Jo,
I am sorry to hear about this unexpected turn of events. It seemed that everything was going so well.
I agree with everyone else that this growth sounds unusual, maybe the radiologist is misreading all this? After all he/she is not necessarily familiar with your particular case. Could it be just scar tissue? I would wait to see what the neurosurgeon says.
If you do end up needing follow up and decide to go with radiation, there is the LINAC option right there in Ottawa, which you may want to investigate. I have never heard about proton being available in Canada.
And the Gamma Knife Centre in Toronto has excellent expertise, with doctors trained elsewhere at more experienced centres. They are not the friendliest bunch, but I couldn't have been happier with my results. Travelling is not too bad (I just hopped on the train the previous day and stayed overnight). TWH is located downtown Toronto. They are also pretty good about following up by phone, so that you don't need to travel all the way every time.
There is also GK in Quebec, Sherbrooke (Tatianne had hers there). And a new CK centre in Montreal. I really don't see a reason why you would need to travel to the States, since good facilities do exist here.
I hope though that you won't need any of this, and it is just a misreading from the radiologist. Oh, and all the best for your grandson, hopefully he is recovering nicely.
Marianna