Hi,
Just make sure your hospital network is using the latest hardware/software in either case. Even if the recent advances in Photon based radiation make it equal to Proton, I personally still like the concept of fixed beam length by design, it just makes sense. The study referenced did not say yes or no if space-or gel was used with Photon, it was at the discretion of the surgeon. Photon can damage the rectum if no gel is used as the beam passes past the cancer and exits the body. The gel is a very good idea if going with photon based in my humble non medical opinion. Choose wisely……..

Dave 3+4