JPH09149898A - X-ray ct device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the number of the kinds of the switchable stop width of an irradiation X-ray flux without substantially changing the constitution of a collimator rod in an X-ray collimator device for an X-ray CT device. SOLUTION: The X-ray collimator device for this X-ray CT device is provided with the collimator rod 21 having cross section in which plural opening parts 26a-26d are formed radially, a stepping motor for rotating the collimator rod 21 around an axial center RJ and stopping rotation at plural stop positions where the center axes QJ1-QJ4 of the respective opening parts 26a-26d and an irradiation center axis XJ in the width direction of the irradiation X-ray flux are matched with each other and slits 27a-27d for regulating the irradiation X-ray flux to the stop widths w1-w4 at the respective stop positions, etc., and the stop width of the irradiation X-ray flux is switched to the plural kinds. The rotation of the collimator rod 21 is also stopped at a shutter position other than the stop position and the irradiation of the X-ray flux is interrupted by a shutter part 30 provided on the collimator rod 21 in this state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is capable of switching the aperture width of an irradiation X-ray flux from an X-ray tube to a plurality of types according to various slice widths in order to capture tomographic images of a plurality of types of slice widths. The present invention relates to an X-ray CT apparatus in which the constructed X-ray collimator apparatus is attached to an X-ray tube, and more particularly to an improved technique of the X-ray collimator apparatus.

[0002]

2. Description of the Related Art A conventional X-ray collimator device of this type is
A mechanism in which a cylindrical member called a collimator rod is rotated around the axis is used. In this collimator rod, a plurality of openings are formed in a radial shape in cross section, and the collimator rod is rotated around the axis by a motor or the like, and the central axis of each opening and the irradiation X-ray flux from the X-ray tube. The rotation of the motor is controlled so that the rotation is stopped only at a plurality of diaphragm positions aligned with the irradiation center axis in the width direction. Then, for example, an X-ray shielding member such as a lead plate in which a slit is formed is attached to one end side of the opening, and X
The irradiation X-ray flux from the X-ray tube is focused by this slit to a diaphragm width corresponding to the slice width, and is irradiated from the X-ray collimator device.

By the way, when the X-ray CT apparatus is installed or when the X-ray tube is adjusted during maintenance, the X-ray tube is irradiated with the X-ray flux. However, if the irradiation X-ray flux during the adjustment leaks to the outside, the adjustment is performed. X-ray exposure to workers who perform the work becomes a problem.
Further, even when a tomographic image is taken, if X-rays are emitted when it is not necessary to be emitted due to an operation error or a malfunction of the apparatus, unnecessary X-rays are emitted to the subject. Therefore, it is necessary to prevent such inconvenience from occurring.

Therefore, this type of X-ray collimator device is
The aperture width of the irradiation X-ray flux is regulated, and a shutter mechanism for blocking the irradiation X-ray flux from the X-ray tube with the X-ray collimator device is provided to prevent the X-ray flux from being irradiated to the outside when unnecessary. I am trying.

In the conventional X-ray collimator device, a shutter plate such as a lead plate is attached to one end of one of the plural (at least three or more) openings formed in the collimator rod. Of the X-ray flux in a state where the central axis of this opening and the central axis of the irradiation X-ray flux from the X-ray tube in the width direction are aligned (the rotation of the collimator rod is stopped at a position corresponding to a specific diaphragm position). Irradiation is blocked by a shutter plate, which serves as a shutter mechanism, and the central axis of the remaining openings (at least two) and the irradiation X from the X-ray tube.
By switching the irradiation center axes in the width direction of the beam bundle (stopping the rotation of the collimator bar at each diaphragm position corresponding to the remaining opening), the diaphragm width of the irradiated X-ray flux is switched according to various slice widths. I am trying.

[0006]

However, the prior art having such a structure has the following problems. That is, in an X-ray collimator device using a collimator rod, there is a limit to the number of openings that can be formed in the collimator rod. The number of width types) is also limited. However, in the structure in which one of the openings is used as a shutter as in the conventional example,
The number of types of aperture widths that can switch the irradiation X-ray flux is further reduced.

If it is attempted to increase the number of types of aperture widths that can switch the irradiation X-ray flux in the conventional X-ray collimator device, a new opening must be formed in the collimator rod, and accordingly the collimator rod must be formed. Because the strength decreases
The size of the collimator bar must be increased. However, if the size of the collimator rod becomes large, the rotation speed of the collimator rod is reduced, the function of the device is degraded, the size of the X-ray collimator device is increased, and in some cases, the X-ray collimator device is attached. The design of the line CT apparatus itself may need to be changed, which is not preferable.
Further, if the number of openings formed in the collimator rod is increased, there is a problem that the time and labor required to process the collimator rod increases.

The present invention has been made in view of the above circumstances, and is provided with a shutter mechanism and increases the number of types of aperture widths that can switch the irradiation X-ray flux without causing the above-mentioned inconvenience. It is an object of the present invention to provide an X-ray CT apparatus including an X-ray collimator device capable of performing the above.

[0009]

The present invention has the following configuration to achieve the above object. In other words, the present invention is configured so that the aperture width of the irradiation X-ray flux from the X-ray tube can be switched to a plurality of types according to various slice widths in order to capture tomographic images of a plurality of types of slice widths. In an X-ray CT apparatus in which a collimator device is attached to the X-ray tube, the X-ray collimator device has a cylindrical collimator rod in which a plurality of openings are radially formed in a cross section, and the collimator rod has an axial center. A rotation driving unit that rotates around and stops rotation at a plurality of diaphragm positions where the central axis of each of the openings and the irradiation central axis of the irradiation X-ray flux in the width direction are aligned, and the rotation driving unit that is stopped at each of the diaphragm positions. A plurality of slits arranged on the path of the irradiation X-ray flux in a state and regulating the width of the irradiation X-ray flux with various aperture widths for each aperture position (the opening) according to various slice widths. ,
Further, the rotation driving means is configured to stop the rotation of the collimator rod even at a predetermined shutter position other than the aperture position, and is arranged on the path of the irradiation X-ray flux while being stopped at the shutter position. As described above, the X-ray shielding member is provided on the collimator rod.

[0010]

The operation of the present invention is as follows. When the rotation driving means stops the collimator rod at each diaphragm position, each slit switches the width of the irradiation X-ray flux to various diaphragm widths. Further, when the rotation driving means stops the rotation of the collimator rod at a predetermined shutter position other than the diaphragm position, the X-ray shielding member provided on the collimator rod irradiates the collimator rod stopped at the shutter position. Since it is arranged on the path of the X-ray flux, the irradiation of the X-ray flux from the X-ray collimator device is blocked by this X-ray blocking member, and it acts as a shutter.

Therefore, all the openings formed in the collimator rod can be used for adjusting the aperture width of the irradiation X-ray flux, and the collimator rod having the same size and the same number of openings as the conventional apparatus is used. However, the aperture width of the irradiation X-ray flux can be switched more by one type than in the conventional apparatus.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. 1 and 2 are diagrams showing a schematic configuration of an X-ray CT apparatus according to an embodiment of the present invention.
In Fig. 2, the gantry portion is shown in a vertical sectional view as seen from the side, and in Fig. 2, the gantry is shown as a vertical sectional view as seen from the front.

This device comprises a bed 1 and a gantry 2. Bed 1 is bed base 3 installed on the floor
The top plate 4 on which the subject M is placed is supported and configured on the upper part of the. The bed base 3 is internally provided with a drive source 5 such as a motor and an air cylinder, and a drive source 6 such as a motor. By driving the drive source 5, the top plate 4 is moved up and down, and by driving the drive source 6, the top plate 4 moves back and forth from the bed base 3 to the opening 7 of the gantry 2 (horizontal movement).
It is configured to be.

The gantry 2 is formed with an opening 7 through which the subject M placed on the top plate 4 is inserted and removed, and the rotary frame 8 and X
A ray tube 9, an X-ray detector 10, a driving source 11 such as a motor,
An X-ray collimator device 12, a data acquisition electronics (DAS) 13, and the like, which are essential parts of the present invention, are internally provided. The rotating frame 8 is rotatably supported in the gantry 2 around the central axis CJ of the opening 7. In this rotating frame 8,
The X-ray tube 9 and the X-ray detector 10 are arranged facing each other and attached. Then, by driving the drive source 11, the rotary frame 8 is rotated around the central axis CJ of the opening 7 via the belt transmission mechanism 14, and the X-ray tube 9 and the X-ray detector 10 are kept facing each other. Meanwhile, it is adapted to be rotated around the central axis CJ of the opening 7.

An X-ray high voltage generator (not shown) is connected to the X-ray tube 9, and a predetermined tube voltage and tube current are supplied to the X-ray tube 9 from the X-ray high voltage generator.
The X-ray tube 9 is configured to irradiate the subject M on the top plate 4 with the X-ray flux. An X-ray collimator device 12 is attached to the X-ray irradiation side of the X-ray tube 9. X
Although details of the line collimator device 12 will be described later, the spread angle α (see FIG. 2) of the irradiation X-ray flux from the X-ray tube 9 and the aperture width w (see FIG. 1) are regulated by the X-ray collimator device 12. It is supposed to be done. The divergence angle α is the subject M
Fixedly so that the X-ray flux is irradiated to the entire body side direction of
On the other hand, the aperture width w can be switched to a plurality of types of aperture width w so that tomographic images of various slice widths SW can be captured according to the shape of the imaged region and the like. . Note that XP in the figure indicates the X-ray focus of the irradiation X-ray flux from the X-ray tube 9.

A DAS 13 is connected to the X-ray detector 10 so that the DAS 13 collects the transmitted X-ray data transmitted through the subject M and detected by the X-ray detector 10. The DAS 13 gives the collected transmission X-ray data to an image processing unit (not shown). The image processing unit is the X-ray detector 1.
Based on the transmission X-ray data from the orbiting direction of the subject M collected while 0 and the like are rotated around the subject M, the region (slice width SW) of the region imaged using a well-known calculation method. A tomographic image is calculated, and the obtained tomographic image is given to an output device (not shown) to be output. The output device may be a monitor that displays the obtained tomographic image, a storage device that stores the obtained tomographic image, or an image recording device that prints or prints the obtained tomographic image on recording paper or film. It is configured.

Imaging by the X-ray CT apparatus having the above structure is performed as follows. First, the subject M is placed on the lowered top plate 4, and the top plate 4 is raised so that the body axis J of the subject M is aligned with the central axis CJ of the opening 7 of the gantry 2. Adjust the height. Next, the top plate 4 is moved horizontally, and the subject M on the top plate 4 is inserted into the opening 7 of the gantry 2, and the part of the subject M to be imaged is captured by the X-ray tube 9 and the X-ray detector. 10 is positioned on the imaging plane SP on which it is rotated.
Then, while irradiating the X-ray flux from the X-ray tube 9,
And the X-ray detector 10 are rotated around the body axis J of the subject M (center axis CJ of the opening 7), transmission X-ray data from the orbiting direction of the subject M is collected by the DAS 13, and based on the collected data. The tomographic image of the part is reconstructed by the image processing unit.

At this time, since the optimum slice width SW is determined according to the shape of the imaged region, etc., the X-ray collimator device 12 has such a slice width SW (it differs depending on the imaged region). The aperture width w of the irradiated X-ray flux is switched and the image is taken. In addition, in order to prevent unnecessary X-rays from being emitted to the subject M due to an operation error or a malfunction of the apparatus after the end of imaging, X
The line collimator device 12 is controlled so that the shutter is closed to block the irradiation of the X-ray flux from the X-ray collimator device 12. Further, even when the X-ray CT apparatus is installed or when the X-ray tube 9 is adjusted during maintenance, the shutter of the X-ray collimator apparatus 12 is closed in order to prevent X-ray exposure to an operator who performs the adjustment work. X-ray collimator device 12
The above-mentioned adjustment work is performed with the irradiation of the X-ray flux from the.

Next, the detailed structure of the X-ray collimator device 12, which is a main part of the present invention, will be described with reference to FIGS.

FIG. 3 is a side view of the X-ray collimator device (see FIG. 1).
FIG. 4 is a vertical cross-sectional view seen from the front side (side of FIG. 2) of the X-ray collimator device, and FIG.
FIG. 6 is a partially omitted view showing a configuration of a collimator rod and the like.

The X-ray collimator device 12 comprises a collimator rod 21, a stepping motor 22, a motor driver 23, a position detector 24, etc., which are housed in an outer envelope 25. The collimator bar 21 is formed of a light metal such as aluminum, and a plurality of (four in the figure) openings 26a to 26d are radially formed in a cross section (see FIG. 3). Among these four openings 26a-26d, in this embodiment, X-ray shielding members 28a-28c such as lead plates having slits 27a-27c formed at one end sides of the three openings 26a-26c are provided. It is attached. The respective slits 27a to 27c have various slice widths SW (for example, S
W1, SW2, SW3: However, SW1 <SW2 <SW
3) Aperture width w of the irradiated X-ray flux so that a tomographic image of 3) can be taken (for example, w1 for SW1, w2 for SW2, S
When it is W3, it is restricted to w3).

The collimator rod 21 is rotatably supported within the outer envelope 25 about the axis RJ, and is driven to rotate about the axis RJ by the stepping motor 22. The rotation of the stepping motor 22 is controlled by the motor driver 23, and the motor driver 23 controls the rotation of the stepping motor 22 based on the position information from the position detector 24 and the like.

An X-ray shield plate 29 such as a lead plate is attached to the lower surface of the outer envelope 25, and an X-ray irradiation window from the X-ray collimator device 12 is provided on the lower surface of the X-ray shield plate 29 and the outer envelope 25. A slit 27d that functions as is formed. The width of the slit 27d in the lateral direction is the maximum slice width (SW
4. However, the aperture width of the irradiation X-ray flux is limited to w4 so that a tomographic image of SW4> SW3) can be captured. In addition, the length of the slit 27d in the longitudinal direction is configured to uniformly control the spread angle of the X-ray flux with which the subject M is irradiated to α, as shown in FIGS. 2 and 4.

As shown in FIG. 5, the position detecting section 24 is composed of a disc 31, a transmission type photodetector 32, and the like.
The light emitter 32a and the light receiver 32b of the photodetector 31 are the disc 3
They are opposed to each other with 1 in between. The center of the disc 31 is connected to the axis RJ of the collimator rod 21, and is rotated about the center (same as RJ) in association with the rotation of the collimator rod 21 around the axis RJ. The disk 31 has a slit 31a formed at one location. Then, for example, when the central axis QJ1 of the opening 26a is aligned (matched) with the irradiation central axis XJ in the width direction of the irradiation X-ray flux from the X-ray tube 9 (the state of FIG. 3), the slit 31a emits light. The measurement light from the projector 32a is positioned at the position where the detector 32 is arranged, the measurement light is received by the light receiver 32b, and the "ON" signal is output from the light detector 32 (light receiver 32b) to the motor driver 23. There is. When the measurement light from the light projector 32a is not received by the light receiver 32b, the light detector 32
Outputs an “OFF” signal to the motor driver 23.

The motor driver 23 includes a photodetector 32.
When the "ON" signal is received from, the position is set as a reference position for rotation of the collimator rod 21, and the number of drive pulses to the stepping motor 22 is controlled to control the rotation of the collimator rod 21. In addition, the motor driver 23, X
A control unit (not shown) of the line CT apparatus gives an instruction regarding switching of the aperture width w (w1 to w4) of the irradiation X-ray flux and a collimating instruction such as an instruction to close the shutter.

Next, the X-ray collimator device 12 having the above structure.
Will be described. First, when the controller of the X-ray CT apparatus gives an instruction to switch to the aperture width w1 of the irradiated X-ray flux corresponding to the slice width SW1, the motor driver 23 rotates the stepping motor 22 and the position detector 24.
When receiving the "ON" signal from, the rotation of the stepping motor 22 is stopped. As a result, the central axis QJ1 of the opening 26a and the irradiation X for setting the aperture width of the irradiation X-ray flux to w1.
The irradiation center axis XJ in the width direction of the ray bundle is aligned with the irradiation center axis XJ (the state shown in FIG. 3), and the irradiation from the X-ray tube 9 is performed to open the opening 2
The X-ray flux that has passed through 6a is narrowed down to w1 by the slit 27a and narrowed down to the narrowing width w1 corresponding to the slice width SW1.
The ray bundle is emitted from the X-ray collimator device 12. In addition,
The spread angle of this X-ray flux is narrowed down to α by the slit 27d.

From the controller of the X-ray CT apparatus, the slice width SW
When an instruction to switch to the aperture width w2 of the irradiation X-ray flux corresponding to 2 is given, the motor driver 23 rotates the stepping motor 22, and the position detection unit 24 outputs “O”.
The number of drive pulses that cause the collimator rod 21 to rotate 3/8 (or 5/8) after receiving the "N" signal (for example, if n drive pulses are required to rotate the collimator rod 21 once). 3 × n / 8 (or 5 × n /
The stepping motor 22 is driven so as to rotate the collimator rod 21 counterclockwise (or clockwise) in FIG. 3 by the driving pulse number of 8), and the rotation of the stepping motor 22 is rotated when a predetermined amount is rotated. Stop. As a result, the opening 26b that sets the aperture width of the irradiation X-ray flux to w2.
Center axis QJ2 of the X-ray and the irradiation center axis XJ in the width direction of the irradiation X-ray flux.
In this state, the X-ray collimator device 12 irradiates the X-ray flux with the aperture width w2 corresponding to the slice width SW2 and the divergence angle α.

Further, from the control unit of the X-ray CT apparatus, the aperture widths w3 and w of the irradiation X-ray flux corresponding to the slice widths SW3 and SW4 are set.
The operation when the instruction to switch to 4 is given is the same as when the aperture width of the irradiation X-ray flux is switched to w2, but when the aperture width of the irradiation X-ray flux is switched to w3,
The number of driving pulses of the stepping motor 22 after receiving the "ON" signal causes the collimator rod 21 to rotate ¼ rotation clockwise (or counterclockwise 3/4 rotation) in FIG.
Is the number of drive pulses to be used, and the aperture width of the irradiation X-ray flux is w4
When switching to, the number of drive pulses of the stepping motor 22 after receiving the "ON" signal drives the collimator rod 21 to rotate counterclockwise 1/8 rotation (or clockwise 3/8 rotation) in FIG. The number of pulses. In addition,
QJ3 and QJ4 in FIG. 3 are the central axes of the openings 26c and 26d. When the central axis QJ4 of the opening 26d and the central irradiation axis XJ of the irradiation X-ray flux in the width direction are aligned with each other, the aperture width of the irradiation X-ray flux is narrowed to w4 by the slit 27d serving as the X-ray irradiation window. . The opening 26
In the state where the central axes QJ1 to QJ3 of a to c and the irradiation central axis XJ in the width direction of the irradiation X-ray flux are aligned, the slit 27 is formed.
Since the width of the irradiation X-ray flux is narrowed to the narrower widths w1 to w3 which are narrower than the narrower width w4 of d, the slit 27d acts only to restrict the spread angle to α.

The central axis QJ of each of the openings 26a to 26d.
The positions of the collimator rods 21 when 1 to QJ4 and the irradiation center axis XJ in the width direction of the irradiation X-ray flux are aligned correspond to the respective diaphragm positions (four positions in this embodiment) in the present invention.

Next, the operation when the shutter closing instruction is given from the control unit of the X-ray CT apparatus will be described. At this time, the central axes QJ1 to QJ4 of any one of the openings 26a to 26d and the irradiation central axis XJ in the width direction of the irradiation X-ray flux are aligned (positioned at any diaphragm position),
It is assumed that the aperture width of the irradiated X-ray flux is regulated by any of the aperture widths w1 to w4. For example, as shown in FIG. 3, when the central axis QJ1 of the opening 26a and the irradiation central axis XJ in the width direction of the irradiation X-ray flux are aligned with each other, the motor driver 23 receives the instruction to close the shutter. , The collimator rod 21 drives the motor 22 with the number of drive pulses rotated clockwise by the angle θ of FIG. 6 in FIG.
Stop the rotation of. This position is the shutter position in this invention. When the rotation of the collimator rod 21 is stopped at this shutter position, as shown in FIG. 6, the X-ray shield member 28a provided on the collimator rod 21 is arranged on the path of the irradiation X-ray flux in that state. Slit 27
The irradiated X-ray flux hits the portion (shutter portion) 30 where a is not formed, and the irradiation of the X-ray flux from the X-ray collimator device 12 is blocked, and the shutter functions as a shutter. Therefore, the width d of the shutter portion 30 of the X-ray shielding member 28a (same for 28b and 28c) is set wider. In addition,
In the figure, the X-ray flux passes through a portion other than the opening of the collimator rod 21, but since the collimator rod 21 itself is made of a light metal such as aluminum, X-rays are transmitted.
Further, at the diaphragm position, the X-ray flux has openings 26a, 26d.
Therefore, the irradiation X-ray flux is not attenuated by the collimator rod 21.

For comparison, FIG. 7 shows a main part of the X-ray collimator device 12 having the conventional structure. In the X-ray collimator device 12 having the conventional configuration, the shutter plate 40 is attached to one end side of the opening 26a and is used as a shutter. Therefore, only three types of switching of the aperture width w of the irradiation X-ray flux can be performed. However, according to this embodiment, the aperture width w of the irradiation X-ray flux can be switched among four types while realizing the shutter function.

The portion of the X-ray shielding member 28a on the left side of the slit 27a in FIGS. 3 and 6 may be the shutter portion 30, or the slit 27 of the X-ray shielding members 28b and 28c.
The left and right portions of b and 27c may be used as the shutter unit 30. However, it is preferable to use the portion of the X-ray shielding member 28a having the smallest slit width, in which the slit 27a is not formed, as the shutter portion 30 because leakage of X-rays can be more appropriately prevented.

When the instruction to close the shutter is received, the motor driver 23 rotates the stepping motor 22 regardless of the position of the collimator bar 21 and the position detector 24 turns "ON".
After receiving the signal, the collimator bar 21 may be rotated clockwise (or counterclockwise) in FIG. 3 by θ so that the shutter portion 30 of the X-ray blocking member 28a is always used as a shutter. In the case of such control, only the X-ray blocking member 28a needs to widen the portion (shutter portion 30) where the slit is not formed. Further, when controlling to use only the shutter portion 30 on either the left or right side of the X-ray shielding member 28a as a shutter, the shutter portion 30 on either the left or right side (a wide portion) is provided on the X-ray shielding member 28a. It only needs to be formed.

In the structure of the above embodiment, it is necessary to form a recess in the collimator bar 21 for attaching the wide X-ray shielding member 28a provided with the shutter portion 30, for example, as shown in FIG. As shown in a), the shutter portion 30 having a shape along the peripheral surface of the collimator rod 21 is provided on the left and right of the slit 27a of the X-ray shielding member 28a, and the X-ray shielding member 28a has an anchor-shaped cross section. , Collimator rod 2
It is not necessary to form the above-mentioned concave portion in 1. FIG. 8 (a)
Shows the case where the shutter unit 30 is provided only on the X-ray shielding member 28a, the X-ray shielding members 28b and 28c.
Also, a similar shutter unit 30 may be provided.

Further, as shown in FIG. 8B, an X-ray shielding member 50 is attached on the peripheral surface of the collimator rod 21 where the openings 26a to 26d are not formed, and when the shutter is closed, the irradiation X-ray flux is increased. This X-ray shielding member 50 on the path
Collimator bar 2 at the position (shutter position) where
1 rotation is stopped (for example, in the case of FIG. 8B, from the state where the central axis QJ1 of the opening 26a and the irradiation central axis XJ in the width direction of the irradiation X-ray flux coincide with each other, rotate clockwise by ρ in the figure. It can be stopped in the state where it was made).

Further, as shown in FIG. 9A, a new photodetector 33 (projector 33a, photoreceiver 3) is provided in the position detector 24.
3b) is provided, and the slit 31b acting on the photodetector 33 is rotated by θ from the slit 31a in the clockwise direction.
(Or ρ) The new photodetector 3 is provided at the rotated position.
3 gives an “ON” signal to the motor driver 23, the motor driver 23 causes the stepping motor 2
The rotation of the collimator rod 21 is stopped at the shutter position where the shutter unit 30 (or the X-ray shielding member 50) is arranged on the path of the irradiated X-ray flux, and the shutter is closed. You may.

Further, as shown in FIG. 9B, three sets of photodetectors 32, 33, 34 are provided, and the disc 31 is provided.
Slit 31a acting on the photodetector 32, and the photodetector 3
3 acting on the slit 3b, the photodetector 34 (the projector 3
3a, a slit 31c acting on the photodetector 33b) is provided, and “ON” from the three sets of photodetectors 32, 33, 34,
Depending on the combination of "OFF", the openings 26a-26
The central axes QJ1 to QJ4 of d and the irradiation central axis XJ of the irradiation X-ray flux in the width direction are individually identified, and the shutter unit 30 (or the X-ray shielding member 50) is provided on the path of the irradiation X-ray flux. ) May be configured to identify the state in which they are placed.

[0038]

As is apparent from the above description, according to the present invention, the irradiation X-ray flux is cut off at the shutter position other than the stop position of the rotation of the collimator rod, so that the collimator rod is formed. All the openings can be used for switching the aperture width of the irradiation X-ray flux, and while using a collimator rod having the same size and the same number of openings as the conventional apparatus, one more irradiation X than the conventional apparatus can be used. It is now possible to switch the aperture width of the wire bundle.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an X-ray CT apparatus according to one embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of a gantry of the embodiment apparatus as seen from the front.

FIG. 3 is a vertical cross-sectional view of the X-ray collimator device as seen from a side surface.

FIG. 4 is a vertical cross-sectional view of the X-ray collimator device as viewed from the front.

FIG. 5 is a partially omitted view showing the configuration of a collimator rod and the like.

FIG. 6 is a diagram showing a state in which a shutter is closed by the X-ray collimator device provided in the apparatus of the embodiment.

FIG. 7 is a longitudinal sectional view of a main part of an X-ray collimator device having a conventional structure.

FIG. 8 is a vertical cross-sectional view showing configurations of various modifications of the collimator rod.

FIG. 9 is a diagram showing a configuration of various modified examples of a position detection unit.

[Explanation of symbols]

 9 ... X-ray tube 12 ... X collimator device 21 ... Collimator rod 22 ... Stepping motor 23 ... Motor driver 24 ... Position detection part 26a-26d ... Opening part 27a-27d formed in the collimator rod ... Slit 30 ... Shutter part 50 ... X-ray shielding member SW ... Slice width w (w1 to w4) ... Aperture width RJ ... Collimator rod axis QJ1 to QJ4 ... Center axis of each opening XJ ... Irradiation center axis of irradiation X-ray flux in width direction.

Claims (1)

[Claims] 1. An X-ray collimator configured to switch a diaphragm width of an irradiation X-ray flux from an X-ray tube to a plurality of types according to various slice widths in order to capture tomographic images having a plurality of slice widths. X-ray C attached to the X-ray tube
In the T-apparatus, the X-ray collimator device has a cylindrical collimator rod in which a plurality of openings are formed in a radial shape in a cross section, and the collimator rod is rotated about an axis to form a central axis of each of the openings. Rotation driving means for stopping rotation at a plurality of diaphragm positions aligned with the irradiation center axis of the irradiation X-ray flux in the width direction, and arranged on the path of the irradiation X-ray flux while being stopped at each diaphragm position, A plurality of slits for restricting the width of the irradiation X-ray flux with various aperture widths for each aperture position (the opening) according to various slice widths; and the rotation driving means other than the aperture position. Of the collimator rod is stopped even at the predetermined shutter position, and the collimator is provided with an X-ray shielding member so that the collimator rod is arranged on the path of the irradiation X-ray flux while being stopped at the shutter position. X-ray CT, characterized in that provided in
apparatus.