Congratulation on completing treatment! When asked if I wanted my mask, I turned them down and just punched it, except my last mask with Proton Therapy I decided to keep it, and hopefully decorate. Well, that was 1.5 years ago, and finally just about finishing making it into Spiderman, and hate it now just as much as I did before
since it wasn't as easy as I thought. It looks good though.
There is an organization, and is how I learned, that make radiation masks into art called, "Courage Unmasked."
http://courageunmasked.org/photo-gallery/Good luck