JPH0319778B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to an X-ray inspection apparatus, and more particularly to an X-ray inspection apparatus equipped with a device for projecting an X-ray irradiation field with light.

BACKGROUND ART In cardiovascular X-ray examinations, etc., there are two types of imaging methods: one in which X-rays are irradiated from the front of a subject lying on the top of an examination table, and the other in which X-rays are irradiated from behind. The former is called AP photography (abbreviation for Antero-Posterior photography), and the latter is called PA photography (abbreviation for Postero-Anterior photography).

Comparing these two imaging methods, A-P
In photography, the image amplifier amplifier and film chain of the image receiving system are located below the top plate, making it difficult to rotate due to space considerations, whereas in P-A photography, the image amplifier amplifier and film chain are located on the top. Since they are located above the plate, they can be easily rotated and replaced, allowing for quick switching from fluoroscopy to imaging. Also, when photographing the head, make sure to
Radiation exposure is lower with P-A imaging. Furthermore, regarding fluoroscopy, PA imaging is said to be better mainly from the viewpoint of X-ray exposure to the operator. However, in P-A imaging, even if a light beam similar to an It is difficult to confirm the irradiation field by On the other hand, in AP imaging, if a light beam is generated in the same way as an X-ray beam, the light is directly projected onto the subject, making it easy to confirm the irradiation field with the light.

Problems to be Solved by the Invention As described above, although P-A imaging has many advantages, there is a problem in ease of use in that it is difficult to confirm the irradiation field with light.

An object of the present invention is to provide an X-ray inspection apparatus that can overcome the difficulty in confirming the irradiation field using light in PA imaging.

Means for Solving the Problems According to the present invention, an examination table has an X-ray tube disposed below the top plate, and an image receiving system disposed above the top plate, In an X-ray inspection apparatus that performs an examination by irradiating X-rays from behind a subject lying on the body, the number of subjects to be examined is determined based on parameters including the aperture of the X-ray aperture device installed in the a computing unit that calculates a position corresponding to the outside edge of the X-ray irradiation area on the surface of the examiner; and the image receiving system side that projects light from the image receiving system side toward the subject at the calculated position. It is characterized by being equipped with an irradiation field projection device installed at the

Function: It has an X-ray tube placed under the top plate of the examination table and an image receiving system placed above the top plate. In an X-ray inspection device that performs examinations by irradiating X-rays, when performing P-A imaging, the X-ray tube is placed below the top plate of the examination table, the image receiving system is placed above the top plate, and the image receiving system is placed above the top plate. X-rays will be irradiated from behind the subject who is lying on top of the body.

An X-ray irradiation field projection device is provided on the image receiving system disposed above the top plate, and light representing the irradiation field is projected from the image receiving system side. That is, a position corresponding to the outside area of the X-ray irradiation area on the surface of the subject is determined by a computing unit from parameters such as the aperture of the X-ray aperture device installed in the X-ray tube and the imaging distance. Light is projected from the X-ray irradiation field projection device onto this calculated position.

In other words, the light projected from above the subject lying on the top of the examination table represents the irradiation field of X-rays irradiated from the bottom of the top to the top. can.

Therefore, even though the X-rays are irradiated from below the subject, the irradiation field can be represented on the subject's surface by the light projected from above, and the X-ray irradiation is The position and size of the X-ray irradiation field is directly displayed on the surface of the subject's body, making it easy for the operator to confirm the X-ray irradiation field.

Embodiment In FIG. 1, a top plate 2 is held on an examination table 1 so as to be movable up and down. Subject 1 is placed on this top plate 2.
0 is laid down. An X-ray tube 3 and a diaphragm device 4 for narrowing down the X-rays are located below the top plate 2, and image receiving systems such as an image amplifier amplifier 5, an X-ray television set 6, and a film changer 7 are located above the top plate 2. These are held by the C-arm 8 so that they are in their respective positions. This C-arm 8 is held by a C-arm stand 9. Image amplifier amplifier 5,X
The X-ray television device 6 and the film changer 7 are designed to be able to rotate together with the axis 0 as the rotation axis, and this rotation changes the direction from fluoroscopy using the X-ray television to photographing on the film. .

An L-shaped irradiation field projection device 71 is attached around the film changer 7. The reason for the L-shape is to not obstruct the X-rays entering the film chainer 7. The irradiation field projection device 71 is
It consists of a horizontal projector 72 and a vertical projector 73.

As shown in FIG. 2, the aperture device 4 has a horizontal leaf and a vertical leaf 42 for aperture, and the X-ray irradiation field is adjusted by moving these leaves in the horizontal and vertical directions, respectively. . Then, from the horizontal projector 72, a linear light pattern indicating the lateral outer edge of the irradiation field (corresponding to the position of the horizontal leaf 41) is projected onto the body surface of the subject 10, and from the vertical projector 73,
A linear light pattern indicating the longitudinal outer edge of the irradiation field (corresponding to the position of the vertical leaf 42) is projected onto the representative surface of the subject 10.

Next, for convenience of explanation, the horizontal projector 72 will be explained. The vertical projector 73 is completely the same except for the vertical and horizontal dimensions, so the explanation will be omitted. As shown in FIG. 3, a laser beam from a laser generator 81 is guided through an optical fiber 82 to a laser head 83, and a planar light beam emitted from there is split into two directions by a beam splitter 84.
The mirrors 85 and 85 are bent at right angles, respectively.
In this way, a light beam is projected at right angles to the film, thereby displaying a linear light pattern on the body surface of the subject 10.

Here, the positions of the mirrors 85, 85 are adjusted by a motor 86 so that the interval a between the linear light patterns can be changed. The value of this interval a is determined by a=b·(A/B). Here, b is the opening amount of the horizontal leaf 41, B is the distance from the X-ray focal point to the horizontal leaf 41,
A is the distance from the X-ray focal point to the light pattern projection surface of the subject 10. However, A=A′+δ. A′ is the distance from the focal point to the top of the top plate 2,
δ is the distance from the upper surface of the top plate 2 to the light pattern projection surface of the subject 10.

That is, while the opening amount b of the horizontal leaf 41 is detected by the leaf potentiometer 43,
The value of A' is detected by the examination table potentiometer 11, and these values and the value of δ manually set by the operator according to the thickness of the patient 10 are calculated. The value of a is calculated by inputting it to a device 91. This value becomes a setting signal and is given to the comparator 92, and is compared with the output of the potentiometer 87 that detects the interval between the mirrors 85, thereby controlling the motor 8.
6 is controlled. In this way, even if each parameter changes, a light pattern with an interval a calculated accordingly will be projected toward the subject 10.

FIG. 4 shows a second embodiment of the transverse projector 72.
Here, the light is not projected perpendicularly to the film as shown in FIG. 3, but directed toward the X-ray focal point. That is, in addition to the configuration shown in FIG. 3, an angle motor 88 for adjusting the angle of the mirror 85 is added, and not only the distance a between the mirrors 85 and 85 but also the light projection angle θ is controlled. It's becoming like that. This angle θ is given by θ=tan ⁻ (a/2A), and the arithmetic unit 91 calculates θ as well as a=b·(A/B). However, in these formulas, A is the distance from the focal point to the mirror 85. The angle motor setting signal corresponding to θ and the angle signal detected from the angle potentiometer 89 are compared by comparators 93, 93, and the angle motors 88, 8
8 is controlled, light is projected at an angle θ such that it is directed toward the focal point.

Here, if we compare the vertical projection method (Fig. 3) and the focal projection method (Fig. 4), mechanically,
The latter requires angle control and is complicated, whereas the former has a simple mechanism and can be easily miniaturized.
On the other hand, in the former case, the value of δ must be entered manually, which is both cumbersome and inaccurate, and it also becomes inaccurate in principle if the imaging system is tilted (however, in practice, it is often used tilted). Although not).
In this respect, the latter does not require manual input and is not complicated, and is accurate in principle, even if the imaging system is tilted.

In short, the vertical projection method has a simple mechanism but is not always accurate, while the focal projection method has a complicated mechanism but is accurate, and it is thought that it is better to use one depending on the purpose.

Although a laser generator was used as the light source in the above embodiment, it goes without saying that any light source capable of projecting a linear light pattern may be used.
For example, as shown in FIGS. 5 and 6, a projector 90 that combines an incandescent lamp and a lens may be used.

Further, although the control system is a closed loop in the above example, it may be an open loop control system using a stepping motor or the like depending on the purpose of use.

Effects of the Invention According to the present invention, it is possible to easily confirm the X-ray irradiation field using light in PA imaging. Therefore,
Faster alignment, lower radiation dose, and
Since it becomes possible to narrow down the X-rays as necessary and sufficiently, effects such as being able to take good images without halation can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of one embodiment of the present invention, Fig. 2 is a schematic diagram for explaining the principle, Fig. 3 is a block diagram of the horizontal projector, and Fig. 4 is another embodiment of the horizontal projector. FIGS. 5 and 6 are block diagrams of modified examples. 1...Examination table, 2...Top plate, 3...X-ray tube, 4
...Aperture device, 5...Image amplifier amplifier, 6...X-ray television device, 7...Film changer, 8...C-arm, 9...C-arm stand, 71...Irradiation field projection device, 72... ...Horizontal projector, 73...Vertical projector.

Claims (1)

[Claims] 1. An X-ray tube placed under the top plate of the examination table,
an image receiving system disposed above the top plate, and an X-ray inspection apparatus that performs an examination by irradiating X-rays from behind a subject lying on the top plate, a computing unit that calculates a position on the surface of the subject corresponding to the outside area of the X-ray irradiation area from parameters including the aperture amount of the X-ray diaphragm device and the imaging distance;
An X-ray inspection apparatus comprising: an irradiation field projection device provided on the image receiving system side that projects light to the calculated position from the image receiving system side toward the subject.