JP4157945B2 - X-ray CT system - Google Patents

Description

The present invention relates to an X-ray CT apparatus, which is an industrial nondestructive inspection, visualization of moving objects, multiphase flow visualization and interface velocity measurement, opaque fluid distribution measurement, chemical engineering, powder transportation velocity measurement, oil -It is an invention related to an X-ray CT apparatus used in fields such as flow velocity, volume measurement, opaque fluid flow velocity / flowmeter, etc. mixed with water-air.

  An X-ray CT (computer tomography) apparatus generally used for medical and industrial purposes is used to measure an absorption coefficient distribution in a cross section of a stationary measurement object such as a human organ or structure. These preconditions are that the object is stationary during the scan time, that is, during the time when data is collected by irradiating X-rays from multiple directions.

  If the measurement object moves during imaging, the overlay will not be accurately performed in the back projection process at the time of image reconstruction. Therefore, the reconstructed tomographic image becomes an image blur called a motion artifact. appear.

(High-speed X-ray CT)
However, devices called high-speed X-ray CT scanners such as an ultrahigh-speed X-ray CT scanner (see Patent Document 1) and a high spatial resolution high-speed X-ray CT scanner (see Patent Document 2) (in addition to Non-Patent Documents 1 and 2). Reference)) is originally designed assuming a multiphase fluid including gas and liquid, and therefore has a feature that the scan time can be set extremely short compared to the change time of the fluid.

  In order to realize high-speed scanning, a method called fourth generation CT in which a detector is fixedly arranged around a measurement object and an X-ray source is mechanically rotated has been studied (see Patent Document 4). In the application of high-speed X-ray CT, since a higher-speed scan is required, a plurality of X-ray sources are fixedly arranged outside the detector and electrically switched to increase the X-ray irradiation speed. It belongs to a system called 5-generation CT.

  The high-speed X-ray CT apparatus has a very short time (= scanning time) required for data collection of one cross section of 4 milliseconds or less, and the scanning time is about 1 / seven compared to X-ray CT which is said to be high speed for medical use. 100.

  A conventional high-speed X-ray CT for realizing such high speed is shown in FIG. The high-speed X-ray CT apparatus 1 shown in FIG. 1 has a special structure in which an X-ray generator (pulse X-ray source) 2 and a detector 3 are fixedly arranged.

  By the way, in a normal X-ray CT apparatus (apparatus belonging to the third generation and fourth generation CT) which is not a high-speed X-ray CT apparatus, a combination of one X-ray source and a detector is rotated around a measurement object. Or, an X-ray source and a detector are fixed and a measure is rotated. In such a means, since a mechanical motion is accompanied during data collection, it is very difficult to realize a high-speed scan time on the order of milliseconds.

  On the other hand, in the high-speed X-ray CT apparatus 1 shown in FIG. 1, a detection comprising a plurality of pulse X-ray sources 2 and a plurality of detector pixels 4 (see FIG. 2) corresponding to the pulse X-ray sources 2. The instrument 3 is fixedly arranged around the measurement region 5 (measurement object), and mechanically movable parts are excluded.

  In the high-speed X-ray CT apparatus 1, in order to perform a scanning operation equivalent to a normal X-ray CT apparatus, a plurality of X-ray sources 2 are electrically controlled, and X-rays are sequentially pulsed from each X-ray source 2. Irradiate to complete the scan.

  The configuration of the X-ray source 2, the detector pixel 4, and the measurement region 5 and the mechanism of pulse X-ray generation are shown in FIG. In order to operate each X-ray source 2 in a pulsed manner, thermoelectrons emitted from the filament 6 are negatively charged to the bias grid 7 positioned above the filament 6 to control the irradiation timing (FIG. 2). .

  That is, only when the negative electric field of the bias grid 7 is released, the electrons generated from the filament 6 reach the acceleration electric field and are accelerated, and collide with the target 8 such as tungsten to generate X-rays.

  Here, the release timing and time of the bias grid 7 are synchronized with the data collection system by inputting a signal from an external controller according to a timing chart created by the user.

  In such an apparatus, even if the moving measurement object 9 (for example, a bubble moving in the tube shown in FIG. 2) can be regarded as being approximately stationary during a scan time on the order of milliseconds, the velocity is 1 m / Tomography can be performed even with a moving object at about s, and the absorption coefficient distribution inside the subject can be visualized instantaneously.

(Velocity measurement using high-speed X-ray CT)
By the way, in order to measure a speed that is important for fluid measurement, it is necessary to provide another detection surface at a position separated by a certain distance in the moving direction and to obtain a time for passing this distance. Therefore, at least two measurement cross sections are required.

  Based on such motivation, the present inventor has already invented the "measurement method and apparatus for moving object speed and high resolution information by high-speed X-ray CT" for speed measurement by high-speed X-ray CT. (See Patent Document 3).

  In this example, as shown in FIGS. 3 and 4, one end of the rectangular parallelepiped-shaped semiconductor light receiving elements 11 to be the pixels of the detector module 10 are arranged so as to be alternately overlapped in parallel, and the two slits 12 are used to X-rays 15 can be transmitted only through the first cross-sectional position 13 and the second cross-sectional position 14. The distance ΔZ between the two cross sections, which is the distance between the two slits 12, can be adjusted by exchanging slits having different ΔZ.

  When the apparatus as shown in FIGS. 3 and 4 is used for measurement, the detector module 10 is installed so that the longitudinal direction of the semiconductor light receiving element 11 is parallel to the moving direction of the measurement object 9, and the two slits 12 are formed. The detector module 10 is used by being arranged on the X-ray side front surface so that the longitudinal direction is perpendicular to the moving direction of the measurement object.

Since the X-ray 15 is generated conically from the focal point of the radiation source 2, only the X-ray beam defined by the width of the slit 12 passes through the slit 12 at the same time and reaches the semiconductor light receiving element 11 of the detector at the same time. To do. By sampling this simultaneously, data of the first cross-sectional position 13 and the second cross-sectional position 14 can be collected simultaneously.
JP-A-5-60381 JP 10-295682 A Japanese Patent No. 3208426 JP-A-4-354492 Hori, K., Fujimoto, T., Kawanishi, K., Nishikawa, H., "Advanced high-speed X-ray CT scanner for measurement and visualization of multiphase flow", OECD / CSNI Specialist Meeting on Advanced Instrumentation and Measurement Techniques , Santa Barbara, March 17-20, USA (1997) Masaki Misawa, Naoki Ichikawa, Makoto Akai, Keiichi Hori, Koichiro Tamura, Goichi Matsui, “Development of Fast X-ray CT System for Transient Two-phase Flow Measurement”, Proc. 6th International Conference on Nuclear Engineering, San Diego.USA. CD-ROM, 6383-, pp.1-18 (1998)

  The above-described high-speed X-ray CT apparatus has a feature capable of reproducing an instantaneous tomographic image of a moving measurement object. However, when the measurement symmetry is fluid or the like, the moving speed is important information in addition to the distribution of the absorption coefficient. A high-speed X-ray CT system can reproduce a single tomographic image at a certain time. However, if the measurement object is a bubble with temporal deformation, it can move even if the time interval between successive tomographic images is known. Since time is undecided, the speed cannot be determined.

  In other words, the moving speed in the direction of flow cannot be obtained only with tomographic images taken at the same position, even with continuous tomographic images. Although the speed can be calculated when the dimensions of the measurement object are known, X-rays are often used to determine the distribution of opaque measurement objects that cannot be measured with visible light, so this is rare. is there.

  In particular, the high-speed X-ray CT apparatus 1 described in Patent Documents 1 and 2 cannot measure speed because it does not have a plurality of measurement cross sections. Further, no particular reference is made to the speed measurement method for the movement of the measurement object in the tomographic image.

  In the example of Patent Document 3, it is desirable that ΔZ is continuously changed according to the speed of the measurement object 9. However, in this apparatus, ΔZ is determined by the manufactured slit 12 and cannot be varied according to the speed. . Further, since the length of the semiconductor light-receiving element 11 that can be manufactured is limited, there is a possibility that the slit distance ΔZ cannot be increased when the moving speed is high.

  In addition, since the semiconductor light receiving elements 11 are arranged alternately, the spatial resolution of each cross section is ½ that of a dense array, and there is a demerit that the spatial resolution is reduced in the reconstructed tomographic image. The object of the present invention is to solve the above conventional problems.

  In order to solve the above problems, the present invention is an X-ray CT apparatus provided with two high-sensitivity X-ray detectors arranged at a minute distance with respect to the moving direction of the measurement object. The high-sensitivity X-ray detector of the system detects tomograms over time for each of the moving objects, and the density and attenuation coefficient are determined based on the data of the different tomograms detected over time. Provided is an X-ray CT apparatus characterized in that the speeds of different measurement objects can be obtained.

  The distance between the detection surfaces, which is the distance between the detection surfaces of the two high-sensitivity X-ray detectors, and the time interval obtained from the tomographic image of the measurement object reconstructed from the detection data on the respective detection surfaces Based on the above, it is possible to determine the moving speed of the measurement object.

  A drive mechanism that can arbitrarily set the distance between the detection surfaces of the two systems according to the moving speed of the measurement object is provided.

  In order to solve the above-mentioned problems, the present invention is an X-ray CT apparatus provided with three or more high-sensitivity X-ray detectors arranged at a minute distance from the moving direction of the measurement object. The high-sensitivity X-ray detector of one system detects a tomographic image of the moving measurement object over time, and allows for reconstruction of a two-dimensional tomographic image. Based on a time interval obtained from a tomogram of a measurement object reconstructed based on data detected by a combination of two consecutive detectors of the three or more highly sensitive X-ray detectors. The X-ray CT apparatus is characterized in that it is possible to obtain the time change of the speed of the measurement object, that is, the acceleration.

  In order to solve the above-described problems, the present invention uses two high-sensitivity X-ray detectors that are arranged at a minute distance from the moving direction of the measured object, and the tomographic image of the measured object over time. And compare temporal changes in spatial average luminance values of tomographic images reconstructed based on the data obtained from the two high-sensitivity X-ray detectors, and cross-correlate the time lag of similar profiles. There is also provided a method for calculating a moving speed of a measuring object using an X-ray CT apparatus characterized by calculating the moving speed of the measuring object from this time difference.

  In order to solve the above-mentioned problems, the present invention provides a high-sensitivity X-ray detector of an X-ray CT apparatus arranged with respect to a moving measurement object, and a series of tomographic images of the moving measurement object over time. The brightness value distributions of successive tomographic images are compared with a series of tomographic images that are reconstructed with the detection data over time, and the moving speed in the radial direction is calculated from the change in the center of gravity position of the cross section of the measurement object. There is provided a method for calculating a moving speed of a measurement object using an X-ray CT apparatus.

  In order to solve the above-mentioned problem, the present invention compares the luminance value distributions of successive tomographic images with a series of tomographic images reconstructed with detection data over time, and the position of the center of gravity of the measurement object cross section within the set analysis region. Alternatively, after calculating the moving speed of the radius method from the change of the distance, a moving change of the measurement object may be calculated using an X-ray CT apparatus that calculates the acceleration from the temporal change of the moving speed.

  In order to solve the above-mentioned problems, the present invention provides a high-sensitivity X-ray detector of an X-ray CT apparatus arranged with respect to a moving measurement object, and a series of tomographic images of the moving measurement object over time. The luminance value distributions of successive tomographic images are compared with a series of tomographic images that are reconstructed with the detection data over time, and the change rate of the contour is calculated from the change in the contour shape of the cross section of the measurement object. A method for calculating the change rate of the contour of the cross section of the measurement object using an X-ray CT apparatus characterized by

  Since the present invention has the above configuration, if an X-ray detector having two detection surfaces separated by a minute distance is used in the moving direction of the object to be measured, two cross sections can be maintained while maintaining high spatial resolution. The distance can be changed continuously and greatly, and the performance lacking in the invention described in Patent Document 3 can be compensated.

  Also, based on the data from the two detectors, the vertical value of the measured object can be calculated from the temporal change in the luminance value of the reconstructed image and the temporal change in the absorption coefficient distribution in the tomographic image obtained by the image reconstruction. The moving speed in the direction and the horizontal direction can be calculated.

  Further, the vertical and horizontal accelerations of the measurement object can be calculated from the temporal change of the moving speed measured in three or more measurement cross sections and three or more continuous tomographic images recorded over time.

  This is because new information such as moving velocity and acceleration is added to the phase distribution of the multiphase flow corresponding to the absorption coefficient distribution of the tomographic image, so the volume and surface area of the moving body in the opaque material, and the velocimeter of the multiphase fluid Also works. In addition, since acceleration represents an acting force, it becomes an important physical quantity for fluid analysis. There has never been an X-ray CT or a high-speed X-ray CT capable of obtaining information on the dynamics of such a measurement object.

  The best mode for carrying out the present invention will be described below with reference to the drawings based on the embodiments.

  In the detector for high-speed X-ray CT according to the present invention, two high-sensitivity semiconductor line sensors are installed on the drive stage, and the light receiving portions of the two line sensors are relatively arbitrary with respect to the moving direction of the measurement object. And a structure having a mechanism capable of moving at a step size. And in this invention, the speed calculation method using this is provided.

  The configuration of the high-speed X-ray CT detector 20 according to the present invention will be described. 1 and 2, the entire structure as a premise of the high-speed X-ray CT detector 20 includes a plurality of pulse X-ray sources 2 and a detector 3 corresponding to the pulse X-ray source 2 in a measurement region 5. , Fixedly arranged around the measurement object 9.

  The structure of the pulse X-ray generator 20 and the mechanism of the pulse X-ray generator according to the present invention are the same as those of the pulse X-ray generator shown in FIGS. Therefore, scanning is performed by sequentially irradiating X-rays from each X-ray source 2 in a pulsed manner.

  In such an overall structure, the feature of the present invention is that, in FIG. 5, the flow around the flow in the pipe 21 to be measured is around a concentric circle centering on the center of the measurement region 5, and a plurality of them in order from the outside. The pulse X-ray source 2, the first cross-section detector 22, and the second cross-section detector 23 are arranged. The distance between the first cross-section detector 22 and the second cross-section detector 23 in the radial direction (X and Y directions in the figure) is set to the shortest distance that does not interfere with each other.

  The first cross-section detector 22 has a polygonal shape in which a plurality of first cross-section detector modules 24 are arranged along the circumference. The second cross-section detector 23 has a polygonal shape in which a plurality of second cross-section detector modules 25 are arranged along the circumference.

  In the first cross-section detector module 24 and the second cross-section detector module 25, a plurality of light-receiving unit pixels are continuously attached in a line shape in the circumferential direction on the inner surface of a rectangular module support wall, respectively. Two detection surfaces are formed.

  Each of the first cross-section detector module 24 and the second cross-section detector module 25 includes a plurality of pixels (for example, 16, 32, 64, etc.) and a signal processing processor.

  As shown in FIGS. 11A and 11B, the detector modules 24 and 25 are compound semiconductors (in this case, a pixel electrode pattern of one column is formed by photolithography at the lower end of a rectangular wiring board 26, here. CdTe) piece is installed, and this is the light receiving unit 27.

  The light receiving unit 27 is connected to the signal processing preamplifier 28 and is connected to the signal processing amplifier 46 through the wiring 29 on the wiring substrate 16 and the connector 30. It is configured to connect to the main amplifier through wiring and connectors on the board. The signal processing preamplifier 28 is covered with a lead shielding plate 31 to avoid radiation damage.

  The compound semiconductor in which the pixel electrode pattern is formed operates as the light receiving unit 27 with high detection efficiency. The light receiving unit 17 is attached to the lower end of the wiring board 16 when the relative distance (ΔZ) between the first cross-section detector 33 and the second cross-section detector 34 in FIG. 5 is set to an arbitrary value. This is because the X-ray 15 is not obstructed by the wiring board 16 of the second cross-section detector 23, and at the same time, the first cross-section detector 33 and the second cross-section detector 34 detect the transmission image.

  In the present invention, two independent detectors (first cross section detector 22 and second cross section detector 23) are used, but today, a flat panel type two-dimensional having a two-dimensional pixel array. Detectors are widespread. The problem with such a two-dimensional detector is that it takes a long time to transfer a large amount of data. The analysis method of the present invention can be applied even if one pixel column corresponding to one cross section or the second cross section is extracted.

In order to make the circumferential width of the first and second detector modules 24 and 25 the same spread angle θ as seen from the measurement region center O, the circumferential width W _{2 of} the second cross-section detector module 25. Is smaller than the circumferential width W _{1 of} the first cross-section detector module 24. For this reason, even if the number of pixels is the same, the second cross-section detector module 25 has a smaller pixel pitch in the circumferential direction.

  Further, the X-ray generation surface 32 (see FIGS. 2 and 5) of the pulse X-ray source 2 is set below the first detection surface 33 (in the negative direction of the Z axis in the figure), and in the X-ray measurement region. The irradiation direction is directed from the X-ray focal point (X-ray source, more specifically, the X-ray focal point at the target surface in FIG. 2) toward the first detection surface 33 and the second detection surface 34 by a predetermined angle α1, It is launched upward by α2 (upward plus direction in the Z axis in the figure).

  As a result, even if the first cross-section detector module 24 and the second cross-section detector module 25 are arranged so as to surround the measurement object 9, the X-ray fan beam 35 is transmitted through the first and first X-ray fan beams before passing through the measurement region 5. Interference with the two detectors 22 and 23 can be avoided.

  In accordance with a signal from the external controller, the plurality of pulse X-ray sources 2 are turned on sequentially or selectively to emit pulse X-rays, irradiate and transmit the measurement object in the measurement region, and perform image reconstruction. Necessary projection data from multiple directions are measured by the first cross-section detector 22 and the second cross-section detector 23, respectively.

  The data acquisition systems of the first cross-section detector 22 and the second cross-section detector 23 are independent of each other. A trigger is given at the same time to start data acquisition, and a small distance ΔZ is separated by one X-ray pulse irradiation. Data acquisition of two cross sections is simultaneously performed at different height positions (positions of the first detection surface 33 and the second detection surface 34). The height difference ΔZ between the first cross-section detector 22 and the second cross-section detector 23 in the Z direction is continuously variable according to the moving speed of the measurement object 9.

FIG. 6 is a diagram for explaining the timing of data collection. The scan time Δts is the time until all the X-ray sources 2 are turned on. If the number of X-ray sources 2 is Nx,
Δts = Nx x Δtx
Here, Δtx is the time until one pulse X-ray is turned on (ΔtxON) and extinguished (ΔtxOFF).
Δtx = ΔtxON + ΔtxOFF
It becomes. Here, the time width (duty) of ΔtxON and ΔtxOFF can be controlled by an external controller.

The data acquisition start trigger signals (respective trigger signals in the first cross section and the second cross section in FIG. 6) of the first detection surface 33 and the second detection surface 34 are given almost simultaneously with the start of X-ray irradiation, and data accumulation is performed. , And ends within the time when the X-ray source 2 is on. That is, assuming that the detection data accumulation times of the first detection surface 33 and the second detection surface 34 are Δtp1 and Δtp2, respectively.
Δtp1, Δtp2 <ΔtxON
Data collection is performed under the conditions. Δtp1 and Δtp2 are usually set to be the same, but different values can be set according to the sensitivity and characteristics of the detector. Image reconstruction is performed using the projection data of the first detection surface 33 and the second detection surface 34 photographed by this method.

  As shown in FIG. 7, when the luminance average of the tomographic planes taken at equal time intervals is obtained for each cross section and the temporal change of the luminance value is plotted, the two are similar plots, but the minute distance ΔZ Depending on the travel time, the time axis is slightly shifted.

In order to obtain the time difference Δtv between the two time series data, the time difference Δtv can be calculated as a multiple of the scan time Δts by obtaining the cross-correlation for the section to be compared between the two time series data. When this multiple is n, the time difference is Δtv = n × Δts.
Therefore, the instantaneous moving speed Vz of the measurement object in the Z direction (for example, the Z direction in FIG. 5) is
Vz = ΔZ / Δtv
Given in.

When the vertical acceleration is obtained by an apparatus having three detection surfaces, the time differences Δtvl and Δtv2 and the moving speeds Vz1 and Vz2 can be obtained from the two adjacent cross sections by the method described above. If the time difference is small, it can be regarded as a linear movement, and the acceleration Az12 can be obtained by dividing the speed difference (Vzl−Vz2) by the time (Δtvl + Δtv2).
Az12 = (Vzl−Vz2) / (Δtvl + Δtv2)
Even when there are three or more detection surfaces, acceleration can be calculated continuously by the same method.

  On the other hand, the moving speed Vri in the radial direction of each measurement object can be calculated by comparing temporally continuous tomographic images of only the first detection surface 33 or only the second detection surface 34. . As shown in FIG. 8, for example, two continuous tomographic images obtained at the first detection surface 33 at a certain time are compared.

In order to specify the shape of the measurement object displayed on the tomographic image, an appropriate threshold value such as a value at which the change rate of the luminance value is maximized is set, and the tomographic image is binarized. By calculating the centroid of the luminance distribution corresponding to the detection surface of the extracted measurement object from the image and connecting the positions of the centroid points with successive tomographic images, the instantaneous radial direction of each measurement object is obtained from the displacement ΔRi. Speed VRi is determined by:
VRi = ΔRi / Δts
If the scan time Δts is set sufficiently shorter than the movement time, the center-of-gravity movement amount ΔRi can be linearly approximated, so an instantaneous speed is obtained.

When obtaining the acceleration in the radial direction, the time differences Δtrl and Δtr2 and the center-of-gravity moving speeds VR1 and VR2 can be obtained from two consecutive cross sections. If the time difference is small, it can be regarded as a linear movement. Therefore, the acceleration AR12 can be obtained by dividing the speed difference (VR1−VR2) by the time (Δtrl + Δtr2).
AR12 = (VRl−VR2) / (Δtrl + Δtr2)
Even when there are tomographic data of three or more cross sections, acceleration can be continuously calculated by the same method.

  When the measurement object 9 is deformed while moving like bubbles in a liquid, the interface deformation speed and the interface area are important physical quantities in the design and analysis of the apparatus. In that case, as shown in FIG. 9, only the first detection plane or only the second detection plane is extracted by image processing, and the tomograms of T = t1 and T = t1 + Δts are extracted. By dividing the contour of the image by the same number and connecting corresponding points, a displacement ΔLi between Δts is obtained.

However, it is necessary to set the scan time Δts sufficiently smaller than the deformation time so that the displacement ΔLi can be linearly approximated. From the scan time Δts and the displacement ΔLi, the contour change rate VLi is obtained by the following equation.
VLi = ΔLi / Δts

  In the above example, the first cross-section detector 22 and the second cross-section detector 23 have been described as examples. However, even in a two-dimensional detector having three or more cross sections and capable of high-speed sampling, the same applies. Applicable.

  An embodiment of the high-speed X-ray CT apparatus 36 according to the present invention is shown in FIG. The high-speed X-ray CT apparatus 36 was equipped with a detector having detection surfaces with different positions in the height direction. The high-speed X-ray CT apparatus 36 includes an X-ray generator 37 and a detection unit 38. The X-ray generator 37 has a space 39 in which the detection unit 38 can be accommodated, and has a recess 40 in which the pipe 21 through which the measurement object 9 flows is arranged with its axis aligned.

  A first cross-section stage 41 and a second cross-section stage 42 are disposed on the X-ray generator 37 via a leveler 49. The detection unit 38 arranges the first cross-section detector module 24 and the second cross-section detector module 25 fixed through the first cross-section stage 41 and the second cross-section stage 42 in a polygonal shape along the circumference. Configured.

  The inside of the X-ray generator 37 is maintained in a vacuum, and a plurality of X-ray sources 2 are arranged around the axis of the pipe 21 and outside the first cross-section detector module 24 and the second cross-section detector module 25. Are arranged so as to be arranged along the circumference. That is, the X-ray sources 2 are arranged so that their focal points are on a horizontal plane along a circle centered on the measurement region 5.

  X-rays are irradiated from the focal point of each X-ray source 2 to the measurement object 9 through the thin metal window 43. As described above, the pulse X-ray generation surface 32 for generating pulse X-rays from each X-ray source 2 is set below the first detection surface 33, and the X-ray fan beam 35 is emitted slightly upward. Therefore, the X-rays that have passed through the measurement object 9 are detected by the first and second detection surfaces 33 and 34 without interfering with the first detection surface 33.

  The distance between the X-ray generation surface 32 and the first detection surface 33 can be adjusted by the leveler 49 via the first section stage 41. Here, the first cross-section detector module 24 and the second cross-section detector module 25 are fixed to the first and second stages 41 and 42 via the detector module holding ring 44, and further the second cross-section stage 42. Is designed so that it can be moved in the Z direction relative to the first section stage 41 by the drive mechanism 45. By adjusting the drive mechanism 45 in this way, the detection surface distance ΔZ between the first detection surface 33 and the second detection surface 34 can be changed by an arbitrary amount according to the moving speed of the measurement object 9.

  Here, the drive mechanism 45 is operated automatically or manually, for example, by rotating the dial 48 to operate a conduction mechanism such as a well-known rack and pinion, so that the second cross-section stage relative to the first cross-section stage 41. This is a mechanism that can relatively move the heights of the first detection surface 33 and the second detection surface 34 by relatively moving 42.

  The first cross-section detector module 24 and the second cross-section detector module 25 are connected to a first signal processing amplifier 46 and a second signal processing amplifier 47 (not shown), respectively. Since the first signal processing amplifier and the second signal processing amplifier are fixed to correspond to the first section stage 41 and the second section stage 42, respectively, the first section detector module 24 and the first signal processing amplifier 46 are , Do not move relative to each other. Similarly, the second cross-section detector module 25 and the second signal processing amplifier 47 do not move relative to each other.

  The outputs from the first signal processing amplifier 46 and the second signal processing amplifier 47 are connected to a board that captures data transferred from the detector into a personal computer with a flexible cable that does not interfere with the movement of the second stage 42, that is, a frame grabber. And transferred to a data recording PC. In the personal computer, data processing such as calculation of the moving speed of the measurement object is performed.

  Since the present invention has the above-described configuration, industrial nondestructive inspection, multiphase flow visualization and interface velocity measurement, chemical engineering, velocity of oil-water-air mixed flow, volume measurement, flow rate and flowmeter of opaque fluid The present invention can be applied to the measurement of the solid amount of a flow in which a solid is contained in a liquid, the volume flow measurement when a solid is transported by gas, and the like.

It is a figure which shows the basic composition of high-speed X-ray CT. It is a figure explaining the basic mechanism of pulse X-ray generation. It is a figure which shows the detector module of a prior art example (patent 3208426). It is a figure explaining the Example of a prior art example (patent 3208426). It is a figure explaining the principle of the two-section measurement implementation apparatus and method of this invention. It is a figure which shows X-ray irradiation and the data collection timing of 2 cross sections. It is a figure explaining the method of calculating | requiring the speed of the axial direction (Z direction) of this invention. It is a figure explaining the method of calculating | requiring the speed of the radial direction (XY direction) of this invention. It is a figure explaining the method of calculating | requiring the expansion rate (XY direction) of the outline of this invention. It is a figure which shows the high-speed X-ray CT apparatus of this invention which installed the two-section detector. It is a figure which shows the structure of the detector module of this invention.

Explanation of symbols

1 High-speed X-ray CT system
2 (Pulse) X-ray source
3 Detector
4 detector pixels
5 Measurement area
6 Filament
7 Bias grid
8 Target
9 Measurement object
10 Detector module
11 Semiconductor light receiving element
12 Slit
13 First section position
14 Second section position
15 X-ray
20 Detector for high-speed X-ray CT
21 Piping
22 First section detector
23 Second section detector
24 First cross-section detector module
25 Second section detector module
26 Wiring board
27 Receiver
28 Preamplifier for signal processing
29 Wiring on the wiring board
30 connectors
31 Lead shield
32 X-ray generation surface
33 First detection surface
34 Second detection surface
35 X-ray fan beam
36 High-speed X-ray CT system
37 X-ray generator
38 detector
39 space
40 recess
41 First section
42 Second Section Stage
43 metal windows
44 Detector module retaining ring
45 Drive mechanism
46 First signal processing amplifier
47 Second signal processing amplifier
48 dial 49 leveler
Z direction Movement direction X and Y direction of the measurement object Direction ΔZ perpendicular to the movement direction of the measurement object ΔZ Distance Zts between the first cross section detection surface and the second cross section detection surface Δts Scan time
Δtx Pulse X-ray irradiation time interval ΔtxON Pulse X-ray lighting time ΔtxOFF Pulse X-ray extinguishing time Δtp1 First cross-section data storage time Δtp2 Second cross-section data storage time Δtv Determined from time variation of tomographic plane average luminance value Measurement time
n Number of slices with which temporal changes in brightness value Vz V-direction moving speed VRi of the measurement object Radial movement speed ΔRi of the measurement object VLi Amount of movement of the center of gravity during the scan time VLi Change rate of the contour of the measurement object ΔLi During the scan time Contour movement

Claims (2)

The moving direction of the measurement object is a multi-phase flow, with a high sensitivity X-ray detector of independent two systems are separated by a small distance arrangement, sensitive X-ray detector of the two systems, respectively multiphase flow An X-ray CT apparatus for detecting X-rays that are arranged around and held by a holding ring that is movable in the vertical direction and are sequentially irradiated and transmitted by the plurality of pulse X-ray sources to the measurement object,
The two high-sensitivity X-ray detectors each have a detection surface that is formed by photolithography and has a plurality of light receiving unit pixels that are continuously attached in a line in the circumferential direction. To detect tomograms over time,
The plurality of pulse X-ray sources are configured below the detection surfaces of the two high-sensitivity X-ray detectors and configured to detect X-rays transmitted through the measurement object without interfering with each other,
Based on the data of the different tomographic images detected over time, the speed of the measurement object having different density and attenuation coefficient can be obtained,
One high-sensitivity X-ray detector of the two high-sensitivity X-ray detectors can move continuously and relatively in the moving direction of the object to be measured by the drive mechanism with respect to the other high-sensitivity X-ray detector. An X-ray CT apparatus characterized in that a distance between detection surfaces, which is a distance between detection surfaces of the two high-sensitivity X-ray detectors, can be arbitrarily set according to the moving speed of the measurement object. . It is possible to determine the moving speed of the measurement object based on the distance between the two detection surfaces and the time interval obtained from the tomographic image of the measurement object reconstructed from the detection data on the respective detection surfaces. The X-ray CT apparatus according to claim 1.