I cant speak for radiation, my case was RRP surgery 3 months ago, and I
suspect these are different situations.  I cant describe dilation very well,
but it involves the urologist inserting a metal tool up the penis to stretch
the urethra larger.  I think it is done for more reasons than just RRP
surgery, but after prostate surgery, scar tissue can form where the urethra
was reattached to the bladder, or some other form of stricture blockage can
develop. After surgery, I had peeing problems, usually a worrisome small slow
stream, sometimes just a dribble and getting worse, and there were three
times I had to go to the doctors office because I was totally unable to pee
at all after trying for a few hours (and this gets urgent). Seemed to be a
complete blockage.  A routine temp catheter procedure fixes that for a few
days, but isnt a cure.  I think dilation is intended to be the cure.

I had two failed attempts at dilation, no doubt stopped due to my hollering
and complaining.  It hurt and bled, my first time big time, but that first
time was a different urologist because my own surgeon wasnt in then, when I
went in totally stopped up.  My impression of that first one was like
inserting barbed wire, lots of very red blood.  I suspect he didnt lubricate
it, at least I wasnt aware of it.  My own doctor is very much more gentle,
and injects some lubrication into me first.

The two successful procedures were much easier, almost more like normal
catheter insertion, except there is a strong pop or snap felt when the
dilation tool is pushed in to enter the small blocked area in there.  I was
still scared stiff, which doesnt help, but the last time was fairly easy and
uneventful, and it worked well and helped a lot, that time with no more
bleeding and no soreness afterwards.  The doctor said he was pleased to have
accomplished fr 26, which is about 1/3 inch diameter, which seems pretty
large to me.

After the dilation, the urethra is a clear path, and peeing a regular strong
stream is accomplished, at least as good as normal old times.  That is a real
pleasure after weeks of problems.  The time before also worked well too, but
it finally slowed some and was repeated at 3 weeks, which was already
scheduled in advance.  The next future one is already scheduled at 4 weeks.
I am much less scared of it now, but nevertheless I hope the stream is still
strong then, so that maybe I can talk him out of it :)

I am not aware of anyone else mentioning this, so I have no idea how often it
is necessary after RRP.  I suspect fairly routinely, at least it seems old
hat to the urologist.

Jimmie,

Don't despair.  You're in the worst part of it now.  But the problem
will very likely clear up by itself.

After seeding the radiation causes the prostate tissue to
swell, closing off the urethra.  When pressure builds up in
the bladder you're able to force a little out, but only enough
to reduce the pressure a little.  So you have to go many times
a day and only urinate a bit each time.

Eventually, two things happen.  The radiation from the seeds
abates (how long that takes depends on which type of seeds
you got), and the prostate tissue adapts to the situation and
the swelling goes down.

It took me about three months for things to get better and
by 6 months or so I was completely back to normal.  While
it was bad I kept a urinal in my car so that on a long trip over
an hour or two I could pull over and pee in the urinal if I had
to.

If you haven't gotten it yet, ask your doctor about Flowmax
or a similar drug.  It helps a lot.

   Alan

Thanks Curtis.  Yes, peeing does become real important. :)   I sure dont envy
your experience, and I'm glad it finally worked out for you.  I knew
additional surgery was sometimes needed, but of course I'm hoping I wont need
that.  

My first two dilation attempts failed and were no fun at all, but the next
two worked, and were bearable (the last one was actually easy except for
the mental). The progress makes my wishful thinking suggest that maybe the
diameter is increasing in there.  They did do a lot of good.  The first good
one did slow in 3 weeks, but it was still better than prior to it.  Next one
was a week ago, and it is still effective so far.  I asked the doctor how
many more dilations would be necessary, and only got a vague "hard to tell"
reply, but he did schedule another at 4 weeks.