Patent ID: 8193512
Filing Date: 2012-06-05
Classification: A61N,G21K,H05H

Abstract:
1. An irradiation field forming device configured to form an irradiation field when a specimen is irradiated with a charged particle beam generated by an accelerator, the irradiation field forming device comprising: a range shifter, disposed on a beam axis of the charged particle beam, configured to regulate an irradiation depth of the charged particle beam; at least two converging electromagnets, disposed in a downstream of the range shifter, configured to regulate a beam diameter of the charged particle beam, which is enlarged by the range shifter, to a constant value; two deflection electromagnets disposed downstream of the at least two converging electromagnets, wherein the two deflection electromagnets are configured to form two magnetic fields that are mutually orthogonal and used to deflect a beam orbit in the X-direction and Y-direction, respectively; and a control unit configured to change a plate thickness of the range shifter and to control a power of a direct current applied to the at least two converging electromagnets according to the plate thickness of the range shifter.