X-ray diagnostic apparatus

U.S. Patent Number: 5388138

Abstract: An X-ray diagnostic apparatus includes: an X-ray tube; an X-ray controller for controlling a dose of X-rays generated by the X-ray tube; an image intensifier for converting X-rays radiated by the X-ray tube and passed through an object to be diagnosed, into an optical image; an optical system through which the optical image is passed; an image forming device for transducing the optical image obtained through the optical system into electric signals, the image forming device being provided with Knee characteristics such that photoelectric transduction characteristics into the electric signals has a point of inflection beyond which gradient thereof is reduced; a memory device for storing the electric signals outputted by the image forming device; an image displaying unit for processing the electric signals of the memory device for display of diagnosis information of the object to be diagnosed; an interest region determining section for determining a region of interest with respect to the diagnosis information displayed on the image display unit; and a luminous energy control section for controlling the dose of the X-rays through the X-ray controller on the basis of pixel values of the image forming device obtained in the determined region of interest, in such a way that values on the photoelectric transduction characteristics are always kept lower than a value at the point of inflection.

Inventors: Fujiwara; Shigemi (Tochigiken, JP)

Assignee: Kabushiki Kaisha Toshiba (Kanagawa, JP)

Application Number: 08/157,278

Issued: 1995-02-07

Expired: 2007-02-07

Classes: 378/108 ; 378/110; 378/112; 378/98.7; 378/98.8

Field of search: 378/98,98.2,98.4,98.7,98.8,108,110,97,109,111,112

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