Abstract: A radiation ray (gamma ray) radiated from a test subject previously dosed with radioisotope is incident on a scintillator and converted into scintillation light. A plurality of photomultipliers arranged in a hexagon receive and convert the scintillation light into electrical signals. Photomultipliers arranged in parallel with sides of the hexagon constitute a group. Output signals of the photomultipliers are supplied to a first position detector for detecting a group of photomultipliers which receives the scintillation light and deriving position information Xo and Yo representing the approximate gamma ray incident position. The position information Xo and Yo and the output signals of the photomultiplier are supplied to a second position detector for deriving position information x and y representing the precise gamma ray incident position. Outputs of the photomultiplier are supplied to a pulse height analyzer which derives incident radiation energy information z.

Abstract: A data processing device applied to a computed tomography system which examines a living body utilizing radiation of X-rays is disclosed. The X-rays which have penetrated the living body are converted into electric signals in a detecting section. The electric signals are acquired and converted from an analog form into a digital form in a data acquisition section, and then supplied to a matrix data-generating section included in the data processing device. By this matrix data-generating section are generated matrix data which correspond to a plurality of projection data. These matrix data are supplied to a partial sum-producing section. The partial sums respectively corresponding to groups of the matrix data are calculated in this partial sum-producing section and then supplied to an accumulation section. In this accumulation section, the final value corresponding to the total sum of the matrix data is calculated, whereby the calculation for image reconstruction is performed.