Patent ID: 8586948

Claim:
A particle beam irradiation apparatus in which an incident particle beam is scanned so as to irradiate the particle beam on a target comprising: a particle beam shielding member configured to shield a part of a scanned particle beam; a prompt signal detector configured to detect a prompt signal, said prompt signal being generated when the scanned particle beam collides with the shielding member; and a signal comparison device configured to (1) predict a pattern of generation of a prompt signal having been generated by a pre-determined scanning pattern and (2) obtain the predicted pattern to store thereof as a signal time pattern for comparison, wherein the signal comparison device compares the detected signal time pattern, which is the time pattern of the signal detected by the prompt signal detector when the particle beam is scanned according to the pre-determined scanning pattern and the particle beam is irradiated upon a target, to the stored predicted signal time pattern for comparison, so as to detect an anomaly of the particle beam scanning or that of the particle beam shielding member.