Interactions of Protons with Matter

Within the energy range of importance in proton therapy (from stopping protons to -250 MeV), it is convenient to consider two energy intervals separately (Sjirk Niels Boon, 1998)  

High energy for proton energies between =0.5 and 250 MeV, the atoms in the stopping medium can be excited or ionized. The collision process is well understood, and in principle the stopping power can be calculated theoretically. 

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