WO2021172751A1

WO2021172751A1 - Cone beam ct apparatus equipped with dynamically controllable collimator

Info

Publication number: WO2021172751A1
Application number: PCT/KR2021/000517
Authority: WO
Inventors: 정홍
Original assignee: 주식회사 에이치디엑스윌
Priority date: 2020-02-27
Filing date: 2021-01-14
Publication date: 2021-09-02
Also published as: KR20210109304A

Abstract

The present invention relates to a cone beam CT apparatus equipped with a dynamically controllable collimator. The apparatus of the present invention comprises: an X-ray generation unit for radiating cone beam-shaped X-rays toward a subject; a collimator which limits the irradiation area of the X-rays through an opening portion so that the X-rays radiated from the X-ray generation unit are emitted to only a selected image-capture area; an X-ray detection unit for detecting the X-rays that are emitted through the collimator and pass through the subject; a rotator on which the X-ray generation unit, the collimator, and the X-ray detection unit are arranged in the longitudinal direction; and a control unit which controls the operation of the collimator and rotates the rotator about a rotation center. The control unit may control the opening position of the collimator so that the X-rays are emitted to only the selected image-capture area when the rotator rotates while the center of the selected image-capture area is spaced apart from the rotation center of the rotator.

Description

Cone-beam CT device with collimator capable of dynamic control

The present invention relates to a cone-beam CT apparatus having a collimator capable of dynamic control, and more particularly, to a cone-beam CT apparatus that eliminates the need to move the rotational center of a rotator to a central position of an area to be photographed during cone-beam CT imaging. will be.

Cone-beam CT uses an area detector to detect cone-shaped transmitted X-rays two-dimensionally, and uses this to acquire three-dimensional volume information, so that three-dimensional and multi-dimensional images can be reconstructed with only one rotational scan of a subject. am.

In cone-beam CT, an area capable of reconstructing a 3D image from data obtained through rotational scan is defined as a field of view (FOV), and the shape and size of the FOV is determined according to the geometric arrangement of the X-ray beam and the rotation axis. In addition, the maximum area that can be diagnosed by one rotation imaging using cone beam CT is called the maximum FOV, and the subject can be photographed according to the maximum FOV of the cone beam CT.

1 (a) and (b) are, respectively, in the case of using the entire range of the entire X-ray detection unit 2 in the conventional cone beam CT, when the rotator 3 is positioned at 0° and 90°, the rotator ( 3) is a view from the top.

1 (a) and (b), in general, in order to implement cone beam CT, the rotator 3 is disposed so that the rotating center 4 is located at the center of the area to be imaged, and the rotator 3 ) is to arrange the X-ray generator 1 and the X-ray detector 2 in opposite directions and place the subject to be photographed between them, so that the maximum FOV photographing and restoration area 6 is more than 360° or 180°. It rotates to a slightly larger angle and shoots.

However, when cone beam CT is used, it is not always necessary to photograph all the maximum FOV, and it is desirable to reduce the exposure dose to the subject by photographing only the region of interest within the maximum FOV if necessary. At this time, a technique required to photograph a small area as needed along with the maximum FOV in one device is called a free FOV method.

2(a) and 2(b) are diagrams showing the implementation of the conventional pre-FOV method in FIGS. 1(a) and (b), respectively.

Referring to (a) and (b) of Figure 2, the conventional pre-FOV method places the rotating center 4 in the center of the pre-FOV photographing and restoration area 7 to be photographed, and in the other areas After adjusting and fixing the collimator 5 so that the X-rays do not reach, the rotator 3 is rotated to proceed with shooting.

However, in this case, since the rotating center 4 has to be moved to the center of the pre-FOV imaging and restoration area 7 to be photographed during imaging, there is a problem in that the cone beam CT equipment is enlarged.

In detail, in the case of rotating the rotator 3 in FIG. 2 (a) to (b) in FIG. 2 and proceeding with the photographing, the center of the rotating center 4 and the photographing and restoration area 7 coincides with each other. Only a specific portion of the X-ray detection unit 2 is irradiated with X-rays. However, in this case, the problem of deterioration of the X-ray detection unit 2 occurs, and it becomes difficult to photograph a subject while using most of the range of the X-ray detection unit 2 .

If the collimator 5 is fixed and the rotator 3 is rotated to use most of the range of the X-ray detection unit 2, since the rotating center 4 must move, the As the turning radius increases, the cone beam CT equipment becomes larger.

However, as shown in FIG. 3 , in general, the scale of cone beam CT is quite large compared to the subject, and in institutions such as hospitals using cone beam CT, the small cone beam CT is preferred because the X-ray imaging room is very narrow.

Accordingly, there is a need for a cone beam CT apparatus capable of effectively implementing a free FOV method while reducing the size of the apparatus.

An object of the present invention is to dynamically control the collimator for each angle at which data of the selected detection area is obtained when the rotator rotates during cone beam CT imaging, so that the rotation center of the rotator does not need to be moved to the center position of the area to be photographed. An object of the present invention is to provide a cone-beam CT device that can be miniaturized.

The present invention for solving the above problems is a cone beam CT apparatus having a collimator capable of dynamic control, the apparatus of the present invention comprising: an X-ray generator for emitting cone-beam X-rays toward a subject; a collimator for limiting the irradiation area of X-rays through the opening so that the X-rays emitted from the X-ray generator can be irradiated only to the selected imaging area; an X-ray detection unit irradiated through the collimator and detecting X-rays passing through the subject; and a rotator in which the X-ray generator, the collimator, and the X-ray detector are disposed in a longitudinal direction. and a control unit for controlling the driving of the collimator and rotating the rotator with respect to a rotation center, wherein the control unit has a center of the selected imaging area spaced apart from a rotation center of the rotator and when the rotator rotates, the selected The position of the opening of the collimator may be adjusted so that only the imaging area can be irradiated with X-rays.

According to an embodiment of the present invention, the controller may differently adjust the opening position of the collimator according to the rotation angle of the rotator.

According to an embodiment of the present invention, the controller may rotate the rotator in a state in which the positions of the center of the selected photographing area and the rotation center of the rotator are respectively fixed.

According to an embodiment of the present invention, the collimator includes first and second plates, and the control unit may move the first and second plates in one direction perpendicular to the radial direction of X-rays.

According to an embodiment of the present invention, when the rotator rotates, when the selected imaging area is biased to the right of the maximum FOV imaging and restoration area based on the X-ray generator, the first and second plates The first and second plates may be moved to the left when the selected imaging region is biased toward the left of the maximum FOV imaging and restoration region based on the X-ray generator.

According to an embodiment of the present invention, the collimator may be formed of four rectangular-shaped plates positioned above, below, left, and right, respectively, with respect to the traveling direction of X-rays radiated from the X-ray generator.

According to the present invention, when the rotator rotates during cone beam CT imaging, by automatically and dynamically controlling the collimator for each angle at which data of the selected detection area is obtained, the opening position of the collimator is continuously changed during the rotation of the rotator, so that the rotational center of the rotator is adjusted. Since there is no need to move to the central position of the area to be photographed, the device can be miniaturized.

1 (a), (b) is a view from the top of the rotator 3 when the rotator is positioned at 0° and 90° when the entire range of the X-ray detector is used in the conventional cone beam CT, respectively. It is a drawing.

3 is a block diagram showing a generally large cone beam CT.

4 is a block diagram showing a schematic configuration of a cone beam CT apparatus having a collimator capable of dynamic control according to an embodiment of the present invention.

5 and 6, respectively, in the cone beam CT apparatus according to the embodiment of the present invention, when the rotator is positioned at 0° and 90°, the X-ray irradiation direction according to the dynamic control of the collimator is a view viewed from the top of the rotator .

7A and 7B are diagrams exemplarily illustrating a collimator capable of dynamic control according to an embodiment of the present invention.

8A and 8B are diagrams illustrating detection images obtained through a cone beam CT apparatus having a collimator capable of dynamic control according to an embodiment of the present invention.

Hereinafter, detailed contents for carrying out the present invention will be described with reference to the accompanying drawings. In the description of the present invention, when it is determined that the subject matter of the present invention may be unnecessarily obscured as it is obvious to those skilled in the art with respect to related known functions, the detailed description thereof will be omitted.

4 is a block diagram showing a schematic configuration of a cone beam CT apparatus having a collimator capable of dynamic control according to an embodiment of the present invention. 5 and 6, respectively, in the cone beam CT apparatus according to the embodiment of the present invention, when the rotator 40 is positioned at 0 ° and 90 °, the X-ray irradiation direction according to the dynamic control of the collimator 20 rotator It is a view seen from the top of (40).

Referring to FIG. 4 , the cone beam CT apparatus according to an embodiment of the present invention includes an X-ray generator 10 , a collimator 20 , an X-ray detector 30 , a rotator 40 , and a controller 50 . do.

5 and 6, the X-ray generator 10 is an X-ray generator that generates X-rays in the form of a cone-beam toward a subject. 10) passes through the collimator 20 at the X-ray focus point and is incident on the X-ray detector 30 .

The collimator 20 may limit the irradiation area of the X-rays through the opening 21 so that the X-rays emitted from the X-ray generator 10 can be irradiated only to the selected imaging area 60 . When the rotator 40 rotates once, the opening position or range of the collimator 20 may be adjusted by the control unit 50 for each photographing position for each rotation angle.

Here, the selected photographing area 60 is a partial area to be photographed among the subjects. In the application of the free FOV method, which is a technique necessary to photograph a small area as needed with the maximum FOV in one device, It corresponds to the free FOV shooting and restoration area. When photographing, the photographing area 60 selected together with the subject may be fixed.

The collimator 20 may include first and

second plates

201 and 202 formed on both sides with the opening 21 therebetween. The first plate 201 may be disposed on the right side when viewed from the X-ray generator 10 , and the second plate 202 may be disposed on the left side when viewed from the X-ray generator 10 .

The shape of the opening 21 of the collimator 20 may be set in various shapes according to the configuration of the collimator 20 , and the detailed configuration of the collimator 20 will be described later.

The X-ray detector 30 may detect X-rays irradiated through the collimator 20 and transmitted through the subject. The X-ray detection unit 30 has a detection area 31 formed to have a predetermined length in the direction perpendicular to the X-ray irradiation direction.

The selected detection area 31 in the free FOV method applied to the present invention corresponds to a part of the maximum detection area of the entire X-ray detector because X-rays are irradiated through the collimator 20 . Also, referring to FIGS. 5 and 6 , the selected detection area 31 may correspond to different positions among the detection areas of the entire X-ray detector according to the photographing direction of the subject.

In addition, the data received from the X-ray detector 30 is transmitted to the image processing unit 32 , and the image processing unit 32 may reconstruct a 3D image from the data.

In the rotator 40 , the X-ray generator 10 , the collimator 20 , and the X-ray detector 30 are disposed in the longitudinal direction. The X-ray generator 10 , the collimator 20 , and the X-ray detector 30 may be directly or indirectly connected to the rotator 40 located thereon, respectively. The X-ray generator 10 , the collimator 20 , and the X-ray detector 30 may be sequentially arranged in a straight line in the longitudinal direction of the rotator 40 .

The rotation driving unit 41 according to the present invention rotates the rotator 40 once with respect _{to the rotation center (C r} ) after fixing the subject while the scanning process using the cone beam CT device is in progress. One rotation means, for example, rotating the selected photographing area 60 at an angle slightly larger than 360° or 180°.

_{The rotator 40 may rotate once with respect to the rotation center (C r} ) for each photographing by the rotation driving unit 41 , and not only forward rotation but also reverse rotation is possible. When the rotator 40 is rotated, the X-ray generator 10 , the collimator 20 , and the X-ray detector 30 interlocked with the rotator 40 also rotate.

The control unit 50 dynamically controls the driving of the collimator 20 , and may rotate the rotator 40 with respect _{to the rotation center C r .} That is, the control unit 50 may adjust the opening position of the collimator 20 , and may drive the rotation driving unit 41 to rotate the rotator 40 . As described above, since the rotator 40 is interlocked with the collimator 20 , when the control unit 50 rotates the rotator 40 , the collimator 20 is also rotated.

The control unit 50 controls the center (C _f ) of the selected imaging area to be spaced apart from the rotation center of the rotator 40, and when the rotator 40 rotates, a collimator ( 20) this opening position can be adjusted.

The control unit 50 may move the first and

second plates

201 and 202 together in one direction perpendicular to the radial direction of X-rays.

The controller 50 may differently adjust the opening position of the collimator 20 according to the rotation angle of the rotator 40 so that only the selected imaging area 60 is exposed to X-rays. As the opening position of the collimator 20 is adjusted, the selected detection area 31 to which the X-rays reach also varies according to the rotation angle of the rotator 40 .

For example, referring to FIG. 5 when the rotator 40 is at the 0° position, the selected imaging area 60 is on the right side of the maximum FOV imaging and restoration area 6 when viewed from the X-ray generator 10 . In the case of bias (hereinafter, the division of the right and left sides is based on the view from the X-ray generator 10), the collimator 20 is controlled so that the X-rays can be irradiated to the selected imaging area 60 on the right side. The opening position is adjusted by (50).

In detail, the controller 50 may move the first and

second plates

201 and 202 to the right to direct the radiated X-rays to match the range of the selected imaging area 60 on the right. At this time, the first and

second plates

201 and 202 move together to the right.

Accordingly, the object is detected through the X-rays irradiated to the selected detection area 31 on the right side, which is a part of the maximum detection area of the X-ray detection unit 30 .

Referring to FIG. 6 when the rotator 40 is at the 90° position, if the selected imaging area 60 is biased to the left of the maximum FOV imaging and restoration area 6, the collimator 20 is located on the left side of the selected imaging area ( 60), the opening position is adjusted by the control unit 50 so that X-rays can be irradiated.

In detail, the controller 50 may move the first and

second plates

201 and 202 to the left to direct the radiated X-rays to match the range of the selected imaging area 60 on the left. At this time, the first and

second plates

201 and 202 move together to the left.

Accordingly, the object is detected through the X-rays irradiated to the left selected detection area 31 which is a part of the maximum detection area of the X-ray detector 30 .

In the above description, the case where the selected imaging area 60 is biased to the right and left has been described as an example, but in the case where the selected imaging area 60 is biased toward the upper and lower sides, the collimator 20 controls the X-rays to be irradiated to the selected imaging area 60 . The opening position can be adjusted by (50). In addition, this is applicable even when the selected imaging area 60 has at least two coordinates of top, bottom, left, and right on a two-dimensional plane in the direction in which the X-rays are irradiated at the same time.

In addition, referring to FIGS. 5 and 6 , the selected photographing area 60 of the subject exists within the maximum FOV photographing and restoration area 6 , and the rotation center (C _r ) of the rotator 40 is the center of the selected photographing area (C _f ) and spaced apart.

The controller 50 may rotate the rotator 40 while _{the positions of the center C f} of the selected imaging area _{and the rotation center C r} of the rotator 40 are fixed, respectively. That is, even when the rotator 40 rotates, the position of the center (C _f ) of the selected imaging area with respect to the rotation center (C _r ) of the rotator does not change.

That is, since the position of the rotation center (C _r ) of the rotator is fixed, the rotation radius of the rotator 3 does not change according to the rotation of the rotator 3 .

When the rotator 40 rotates, when the rotator 40 is rotated in a state in which the collimator 5 is fixed, the rotational center of the rotator (C _r ) must move, so that the rotation radius of the rotator 40 is widened. There is a problem in that the cone beam CT device is enlarged.

In the present invention, even when the rotator 40 rotates, the center (C _f ) of the selected imaging area and the center of rotation (C _r ) of the rotator are fixed, respectively, so that X-rays can be irradiated only to the selected imaging area 60. Since the opening position of 20 is adjusted, the rotation radius of the rotator 40 does not change. Accordingly, miniaturization of the cone beam CT apparatus can be achieved.

7A and 7B are diagrams exemplarily illustrating a collimator capable of dynamic control according to an embodiment of the present invention. 8A and 8B are diagrams illustrating detection images obtained through a cone beam CT apparatus having a collimator capable of dynamic control according to an embodiment of the present invention.

Referring to (a) and (b) of Figure 7, the collimator 20 of the cone beam CT apparatus according to the embodiment of the present invention has an image centering on the traveling direction of X-rays radiated from the X-ray generator 10, It may be formed of four rectangular-shaped plates 22 positioned on the lower, left, and right sides.

The first and second plates 201 may be opposite two plates among the four plates 22 .

The control unit 50 may dynamically control each of the plates 22 . Each plate 22 may be moved in a direction selected from among up, down, left, and right along a plurality of axes 23 and rails 24 extending in a horizontal or vertical direction by the control unit 50 . Each shaft 22 receives rotational power through a motor, and a screw groove portion may be formed on an outer peripheral surface of the shaft 22 .

Each plate 22 includes an extension plate 221 extending toward one axis 23 , and an enclosure-type moving part 222 having a hollow body may be formed at an end of the extension plate 221 . The moving part 222 is fitted to each shaft 23 , and can move horizontally or vertically along the shaft 23 . On the other hand, a threaded portion is formed on the inner peripheral surface of the moving part 222 of the housing type, and may be engaged with the outer peripheral surface of the shaft 22 .

The upper and lower plates may move up and down along an axis extending in a vertical direction, and the left and right plates may move left and right along an axis extending in a horizontal direction. The upper and lower plates may move toward or away from each other in a vertical direction, and the left and right plates may move toward or away from each other in a horizontal direction.

For example, the control unit 50 may narrow the opening range of the collimator while moving the position of each plate 22 shown in FIG. 7(a) to the position of FIG. 7(b), and vice versa. case is possible.

In addition, although the configuration for adjusting the opening range of the collimator is shown as an example in (a) and (b) of FIG. 7 , the configuration is not limited thereto, and for example, the upper and lower plates, or the left and right plates are set in the same direction. It is also possible to adjust the opening position of the collimator while moving.

The user adjusts the aperture range of the collimator to photograph the first selected photographing area 60 through the control unit 50, and then automatically positions the collimator's opening to photograph only the selected photographing area 60 according to the rotation of the rotator 40 can be set to adjust.

For example, when the rotator 40 rotates, the control unit 50 determines that the selected imaging area 60 is biased to the left or right of the maximum FOV imaging and restoration area 6 based on the X-ray generator 10 . In this case, the left and right plates can be moved together to the left or right, respectively.

On the other hand, when the control unit 50 rotates the rotator 40, the selected imaging area 60 is biased toward the upper or lower side of the maximum FOV imaging and restoration area 6 with respect to the X-ray generator 10, The upper and lower plates can be moved together upwards or downwards, respectively.

Meanwhile, the movements of the left and right plates and the upper and lower plates may be performed individually or simultaneously.

Through this, even if the selected imaging area 60 is located at any position among the maximum FOV imaging area, when the rotator 40 is rotated, the center (C _f ) of the selected imaging area 60 and the rotation center (C _r ) of the rotator are respectively Filming may proceed in a fixed state. At the same time, since the position of the detection region 31 of the X-ray detection unit 30 changes during imaging, most of the area of the X-ray detection unit 30 can be irradiated with X-rays according to one rotation of the rotator 40 . have.

Referring to (a) and (b) of FIG. 8 , in the cone beam CT apparatus according to an embodiment of the present invention, the collimator 20 partially blocks the X-rays emitted from the X-ray generator 10 , so that the X-ray detection unit It can be seen that the image area obtained in (30) is narrowed.

According to the cone beam CT apparatus of the embodiments of the present invention described above, when the rotator rotates during cone beam CT imaging, the collimator automatically and dynamically controls the collimator for each angle at which data of the selected detection area is obtained to continue the aperture range of the collimator during rotation of the rotator. By changing it, it is not necessary to move the rotational center of the rotator to the central position of the area to be photographed, and thus the device can be miniaturized.

The scope of protection in this field is not limited to the description and expression of the embodiments explicitly described above. In addition, it is added once again that the protection scope of the present invention cannot be limited due to obvious changes or substitutions in the technical field to which the present invention pertains.

[Explanation of code]

10: X-ray generator

20: collimator

30: X-ray detection unit

31: selected detection area

40: Rotator

41: rotation drive unit

50: control unit

60: Selected shooting area

C _f : Center of the selected shooting area

C _r : center of rotation of the rotator

Claims

an X-ray generator that radiates X-rays in the form of cone beams toward the subject;

a collimator for limiting the irradiation area of X-rays through the opening so that the X-rays emitted from the X-ray generator can be irradiated only to the selected imaging area;

an X-ray detection unit irradiated through the collimator and detecting X-rays passing through the subject; and

a rotator in which the X-ray generator, the collimator, and the X-ray detector are disposed in a longitudinal direction;

A control unit for controlling the driving of the collimator and rotating the rotator with respect to a center of rotation,

The control unit, the center of the selected photographing area is spaced apart from the rotation center of the rotator, and when the rotator rotates, adjusting the opening position of the collimator so that only the selected photographing area can be irradiated with X-rays , a cone-beam CT device.
According to claim 1,

The control unit, Cone-beam CT apparatus, characterized in that for adjusting the opening position of the collimator differently according to the rotation angle of the rotator.
3. The method of claim 2,

The control unit, the cone beam CT apparatus, characterized in that the rotation of the rotator in a state in which the positions of the center of the selected imaging area and the rotation center of the rotator are respectively fixed.
4. The method of claim 3,

The collimator includes first and second plates,

The control unit, Cone beam CT apparatus, characterized in that the movement of the first and second plates in one direction perpendicular to the radiation direction of X-rays.
5. The method of claim 4,

When the control unit rotates the rotator,

When the selected imaging area is biased to the right of the maximum FOV imaging and restoration area based on the X-ray generator, the first and second plates are moved to the right,

When the selected imaging region is biased to the left of the maximum FOV imaging and restoration region based on the X-ray generator, the first and second plates are moved to the left.
According to claim 1,

The collimator is a cone beam CT device, characterized in that it is formed of four rectangular plates positioned on the upper, lower, left, and right sides of the X-rays radiated from the X-ray generator, respectively.