Hitachi Medical Corporation

Hitachi, Ltd.

Kouichi Koike

Hisatake Yokouchi

Yoichi Onodera

Masayuki Tsuneoka

Minoru Yoshida

Hiroyuki Takeuchi

Hiromichi Yamada

Tadaaki Hirai

Yukio Takasaki

Fumio Kawaguchi

Keiji Umetani

Isao Horiba

Hiroshi Takagi

Atsushi Suzuki

Manabu Nakagawa

Shigenobu Yanaka

Yasuo Kuwabara

Takakazu Funo

Takakazu Huno

An X-ray television apparatus applies an X-ray to an object to be inspected, converts the X-ray projection image of the object into an optical image by a fluorescent screen or an X-ray image intensifier, picks up the optical image by a TV camera, displays the video signal obtained by a TV monitor for fluoroscopic monitoring, and records radiograph of the object by using the video signal. Avalanche multiplication is caused on the photoconductive layer of the image pick-up tube of the TV camera so as to enable monitoring or imaging with high sensitivity at a low X-ray dose rate.

X-ray television apparatus

In an image input device, in which an image is photographed by a television camera using a plurality of operational modes having numbers of scanning lines different from each other, a video signal thus obtained is subjected to an analogue to digital conversion and a digital image signal is stored, one of a plurality of sampling clocks obtained by dividing a main clock is selected; the analogue to digital conversion is effected by using the sampling clock thus selected; and at the same time synchronization signals of the horizontal and the vertical scannings of the television camera are formed by counting the selected sampling clock.

Image input device

In an X-ray tomograph having an X-ray source and a multi-channel detector rotatable around a body under examination, circuitry for compensating for changes in the characteristics of the X-ray source or the channels of the detector by extracting from the X-ray transmission data at least one sensitivity correction component and using this component to correct the transmission data and thus effect the desired compensation.

System for computing correction factors for sensitivity differences in

A multielement radiation detector in which many elements are arranged in array. Each element includes a scintillator which is tilted with respect to the incident direction of radiant rays, and a silicon photodiode which is opposed to the plane of incidence of the scintillator. The light-receiving plane of the silicon photodiode is tilted to meet the inclination of the scintillator. Therefore, the gradient of detection sensitivity distribution is reduced in the thickness direction of the detectors.

Multielement radiation detector

In the X-ray CT system, the X-ray detectors vary in output characteristics such as linearity, directivity and radiation quality from one detector to another. To make compensations for such irregularities, a plurality of phantoms of different absorption is prepared in the CT system according to the present invention. Namely, this plurality of phantoms is set one by one in the measuring space in the same manner as in the examination of an examinee or subject to be examined; the coefficient of X-ray absorption is determined for each of these phantoms. Further, theoretical values of absorption for each phantom are compared to the actual absorption measurements on each phantom to provide an absorption error value for each detector at differing absorption levels. The actual subject absorption value for each detector is used to pick the two error values closest to the actual value. The two error values are interpolated or extrapolated to find an error value for correcting the actual absorption value. The above method steps are advantageously implemented by one or more digital computers. The corrected subject absorption values are provided to a conventional image reconstruction device to provide the desired X-ray video image.

Method and apparatus for examining a subject

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Kashiwa, Japan

Kouichi Koike