[摘要]:In proton therapy, the dose distribution of proton beams in the human body needs to be measured accurately. The distribution of prompt gamma rays emitted from patients during irradiation is strongly associated with the dose distribution of the proton beam. The (three-dimensional) 3D distribution of the prompt gamma rays detected by a single photon emission computed tomography was simulated using a Monte Carlo method. The 3D distribution of the prompt gamma rays was well matched with the dose distribution of the proton beam and was superior to the (two-dimensional) distribution of the prompt gamma rays detected using a conventional gamma camera. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3502612]