Abstract: A radiation image readout apparatus scans an excitation light in a main scanning direction and a sub scanning direction over a stimulable phosphor sheet, on which radiation energy has been stored, and detects the stimulated emission emitted thereupon; wherein, various types of phosphor sheets can be read out at a high resolution and high sensitivity. The excitation light energy level for obtaining an adequate sensitivity for each type of phosphor sheet is obtained. A controller controls the intensity of the excitation light emitted from the light source and the speed of the scanning mechanism, that is, the readout speed, whereby the excitation light projected onto a phosphor sheet of which the diffusion rate has been controlled by the inclusion therein of an navy blue colorant is of a greater energy level than the excitation light projected onto the white stimulable phosphor sheet not containing the navy blue colorant.

Abstract: A stimulable phosphor sheet stored thereon a radiation image is two-dimensionally scanned by a stimulating light beam by projecting the light beam along a main scanning line extending in a main scanning direction and moving one of the stimulable phosphor sheet and the stimulating light beam in a sub-scanning direction relatively to the other so that the stimulable phosphor sheet is exposed to the stimulating light beam along a plurality of main scanning lines arranged in the sub-scanning direction at a predetermined pitch and stimulated emission emitted from the part of the stimulable phosphor sheet exposed to the stimulating light beam is photoelectrically converted to an electric image signal by a photoelectric convertor. The power of the stimulating light beam is controlled depending on the pitch at which the main scanning lines are arranged in the sub-scanning direction.

Abstract: An integration circuit is DC-coupled with a photomultiplier to convert a current signal output from the photomultiplier, to a voltage signal. The voltage signal converted by the integration circuit is logarithmically compressed with a logarithmic conversion circuit. An offset compensation circuit is provided for reducing an offset voltage that could occur because of charge injection in the integral action of the integration circuit.