JP4421237B2 - X-ray CT system - Google Patents

Description

The present invention relates to an X-ray computed tomography apparatus (hereinafter referred to as an X-ray CT apparatus),
The present invention relates to an X-ray CT apparatus having a function of an X-ray TV apparatus for obtaining a fluoroscopic image.

A known X-ray CT apparatus referred to as a third generation has an X-ray tube and a multi-channel X-ray detection element arranged in a row with a subject in between, and these are arranged oppositely. , 3 around the subject
While rotating through 60 °, the subject is irradiated with an X-ray beam from the X-ray tube, the X-ray dose transmitted through the subject is measured as projection data by an X-ray detector, and a computer is used based on this data. The tomographic image of the subject is obtained by performing image reconstruction processing.

As described above, the X-ray CT apparatus can usually obtain only a tomographic image. However, for example, during surgery, a fluoroscopic image of the entire region of interest of the subject may be required together with the tomographic image. Attempts have been made to place an X-ray CT apparatus and an X-ray TV apparatus in the operating room. However, space is limited in the operating room, and it is often difficult to install these two types of large medical image diagnostic apparatuses.

Therefore, a two-dimensional X-ray detector is arranged so as to face the X-ray tube, a fluoroscopic image is obtained by this two-dimensional X-ray detector, and projection data is obtained from the same two-dimensional X-ray detector. An X-ray CT apparatus that can reconstruct a tomographic image, a stereoscopic image, and the like has been proposed (see, for example, Patent Document 1). As a result, a fluoroscopic image and a tomographic image can be obtained with a single apparatus, so that the space in the operating room is effectively utilized. In addition, in this X-ray CT apparatus, two X-ray tubes are arranged on a gantry at an interval of 90 degrees to obtain a fluoroscopic image in two directions, for example, a needle for performing a percutaneous needle biopsy And facilitated catheter guidance.

An X-ray CT apparatus has also been proposed in which an X-ray film cassette or an X-ray flat panel detector can be arranged at a position corresponding to the X-ray detector of the X-ray CT apparatus (see, for example, Patent Document 2).
). This device requires that the X-ray film cassette or X-ray flat panel detector be set at a predetermined position when obtaining a fluoroscopic image, and when obtaining a tomographic image, the X-ray beam is shaped into a fan shape. When obtaining a fluoroscopic image, a collimator is set so that the X-ray beam is shaped into a cone shape.
JP-A-7-231888 (page 3-4, FIG. 1) JP-A-11-146874 (page 4, FIG. 1)

However, the technique disclosed in Patent Document 1 has a drawback that the fluoroscopic image becomes a curved and distorted image because the two-dimensional X-ray detector is curved. Moreover, the thing of patent document 2 has the trouble which sets an X-ray film cassette or an X-ray flat panel detector in a predetermined position, and lacks real-time property, when obtaining a fluoroscopic image.

Recently, for example, a so-called multi-slice X-ray CT apparatus has been put into practical use in which tomographic imaging of a large number of slices is simultaneously performed by an X-ray detector in which, for example, 800-channel X-ray detection elements are arranged in a matrix of 256 columns, for example. According to the X-ray detector having such a number of columns, it is possible to cover the fluoroscopic range of the entire region of interest.

Based on such a situation, the present invention regards an X-ray detector having a plurality of rows of multi-channel X-ray detection elements as a surface detector to obtain a perspective image without distortion, and from the same X-ray detector. The present invention has been made for the purpose of providing an X-ray CT apparatus capable of forming a tomographic image by using projection data.

In order to solve the above-described problem , an X-ray generation unit and an X-ray detection unit including a plurality of rows of multi-channel X-ray detection elements arranged in a row with a subject in between are disposed on the body axis of the subject. In the X-ray CT apparatus, which is disposed so as to be capable of rotating around, and measures the X-ray dose transmitted through the subject as X-rays irradiated from the periphery of the subject as projection data, the X-ray generating means disposed oppositely Position adjustment means for stopping the X-ray detection means at a desired angular position in the rotation around the body axis, and the angular position in the rotation around the body axis of the X-ray generation means can be visually recognized. And a position display means .

According to the present invention, a fluoroscopic image can be obtained by stopping the X-ray generation means and the X-ray detection means in a desired direction with respect to the body axis direction of the subject, and by observing the fluoroscopic image, For example, the insertion of a catheter when performing a percutaneous needle biopsy can be accurately guided.

Hereinafter, an X-ray CT apparatus according to an embodiment of the present invention will be described in detail with reference to FIGS.

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

As shown in FIG. 1, the X-ray CT apparatus according to the present invention includes an X-ray tube 2 that irradiates a subject P with X-rays toward a subject P, and an X-ray with the subject P in between. An X-ray detector 4 that is disposed so as to face the tube 2 and detects an X-ray dose that has passed through the subject P is provided, and these are configured to rotate together with the gantry 1. The X-ray tube 2 is given a tube voltage and a tube current by the high voltage generator 5, and the values are appropriately changed according to a CT mode and a fluoroscopy mode described later.

Further, the gantry 1 is controlled to be continuously driven to rotate in a predetermined direction by the rotation driving unit 6 or to rotate in the forward direction or the reverse direction at every desired angle with reference to the predetermined position. A couch top 7 on which the subject P is placed is placed in a space between the X-ray tube 2 and the X-ray detector 4 arranged facing each other. A bed driving unit 8 is provided that moves horizontally in the body axis direction (front-rear direction) of the subject P, or moves in the left-right direction (width direction) with respect to the body axis direction, and further moves in the up-down direction. .

As shown schematically in FIG. 2 as a schematic plan view, the X-ray detector 4 includes, for example, 800 channels of X-ray detection elements arranged in a line in accordance with the spread of the X-ray beam emitted from the X-ray tube 2. The arrangement (C1 to C800) is configured by arranging, for example, 256 rows (S1 to S256) in parallel in the slice direction (that is, the body axis direction of the subject P), and is so-called multi-slice compatible. Yes. A mode switch 9 is provided on the output side of the X-ray detector 4, and the mode switch 9 outputs the output of the X-ray detector 4 in accordance with switching between a CT mode and a fluoroscopic mode, which will be described later. The data collection unit 10 and the perspective image generation unit 11 which are selectively supplied are connected.

Subsequent to the data collection unit 10, an image reconstruction unit 12 for reconstructing a tomographic image based on transmission data collected by the data collection unit 10, a display unit 13 for displaying the reconstructed tomographic image, and the like are provided. ing. Further, the fluoroscopic image generated by the fluoroscopic image generating unit 11 is also supplied to the display unit 13 and displayed. The display unit 13 includes a plurality of display devices such as a television monitor, and the tomographic image and the fluoroscopic image are displayed on separate display devices.

A system controller 15 having a computer or a memory that performs a central function of organically controlling each unit constituting the X-ray CT apparatus, and an operator makes various settings for the system controller 15. An operation unit 16 is provided for inputting values and instructions. The operation unit 16 includes a touch panel 17 that can display operation contents and the like in figures and characters, and can be operated by touching display items with a finger, and an X-ray that displays the position of the X-ray tube 2 in the fluoroscopic mode. A tube position indicator 18 is also provided.

Next, the operation of the X-ray CT apparatus according to the present embodiment configured as described above will be described.

First, depending on whether the operator uses the X-ray CT apparatus as a CT mode for obtaining a tomographic image or as a fluoroscopic mode for obtaining a fluoroscopic image like an X-ray television, the mode of the operation unit 16 is selected. A changeover switch (not shown) is operated to switch between the CT mode and the fluoroscopic mode. Thereby, when the CT mode is selected, the mode switch 9 is switched via the system control unit 15 so as to supply the output of the X-ray detector 4 to the data acquisition unit 10. Furthermore, the system control unit 15 controls the high voltage generation unit 5 so that the application condition of the high voltage to the X-ray tube 2 is, for example, 120 kV and 300 mA suitable for CT imaging, and further, the gantry 1 is moved in a predetermined direction. For example, the rotational drive unit 6 is controlled so as to be continuously driven at a speed of 0.5 seconds / rotation. Since the operation at the time of such CT imaging is the same as that of a normal X-ray CT apparatus, the description thereof is omitted.

On the other hand, when the fluoroscopic mode is selected by a mode selector switch (not shown) of the operation unit 16, the system control unit 1 is configured to supply the output of the X-ray detector 4 to the fluoroscopic image generation unit 11.
The mode switch 9 is switched via 5. At the same time, the setting is changed so that 120 kV, 100 mA suitable for fluoroscopic imaging, for example, 120 kV is applied to the X-ray tube 2 for the high voltage generation unit 5, and continuous rotation is stopped for the rotation drive unit 6 For example, the control means is changed so that the gantry 1 is rotated by a predetermined angle in the forward direction or the reverse direction with reference to the position where the X-ray tube 2 is directly above the subject P.

When the fluoroscopic mode is set, the system control unit 15 drives the rotation driving unit 6 to temporarily stop the X-ray tube 2 at a reference position directly above the subject P. In addition, the operator may
Is positioned by moving the couch top 7 back and forth, up and down, and left and right by the couch driving unit 8 so that the desired shooting position is obtained. Further, a position where the X-ray tube 2 and the X-ray detector 4 face the subject P is set (an X-ray irradiation angle with respect to the body axis of the subject P). These settings such as positioning are performed by operating the touch panel 17 provided in the operation unit 16. An outline of an example of the touch panel 17 is shown in FIG.

That is, in FIG. 3 (a), reference numeral 17a denotes a position operating portion of the X-ray tube 2, which is shown in FIG.
As shown enlarged in (b), the operator's fingertip is applied to the tube mark M, and the information is transmitted to the system control unit 15 by tracing this to the desired position on the displayed trajectory. Then, the system control unit 15 drives the rotation driving unit 6 to rotate the gantry 1 so that the X-ray tube 2 comes to the designated position. As indicated by the arrows, movement in the forward direction and the reverse direction is possible.

Further, in FIG. 3A, reference numeral 17b denotes an operation unit for moving the couch top 7 in the width direction. By tracing the displayed arrow in a desired direction with the fingertip of the operator, the information is indicated. Is transmitted to the system control unit 15, and the system control unit 15 drives the couch driving unit 7 to move the couch top 7 so that the subject P is at the designated position. Similarly, reference numeral 17c is
An operation unit for moving the couch top 7 in the front-rear direction and the up-down direction is shown. By tracing the displayed arrow with a fingertip of the operator in a desired direction, the information is transmitted to the system control unit 15, The system control unit 15 drives the bed driving unit 7 to drive the bed top plate 7 in the front-rear direction and the vertical direction to place the subject P at a specified position.

When the position of the subject P and the imaging direction are determined, the operator selects an imaging button (not shown) on the operation unit 16.
Press to start fluoroscopy. Therefore, for example, 120 kV and 100 mA suitable for fluoroscopic imaging are applied from the high voltage generator 5 to the X-ray tube 2, and X-rays are irradiated from the X-ray tube 2 toward the subject P. FIG. 4 shows a state of an X-ray bundle irradiated from the X-ray tube 4 and incident on the X-ray incident surface of the X-ray detector 4. The X-ray is an X-ray incident surface of the X-ray detector 4. The size is shaped by a collimator (not shown).

By the way, although the X-ray detector 4 is shown in FIG. 2 as a schematic plan view, actually, as shown in FIG. 4, each X-ray detection element from the focal point (X-ray source F) of the X-ray tube 2 is used. The X-ray incident surface of the X-ray detector 4 is curved so that the distance up to is constant. Therefore, when the detection data of the X-ray detector 4 is used as it is and displayed as a fluoroscopic image of the subject P, a distorted image is obtained. Therefore, the perspective image generation unit 11 receives the data from the X-ray detector 4 and, as shown in FIG. 5, the plane So orthogonal to the X-ray path Lo connecting the X-ray source F and the center of the X-ray detector 4. Alternatively, a re-projection process is performed on a plane parallel to the plane So, and the re-projected image is displayed on the display unit 13 as a perspective image. Here, the surface So is a surface passing through the rotation center O of the gantry 1. In addition, the perspective image generation unit 11 adjusts the sampling period and frame addition so that the image rate is, for example, about 30 frames / second.

Now, since the gantry 1 is usually covered with a cover, it is difficult to confirm from the outside where the X-ray tube 2 is located. However, when setting the X-ray irradiation angle with respect to the body axis of the subject P and photographing a fluoroscopic image, it is desirable that the operator can confirm the position of the X-ray tube 2. . Therefore, in the present embodiment, an X-ray tube position display unit 18 as shown in FIG. 6 that simply displays the position of the X-ray tube 2 based on a signal from an encoder provided on the gantry 1 is displayed on the operation unit 16. Is provided. Here, 18a in the figure is a mark indicating the current stop position of the X-ray tube 2. The X-ray tube position display unit 18 is shared with the position operation unit 17a of the X-ray tube 2 shown in FIG.
You may make it light a.

It goes without saying that the present invention is not limited to the embodiment of the invention described as the first embodiment and can be implemented in various forms. For example, as a means for indicating the position of the X-ray tube 2, around the through hole for inserting the subject P of the gantry cover covering the gantry 1,
For example, an LED may be arranged every 15 degrees, and an LED substantially corresponding to the position of the stopped X-ray tube 2 may be turned on by a signal from an encoder provided on the gantry 1. Then, the approximate position of the X-ray tube 2 can be displayed. This LE
D does not necessarily have to be provided on the entire circumference of the through-hole, and may be provided in a range of about 180 degrees above the couch top 4.

Further, the X-ray tube 2 inside the gantry cover covering the gantry 1 is partially or partially transparent around the through hole for inserting the subject P so that the internal X-ray tube 2 can be seen directly from the outside. It may be. In this way, the position of the X-ray tube 2 can be directly visually recognized from the outside without providing a special display. At this time, if an LED or other light emitter is provided in the X-ray tube 2 itself, the internal X-ray tube 2 covered by the gantry cover can be more easily observed from the outside through a transparent or translucent portion. .

In addition, since the X-ray tube 2 is normally stored in the envelope, in the present specification, the words such as the X-ray tube 2 being visible or the X-ray tube 2 itself are stored in the envelope. The X-ray tube 2 is also included.

1 is a system diagram showing a schematic configuration of an X-ray CT apparatus according to the present invention. Example 1 It is the plane schematic diagram which showed the outline of an example of the X-ray detector. Example 1 It is explanatory drawing which showed the principal part of the operation part. Example 1 It is explanatory drawing shown in order to demonstrate the mode of the X-ray bundle irradiated from the X-ray tube and injecting into the X-ray entrance plane of an X-ray detector. It is explanatory drawing shown in order to demonstrate the surface which reprojects as a fluoroscopic image. Example 1 It is explanatory drawing which showed the means for displaying the position of an X-ray tube. Example 1

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stand 2 X-ray tube 4 X-ray detector 5 High voltage generation part 6 Rotation drive part 7 Bed top plate 8 Bed drive part 9 Mode switch 10 Data collection part 11 Perspective image generation part 12 Image reconstruction part 13 Display part 15 System control unit 16 Operation unit 17 Touch panel 18 X-ray tube position display unit

Claims (5)

An X-ray generation means and an X-ray detection means having a plurality of rows of multi-channel X-ray detection elements arranged in a row are arranged opposite to each other so as to be rotatable around the body axis of the subject with the subject in between. In the X-ray CT apparatus for measuring, as projection data, the X-ray dose transmitted through the subject of the X-rays irradiated from around the subject,
Position adjusting means for stopping the X-ray generation means and the X-ray detection means arranged opposite to each other at a desired angular position in rotation around the body axis;
A position display unit provided in an operation unit of the X-ray CT apparatus, and enabling visual recognition of an angular position in rotation around the body axis of the X-ray generation unit;
An X-ray CT apparatus comprising: An X-ray generation means and an X-ray detection means having a plurality of rows of multi-channel X-ray detection elements arranged in a row are arranged opposite to each other so as to be rotatable around the body axis of the subject with the subject in between. In the X-ray CT apparatus for measuring, as projection data, the X-ray dose transmitted through the subject of the X-rays irradiated from around the subject,
Position adjusting means for stopping the X-ray generation means and the X-ray detection means arranged opposite to each other at a desired angular position in rotation around the body axis;
The gantry cover that houses the X-ray generation means and the X-ray detection means is formed of a light emitting member provided at predetermined angles around the subject insertion position, and the angle of rotation of the X-ray generation means about the body axis Position display means for making the position visible,
An X-ray CT apparatus comprising: An X-ray generation means and an X-ray detection means having a plurality of rows of multi-channel X-ray detection elements arranged in a row are arranged opposite to each other so as to be rotatable around the body axis of the subject with the subject in between. In the X-ray CT apparatus for measuring, as projection data, the X-ray dose transmitted through the subject of the X-rays irradiated from around the subject,
Position adjusting means for stopping the X-ray generation means and the X-ray detection means arranged opposite to each other at a desired angular position in rotation around the body axis;
The body of the X-ray generation means is made transparent or semi-transparent along at least a part of the gantry cover that houses the X-ray generation means and the X-ray detection means along the rotation trajectory of the X-ray generation means. Position display means for enabling visual recognition of the angular position in rotation around the axis;
An X-ray CT apparatus comprising: The X-ray CT apparatus according to claim 3 , wherein the X-ray generation unit is provided with a light emitting member that is visible from the outside. The X-ray detection means includes the X-ray detection element disposed along a curved X-ray incident surface,
And a fluoroscopic image generating means for generating an X-ray image of a plane orthogonal to an X-ray path connecting the X-ray generating means and the center of rotation based on a detection signal of the X-ray detecting means. The X-ray CT apparatus according to claim 1 .

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