I completed 25 Proton Therapy treatments, 50Gy, in January. Compared to IMRT, it was easier, entry point may he higher than IMRT, and beams stay in the tumor, so there is no exit wounds like loss if hair in the nape of the neck, but it takes takes longer to set up, position. For the two locations in the cervical neck it took 30-45 minutes vs 17 zaps with IMRT in 17 minutes, but you don't hear anything with PT like IMRT, and the proton beams itself takes a minute. I went to ProCure in NJ that has 4 machines, 2 flat beam, incline beam, and the large Gantry, but only one machine can be use the proton beams at a time from the cycletron. I believe MDAnderson has IMPT, Intenisty Modulated Proton Therapy, aka Pencil Beam, which is even more direct than other PT, with no need to change positions, brass snubs. Mine had to be changed twice, as well as the table position, although it's robotic.

I made a post with Proton Therapy in the currently treatment section that has some information, links.

I hope this helps.