METHOD FOR DETECTING PROSPECTIVE ABNORMAL PATTERNS

A stimulable phosphor sheet, on which a radiation image of an object has been stored, is exposed to stimulating rays, which cause the stimulable phosphor sheet to emit light in proportion to the amount of energy stored thereon during its exposure to radiation. The emitted light is detected by a photoelectric read-out device, and an image signal representing the radiation image is thereby obtained. Threshold value processing is carried out in accordance with the obtained image signal, and a prospective abnormal pattern is thereby detected from the radiation image. A predetermined threshold value, which is used in the threshold value processing for detecting the prospective abnormal pattern, is set to be a small value as the amount of change in the image signal corresponding to the region in the vicinity of the prospective abnormal pattern becomes large.