Saving Sampson

I rescued Sampson from the dog pound 5 years ago, or  actually he rescued me.  He has been my first male dog and he is amazing.  He had a cyst on his leg that was surgically removed a few weeks ago.  Sadly it came back as Cancer.  It is stage one and the slow growing kind.  After speaking with my Vet she felt encouraged that radiation would help cure him.  He is only five years old.  He is an amazing dog.    He loves to play ball, go on car rides, go to the dog park and meet new people.  He is a strong alpha male and is my protector.  I want to do the radiation treatment, but sadly I cant afford the enormous cost.   He is my heart and I would appreciate any help at all.