Patent ID: 8809815
Filing Date: 2014-08-19
Classification: A61N,G21K

Abstract:
1. A particle-beam energy changing apparatus comprising: a first energy changing unit and a second energy changing unit each having a particle-beam energy attenuator and arranged so that a particle beam passes through the first energy changing unit and the second energy changing unit, to change energy of the passing particle beam by varying thicknesses of the attenuators; and an energy-change substitution control unit which controls the first energy changing unit and the second energy changing unit, wherein a maximum attenuation amount by the first energy changing unit is set smaller than a maximum attenuation amount by the second energy changing unit, and the energy-change substitution control unit is configured to perform a control of changing energy of the particle beam at least by changing an attenuation amount by the first energy changing unit when energy of the particle beam is controlled to change, and a substitution control that substitutes an attenuation amount by the first energy changing unit and an attenuation amount by the second energy changing unit for each other by changing the attenuation amount by the first energy changing unit and the attenuation amount by the second energy changing unit so that a total attenuation amount of the attenuation amount by the first energy changing unit and the attenuation amount by the second energy changing unit remains unchanged when energy of the particle beam after passing through the particle-beam energy changing apparatus is controlled to be constant.