Table 2.

Differences between proton and photon radiation.

Photon	Proton
Uses ionising photon (X-rays)	Uses positive charged particle (hydrogen)
Produced with a linear accelerator	Produced with accelerators known as cyclotrons and synchrotrons
The beam loses energy but does not stop, so a dose is delivered behind the target	The beam stops at a specific depth based on the energy, so there is no exit dose
The machine can be housed in a standard hospital building	The machine has to be placed in a specifically designed self-contained building