Patent ID: 8571178

Claim:
A radiation imaging apparatus comprising: a radiation source for performing multiple radiation emissions to a subject; a filter having at least one filter area for changing energy distribution of radiation in at least one of the multiple radiation emissions, the filter periodically shifting between an inserted state in which the at least one filter area is inserted in a path of radiation and a retracted state in which the at least one filter area is retracted from the path; a cycle determining section for determining a shift cycle of the filter for shifting the at least one filter area between the inserted state and the retracted state before a start of the first radiation emission based on subject information; a driver for driving the filter to shift at the determined shift cycle, the driver driving the filter to start shifting before a start of the first radiation emission and to shift until an end of the last radiation emission after the first radiation emission; and an emission controller for outputting a signal for starting a radiation emission to the radiation source to control emission timing of radiation, wherein the subject information includes cardiac cycle information and respiration information of the subject, and the radiation imaging apparatus further includes a signal detector for detecting a cardiac signal indicating a state of the cardiac cycle information and a respiratory signal indicating a state of the respiration information, and wherein the cycle determining section determines the shift cycle so as to be in synchronization with the cardiac cycle information, and the emission controller synchronizes the emission timing with a phase of the respiration based on the respiratory signal.