Semiconductor radiation detector, positron emission tomography apparatus, semiconductor radiation detection apparatus, detector unit and nuclear medicine diagnostic apparatus

Abstract

Each semiconductor radiation detector used for a nuclear medicine diagnostic apparatus (PET apparatus) is constructed with an anode electrode A facing a cathode electrode C sandwiching a CdTe semiconductor member S which generates charge through interaction with γ-rays. Then, a thickness t of the semiconductor member S sandwiched between these mutually facing anode electrode A and cathode electrode C is set to 0.2 to 2 mm. Furthermore, the devices are mounted (laid out) on substrates in such a way that the distance (distance of conductor) between the semiconductor radiation detector and an analog ASIC which processes the signal detected by this detector is shortened. Furthermore, the substrates on which the detectors are mounted are housed in a housing as a unit (detector unit).

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] The present application is related to a U.S. Ser. No. ______ being filed based on Japanese Patent Application No. 2003-342437 filed on Sep. 30, 2003, the entire content of which is incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] The present invention relates to a nuclear medicine diagnostic apparatus, and more particularly, to a positron emission tomography (hereinafter referred to as “PET”) apparatus, which is a kind of a nuclear medicine diagnostic apparatus using a semiconductor radiation detector, semiconductor radiation detection apparatus or detector unit. [0003] A detector using a NaI scintillator is known as a conventional radiation detector for detecting radiation such as γ-rays. With a gamma camera (a kind of nuclear medicine diagnostic apparatus) provided with a NaI scintillator, radiation (γ-rays) incident on the scintillator at an angle restricted by many collimators interacts with NaI crystals and emits...

AI Technical Summary

Benefits of technology

[0011] In order to solve the above described problems, a first embodiment of the present invention improves detection sensitivity by shortening a distance between electrodes for charge collection of a semiconductor radiation detector. That is, the distance between an anode electrode and cathode electrode or the thickness of a semiconductor area sandwiched between the anode electrode and cathode electrode is 0.2 to 2 mm. In this structure, the distance from positions of electrons and holes generated by interaction between the semiconductor material and radiation to the electrodes is shortened, and therefore the time required for them to reach the electrodes is shortened. Furthermore, shortening the distance up to the electrodes reduces the probability that holes may be annihilated midway the distance.

[0012] A second embodiment of the present invention is a nuclear medicine diagnostic apparatus comprising a plurality of unit substrates including a plurality of semiconductor radiation detectors for introducing radiation and an integrated circuit for processing radiation detection signals output from the plurality of semiconductor radiation detectors. This allows the semiconductor radiation detectors and the integrated circuits which process the outputs to be disposed close to one another, with the result that when weak output signals of the semiconductor radiation detectors are transmitted to the integrated circuits, it is possible to reduce influences of noise on the weak output signals.

[0013] The semiconductor radiation detector, analog LSI (Large Scale Integrated Circuit), AD converter and digital LSI are preferably arranged on the unit substrate in that order and the respective elements are connected by wiring so that a signal detected by the semiconductor radiation detector is processed by the analog LSI, the signal processed by the analog LSI is processed by the AD converter, and the signal processed by the AD converter is processed by the digital LSI. By shortening the distance between the semiconductor radiation detector and analog LSI in particular, this structure can shorten the wiring distance between the semiconductor radiation detector and analog LSI and thereby reduce noise superimposed on the wiring until the signal detected by the semiconductor radiation detector reaches the analog LSI. In an embodiment which will be described later, the LSI (integrated circuit) corresponds to an ASIC. Also, the semiconductor radiation detection apparatus corresponds to a combined substrate (detector substrate+ASIC substrate) in the embodiment which will be described later.

Problems solved by technology

Furthermore, shortening the distance up to the electrodes reduces the probability that holes may be annihilated midway the distance.

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