X-ray or gamma ray systems or devices – Beam control – Collimator
Reexamination Certificate
2000-09-26
2003-04-15
Dunn, Drew A. (Department: 2882)
X-ray or gamma ray systems or devices
Beam control
Collimator
C378S098800
Reexamination Certificate
active
06549609
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention is related to an X-ray apparatus for diagnosis of patients.
An X-ray apparatus has an X-ray limiting device, adjusting an X-ray irradiation field, attached to an aperture, for irradiating X-rays, of an X-ray tube. This X-ray limiting device makes it possible to reduce X-ray exposure dose of a person and also to enhance an X-ray image.
In this X-ray apparatus, an X-ray limiting device
4
is attached to an aperture, for irradiating X-rays, of an X-ray tube
3
which is held to a supporting arm
35
, as shown in FIG.
7
. An image intensifier
5
is attached below the table
1
upon which rests a person
2
for examination. The whole structures, including the supporting arm
35
, the image intensifier
5
, and so on, are supported by a supporting base
36
.
As shown in
FIG. 7
, the X-ray limiting device
4
has two stages of blades which consist of lower blades
7
,
8
and upper blades
9
,
10
. The lower blades
7
and
8
limit X-rays in the right and left directions, facing the FIG.
7
. The upper blades
9
and
10
limit X-rays in the front and back directions, facing the FIG.
7
. X-rays generated at an X-ray focal point
3
a
are limited by these blades
7
,
8
,
9
, and
10
to form an X-ray flux
19
and then are irradiated onto the target part of the person
2
.
When imaging the left part of the person
2
, the table
1
is moved in the direction shown as the arrow A until the center of the imaging part of the image intensifier
5
and the center of an X-ray irradiation field reach the target part of the left part, and then imaging of the target part is carried out. When imaging the right part of the person
2
, the table
1
is moved in the direction along the arrow B until the center of the imaging part of the image intensifier
5
and the center of an X-ray irradiation field reach the target part of the left part, and then imaging of the target part is carried out.
The following is a description of a structure of the X-ray limiting device
4
, with reference of FIG.
8
. The lower blades
7
,
8
, formed mainly of laden boards, are disposed in a case
25
and limit X-ray flux
19
to form a necessary and sufficient X-ray irradiation field. The lower blades
7
,
8
are driven in a circular movement by a gear and link structure, or in a parallel movement by wire ropes, pulleys, and shafts disposed in parallel. The former allows for a simple structure. The other one makes it possible to limit an X-ray irradiation field accurately.
The upper blades
9
,
10
and back blades (not illustrated) are also driven, engaging with the lower blades
7
,
8
. A small motor can be used to drive these blades. The upper blades
9
,
10
greatly contribute to reduction of scattered radiation and leakage dose. The back blades efficiently reduce X-rays generated from the part other than the focal point
3
a
. The total performance of these three pairs of blades depends on their assembly dimensional accuracy and geometric relation to one another, as well as the performance of each blade.
The X-ray irradiation field is confirmed in a manner of visual observation of an optical irradiation field shown on the person
2
. The optical irradiation field is formed by light, from a projector
13
, reflecting on the mirrors
14
,
15
and then going by the lower blades
7
,
8
. The X-ray irradiation field is also confirmed in a manner of visual observation of a needle
16
which moves, along a scale board
17
, engaging with the lower blades
7
,
8
. These indicators make it possible to confirm the X-ray irradiation field without irradiating X-rays actually. Some of the prior art X-ray limiting devices do not have projector
13
. A detachable filter
18
for controlling an amount of the total leakage which regulates X-ray quality is also usually provided with the X-ray limiting device
4
.
In the conventional X-ray apparatus, constructed as described above, an imaging part which has the X-ray tube
3
, the image intensifier
5
, a snap shot device, not shown in the Figures, and so on, is fixed not to move along the width of the person
2
, through the supporting arm
35
. Thus, it is necessary to move the table
1
for changing an imaging area along the width of the person
2
. When an examination with a brouchoscope, endoscope, and so on is also carried out, with the hardware inserted into the person being examined, this results in a heavy burden on the person
2
. Also when an examination, making an X-ray irradiation field smaller with the X-ray limiting device
4
than the field of view of the image intensifier
5
for the purpose of reducing useless exposure, is carried out, the same problem occurs when changing an imaging area along the width of the person
2
.
SUMMARY OF THE INVENTION
It is, therefore, an object of this invention to provide an X-ray apparatus which makes it possible to change an imaging area along the width of the person
2
, for example, without burdening the person
2
in an examination with a brouchoscope, endoscope, and so on.
An X-ray apparatus of this invention has an X-ray tube, a solid state flat detector opposing said X-ray tube across a person for examination, an X-ray limiting device for limiting the X-rays from said X-ray tube, and a driver for rotating said X-ray tube and said X-ray limiting device along a plane which is perpendicular to the body axis of the person.
The X-ray apparatus also has an edge detector for detecting X-ray irradiated onto an edge part of the solid state flat detector, a controller for receiving a signal from the edge detector and controlling, with the signal, the X-ray limiting device so that X-rays do not come outside of the solid state flat detector.
In the X-ray apparatus, the edge detector consists of X-ray semiconductor elements in edge parts on the solid state flat detector.
In the X-ray apparatus, the edge detector may also consist of a separate X-ray detector from the solid state flat detector.
The X-ray apparatus also has a handle for providing signals depending on an amount set by an operator, and an X-ray tube rotation controller for rotating the X-ray tube depending on the signals.
The X-ray apparatus also has two handles for providing signals based on amounts set by an operator, and a shield blade movement controller for moving the two shield blades independently, depending on the signals.
The X-ray apparatus also has a detector for detecting a rotation angle of the X-ray tube, and providing signals related to the rotation angle, a controller for receiving the signals from the detector and controlling the X-ray limiting device so that X-rays from the X-ray tube do not go outside of the solid state flat detector.
REFERENCES:
patent: 4490835 (1984-12-01), Wons
patent: 5142559 (1992-08-01), Wielopolski et al.
patent: 5539798 (1996-07-01), Asahina et al.
patent: 6243441 (2001-06-01), Zur
patent: 2 700 259 (1994-07-01), None
Christensen's Physics of Diagnostic Radiology, Thomas S. Curry, James E. Dowdey, and Robert C. Murray, Jr., Lippincott Williams and Wilkins, 4th Edition, Chapter 18, pp. 266-288.
Iinuma Masao
Takemoto Hajime
Barber Therese
Dunn Drew A.
Rader & Fishman & Grauer, PLLC
Shimadzu Corporation
LandOfFree
X-ray generator with a limiting device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with X-ray generator with a limiting device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and X-ray generator with a limiting device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3107113