Radiation imaging system and radiation imaging method

A radiation imaging apparatus comprising:

• a radiation camera including
• a scintillator on which radiation transmitted through an imaging target from a radiation source is incident and which emits fluorescence having a longer wavelength than that of the radiation,
• an imaging optical system which forms an image on an imaging plane through an objective lens of which depth of field is adjusted to a specimen surface set in the scintillator, and
• an image sensor which has a light receiving surface arranged on the imaging plane and including a plurality of pixels;
• and
• a control unit which generates an image based on a sensor signal for each of the plurality of pixels output from the image sensor of the radiation camera, wherein
• the control unit has an exposure time control unit which controls a subframe exposure time of the image sensor such that focused fluorescence at a depth of field generated by radiation reaching the scintillator and out-of-focus fluorescence deviating from the depth of field are discretely imaged on a light receiving surface of the image sensor for each particle of the radiation, a focused signal discrimination unit which discriminates between point image sensor signals of a light receiving pixel group corresponding to spots of the focused fluorescence discretely included in each subframe and point image sensor signals of a light receiving pixel group corresponding to spots of the out-of-focus fluorescence, and an image signal processing unit which generates the image by integrating subframe data based on the point image sensor signals from the light receiving pixel group corresponding to the spots of the focused fluorescence.