Preventing damage from pelvic radiation?

Definitely plenty of water. Eat healthy foods within limits specific to radiation treatment. I'm not sure there's anything you can do to prevent damage per se. The radiation keeps working many months after treatment is over. There are nearby organs that may get irritated like the bladder and rectum. Everyone's side effects and long term effects are different. You can help yourself feel comfortable by watching your bowel movements carefully. My issue was diarhea and nausea. I had chemo at the same time too. So I was switching between Immodium and Miralax. My skin turned darker and the radiation was actually pointed along my incision scars so they had a tough time healing. Some women get sun burn so moisturize the night before radiation! I'm already noticing long term effects but it could also be related to surgery and chemo. But some of them are: colitis, weak pelvic floor, tight and achy muscles, scar tissue, adhesions, pubic bone pain, etc. Not terrible but noticable. Good luck. You'll get through it.

You might want to find out exactly what type of external radiation you'll be receiving. I had "external - photon - 3D conformal" which is a very low-dose, targeted type.

As far as advice, I agree with what everyone has already mentioned about drinking enough before each treatment (to move your bladder up and out of the way of the laser) and taking Imodium for diarrhea. You may want to ask about taking probiotics. I took them during radiation and had only very minor digestive side effects. Good luck to you!

I took Culturelle probiotic and I didn't have any problems with diarrhea. If you are radiated high, be sure to take your nausea meds in advance. Have some Pandora stations in mind since they often can play music that you like. I didn't have any problems with my skin. I've got some ongoing bladder problems and had an insufficiency fracture of the sacrum but not sure they could be prevented. Try to stay active and take your calcium and vitamin D supplements. 

I have just read the responses to SandyD's post.  They have really been insightful and I will definitely up my water intake before treatment and start probiotics.   Thanks to all who had responded ! 

I had 28 pelvic radiation sessions and to brachtherapy.  The center I was at had me start out drinking 16 0z. of water in the hour prior to treatment.  They also never did the treatment without first using a machine to check the fullness of my bladder.  Two times the bladder was not full enough and they gave me a bottle of water to drink and I had to wait twenty minutes and then be checked again.  I quickly discovered how much I needed to drink and what timeframe worked best fo my body.  They also inserted a balloon in the rectum before each treatment.  This was said to push intestines up as far as they could out of the radiation field.  I also frank a glass of Beet Kvass(home made fermented beets daily.  This was probably doing what probiotics do.  My daughter had researched and found this drink was a common beverage in places that had radiation leakage from nuclear facilities and that people consuming it had less radiation damage, so I decided it couldn"t hurt to drink.  I still drink a glass to this day.  I was lucky and had very little symptoms during radiation... just some bladder irritation for a couple days after brachytherapy.  I already was cathing from bladder dysfunction after my radical hysterectomy so this may have been from catheter irritation. I am a year and 4 months out from radiation and feeling fortunate to be doing well....occasional bowel issues that I am not sure if related to radiation, or certain foods, but doesn't happen that often. I hope things go well for you.  My center was the Mayo Clinic....they are awesome.