Can’t answer about whether Brachytherapy but bear in mind if you go down the HT/RT route, HT will probably mean you have zero libido, so the desire for sex will be a distant memory for the length of time you are on HT(up to 3 years) and then beyond until you get(if you ever do) your libido back. You’ll also likely suffer some level ED as well, but this seems to vary between men…as with ALL side effects of HT….and RT for that matter.
One things for sure…your sex life WILL never be quite the same, but you can still have fun…and if you experiment you’ll find a way. As Adrian says ‘Laugh or Cry’…..much better to laugh😂
Derek