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. Author manuscript; available in PMC: 2016 Apr 21.
Published in final edited form as: Phys Med Biol. 2015 Mar 24;60(8):R155–R209. doi: 10.1088/0031-9155/60/8/R155

Figure 18.

Figure 18

Absorbed dose D as a function of depth z in water from various spread out Bragg peaks (SOBP) from the Northeast Proton Therapy Center (NPTC) nozzle. Open- beam central-axis depth-dose curves are plotted for each of the eight range modulator wheel tracks. The experimental values (open circles) are from charge measurements with an air-filled ionization chamber, and the model fits are shown with solid lines. Each range modulation track was designed to work over an interval of proton energies. The flat modulated-peak region was achieved by modulating the proton-beam current synchronously with the modulator wheel rotation.