Proton vs. Photon accelerator

Ayal, a radiology fellow, came to talk to us and introduce the MGH radiology team. They recommend that Orion have his radiation treatment here because they have a proton machine ($155 million; one of about 8 in the country) rather than "just" a photon machine. The advantage is that photons go through the tumor and out the other side. Protons stop at the tumor and so protect more parts of the body from radiation. That's good.
He also told us that Orion will be treated by the pediatric radiology team since he's on the cusp age-wise and they have more experience with this kind of tumor.