Hello bwparker. Proton beam therapy as you probably are aware has a very accurate beam and penetration point for clean up work that surgery could not get to without causing damage to surrounding tissue. That being said it is really impossible to know what additional damage may occur to vital areas in your specific case.
You are asking what side effects you might have with a few needles to the throat versus a few baseball bats to the throat? I guess the answer would be that you can expect far fewer side effects than most people experienced.
Exactly where these areas are that will be exposed will determine side effects. Certainly therapy to the vocal cord area will most likely effect speech or the ability there of. You may have issues swallowing, sore throat, pain turning your head, nerve tingling, etc. You will most likely continue feeling worse for a couple weeks after you therapy ends until you finally rebound and begin to heal.
All of us experienced some dismal side effects from radiation therapy but those who have had proton have often had an easier go of it.
You should ask, as your treatment schedule continues, how to deal with any specific issues that crop up. There is a wealth of experience out here willing to help you get through this.
When does your treatment begin?