I had a bad experience in the MRI, and thought I'd be claustrophobic in the mask. But the staff are great and rads soon becomes routine. Make sure you get them to cut the eyes out. It feels more like a mask and less like a cage. In fact these days I find it quite empowering to see my reflection in the mask. Like a cancer fighting superhero.

Its all about the self talk in the head mate, keep it as positive as you can.