X-ray fluoroscopic apparatus
First Claim
1. An X-ray fluoroscopic apparatus comprising:
- fluoroscope means for obtaining a fluoroscopic image of an object to be examined by detecting X-rays radiated by an X-ray tube and transmitted through the object;
camera means, having an iris closed to a predetermined setting, for receiving through the iris a fluoroscopic image of the object obtained from X-rays transmitted through the object;
input means for inputting an entrance exposure rate of the X-rays radiated by said X-ray tube; and
exposure rate setting means, connected to said fluoroscope means and said input means, for comparing the entrance exposure rate with a predetermined reference exposure rate, and for applying in said X-ray tube a tube current and a tube voltage which are determined in accordance with the entrance exposure rate input by said input means;
said exposure rate setting means having means for adjusting said iris to a predetermined setting when the input entrance exposure rate is less than the reference exposure rate; and
said exposure rate setting means having means for opening said iris such that the brightness of an image received by said camera means becomes a desired value when the entrance exposure rate input by said input means is greater than the reference rate.
1 Assignment
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Accused Products
Abstract
An F-kV and an F-mA output from tube-voltage adjuster and tube-current adjuster, respectively, are supplied to exposure-rate controller. Controller compares an input entrance exposure rate determined by the F-kV and the F-mA with a preset exposure rate set in view of a patient'"'"'s safety. When the former is equal to or less than the latter, controller supplies the input F-kV and F-mA to X-ray tube. When the former exceeds the latter, controller supplies an F-kV and an F-mA corresponding to the preset exposure rate to X-ray tube and a limit signal to auto-iris controller. X-rays output from X-ray tube are transmitted through patient to form an X-ray image. The X-ray image is converted into an optical image by image intensifier tube. After the light quantity of the optical image is reduced by auto-iris, the optical image is picked up by TV camera. TV camera outputs an image signal to TV monitor and brightness detector. Brightness detector detects the brightness of an image displayed on TV monitor, and outputs it to auto-iris controller. In the normal mode wherein no limit signal is supplied, auto-iris controller closes auto-iris based on the operation method and the input size of the field of view of the image intensifier tube. When a limit signal is input, auto-iris controller opens auto-iris such that an output from brightness detector becomes a predetermined value.
15 Citations
8 Claims
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1. An X-ray fluoroscopic apparatus comprising:
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fluoroscope means for obtaining a fluoroscopic image of an object to be examined by detecting X-rays radiated by an X-ray tube and transmitted through the object; camera means, having an iris closed to a predetermined setting, for receiving through the iris a fluoroscopic image of the object obtained from X-rays transmitted through the object; input means for inputting an entrance exposure rate of the X-rays radiated by said X-ray tube; and exposure rate setting means, connected to said fluoroscope means and said input means, for comparing the entrance exposure rate with a predetermined reference exposure rate, and for applying in said X-ray tube a tube current and a tube voltage which are determined in accordance with the entrance exposure rate input by said input means; said exposure rate setting means having means for adjusting said iris to a predetermined setting when the input entrance exposure rate is less than the reference exposure rate; and said exposure rate setting means having means for opening said iris such that the brightness of an image received by said camera means becomes a desired value when the entrance exposure rate input by said input means is greater than the reference rate. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An X-ray fluoroscopic apparatus comprising:
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means for radiating X-rays onto an object to be examined; an image intensifier tube for converting an image formed by X-rays transmitted through the object into an optical image; means for reducing a diameter of an optical image output from said image intensifier tube by an iris and displaying the reduced optical image; means for detecting a transmitted X-ray quantity from the optical image which is output from said image intensifier tube whose diameter is reduced; determination means for determining an exposure rate of said X-ray radiating means in accordance with a detected transmitted X-ray quantity; means for comparing the determined exposure rate with a reference exposure rate; means for setting a voltage and a current of said X-ray radiating means in accordance with the determined exposure rate when the determined exposure rate is not greater than the reference exposure rate; means for setting a voltage and a current of said X-ray radiating means in accordance with the reference exposure rate and generating a limit signal when the determined exposure rate is greater than the reference exposure rate; and means, in response to the limit signal, for detecting a brightness of a displayed image and for opening said iris such that the detected brightness coincides with a predetermined brightness.
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Specification