You didn't say what part of your body is being scanned, but sometimes they can leave your head poking out... Or even just the top of your head. I always keep my eyes closed to help me stop thinking about being in a tube. In some places they will play music, which is a good distraction. You might been be able to take your own music for them to play, or a relaxation CD, if that is something that helps you. You should be able to take an oral sedative at a high enough dose to help with your claustrophobia (provided you don't have to drive/work afterwards of course. Wishing you all the very best with it