Hi, Cave -- A little late in responding as I haven't been able to visit the site lately. My husband was claustrophobic also and the idea of the mask frightened him. He is now in his second "round" of radiation and states it is a breeze. He has, however, asked for and has taken valium or a similar drug to help him to relax while using the mask for radiaion. As I have stressed to him many times, the radiologists (and all other caregivers) are there to help you -- if you don't tell them your concerns, they assume you have none -- always, always !! tell them!! You'll be surprised how willing they are to make you as comfortable as possible. My husband was reluctant to tell them how uncomfortable he was in the position they put him in for radiation. He spent 3 days miserable before he broke down and let them know -- they immediately adjusted things to make him comfortable. They (as I) are CAREGIVERS -- take advantage of that for your mental and emotional health during this trying time for you.