Besides asking about type of machinery used(there are many) and type of ray(s) used, delivery areas, exposure rates(dosemetrics), sessions in total, overall maximum exposure that could be safe (there are limits), his experience in years or numbers of patients, perhaps a patient you can talk to of his. Its up to you maybe ask questions that may reveal how truthful is this doc (frankness, openess): 'in your clinical experience' how effective generally is salvage radiation for patients (25%-50%-80%-???) Do you have a large number of patients whom appear cured, say 7-10 yrs. post salvage treatment???
Not that those answers are black and white, but listen closely to his frankness and words, does this sound like more truth or more of a sales pitch of what I would want to hear a patient??? Then you can weight everything you know and/or heard on PCa and read, etc. Make your decision (not his decision), maybe you can wait still, maybe you can consider hormone therapy now and still do radiation later (if you wish). Maybe do hormone therapy now and wait a couple years to see what new stuff if on the horizon, it is coming (slowly) . Maybe this is the best course to try and take at this juncture, it is always an overwhelming task for us PCa patients that are at a huge disadvantage when talking to the "experts".
It seems salvage radiation is less than 50%, so if the doc says 75% and higher....question on how he arrived at his percentages. Anyway best to you in what ever you might decide, always choices within PCa scenarios.
Bob (aka-zufus, not dufus or zufas although those are humor-ass and I like some humor, which is badly needed for us patients whom don't see alot of laughs in this jungle)