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. Author manuscript; available in PMC: 2019 Jan 11.
Published in final edited form as: Phys Med Biol. 2018 Jan 11;63(2):025018. doi: 10.1088/1361-6560/aa9d16

Figure 4.

Figure 4

A sagittal slice through the prostate CT is shown (left) with the simulation volume boundary. The BP depth of the five simulated proton beams is shown (dots) along with the outline of the digitally-inserted transrectal probe volume. At center, the simulation volume is shown with dose deposition and detector points for the five separately simulated proton dose depositions. Beams #1,2,4,5 have the same energy (125.6 MeV), but different sup-inf propagation axes. Beam #3 has a higher energy (136.3 MeV), but the same propagtion axis as beam #4. At right, a transverse slice shows the beam #4 dose deposition. The triangulation process is illustrated for beam #4 (δ proton pulse excitation). Converting the arrival time to distance specifies a sphere. After setting the x and z beam coordinates based on the known beam axis position, the penetration depth can be calculated (restricted triangulation). The actual BP and protoacoustically-triangulated positions are indicated with a white dot and blue asterisk, respectively.