Abstract: A rotational drive sensor 31 which allows a radiation source 10 and a twomensional sensor 20 which are caused to be in one body to turn round a subject 50. An X-ray vessel 13 irradiates X-rays to the subject 50 in a pulsated manner. An X-ray/light conversion element 21 converts an X-ray transmitted image to an optical image. A CCD camera 23 picks up this optical image. An information processing unit 40 reconstructs a three-dimensional pictorial image on the basis of two dimensional pictorial images in plural directions obtained, and a display monitor 46 displays this three-dimensional pictorial image. A controller 39 controls the distance between the X-ray vessel 13 and the X-ray/light conversion element 21 and the focal size of the X-ray vessel 13 on the basis of the size of the subject 50.

Abstract: A plurality of input signals are applied to input terminals of first and second priority encoders according to the order of priority in ascending and descending orders, respectively. The encoded output signals of the first and second priority encoders are exclusive-ORed for each corresponding pair of significant bits. A single event detection is executed only if exclusive OR is effected for all the corresponding pairs of significant bits.