulk up a bit before beginning treatment, and keep writing for advice and support. We're here for you!