@tjnoffy The markers will improve the ability of therapists using photons to detect if your prostate has moved during the treatment. If Proton people use a scanning system during treatment to show them if the prostate has moved that is different than the usual for photon therapy, then they might say not to use them. I don't understand the ambiguity about maybe. I'd leave it up to them. How can they expect a patient to understand what they need for the most accurate aim of their beam?

I just had HDR, i.e. high dose rate brachytherapy. Everyone except the patient leaves the procedure room. The radiation source is sent by a machine into the prostate anywhere their plan says, lingering a very short time in each spot, i.e. seconds, then is moved to the next planned spot, etc., and then is withdrawn, and everyone comes back into the room.

They don't call it a "certain number of seeds" that are later withdrawn. Talk of seeds might be LDR, low dose brachytherapy, but the small radioactive "seeds" are permanently left in place.

HDR side effects tend to peak earlier than LDR. I didn't need a catheter. My LUTS are worse now than prior, but I look forward to slow improvement. I've heard the side effects might persist until patients believe they will never go away, i.e. months, then subside. I can easily live with what is happening right now. I need to get up every 2 hours at night to piss, when before it was twice a night. My stream is weaker than it was. Your mileage may vary. I was working out in the gym 3 days after the procedure.