One factor in the dosage is how the radiation is administered.
Dave got IMRT - which is the kind that focusses the xrays most
effectively on the target.

I know that for men with prostates, current thinking is that
72-74 grays is desirable.  However I think those numbers
were derived from data generated before the IMRT era.
If IMRT is, say, 5% more focussed than earlier types of
administration, then 68 grays would equal:

  68 x 1.05 = 71.4 equivalent.

If it's 10% more effective, then we get:

  68 x 1.10 = 74.8 equivalent.

This is pure speculation on my part.  I have no idea whether
IMRT is 5% more effective, whether IMRT is better at all
for salvage radiation, or whether radiation of a man without
a prostate requires fewer rads than for a man with a prostate.
I don't even know if the experts know, or what their theories
are.

I do know however that different ways of administering
radiation do require different dosages.  I got:

   46 grays of 3DCRT external beam
   21 grays of HDR brachytherapy.

The total is only 67 grays - below the current standard
EBRT dose.

However, brachytherapy concentrates all the radiation in the
prostate - within a few millimeters of the seeds.  None
of it is intercepted by the skin or other organs on the way in.
I tried to find out what the equivalent was in external beam
radiation.  I only found one study that compared them and it
seemed to imply that one gray of HDR equalled 2.5 grays of
external beam.  That would make my treatment equal to:

   46 + (2.5 x 21) = 98.5 equivalent

Permanent seeds give even more since the radiation is
administered slowly, but over a very long time.

But the science on all of this appears to be still very much
in progress.  By the time our sons need it, all of this should
be much better understood and methods of administration
should be even more advanced.

   Alan

Hi Bill,

Good luck with your treatment. It really is a breeze.

Alan is right about IMRT. The Doc told me at one point in time that some of
my prostate was getting well above 70+ gy.

I didn't have any long term side effects.

It's kind of fuzzy remembering now.

The simulation was basically taking a bunch of xrays from the IMRT machine
lying down. I believe I did the preparation work on two separate days. One
for xrays and the next when they mark you for positioning.

I remember them putting the catheter in and injected some fluid into it -
the prostate area. That is the worst part of it. It goes by quickly. They
then took numerous xrays from the IMRT machine. .

They then marked me up with a pen and did some light tatoo work of which you
couldn't find on my body now with a magnifying glass now.

They than took more Xrays on the IMRT machine.

They told me to come back in a week.

They then explained that 7 angle IMRT with 68,400 gy would be best for me.

I started on Monday. They took more pictures and then I received my first 7
angle treatment lasting about 10-20 minutes.

After that is was the same thing daily, weekly, monthly. IMRT 7 angles 10-20
minutes per session. Little waiting. Great supportive people.

I exercised, drank alot of water and took some naps. Never really got tired
like they said I would.

If your getting 70gy your right on target. Thats exactly what my Surgeon
wanted me to get.

That's about all I can add. The only tough part was the catheter. The rest
was easy.

Good luck.

Dave P.

The thing that bothered me the most was that they put the catheter back