The mask fitting: they lay you down and fit this special mesh mask to your anatomy, it needs to precisely and tightly match your face. It feels like being restrained with a heavy wet blanket sitting over your face, and you can breathe through a small hole. If you had any claustrophobic tendencies, this is the part that would suck the most. You have to lie perfectly still for half an hour (but there are nice people with you, watching you like Baby Jesus, so try not to be scared). Lying still for half an hour is a skill you're really going to need later.
Daily Treatments: you're slid into a CT-style tube, and yeah if you have claustrophobic tendencies, it's going to feel like a coffin. If that's your grave concern, ask about valium or other strategies. If you're not particularly claustrophobic you just have to soldier through, listen to music, let your mind drift. The mask restrains you but you can still wiggle so you have to try and be as still as possible, it's surgical precision at work (hopefully!). As a head and neck sufferer, I had Mucositis, which is ropey phlegm, kinda like post nasal drip, so lying down was a real trial .. but hey, it's a half hour at a time, just need to soldier through. If there are major mental stresses, seriously ask about valium or other coping strategies.
After: I kept my mask as a souvenier. It looks creepy, but it was key to my cancer survival, so it's a treasure.
