JPH08336520A - X-ray ct system - Google Patents

Abstract

PURPOSE: To photograph an X-ray CT image even in a state in which a various kinds of instruments for treatment are mounted on an examinee by providing the system with an image intensifier and a multielement X-ray detector as an X-ray receiving means and performing X-ray lateral tomographic photographing and X-ray fluoroscopy/photography. CONSTITUTION: When the position of an X-ray source 3 is decided, a scanning center coincides with the center of the circular arc of a multielement detector 4, and also, it is adjusted at a position to cover the scanning range of an X-ray, and it is not required to move the multielement detector 4 while a CT image is image-picked up. The X-ray source 3 is supported with a supporting mechanism 10, and it is moved rotatably on the circular arc of a circular orbit centering about the examinee 1, and the X-ray source 3 is moved along the circular orbit around the periphery of the examinee 1 by locating the examinee 1 in the center of the circular arc of a C arm. The movement of the X-ray source 3 is detected by a position detecting means mounted on a supporting board or an angle detecting means mounting the direction of the X-ray source on an X-ray source carriage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray CT apparatus, and particularly when an operator operates a catheter of a subject, the X-ray is capable of capturing a tomographic image without moving the subject. Regarding a CT device.

[0002]

2. Description of the Related Art A conventional X-ray CT apparatus, as shown in FIG. 8, has a gantry 20 incorporating an X-ray scanner in which an X-ray tube and an X-ray detector are arranged to face each other, and a bed on which a subject 1 is mounted. Two
And a data processing system (not shown), the subject 1 is placed on a dedicated bed 2, and the gantry 2 of the X-ray CT apparatus is arranged in the body axis direction.
Diagnosis was made by entering the 0 opening. As the scanner method, the first to fourth generations, and further the fifth generation have been proposed, but in the method of the second and subsequent generations, there are three X-rays.
It is used as a fan beam having a spread of 0 ° to 50 °, and it is required that the geometry of both the X-ray tube and the detector does not change in order to reconstruct the projection data.
For example, in the third-generation system, the X-ray tube and the X-ray detector in which a plurality of detection elements are arranged are integrally rotated around the subject. In the fourth generation system, detectors are arranged in a circle around the subject, and X or
Rotate the tube. When the rotation trajectory of the X-ray tube is outside the detector ring, the N / R method (nutate / rotate) is adopted to move the detector so that the detector and the X-ray source do not interfere with each other. . Furthermore, as the fifth generation, an X-ray CT apparatus that deflects an electron beam generated from an electron gun and hits a target arranged in an annular shape to generate an X-ray, and further, a plurality of electron guns are used for such a target. X-ray CT apparatus having deflection means (Japanese Patent Application Laid-Open No. 60-9274)
No. 1) etc.

By the way, in recent years, a treatment method called interventional radiology (hereinafter referred to as IVR) for diagnosing an image while operating with a catheter or the like has been adopted. However, each of the above-described conventional X-ray CT apparatuses has an annular structure, and since a subject is imaged by passing through the opening of the annular ring, various instruments are attached for treatment. It was difficult to take an image in the state.

On the other hand, an X-ray fluoroscopic apparatus for IVR has been developed. FIG. 9 shows an example of an X-ray fluoroscopic imaging apparatus for the purpose of treatment using a catheter, which has two imaging systems consisting of an X-ray tube and a detector, and these are detectors. An intensifier (hereinafter referred to as II) 23, an X-ray tube 24, a support mechanism 22 and I.26 supporting them, an X-ray tube 27 and a support mechanism 25 supporting them. . Further X
An X-ray television monitor 21 for observing the line image is provided.

To perform IVR, for example, a catheter is inserted into a subject having an infarct in the coronary artery of the heart, and the progress of the catheter is confirmed by X-ray fluoroscopy on the X-ray television monitor 21. While proceeding. The catheter is advanced to the target blood vessel, and at the target site, a balloon catheter or an atherectomy catheter is used to open the stenosis. In such an IVR procedure, it is necessary to find the target blood vessel under fluoroscopy and quickly insert the catheter into the target blood vessel. Further, in particular in the heart and the head, it is difficult to understand the complicated state of running blood vessels only by fluoroscopy in one direction in order to select and advance a blood vessel for advancing a catheter. Therefore, the running direction of the blood vessel is confirmed by changing the perspective direction and looking at another angle.

However, it may be easier to determine the three-dimensional positional relationship between blood vessels and lesions by acquiring a tomographic image with an X-ray CT apparatus. Conventionally, a method has been used in which the subject is moved at this time, and the subject is placed on the bed again to make a diagnosis by X-ray CT. However, in this case, there is a drawback that the positions of blood vessels and lesions are different between when the images are taken by the X-ray CT apparatus and during the IVR operation.

[0007]

SUMMARY OF THE INVENTION The present invention provides an X-ray CT apparatus capable of capturing an X-ray CT image under such an IVR treatment even when a subject is attached with various instruments for treatment. Therefore, it is an object of the present invention to provide an X-ray CT apparatus in which the positional accuracy required for treatment is improved.

[0008]

In order to achieve the above object, in the present invention, an X-ray generating means and a multi-element X for detecting X-rays transmitted through an object irradiated from the X-ray generating means.
A line detector, a means for changing the relative position of the multi-element X-ray detector and the X-ray generation means, and a drive for independently controlling the position of the multi-element X-ray detector and the X-ray generation means. And an image intensifier (hereinafter referred to as II) together with the multi-element X-ray detector as X-ray receiving means in an X-ray CT apparatus including
This allows for fluoroscopy and photography.

Further, according to the present invention, there is provided means for moving the multi-element X-ray detector and the I.I. to a use position or retracting the I.I. from the use position.

Further, according to the present invention, there is provided means for causing the II and the X-ray generating means to face each other so as to rotate around the subject.

Further, according to the present invention, means for detecting and controlling the positions of the I.I. and the X-ray generating means is provided.

Further, according to the present invention, a means for performing difference processing of image data is provided.

Further, in the present invention, there is provided means for holding the light receiving surface of the I.I. in parallel with a predetermined tomographic plane of the subject while rotating the I.I.

[0014]

According to the present invention, under the IVR treatment, the positions of the multi-element detector and the I.I. are exchanged as necessary, and the position is controlled by the combination of the X-ray generating means and the multi-element detector. As a result, a desired X-ray CT image can be obtained even during the IVR procedure. In particular, an X-ray CT image can be taken even when the subject is attached with various instruments for treatment by bringing the arc-shaped multi-element detector close to or away from the subject in a direction substantially orthogonal to the body axis of the subject. . Further, by moving the X-ray source of the X-ray generating means in a semi-circular shape, it is possible to secure the positional accuracy required for IVR treatment.

[0015]

Embodiments of the X-ray CT apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of an X-ray CT apparatus capable of X-ray fluoroscopy / imaging according to a first embodiment of the present invention. FIG. 1 (a) is a perspective view and FIG. 1 (b) is a side view (however, both configurations are slightly different in detail). Figure 1 (a) shows X-ray C
It shows a state in which a T image is being captured.
In FIG. 1A, in the X-ray CT apparatus, an X-ray source 3 and a multi-element detector 4 are arranged facing each other around a subject 1 placed on a bed 2, and the X-ray source 3 and The element detectors 4 are separated from each other, driven independently of each other, and provided with a mechanism for controlling their respective positions. The X-ray source 3 is supported by the support mechanism 10 and moved along an arcuate trajectory.
The multi-element detector 4 is supported by a stretchable support mechanism 42 coupled to an overhead traveling device 41 fixed to the ceiling.
It is possible to move independently along the ceiling. Further, the support mechanism 42 may be bendable as shown in FIG. By configuring the support system of the multi-element detector 4 as described above, when capturing an X-ray CT image, the multi-element detector 4 is moved to a position where the multi-element detector 4 is opposed to the X-ray source 3. An X-ray CT image is taken, and when it is completed, it can be evacuated from its use position.

When an X-ray CT image is taken in FIG. 1A, it is performed as follows. First, since the X-ray source 3 and the multi-element detector 4 are not mechanically coupled to each other,
They are independently driven by independent drive mechanisms (not shown, including support mechanisms 10 and 42) and their positions are controlled.

The multi-element detector 4 has a C-shaped structure in which a large number of scintillators and semiconductor photo-detecting elements as detection elements are arranged on a substantially semi-circular arc, and is supported by a support mechanism 42. In the X-ray CT apparatus, the X-ray source 3 originally does not need to rotate the entire circumference of the subject 1 by 360 degrees, but only 180 degrees is sufficient. Therefore, the multi-element detector 4 can have a C-shaped structure with the lower side of the subject 1.

The support mechanism 42 is provided with an up / down moving mechanism (not shown) such as an air cylinder, a hydraulic cylinder, or a ball screw, and can move the multi-element detector 4 toward or away from the subject 1 from above. In addition, it is possible to move horizontally along the rail of the overhead traveling device 41 fixed to the ceiling. As a result, it can be evacuated when not in use. The position of the multi-element detector 4 can be detected by the amount of movement of the vertical movement mechanism and the horizontal movement mechanism, or by a position sensor, and the position of the multi-element detector 4 itself with respect to the X-ray source 3 before the start of imaging. Adjustment. That is, in the X-ray CT apparatus of the present embodiment, when the position of the X-ray source 3 is fixed, the scanning center thereof coincides with the center of the arc of the multi-element detector 4 and covers the X-ray scanning range. Adjusted to position. It is not necessary to move the multi-element detector 4 during the CT image capturing, and the X-axis remains stationary.
The data of the X-ray irradiation area may be acquired according to the direction (angle data) of the radiation source 3.

On the other hand, the X-ray source 3 is connected to a high voltage power supply circuit (not shown) via a cable and is supported by a support mechanism 10. The support mechanism 10 drives the X-ray source 3 so as to rotate on an arc of a predetermined circular orbit centered on the subject 1.

Various mechanisms are adopted as a mechanism for moving the X-ray source 3 along a circular orbit, and FIG. 2 shows an example of such a supporting mechanism 10. This support mechanism 10 is shown in FIG.
As shown in (a), the support 5 fixed to the floor or bed.
1, a C arm 53 that is driven by driving wheels 52 provided in the support base 51 and reciprocates on the support base 51 in an arcuate path, and a plurality of pulleys 54 pivotally supported by the C arm 53. X-ray source carriage 5 that is wound around and fixes the X-ray source 3
5 and a belt 56 fixed to the support base 51.

In such a structure, when the C-arm 53 is moved on the support base 51 by the drive wheel 52 incorporated in the support base 51, for example, in the direction of the arrow in FIG. As the distance from the base 51 to the left end of the C arm 53 becomes longer, the belt 56 connecting the support base 51 and the left end of the X-ray source carriage 55 is pulled toward the support base 51 side, whereby the X-ray source carriage 55 is moved to the C-shape. It moves to the left of the arm 53 ((c) in the figure). That is, as the C-arm 53 moves to the left, the X-ray source carriage 55 and the X-ray source 3 move toward the C-arm 5.
3 moves leftward and reaches the left end at the end point of the leftward movement of the C-arm 53 ((d) in the same figure). Similarly, when the C arm 53 moves in the right direction in the figure, the belt 56 connecting the support 51 and the right end of the X-ray source carriage 55 is pulled toward the support base 51, whereby the X-ray source carriage 55 and the X-ray source. Pull 3 to the right. As a result, the X-ray source 3 moves on the C arm 53 in the direction in which the C arm 53 moves as shown in FIG. In the support mechanism 10, the X-ray source 3 moves on the C arm 53 in accordance with the movement of the C arm 53 on the support base 51 as described above. It can be shortened to about half of the stroke (distance) of the movement of the radiation source 3.
The X-ray source 3 and the C arm 53 do not interfere with each other during treatment and do not interfere with each other.

As described above, the support mechanism 10 allows the X-ray source 3 to move on a constant circular orbit so that X-rays can be emitted toward the center, and the subject 1 can be positioned at the center of the arc of the C arm 53. Thereby, the X-ray source 3 can be moved around the subject 1 along a circular orbit. The movement of the X-ray source 3 can be detected by the position detecting means attached to the support base 51 or the angle detecting means attached to the X-ray source carriage 55.

FIG. 1 (b) shows a state in which fluoroscopy or tomography is being performed. At this time, the multi-element detector 4 is retracted from the use position, and I.I.5 is arranged at a position facing the X-ray source 3. Similarly to the multi-element detector 4, the I.I.5 is also coupled to the overhead traveling device 41 and is supported by the expandable / contractible support mechanism 43 so that it can independently move along the ceiling. Also, I.I.5 is shown in FIG.
As shown in (b), the tip end of the support mechanism 43 is rotatably supported as a fulcrum (a pulse motor or the like is used for rotation), and the support mechanism 43 is used during fluoroscopy and during tomographic imaging. , Or a means for controlling the I.I.5 to rotate so that the I.I.5 is oriented in an appropriate direction or to move or move the I.I.5 according to the classification such as when retreating. With such a configuration, X can be used during IVR treatment or diagnosis with I.I.5.
Place the I.I.5 at an appropriate position facing the radiation source 3,
Fluoroscopy or radiography can be performed. Conversely, X
When the line CT image is taken, I.I.5 is retracted from the use position so as not to get in the way.

FIG. 3 shows an embodiment in which a tomographic image is taken by moving I.I.5 corresponding to the position of the X-ray source 3. FIG. 3 is for explaining a case where a tomographic image of the tomographic plane 9 of the subject 1 is taken with the multi-element detector 4 retracted. First, a simple perspective image is taken of I.I.5 at a position where its image receiving surface 6 is perpendicular to the axis of the X-ray beam 7. Next, when a tomographic image is taken, the tomographic plane 9 of the subject 1 to be imaged and the image receiving surface 6 of I.I.5 are always parallel to each other, and the X-ray source 3 and the tomographic plane 9 are And the distance
To keep the ratio of the distance between the X-ray source 3 and I.I.5 constant,
By rotating the X-ray source 3 and I.5, the tomographic image A of the tomographic plane 9 can be taken. At this time, the X-ray source 3 and I.
I.5 will rotate about the subject 1 about a half turn.

While a general simple fluoroscopic image is an image corresponding to the integrated amount of the degree of X-ray absorption of each part of the subject 1 on the X-ray transmission path, the tomographic image A is a specific layer of the subject 1. It is an emphasized image of (tomographic plane 9). For example, in a chest image,
In contrast to a general simple perspective image showing ribs, a tomographic image can obtain an image of the lung of interest without showing ribs. Since such a tomography apparatus has a long history and has already been widely spread and is useful for actual diagnosis, detailed description of the principle and structure will be omitted.

In order to guide the catheter through a complex blood vessel during IVR treatment, in addition to the information on the fluoroscopic image showing the whole image, the information on the positional relationship in the depth direction of the subject is important. . Conventionally, a simple fluoroscopic image has been used in IVR treatment, but in the present invention, in addition to the fluoroscopic image, a function of obtaining a tomographic image capable of grasping the positional relationship in the depth direction is added. As a result, by combining the tomographic image with the fluoroscopic image, it is possible to know in what depth layer the catheter is located in the fluoroscopic image, and the guiding of the catheter becomes safe and easy.

FIG. 4 shows X around the subject 1 as in FIG.
Although the radiation source 3 and the I.I. 5 are rotationally moved to capture a tomographic image, the I.I.I.
5 is arranged so that it is perpendicular to the body axis 8 of the subject 1, and the I.I.5 is rotationally moved around the body axis 8 of the subject 1. As shown in FIG. 4, the X-ray source 3 and the I.I. 5 are arranged so that the X-ray beam 7 is obliquely incident on the body axis 8 with the subject 1 interposed therebetween. In this arrangement, the X-ray source 3 and the I.I.5 are rotated about the subject 1 about half a turn, and a tomographic image of the tomographic plane 9 of the subject 1 is captured. An example of the imaging is shown in a tomographic image B.

FIG. 5 is a state in which the I.I. 5 and the X-ray source 3 are rotated around the subject 1 while the multi-element detector 4 is retracted, and the organ of interest (for example, blood vessel). , Digestive tract, etc.) is stereoscopically imaged from multiple directions. Figure 5
As described above, the contrast agent 31 is injected into the body of the subject 1, and the I.I.
The I.I.5, which is rotatably supported by the support arm 44, is rotated around the subject 1. The X-ray source 3 rotates around the subject 1 while sandwiching the subject 1 according to the rotation of the I.I.5 while facing the I.I.5, and pulsed at a predetermined angle. Irradiate with X-rays.

A method of controlling the position of the X-ray source 3 corresponding to I.I.5 will be described with reference to FIG. The position of the I.I.5 is controlled by the I.I. driving means 51. The position of the I.I.5 is detected by the I.I. position detecting means 52 using an encoder or the like and sent to the system control unit 53. The system control unit 53 displays X according to the position of I.I.5.
The position of the radiation source 3 is calculated. On the other hand, the current position of the X-ray source 3 is detected by the X-ray source position detecting means 54 using an encoder or the like and sent to the system control unit 53,
The deviation from the position of the X-ray source 3 calculated according to the position of I.I.5 is calculated, and the position of the X-ray source 3 is controlled via the X-ray source driving means 55. When the X-ray source 3 cannot move to the calculated position of the X-ray source 3 due to an obstacle or the like, the system control unit 53 generates an interlock signal and puts the entire system in an interlock state. In this state, X
The radiation source 3 does not operate. In order to release the interlock state, the I.I.5 may be moved so that the I.I.5 and the X-ray source 3 face each other. By the above mechanism, I.I.
The X-ray source 3 can be moved by following the driving of. In this way, contrast imaging of the organ of the subject 1 can be stereoscopically performed from multiple directions according to the position of I.I.5.

FIG. 7 shows an example in which a differential image is picked up in addition to the three-dimensional picking up from multiple directions in FIG. When taking a difference image, as shown in FIG. 7A, an image (mask image) without the contrast agent 31 is first taken. Next, as shown in FIG. 7B, an image (contrast image) containing the contrast agent 31 is picked up, and the difference between the mask image and the contrast image is calculated. At this time, in order to perform an effective difference between both images, in the present embodiment, biological signals such as respiration and heartbeat at both image capturing start positions are monitored by using the biological signal detecting means 56, and the mask image and the contrast image are detected. A mechanism for matching the phases of respiration and heartbeat at the imaging start position of was used. That is, the phases of respiration and heartbeat are aligned at the image capturing start position between the mask image and the contrast image, and the displacement of the organ due to the body movement of the subject 1 between the images is suppressed as much as possible.

In the procedure, first, biological signals such as respiration and heartbeat at the start of image capturing at the image capturing start position of the mask image are monitored using the biological signal detecting means 56. Next, the biological signals such as respiration and heartbeat are monitored at the contrast image capturing start position using the biological signal detecting means 56, and when the biological signals such as respiration and heartbeat at the start of mask image capturing have the same phase,
Imaging of the contrast image is started. After the start of image capturing, I.I.
5 and the X-ray source 3 are rotated around the subject 1, images are taken from multiple directions, and a stereoscopic difference image is created.

[0032]

EFFECT OF THE INVENTION With the above configuration, the IVR
Under treatment, X-ray CT images, tomographic images, and fluoroscopic images can be captured even when the subject is attached with various instruments for treatment, and the positional accuracy required for treatment can be improved. Further, by adding the tomographic image to the fluoroscopic image, it becomes possible to more easily perform treatment such as advancing a catheter in a complicated blood vessel while viewing the fluoroscopic image.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an X-ray CT apparatus capable of X-ray fluoroscopy / imaging according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an example of a support mechanism for rotationally moving an X-ray source.

FIG. 3 is a diagram showing an example of moving a II corresponding to the position of an X-ray source to take a tomographic image of a cross section parallel to a body axis, which is a second embodiment of the present invention. Is.

FIG. 4 is a diagram showing an example of capturing a tomographic image of a cross section perpendicular to the body axis in the third example of the present invention.

FIG. 5 is a view showing an embodiment of rotating an II and an X-ray source around a subject and performing stereoscopic contrast imaging from multiple directions in a fourth embodiment of the present invention.

FIG. 6 is a diagram for explaining a method of position control of an X-ray source corresponding to II in the fourth embodiment.

FIG. 7 is a diagram showing an example of capturing a difference image in the fifth example of the present invention.

FIG. 8 is a diagram showing an example of a conventional X-ray CT apparatus.

FIG. 9 is a diagram showing an example of a conventional IVR system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Subject 2 Bed 3 X-ray source 4 Detector 5 I.I. 6 Imaging surface 8 Body axis 9 Tomographic plane 10, 42, 43 Support mechanism 31 Contrast agent 44 I.I. Support arm 51 I.I. 52 I.I. position detecting means 53 System control unit 54 X-ray source position detecting means 55 X-ray source driving means 56 Biological signal detecting means

Claims (6)

[Claims] 1. A multi-element X-ray detector for detecting X-rays transmitted through a subject irradiated by the X-ray generator, the multi-element X-ray detector, and the X-ray generator. In the X-ray CT apparatus provided with a means for changing the relative position to the means, and a drive mechanism for independently controlling the position of the multi-element X-ray detector and the X-ray generation means, the multi-element as the X-ray receiving means. An X-ray CT apparatus, which is equipped with an image intensifier (hereinafter referred to as II) together with an element X-ray detector, and enables X-ray cross-layer imaging and X-ray fluoroscopy / radiography. 2. The X-ray CT apparatus according to claim 1, further comprising means for moving the multi-element X-ray detector and the I.I. to a use position or withdrawing the I.I. from the use position. An X-ray CT apparatus characterized by: 3. The X-ray CT apparatus according to claim 1 or 2, further comprising means for causing the II and the X-ray generating means to face each other so as to rotate around the subject. X-ray CT system. 4. The X-ray CT apparatus according to claim 3, further comprising means for detecting and controlling the positions of the I.I. and the X-ray generating means. 5. The X-ray CT apparatus according to claim 3 or 4, further comprising means for performing difference processing of image data. 6. The X-ray CT apparatus according to claim 3 or 4, further comprising means for holding the light receiving surface of the I.I. in parallel with a predetermined tomographic plane of the subject while rotating the I.I. An X-ray CT apparatus characterized by: