I finished my 20 sessions of external beam recently. I am 76. I haven't had any previous surgery on my bowels. Prior to the external beam sessions I had one treatment of HDR, i.e. High Dose rate Brachytherapy. As I understand things, my external beam treatments were not as intense as they would have been if I had not already had the HDR. The HDR had already hit my prostate with a very high dose of radiation. The external beam was intended to add a bit to that as well as hit areas the HDR could not do, like some lymph nodes in my pelvis.

I knew nothing about how external beam treatment rooms operate. I had no idea how long the beam would be on during each session. I had no idea what the particular machine they would be using was capable of.

My understanding was that whatever the machine operators did to position me prior to treatment, by adjusting my position with lasers on my tattoos, and with whatever imaging scan their machine could provide while I was on the table, once they turned the beam on, the assumption was, everything is going to stay the same, and they just blast away.

Things do not necessarily stay the same. Gas and feces can move once the beam is on. If I couldn't hold all the water they want me to drink, I could piss myself right on the table which would also move the prostate. If the beam doesn't hit its intended target, it hits normal tissue. Too much radiated normal tissue leads to side effects - some of which are extremely not desirable.

I worried quite a bit about all this.

Prior to this treatment I was producing a lot of gas, and it seemed my rectum would always have something in it or something moving into it, which produced a number of small bowel movements during a typical day.

I experimented at home with drinking the amount of water I would be required to drink prior to each treatment and found I could not hold it for the length of time they were going to ask me to hold it. Great.

I consulted a dietitian and read whatever I could find that the cancer center I was to be treated at had published on how to prepare for external beam treatment. Basically the contradictions in the material and between the dietitian's advice and the material, plus the results of whatever I tried given my own unique situation, left me quite doubtful and confused. Don't change your diet. Change your diet. Get rid of insoluble fiber. Don't go low fiber. Don't eat [insert a favorite food here]. Eat [insert previously said to be verboten food here]. Etc.

I made it through the 20 sessions. The RO said things went well. My decision to be treated at this center, with this doctor supervising, was based on the respect I had developed by meeting and discussing things with him. All the other considerations, like should I have gone to one of the more distant centers where they had an MRI-Linac had faded away.

What would have helped me prepare for these treatments was to know more about what machine they would be using, and how they would be using it.

This center had an Ethos Hypersight. It has a cone beam CT that gives operators a high quality image they use to make sure they have things set up to hit the right target, just before they turn the beam on. A feature that made my treatments more bearable, and in my mind more likely to be successful, was the fact the machine could change the direction its radiation hits the patient from very quickly. Treatments can be short.

The plan when treating me was to blast away for about 3 minutes each session. Once I saw this, a lot of my worries disappeared. Their assumption that things could stay the same looked a lot more reasonable.