File:Pdd sobp photon.JPG

This graph shows the relative contribution of the (a.) spread out bragg peak (SOBP) for protons and (b.) a photon x-ray.

The SOBP, which is the therapeutic radiation distribution, shows that proton treatments give a higher amount of radiation to the skin when compared with photon treatments. This effect is called "skin sparing".

A vector version of this graph, which does not include the photon curve is uploaded at File:SpreadOutBraggPeak_complete.svg.