Figure 2
From: Towards real-time PGS range monitoring in proton therapy of prostate cancer
Energy spectra obtained from the irradiation of several targets by protons. (a) The targets irradiated with the minimum proton energy exhibit very prominent silicon energy peaks. A sulphur energy peak at 1.28 MeV is also visible. (b) Targets located after two flasks of water were irradiated with an energy of 113.6 MeV. The silicon energy peak at 1.78 MeV exhibits relatively low prominence for all materials and is absent for water. A sodium energy peak at 1.278 MeV is also visible. (c) The effect of the prompt gamma attenuation by the two flasks of water on each side of the target in the path to the detectors is shown for the three targets. (d) The commercial silicone insert and the balloon with the mixture of SiO\(_{2}\) inserted in the prostate phantom present similar spectra under irradiation by proton beams of 121.95 MeV.
