Hello Roy and welcome to the newsgroup.

Radiation therapy protocols are pretty standard throughout (most of) the
world, yet individualized per person/per situation.  I can see by your ISP
(internet service provider) where you live. Know that he's getting the
best there is and the correct protocol.

If he said he may not be around much longer after the brain scan, that
means the radiation therapy has not succeeded in stopping the cancer and
it's probably in his brain or is expected to be soon.  They can do only so
much before affecting important parts of the brain and functioning and/or
the nerve that controls the eyes. So from here on in, it's about quality
of life.

Radiation therapy can sometimes cause increasing fatigue after each of his
treatments, so once he seems recovered, be there as a friend.  Visit old
haunts or activities that you've enjoyed together through the years. Or if
his son knows of things his father's always wanted to do, help him to do
them. Help him to live one day at a time, without making a pest of
yourselves. Pick activities where there's lots of people and pick quieter
ones too.  During the quieter ones, he could, at some point, open up to
one of you, when he's ready and the time and situation seems right to
him.   He may need some time to himself also to come to terms with his
disease and prognosis.

His son may want to somehow ensure that his father has got his affairs in
order. Will, power of attorney of care, arrangements for palliative care,
choices about where he wants to die (at home or in hospice).  If he's in
Canada, he'll need to make arrangements early (I would think) for "in
hospice" care (due to possible lack of space), if there'll not be someone
available, at that point, 24/7 at home.  And especially if he's not near a
major hospice centre.

"We can choose to wait for death, or we can choose to live until we die.
Try to keep in mind that survival statistics are just numbers. They are no
guarantee that you will die at a certain time. In fact, the numbers that
should mean the most to you — and perhaps to all of us at any time of life
— are those that measure the good days, the comfortable nights, and the
hours of happiness and joy, however you find them.
I took the above from http://www.cancer.gov/cancerinfo/advancedcancer

He may have already been given something similar from the cancer centre.
If not, then hang onto it, or try to get one, or print it up.  Whatever
you do, do read through the above, to give you an idea about what he may
be thinking and feeling. I'm sure it will help you and the son to know the
right things to do for your friend in the last stage of his life.

If you find out more information or we can be of any more help, do let us
know.
Best,
J