JP2004357723A - X-ray computerized tomograph apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray computerized tomograph apparatus without a rotating part. <P>SOLUTION: This X-ray computerized tomograph apparatus radiates an X-ray to a subject W and regenerates a physical quantity distribution inside the subject based on the intensity distribution of the X-ray transmitting through the subject. This tomograph apparatus is provided with an X-ray generating means 10 generating the X-ray, a plurality of X-ray guide tubes 40 receiving the X-ray generated from the X-ray generating means 10 at one ends 42 and radiating it from tip parts 43 disposed toward the subject, and an X-ray detector 30 detecting the X-ray transmitting through the subject W. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an X-ray computed tomography apparatus that detects a physical quantity distribution in an object from an intensity distribution of X-rays transmitted through the object.
[0002]
[Prior art]
At present, the so-called third-generation X-ray computed tomography apparatus (hereinafter, referred to as “X-ray CT apparatus”) has become mainstream. This third-generation X-ray CT apparatus has a configuration in which an X-ray source and a detector are arranged around a human body so as to face each other, and these X-ray sources and the detector are rotated around the human body.
[0003]
Further, an X-ray CT apparatus called a fourth generation, in which a plurality of detectors are fixedly arranged in a ring around a human body and only the X-ray source is rotated around the human body, is disclosed (for example, see Patent Document 1). .).
[0004]
Further, recently, a so-called fifth generation X-ray CT apparatus in which the X-ray source and the detector do not rotate together has been developed. This fifth-generation X-ray CT apparatus is configured to deflect an electron beam by a deflector and generate an X-ray by colliding with a target anode fixedly arranged around a human body.
[0005]
[Patent Document 1]
JP 2001-17420A.
[0006]
[Problems to be solved by the invention]
However, the above-mentioned third-generation and fourth-generation X-ray CT apparatuses rotate a heavy object such as an X-ray source and a detector around the subject, giving the subject a feeling of oppression and generating large vibrations and noises. There is a problem of doing.
[0007]
In addition, high image quality is required for the X-ray CT apparatus, and the high-speed rotation of the X-ray source and the detector required for that is a serious problem for the strength and rigidity of the apparatus.
[0008]
In the fifth-generation X-ray CT apparatus described above, it is difficult to adjust the deflection of an electron beam, and the image resolution is not sufficient.
[0009]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an X-ray computed tomography apparatus without a rotating unit.
[0010]
[Means for Solving the Problems]
In order to solve the above problems and achieve the object, an X-ray computed tomography apparatus of the present invention is configured as follows.
[0011]
(1) An X-ray computed tomography apparatus that irradiates an object with X-rays and reproduces a physical quantity distribution in the object based on an intensity distribution of the X-rays transmitted through the object generates the X-rays. X-ray generating means for causing, X-rays generated from the X-ray generating means at one end, a plurality of X-ray guide tubes for irradiating from an end arranged toward the subject, and transmitted through the subject A detector for detecting the intensity of X-rays.
[0012]
(2) The X-ray computed tomography apparatus described in (1), wherein the distal ends of the plurality of X-ray guide tubes are annularly arranged around the subject.
[0013]
(3) The X-ray computed tomography apparatus according to (1), wherein the tip of the X-ray guide tube and the detector are displaced from each other in an axial direction of the subject. It is characterized.
[0014]
(4) The X-ray computed tomographic imaging apparatus according to (1), wherein the detector includes a plurality of detectors arranged in a ring around the subject. .
[0015]
(5) The X-ray computed tomography apparatus according to (1), wherein each of the X-ray guide tubes is configured by bundling a plurality of X-ray fibers transmitting the X-rays. I do.
[0016]
(6) The X-ray computed tomography apparatus described in (5), wherein a tip portion of the X-ray guide tube is conically spread toward the subject.
[0017]
(7) The X-ray computed tomography apparatus described in (5), wherein one end of the X-ray guide tube has a conical shape according to the shape of the X-ray radiated conically from the X-ray generating means. It is characterized by being constricted.
[0018]
(8) The X-ray computed tomography apparatus described in (1), wherein a switch for switching between passage and cutoff of the X-ray is provided in a middle portion of each of the X-ray guide tubes. Features.
[0019]
(9) In the X-ray computed tomography apparatus described in (1), the X-ray generating means is composed of a plurality of X-ray sources provided at one end of each of the X-ray guide tubes. It is characterized by the following.
[0020]
(10) The X-ray computed tomographic imaging apparatus according to (9), wherein the X-ray source is a filament, an electronic circuit that supplies an electric current to the filament to generate an electron beam, and is generated from the filament. And a target anode for receiving the electron beam and generating X-rays.
[0021]
(11) The X-ray computed tomographic imaging apparatus according to (9), wherein the X-ray source comprises an X-ray tube.
[0022]
(12) The X-ray computed tomography apparatus according to (1), wherein the intensity of the X-rays generated by the X-ray generating means is vibrated at a different frequency for each of the X-ray guide tubes. And
[0023]
(13) The X-ray computed tomography apparatus according to (10), wherein the intensity of the X-ray generated by each of the X-ray sources is changed by changing the current supplied to the filament to a different frequency. It is characterized by vibrating with.
[0024]
(14) The X-ray computed tomography apparatus according to (11), wherein the intensity of the X-ray generated by each of the X-ray sources is varied by vibrating a voltage applied to the X-ray tube. It is characterized by vibrating at a frequency.
[0025]
(15) The X-ray computed tomographic imaging apparatus according to any one of (12) to (14), wherein X-rays are simultaneously emitted toward the subject from distal ends of the plurality of X-ray guide tubes. It is characterized by the following.
[0026]
(16) The X-ray computed tomography apparatus according to any one of (12) to (14), wherein the X-rays have a time lag from the distal ends of the plurality of X-ray guide tubes toward the subject. Is irradiated.
[0027]
(17) The X-ray computed tomography apparatus according to (15) or (16), wherein a controller is connected to the detector, and the controller is configured to control an X-ray intensity detected by the detector. Are separated for each frequency.
[0028]
(18) The X-ray computed tomography apparatus according to (17), wherein the controller specifies the X-ray guide tube that has emitted the X-ray based on the frequency of the X-ray intensity. Features.
[0029]
(19) An X-ray computed tomography apparatus that irradiates an X-ray to the subject and reproduces a physical quantity distribution in the subject based on an intensity distribution of the X-ray transmitted through the subject. A plurality of X-ray sources arranged annularly to irradiate the subject with X-rays, and an annular detector arranged around the subject and detecting the intensity of X-rays transmitted through the subject Wherein each of the X-ray sources has an electron beam source having a carbon nanotube, and a target anode which receives the electron beam generated from the electron beam source and generates the X-ray. .
[0030]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
[0031]
FIG. 1 is a front view showing a configuration of an X-ray computed tomography apparatus according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view showing a configuration of a main part of the X-ray computed tomography apparatus according to the embodiment. FIG. 3 is a schematic view showing a configuration of a distal end portion of the X-ray guide tube according to the embodiment. In the drawing, W indicates a subject.
[0032]
The X-ray computed tomography apparatus shown in FIGS. 1 and 2 includes an X-ray generation unit 10 (only shown in FIG. 1), an X-ray emission device 20, and an X-ray detection device 30 (detector).
[0033]
The X-ray emission device 20 has an emission base 21. The emission base 21 is formed in a ring shape, and is arranged such that its axis is substantially horizontal. On the emission base 21, a plurality of X-ray emission parts 22 are arranged side by side at predetermined intervals along the circumferential direction. X-rays are emitted from the X-ray emitting unit 22 toward the subject W.
[0034]
The X-ray detection device 30 has a detection base 31. The detection base 31 is formed in a cylindrical shape, and is disposed coaxially with the emission base 21 at a position shifted in the axial direction of the emission base 21. The detection base 31 has a plurality of scintillators 32 arranged side by side in the circumferential direction. The X-ray intensity detected by each scintillator 32 is converted into a voltage signal by the light-voltage conversion unit 33. Here, the detection unit 34 includes the scintillator 32 and the light-voltage conversion unit 33.
[0035]
The X-ray generation means 10 is provided separately from the X-ray emission device 20 and the X-ray detection device 30. This X-ray generation means 10 is constituted by a plurality of X-ray sources 11 (only two are shown). Each X-ray source 11 has an electron generator 12 and a target anode 13.
[0036]
The electron generator 12 includes a filament 14 and a current oscillation circuit 15 (electronic circuit). Each current oscillation circuit 15 supplies a current oscillating at a unique frequency to each filament 14. Thus, each filament 14 generates an electron beam whose intensity oscillates according to the frequency of the current.
[0037]
The target anode 13 is made of a tungsten material, and is arranged to face the filament 14. The target anode 13 rotates in the direction of arrow A about the axis l.
[0038]
The electron beam generated from each filament 14 travels in the direction of arrow B toward the positively charged target anode 14 and irradiates a predetermined portion of the target anode 14. As a result, as shown by Δ in FIG. 1, X-rays are emitted from the target anode 14 while spreading in a conical shape.
[0039]
Since the intensity of the emitted X-ray is proportional to the intensity of the electron beam, it is proportional to the value of the current supplied from the current oscillation circuit 15 to the filament 14. That is, the X-ray intensity oscillates at a frequency substantially equal to the frequency of the current supplied to the filament 14.
[0040]
Although the target anode 14 is heated to a high temperature by the irradiation of the electron beam, in the present embodiment, since the target anode 14 is rotated to circulate the portion to be irradiated with the electron beam, the target anode 14 is heated. 14 is not dissolved by overheating.
[0041]
The X-rays generated from the target anode 14 are transmitted to each X-ray emission part 22 by an X-ray guide tube 40 connecting the X-ray generation means 10 and the X-ray emission device 20.
[0042]
The X-ray guide tube 40 is configured by bundling a plurality of X-ray fibers 41. The X-ray fiber 41 is formed of an elongated tubular member, and can transmit X-rays using a lumen.
[0043]
One end 42 of the X-ray guide tube 40 arranged on the X-ray source 11 side is formed so as to conically converge toward the target anode 14 side by bending the X-ray fiber 41.
[0044]
Further, the distal end portion 43 of the X-ray guide tube 40 arranged on the X-ray emitting device 20 side is formed so as to expand conically toward the subject W side by bending the X-ray fiber 41. . (See FIG. 3).
[0045]
A changeover switch 44 is provided in the middle of each X-ray guide tube 40. The changeover switch 44 utilizes the property of X-ray reflection, and switches between passage and blocking of X-rays by adjusting the angle of a reflection mirror (not shown) provided inside.
[0046]
Note that, as the changeover switch 44, a configuration in which a molybdenum plate material through which X-rays are hardly transmitted may be inserted and removed from the X-ray guide tube 40 may be used.
[0047]
The light-voltage conversion unit 33 and the changeover switch 44 are both connected to a controller 50. The controller 50 performs processing of the voltage signal output from the light-to-voltage conversion unit 33, switching of the changeover switch 44, and the like. Then, the voltage signal processed by the controller 50 is displayed on the monitor 60 as an image.
[0048]
Next, the operation of the X-ray tomographic imaging apparatus having the above configuration will be described.
[0049]
When using this X-ray computed tomography apparatus, all X-ray sources 11 are activated. At this time, by controlling the current supplied to the filament 14, the intensity of the X-ray generated from each X-ray source 11 is oscillated at a unique frequency.
[0050]
The X-rays generated from each X-ray source 11 enter the X-ray guide tube 40, respectively. The X-rays that have entered the X-ray guide tube 40 are sequentially emitted at predetermined intervals along the circumferential direction of the emission base 22 from each X-ray emission section 22 under the control of the changeover switch 44.
[0051]
The X-rays emitted from each X-ray emission unit 22 pass through the subject W and are detected as voltage signals by a plurality of detection units 34 arranged on the opposite side of the X-ray emission unit 22. At this time, the X-ray intensity detected by each detection unit 34 has a partial difference due to the physical quantity distribution in the subject W. Then, the controller 50 constructs a physical quantity distribution in the subject W based on the voltage signal of the X-ray intensity detected by the detection unit 34.
[0052]
4A and 4B show X-ray intensity voltage signals detected by the detection unit according to the embodiment, FIG. 4A is a graph showing X-ray intensity voltage signals detected by the first scintillator 32a, and FIG. FIG. 7 is a graph showing a voltage signal of the X-ray intensity detected by the second scintillator 32b, and FIG. 7C is a graph showing a voltage signal of the X-ray intensity detected by the third scintillator 32c.
[0053]
In general, the detection unit 34 has a very low response speed for converting light into voltage. Therefore, when X-rays are sequentially emitted from the plurality of X-ray emission units 22 at short intervals, the response of the detection unit 34 cannot follow the switching speed of the changeover switch 44, and the physical quantity distribution in the subject W is not clearly formed. Sometimes.
[0054]
That is, when the interval between the X-rays emitted from each of the X-ray emission units 22 is short, the detection unit 34 outputs a voltage signal in which the X-rays emitted from the plurality of X-ray emission units 22 overlap.
[0055]
Therefore, in the present embodiment, the intensity of the X-ray emitted from each X-ray emission unit 22 is vibrated at a unique frequency, and the voltage signal of the X-ray intensity detected by each detection unit 34 is subjected to Fourier transform. By separating each frequency, only X-rays having a desired frequency can be extracted.
[0056]
This makes it possible to know from which X-ray emission unit 22 the X-rays detected by the detection unit 34 are emitted. Therefore, based on the intensity of the detected X-rays, A sharp physical quantity distribution can be constructed.
[0057]
Note that a mountain-shaped portion indicated by D in FIG. 4A indicates scattered light detected by the scintillator 32a.
[0058]
According to the X-ray tomographic imaging apparatus having the above configuration, the X-ray generation unit 10 is separately provided from the X-ray emission device 20, and each X-ray source 11 and each X-ray emission unit 22 are connected by the X-ray guide tube 40. X-rays generated by the X-ray source 11 are transmitted to the X-ray emission unit 22 by the X-ray guide tube 40.
[0059]
A changeover switch 44 for switching between passage and cutoff of X-rays is provided in the middle of each X-ray guide tube 40, and the changeover switch 44 can be controlled by a controller 50.
[0060]
Therefore, X-rays can be emitted toward the subject W from a plurality of directions without rotating the X-ray generating means around the subject W, so that the subject W has a feeling of pressure, vibration, or noise. Can be reduced.
[0061]
Further, the intensity of the X-ray emitted from each X-ray emission unit 22 is vibrated at a frequency unique to the X-ray guide tube 40.
[0062]
Therefore, even if the intensities of the X-rays emitted from the plurality of X-ray emission units 22 overlap in the output of each detection unit 34, only the X-rays of a desired frequency can be separated and extracted.
[0063]
Further, in order to oscillate the intensity of the X-ray emitted from each X-ray emission part 22, the current supplied to the filament 14 is oscillated.
[0064]
Therefore, the intensity of the X-ray emitted from each X-ray emitting unit 22 can be vibrated at a unique frequency without complicating the configuration of the device.
[0065]
Further, the X-ray emitting section 22 and the scintillator 32 are arranged so as to be shifted in the direction of the axis of the axis.
[0066]
Therefore, even when the X-ray emitting unit 22 and the scintillator 32 are arranged annularly around the subject W as in the present embodiment, when the X-ray emitted from the X-ray emitting unit 22 is detected by the scintillator 32. In addition, there is no hindrance by the X-ray emitting unit 22 located on the opposite side of the X-ray emitting unit 22.
[0067]
Further, one end 42 of the X-ray guide tube 40 is formed so as to conically narrow toward the target anode 14 side.
[0068]
Therefore, the X-ray radiated from the X-ray source 11 while spreading in a conical shape can be efficiently made incident on the X-ray guide tube 40.
[0069]
Further, the distal end of the X-ray guide tube 40 is formed so as to expand conically toward the subject W side.
[0070]
Therefore, even in a configuration in which the X-ray is emitted from the tip of the small-diameter X-ray fiber 41 as in the present embodiment, the entire subject W can be uniformly irradiated with the X-ray.
[0071]
In the present embodiment, the electron generator 12 and the target anode 13 are used as the X-ray source 11, but the present invention is not limited to this. For example, as shown in FIG. 5, an X-ray tube 90 can be used. In this case, the intensity of the X-ray emitted from each X-ray emission unit 22 may be oscillated by oscillating the tube voltage applied to the X-ray tube 90.
[0072]
Further, in the present embodiment, the intensity of the X-ray emitted from each X-ray emitting unit 22 is vibrated at a unique frequency. Therefore, even if X-rays are emitted from all the X-ray emission units 22 arranged around the subject W at the same time, the detected X-rays can be separated for each frequency. A distribution can be constructed.
[0073]
That is, since it is not necessary to sequentially irradiate X-rays from the plurality of X-ray emission units 22, the time required for imaging can be reduced.
[0074]
Next, a second embodiment of the present invention will be described with reference to FIG.
[0075]
The description of the same configuration, operation, and action as those of the first embodiment will be omitted.
[0076]
FIG. 6 is a front view showing the configuration of the X-ray computed tomography apparatus according to the second embodiment of the present invention.
[0077]
The X-ray computed tomography apparatus according to the first embodiment includes the number of X-ray sources 11 corresponding to each X-ray guide tube 40. In the present embodiment, as shown in FIG. Has only one X-ray source 11.
[0078]
Therefore, in the present embodiment, a tube switch 70 for distributing X-rays generated by the X-ray source 11 to each X-ray guide tube 40 is provided.
[0079]
The tube switching device 70 is provided between an X-ray guide tube 40a connected to the X-ray source 11 and a plurality of X-ray guide tubes 40 connected to each X-ray emission unit 22, and is provided with a mechanical mechanism. The X-ray guide tube 40 for supplying the line is switched.
[0080]
With such a configuration, the number of X-ray sources 11 can be reduced, so that the configuration of the X-ray computed tomography apparatus can be significantly reduced.
[0081]
Next, a third embodiment of the present invention will be described with reference to FIGS.
[0082]
The description of the same configuration, operation, and action as those of the first embodiment or the second embodiment will be omitted.
[0083]
FIG. 7 is a front view showing a configuration of an X-ray tomographic imaging apparatus according to a third embodiment of the present invention, and FIG. 8 is a schematic diagram showing a configuration of an X-ray source according to the third embodiment.
[0084]
In the present embodiment, a carbon nanotube 80 is used as an electron generator 12b (electron beam source) used for the X-ray source 11b. The carbon nanotube 80 has a property of generating electrons when a voltage is applied. The present embodiment utilizes this property, and irradiates the target anode 13 with an electron beam generated from the carbon nanotube 80.
[0085]
When the carbon nanotubes 80 are used as the electron generator 12b, the size of the electron generator 12b can be considerably reduced, whereby the configuration of the X-ray source 11b can be significantly reduced.
[0086]
Therefore, as in the present embodiment, a plurality of X-ray sources 11b can be provided directly on the emission base 21, so that the configuration of the X-ray computed tomographic imaging apparatus can be considerably reduced in size as compared with the related art.
[0087]
Further, since the plurality of X-ray sources 11b can be arranged around the subject W in this manner, it is not necessary to rotate the X-ray generating means around the subject W.
[0088]
It should be noted that the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the components without departing from the scope of the invention at the stage of implementation. Various inventions can be formed by appropriately combining a plurality of components disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiment. Further, components of different embodiments may be appropriately combined.
[0089]
【The invention's effect】
According to the present invention, it is possible to provide an X-ray computed tomography apparatus without a rotating unit.
[Brief description of the drawings]
FIG. 1 is a front view showing the configuration of an X-ray computed tomography apparatus according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a configuration of a main part of the X-ray computed tomography apparatus according to the embodiment.
FIG. 3 is a schematic diagram showing a configuration of a distal end portion of the X-ray guide tube according to the embodiment.
FIG. 4 shows a voltage signal of X-ray intensity detected by the detection unit according to the embodiment, (a) is a graph showing a voltage signal of X-ray intensity detected by a first scintillator, and (b) is a graph. FIG. 7 is a graph showing a voltage signal of X-ray intensity detected by a second scintillator, and FIG. 7C is a graph showing a voltage signal of X-ray intensity detected by a third scintillator.
FIG. 5 is a schematic diagram showing a configuration of a modification of the X-ray source according to the embodiment.
FIG. 6 is a front view showing the configuration of an X-ray computed tomography apparatus according to a second embodiment of the present invention.
FIG. 7 is a front view showing the configuration of an X-ray computed tomography apparatus according to a third embodiment of the present invention.
FIG. 8 is a schematic diagram showing a configuration of an X-ray source according to the embodiment.
[Explanation of symbols]
Reference Signs List 10 X-ray generating means, 11, 11b X-ray source, 12b Electron generator (electron beam source), 13 target anode, 14 filament, 15 current oscillation circuit (electronic circuit), 30 X-ray detection Apparatus (detector), 34 ... Detector, 40 ... X-ray guide tube, 41 ... X-ray fiber, 42 ... One end, 43 ... Tip, 44 ... Switch, 50 ... Controller, 80 ... Carbon nanotube, W ... Subject.

Claims (10)

An X-ray computed tomography apparatus for irradiating a subject with X-rays and reproducing a physical quantity distribution in the subject based on an intensity distribution of the X-rays transmitted through the subject,
X-ray generation means for generating the X-ray,
A plurality of X-ray guide tubes that receive X-rays generated from the X-ray generation means at one end and irradiate the X-rays from a distal end arranged toward the subject;
A detector for detecting the intensity of the X-ray transmitted through the subject;
An X-ray computed tomographic imaging apparatus comprising: 2. The X-ray computed tomography apparatus according to claim 1, wherein distal ends of the plurality of X-ray guide tubes are arranged annularly around the subject. 2. The X-ray computed tomography apparatus according to claim 1, wherein the detector includes a plurality of detectors arranged annularly around the subject. 2. The X-ray computed tomography apparatus according to claim 1, wherein each of the X-ray guide tubes is configured by bundling a plurality of X-ray fibers transmitting the X-ray. 2. The X-ray computed tomography apparatus according to claim 1, wherein each of said X-ray guide tubes is provided with a changeover switch for switching between passage and blocking of said X-rays. The X-ray generation means includes:
Filament and
An electronic circuit that supplies an electric current to the filament to generate an electron beam;
A target anode that receives an electron beam generated from the filament and generates X-rays;
2. The X-ray computed tomography apparatus according to claim 1, further comprising: 2. The X-ray computed tomography apparatus according to claim 1, wherein the intensity of the X-ray generated from the X-ray generating means is vibrated at a different frequency for each of the X-ray guide tubes. 7. The X-ray computed tomography apparatus according to claim 6, wherein the intensity of the X-ray generated from the X-ray generation unit is oscillated at different frequencies by oscillating the current supplied to the filament. The X-ray generating means has an X-ray tube, and by vibrating a voltage applied to the X-ray tube, the intensity of X-rays generated from the X-ray generating means is vibrated at different frequencies. The X-ray computed tomography apparatus according to claim 1, wherein An X-ray computed tomography apparatus for irradiating a subject with X-rays and reproducing a physical quantity distribution in the subject based on an intensity distribution of the X-rays transmitted through the subject,
A plurality of X-ray sources arranged annularly around the subject and irradiating the subject with X-rays;
An annular detector arranged around the subject and detecting the intensity of X-rays transmitted through the subject;
With
Each of the above X-ray sources is
An electron beam source having carbon nanotubes;
A target anode for receiving the electron beam generated from the electron beam source and generating the X-ray,
An X-ray computed tomography apparatus characterized by having:

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