Apparatus and method for radiation imaging
AssigneeHitachi Medical Corporation
InventorsKeiji Umetani, Ken Ueda, Yoichi Onodera, Hisatake Yokouchi
Life of this patent
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Abstract
An X-ray imaging apparatus is constructed with a combination of an X-ray image intensifier, a relay optical system, and a video camera with avalanche multiplication camera tube. The video camera is controlled by an image acquisition circuit, a synchronizing signal generation circuit, and an applying voltage control circuit. The applying voltage control circuit for controlling the voltage to be applied to the video camera with avalanche multiplication camera tube controls the applying voltage on the basis of image data in an image memory so that the gray scale level of a detected visible image is corrected.
Claims15
A radiation imaging apparatus including means to irradiate radiation to an object to be inspected, means to detect the radiation transmitted through the object to be inspected and convert it to a visible image, and a video camera for detecting said visible image,
- wherein said video camera includes a camera tube having a function for amplifying substantially only a signal representing the gray scale level of a visible image.
A radiation imaging method using a radiation imaging apparatus including means to irradiate radiation to an object to be inspected, means to convert a radiation projection image of the object to be inspected to a visible image, and a video camera which includes a camera tube having a photoelectric conversion layer for converting incident light to electric charges and avalanche-multiplying these electric charges and detects the converted visible image, said method comprising the steps of:
- changing the avalanche multiplication factor by controlling the target voltage of the camera tube to be applied to said photoelectric conversion layer;
- and
- adjusting the output signal level of said video camera by changing the avalanche multiplication factor;
- wherein said target voltage of the camera tube is changed according to a synchronizing signal of the video camera, and the avalanche multiplication factor is changed in correspondence with the electron beam scanning position of the camera tube, and a visible image is detected by converting the gray scale level thereof.
A radiation imaging method using a radiation imaging apparatus including means to irradiate radiation to an object to be inspected, means to convert a radiation projection image of the object to be inspected to a visible image, and a video camera which includes a camera tube having a photoelectric conversion layer for converting incident light to electric charges and avalanche-multiplying these electric charges and detects the converted visible image, said method comprising the steps of:
- changing the avalanche multiplication factor by controlling the target voltage of the camera tube to be applied to said photoelectric conversion layer;
- and
- adjusting the output signal level of said video camera by changing the avalanche multiplication factor;
- wherein said target voltage of the camera tube is changed according to a synchronizing signal of the video camera, and the avalanche multiplication factor is changed in correspondence with the electron beam scanning position of the camera tube, and a visible image is detected by converting the gray scale level thereof;
- and
- wherein said visible image is recorded as an image signal beforehand, and the target voltage of the camera tube of the video camera is determined by applying voltage control signal based on said image signal, and the gray scale level of the visible image is converted.
Dependencies are inferred from the claim text.