Welcome to the forum @Lynnym ... sorry to see you join our select little group!
Feel free to tell us a bit more of your treatment so far - your diagnosis, what surgery you've had ... just for background info ...
Make sure you raise this issue with your Rad Onc - and definitely mention it to the nurses when you go to get 'fitted up' for your treatment. In the past, there has been mention of a 'lead apron' that 'may' be used during radiation to protect specific areas from the rays .... but usually the Rads are aimed much lower than the voice box ....
@Blondy sings with a group ... she may have some insight there ....
take care & all the best