CoachDad, I am currently receiving IMRT treatment and have had 13 of them. Regarding effectiveness, I have been told that the amount of radiation received is the same as from the old style treatment, but this is vastly improved because the radiation can be directed from any angle, and targeted more specifically. This allows the parotid (salivary) glands to be spared, which means your son will not spend his life with a dry mouth. Side effects will be a very sore mouth. Mine is just beginning, made worse by chemotherapy with cisplatin. I cannot help you about the tumor because I had mine surgically excised. The radiation and chemo are my way of throwing absolutely everything at this horrible stuff. If you son does not yet know about the mask, please let me know, and I will go into detail about that. This is something he needs to know about in advance, or it will come as quite a surprise. Good luck to both of you!
Joanna