X-ray or gamma ray systems or devices – Electronic circuit – With switching means
Reexamination Certificate
2000-10-11
2002-07-30
Porta, David P. (Department: 2882)
X-ray or gamma ray systems or devices
Electronic circuit
With switching means
C378S138000
Reexamination Certificate
active
06426996
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an X-ray radiographic/fluoroscopic apparatus, X-ray radiographic method and X-ray radiographic/fluoroscopic method, and more particularly to an X-ray radiographic/fluoroscopic apparatus, X-ray radiographic method and X-ray radiographic/fluoroscopic method that can consistently produce X-ray radiographic images with high quality regardless of the magnitude of body thickness or motion of an examined site.
FIG. 1
illustrates the configuration of an example of a conventional X-ray radiographic/fluoroscopic apparatus.
The X-ray radiographic/fluoroscopic apparatus
500
comprises an X-ray tube
51
in which a single fluoroscopic focus size or a single radiographic focus size is set, an irradiation condition determining section
55
for determining fluoroscopic irradiation conditions and radiographic irradiation conditions (such as the tube voltage and tube current of the X-ray tube
51
, exposure dose and radiographic irradiation time), an irradiation control section
57
for controlling the operation of the X-ray tube
51
, an imaging section
8
comprising an image intensifier or TV camera or the like for capturing an X-ray fluoroscopic image or X-ray radiographic image of a subject and outputting a fluoroscopic video signal Vf or radiographic video signal Vs, and a display section
9
for displaying an X-ray fluoroscopic image or X-ray radiographic image based on the fluoroscopic video signal Vf or radiographic video signal Vs.
FIG. 2
is a flow chart illustrating an X-ray radiographic/fluoroscopic process by the X-ray radiographic/fluoroscopic apparatus
500
.
In Step T
1
, a subject is irradiated with X-rays based on predefined fluoroscopic irradiation conditions, and an X-ray fluoroscopic image is produced and displayed. The fluoroscopic focus size is 0.3 mm, for example, and the input power rating of the X-ray tube
51
in this case is on the order of 10 kW (or less), for example.
In Step T
2
, body thickness is calculated based on the X-ray fluoroscopic image to determine radiographic irradiation conditions from the body thickness. The radiographic focus size is 0.6 mm, for example, and the input power rating of the X-ray tube
51
in this case is on the order of 30-40 kW, for example.
In Step T
3
, the subject is irradiated with X-rays using the determined radiographic irradiation conditions, and an X-ray radiographic image is produced and displayed.
Generally, when the X-rays are emitted from the X-ray tube
51
with a large focus size, an umbra and penumbra of the X-rays tend to simultaneously appear on the image plane, and the image resolution is liable to be degraded. Therefore, the focus size is preferably made small for improved resolution.
On the other hand, when the focus size is small, the input power rating of the X-ray tube
51
is reduced, and hence the radiographic irradiation time (imaging time) required for the same exposure dose is prolonged, leading to a problem that the image is subject to blurring in radiographing an examined site having a large body thickness or large motion. Especially when the gastric wall is radiographed with a contrast material such as barium applied, blurring gets worse due to vibration of the X-ray tube
51
or the gastric wall and rundown of the barium from the gastric wall etc.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an X-ray radiographic/fluoroscopic apparatus, X-ray radiographic method and X-ray radiographic/fluoroscopic method that can consistently produce X-ray radiographic images with high quality regardless of the magnitude of the body thickness or motion of an examined site.
In accordance with a first aspect of the present invention, there is provided an X-ray radiographic/fluoroscopic apparatus comprising: X-ray emitting means having a function of emitting X-rays with a focus selected from at least one fluoroscopic focus size and a plurality of radiographic focus sizes; X-ray fluoroscopic image producing means for producing an X-ray fluoroscopic image by irradiating a subject with X-rays with the fluoroscopic focus size selected; radiographic focus size selecting means for selecting a relatively large radiographic focus size in radiographing an examined site having a relatively large body thickness, and selecting a relatively small radiographic focus size in radiographing an examined site having a relatively small body thickness; and X-ray radiographic image producing means for producing an X-ray radiographic image by irradiating the subject with X-rays equivalent to radiographic irradiation conditions determined based on the X-ray fluoroscopic image with the selected radiographic focus size.
In accordance with a second aspect of the present invention, there is provided an X-ray radiographic/fluoroscopic apparatus comprising: X-ray emitting means having a function of emitting X-rays with a focus selected from at least one fluoroscopic focus size and a plurality of radiographic focus sizes; X-ray fluoroscopic image producing means for producing an X-ray fluoroscopic image by irradiating a subject with X-rays with said fluoroscopic focus size selected; radiographic focus size selecting means for selecting a relatively large radiographic focus size in radiographing an examined site having a relatively large motion, and selecting a relatively small radiographic focus size in radiographing an examined site having a relatively small motion; and X-ray radiographic image producing means for producing an X-ray radiographic image by irradiating the subject with X-rays equivalent to radiographic irradiation conditions determined based on said X-ray fluoroscopic image with said selected radiographic focus size.
In accordance with a third aspect of the present invention, there is provided an X-ray radiographic/fluoroscopic apparatus comprising: X-ray emitting means having a function of emitting X-rays with a focus selected from at least one fluoroscopic focus size and a plurality of radiographic focus sizes; examined site input means for receiving an examined site from an operator; radiographic irradiation time threshold defining means for defining a radiographic irradiation time threshold that is an upper limit of a radiographic irradiation time corresponding to said examined site; X-ray fluoroscopic image producing means for producing an X-ray fluoroscopic image by irradiating a subject with X-rays with said fluoroscopic focus size selected; radiographic focus size selecting means for selecting a relatively large radiographic focus size if a radiographic irradiation time determined based on said X-ray fluoroscopic image is longer than said radiographic irradiation time threshold, and selecting a relatively small radiographic focus size if said determined radiographic irradiation time is shorter than said radiographic irradiation time threshold; and X-ray radiographic image producing means for producing an X-ray radiographic image by irradiating the subject with X-rays with said selected radiographic focus size.
In accordance with a fourth aspect of the present invention, there is provided an X-ray radiographic/fluoroscopic apparatus comprising: X-ray emitting means having a function of emitting X-rays with a focus selected from at least one fluoroscopic focus size and a plurality of radiographic focus sizes; X-ray fluoroscopic image producing means for producing an X-ray fluoroscopic image by irradiating a subject with X-rays with said fluoroscopic focus size selected; radiographic irradiation time threshold input means for receiving from an operator a radiographic irradiation time threshold that is an upper limit of a radiographic irradiation time corresponding to an examined site; radiographic focus size selecting means for selecting a relatively large radiographic focus size if a radiographic irradiation time determined based on said X-ray fluoroscopic image is longer than said radiographic irradiation time threshold, and selecting a relatively small radiographic focus size if said determined radiographic irradiation time is shorte
Izuhara Akira
Moribe Yoshio
GE Medical Systems Global Technology Company LLC
Kojima Moonray
Porta David P.
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