JPH0630922A - X-ray ct apparatus - Google Patents

Abstract

PURPOSE:To provide an X-ray CT apparatus in which a tomographic image is not lost by generating a gap between two slice surfaces even when a tomographic image of a specimen is taken with a less slice thickness in a double slice CT. CONSTITUTION:In an X-ray CT apparatus in which an X-ray tube 1 and an X-ray detector 2 are arranged facing each other sandwiching a specimen and a slit mechanism 3 is provided on the side of the X-ray detector 2, the slit mechanism 3 includes two external slit plates 8 and 9, an internal slit 10 provided between the external slit plates 8 and 9 and a servo motor 14 to drive the external slit plates 8 and 9 across a slice thickness. The internal slit plate 10 is arranged in a cam and includes a servo motor 18 to rotate the internal slit plate 10 by driving.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray optical system of an X-ray CT apparatus capable of taking two tomographic images with one scan.

[0002]

2. Description of the Related Art Generally, in an X-ray CT apparatus, an X-ray tube 101 and an X-ray detector 102 are arranged to face each other with a subject (not shown) interposed therebetween as shown in FIG. A slit mechanism 103 is provided for changing the slice thickness of the tomographic image when performing. The X-ray detector 102 is
One detector row 104 is provided in which a plurality of detector elements are arranged in a fan shape to form a detector element group. The slit mechanism 103 has, for example, a slit 107 formed by slit plates 105 and 106, and a guide rail 108.
Guides the sliding movement of the slit plates 105 and 106 in the slice thickness direction. The distance between the slit plates 105 and 106, that is, the slice thickness, can be changed stepwise such as 1 mm, 2 mm, 5 mm, and 10 mm by rotationally driving the cam 109. The cam 109 is the servo motor 11
It is driven to rotate via the belt 111 and the pulley 112 by 0. The slit plates 105 and 106 are connected by a spring 113, and the spring 113 urges the slit plates 105 and 106.

When taking a tomographic image of a subject with such a structure, X-rays are transmitted from the X-ray tube 101 to the subject while rotating the X-ray tube 101 and the X-ray detector 102 about the subject. Expose to. At this time, the X-ray is focused by the slit mechanism 103 to a desired slice thickness. Then, the X-rays that have passed through the subject are detected by the X-ray detector 102, and one tomographic image is reconstructed for each scan based on this data. On the other hand, an X-ray CT apparatus capable of reconstructing two tomographic images in one scan (hereinafter,
Double-slice CT) is required.

In the double-slice CT, data for reconstructing two tomographic images are collected. Therefore, as shown in FIG. 10, a plurality of detection elements are arranged in a fan shape as an X-ray detector 102 and a detection element group is arranged. In addition to the detector array 104 forming two rows provided in the slice thickness direction, the slit mechanism 103 also has the two slits 107.

[0005]

However, when the above-mentioned slit mechanism is applied to double-slice CT,
There are the following problems. That is, since the slit plate is squeezed inward by each slit 107, a gap is created between two slice planes when imaging is performed with a thin slice thickness (for example, 2 mm or 1 mm). For this reason, the tomographic image of this gap portion is lost.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and its purpose is to obtain a tomographic image of a subject with a thin slice thickness.
An object of the present invention is to provide an X-ray CT apparatus in which a tomographic image is not lost due to a gap between two slice planes.

[0007]

In order to achieve the above-mentioned object, in the present invention, an X-ray generation source and an X-ray generation source are sandwiched with a subject interposed therebetween.
In an X-ray CT apparatus having a line detector facing each other and a slit mechanism provided on the X-ray detector side, the slit mechanism is provided between two outer slit members and the outer slit member. An inner slit member, and an outer slit member driving mechanism for driving the outer slit member in the slice thickness direction, wherein the inner slit member is cam-shaped and rotationally drives the inner slit member. It is characterized in that it is provided with an inner slit member drive mechanism for making it.

Further, in an X-ray CT apparatus in which an X-ray generation source and an X-ray detector are arranged to face each other with a subject being sandwiched therebetween, and a slit mechanism is provided on the X-ray detector side, the slit mechanism is a windmill. A plurality of blades provided in a shape and a blade driving means for driving the blades to rotate are provided, and the blade is characterized in that two slits having different widths are formed for each blade.

[0009]

In the X-ray CT apparatus of the present invention having the above structure, the inner slit member is shared by the two slits, and only the outer slit member is slid inward to reduce the slice thickness. Even when imaging is performed with a thin slice thickness, there is no gap between two slice planes. If a cam-shaped inner slit member is applied, the distance between the two slice planes can be changed by rotationally driving the cam-shaped inner slit member.

Further, when a slit mechanism using a blade is applied, the slice thickness and the distance between the slice planes are preset for each blade. The slice thickness and the distance between the slice planes can be selectively set according to the purpose.

[0011]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the schematic arrangement of an X-ray CT apparatus according to the present invention. In the figure, in the X-ray CT apparatus, an X-ray tube 1 that irradiates the subject P with X-rays and an X-ray detector 2 that detects the X-rays are arranged to face each other across the subject P. The X-ray tube 1 and the X-ray detector 2 are configured to be rotatable around the subject P. 2 on the X-ray tube 1 side
A slit mechanism 3 having two slits and capable of changing the slice thickness when performing imaging is provided. Further, the X-ray detector 2 is provided with two detector rows 4 in which a plurality of detection elements are arranged in a fan shape to form a detection element group. Then, the X-rays that have passed through the subject P are detected by the X-ray detector 2 as data for reconstructing two tomographic images for each scan. This data is collected by the data collection unit 5 and the image reconstruction unit 6
Sent to. The image reconstructing unit 6 reconstructs a tomographic image of the subject P based on the data sent from the data collecting unit 5, and displays the reconstructed tomographic image on the screen of the display unit 7.

As shown in FIG. 2, the slit mechanism 3 has two slits 11 formed by the outer slit plates 8 and 9 and the inner slit plate 10 provided between the outer slit plates 8 and 9, and the guide rail 12 is provided. Guides the sliding movement of the outer slit plates 8 and 9 in the slice thickness direction. The distance between the outer slit plates 8 and 9 can be changed stepwise by rotationally driving the cam 13, and the slice thickness can be changed stepwise such as 1 mm, 2 mm, 5 mm and 10 mm. The cam 13 is rotationally driven by a servo motor 14 via a belt 15 and a pulley 16. The outer slit plates 8 and 9 are connected by a spring 17, and the spring 17 biases the outer slit plates 8 and 9. On the other hand, the inner slit plate 10 is in the shape of a cam, and by rotationally driving it by the servo motor 18, the distance between the two slits 11, that is, the distance between the two slice planes can be changed stepwise.

In such a slit mechanism, the inner slit plate 10 is shared by the two slits 11, and only the outer slit plates 8 and 9 are slidably moved inward to squeeze. FIG. 3 shows a case where imaging is performed with a thick slice, and FIG. 4 shows a case where imaging is performed with a thin slice, and even when imaging is performed with a thin slice thickness, no gap is created between two slice planes.

Further, since the inner slit plate 10 has a cam shape, the inner slit plate 10 having a cam shape is rotationally driven so that the space between two slice planes is as shown in FIGS. 5 (a), 5 (b) and 5 (c). The distance can be changed.

When taking a tomographic image of the subject P, X
The X-ray is irradiated from the X-ray tube 1 to the subject P while rotating the X-ray tube 1 and the X-ray detector 2 about the subject P. At this time, the X-ray has a desired slice thickness (for example, 1 mm, 2 mm, 5 mm, 10 m) by changing the slit width by narrowing only the outer slit plates 8 and 9 inward.
m). Then, X-rays transmitted through the subject P are X-rays.
Detected by the line detector 2 and based on this data, 1
Two tomographic images are reconstructed for each scan.

Therefore, in the double-slice CT, even when a tomographic image of the subject P is taken with a thin slice thickness, it is possible to prevent a gap from occurring between the two slice planes, and thus the gap can be prevented. It is possible to prevent the partial tomographic image from being lost.

Next, another embodiment will be described with reference to the drawings. FIG. 6 is a perspective view showing the configuration of the slit mechanism 3 using a blade. In this slit mechanism 3, for example, four blades 19 are provided in a windmill shape. Each blade 1
9 has two slits 11 having different widths for each blade, and the slit width and the interval between the two slits 11 are set in advance. The blade 19 can be rotationally driven by the servo motor 20, and the slice thickness and the interval between two slices can be set by selecting the blade 19 by this rotational driving. For example, in FIGS. 7 and 8, the slice thickness is 1 mm, 2 mm, 5
FIGS. 7A and 7B show a case in which a blade 19 having a slit 11 having a thickness of 10 mm is applied, FIG. 7 shows a case in which the slice thickness is set to 10 mm, and FIG. 8 shows a case in which the slice thickness is set to 2 mm.

With such a slit mechanism 3, by selecting the blade 19, the desired slice thickness and the distance between the slice planes can be selectively set according to the imaging purpose. Further, even when a tomographic image of the subject P is captured with a thin slice thickness, it is possible to prevent a gap from occurring between the two slice planes, and thus it is possible to prevent the tomographic image from being lost in the gap portion. it can.

The present invention is not limited to the above embodiment, and various modifications can be made. For example, in the slit mechanism of the present embodiment, the cam mechanism and the blade mechanism are used to change the slice thickness and the distance between the slice planes, but the invention is not limited to these means.

[0021]

The X-ray CT apparatus of the present invention has the above-mentioned configuration and operation, and even when a tomographic image of a subject is taken with a thin slice thickness, a gap is created between the two slice surfaces. Since it can be prevented from occurring, it is possible to prevent the tomographic image from being missing in the gap portion.

[Brief description of drawings]

FIG. 1 is a double slice CT according to an embodiment of the present invention.
3 is a block diagram showing a schematic configuration of FIG.

FIG. 2 is a perspective view showing a configuration of a slit mechanism in the example.

FIG. 3 is a diagram showing a case where imaging is performed with a large slice thickness in the same embodiment.

FIG. 4 is a diagram showing a case where imaging is performed with a thin slice thickness in the embodiment.

FIG. 5 is a diagram showing a case where a distance between slice planes is changed by an inner slit plate in the embodiment.

FIG. 6 is a perspective view showing a configuration of a slit mechanism in another embodiment.

FIG. 7 is a diagram showing a case where imaging is performed with a slice thickness of 10 mm in the example.

FIG. 8 is a diagram showing a case where imaging is performed with a slice thickness of 2 mm in the example.

FIG. 9 is a perspective view showing a configuration of a slit mechanism in a conventional example.

FIG. 10 is a front view showing the configuration of a conventional double slice CT.

[Explanation of symbols]

 1 X-ray tube (X-ray generation source) 2 X-ray detector 3 Slit mechanism 8 Outer slit plate (outer slit member) 9 Outer slit plate (outer slit member) 10 Inner slit plate (inner slit member) 11 Slit 14 Servo motor (Outer slit member drive mechanism) 18 Servo motor (Inner slit member drive mechanism) 19 Blade 20 Servo motor (Blade drive means)

Claims (3)

[Claims] 1. An X-ray CT apparatus in which an X-ray generation source and an X-ray detector are arranged to face each other with a subject interposed therebetween, and a slit mechanism is provided on the X-ray detector side. An outer slit member, and an inner slit member provided between the outer slit members,
An outer slit member drive mechanism for driving the outer slit member in the slice thickness direction, and an X-ray CT apparatus. 2. The inner slit member is cam-shaped,
The X-ray CT apparatus according to claim 1, further comprising an inner slit member driving mechanism that rotationally drives the inner slit member. 3. An X-ray CT apparatus in which an X-ray generation source and an X-ray detector are arranged to face each other across a subject, and a slit mechanism is provided on the X-ray detector side, wherein the slit mechanism is a wind turbine. An X-ray C, characterized in that it comprises a plurality of blades provided in a shape of a circle and a blade drive means for rotationally driving the blades, and each of the blades is formed with two slits of different widths.
T device.