Personally I don't know about Proton therapy but am aware of a place in New Jersey called ProCure - www.procure.com - that specializes in Proton therapy. It's located in Somerset, NJ and also has offices inOklahoma, Seattle and Illinois. If I remember correctly, when I checked it out many months ago, I was not eligible because I had Stereotactic Body Radiation Therapy (SBRT).
A lot of the radiation oncologists that staff the NJ location have done residencies at Memorial Sloan, Mass General and other well known cancer hospitals.
Back in March 2013, I spoke to a surgeon at Memorial Sloan about Proton therapy and he told me it is a step up from radiations such as SBRT - much more precise in targeting the tumors. Memorial Sloan is suppose to be either building or acquiring a building in the NY area, by the hospital, to do Proton therapy. I think 2015 was the date he mentioned to me.