WO2014015490A1 - 组合式射线无损检测方法及系统 - Google Patents

组合式射线无损检测方法及系统 Download PDF

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Publication number
WO2014015490A1
WO2014015490A1 PCT/CN2012/079167 CN2012079167W WO2014015490A1 WO 2014015490 A1 WO2014015490 A1 WO 2014015490A1 CN 2012079167 W CN2012079167 W CN 2012079167W WO 2014015490 A1 WO2014015490 A1 WO 2014015490A1
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Prior art keywords
detector
ray
array detector
source
line array
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PCT/CN2012/079167
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English (en)
French (fr)
Inventor
吴志芳
安继刚
刘锡明
王立强
张颜民
丛鹏
黄毅斌
裘伟东
郑健
刘金汇
王振涛
谈春明
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Tsinghua University
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Tsinghua University
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Priority to GB1501147.1A priority Critical patent/GB2519692B/en
Priority to PCT/CN2012/079167 priority patent/WO2014015490A1/zh
Priority to RU2015106330/28A priority patent/RU2598396C2/ru
Publication of WO2014015490A1 publication Critical patent/WO2014015490A1/zh
Anticipated expiration legal-status Critical
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
    • G01N23/06—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and measuring the absorption
    • G01N23/083—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and measuring the absorption the radiation being X-rays
    • G01N23/087—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and measuring the absorption the radiation being X-rays using polyenergetic X-rays
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
    • G01N23/04—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material

Definitions

  • the invention relates to a combined radiation non-destructive testing method and system, in particular to a gamma ray source and an X ray source, and a line array detector and an area array detector, which can be combined in a plurality of ray source-detector combinations.
  • Combined ray non-destructive testing method and system for high-precision DR/CT radiation imaging detection of workpieces belongs to the field of ray non-destructive testing technology and can be applied to fine non-destructive testing in the fields of national defense, aerospace, industry and scientific research.
  • DR Digital Radiography
  • CT Computer Tomography
  • the ray nondestructive testing system is divided into high energy systems and medium and low energy systems.
  • High-energy systems typically use X-ray accelerators as ray sources
  • low- and medium-energy systems typically use X-ray machines or radioisotopes as ray sources.
  • the ray energy is different, the intensity is different, the target size is different, and the output stability is different, which results in different detection indexes such as the thickness range of the detected workpiece and the defect resolution capability.
  • there are many types of detectors for radiation imaging such as detection efficiency, detection sensitivity, pixel size, imaging speed, radiation resistance, and environmental adaptability.
  • the detection performance is also closely related to the incident ray energy.
  • the signal response characteristics of ⁇ / ⁇ rays of different energy segments are significantly different, and the radiation of a certain energy segment is not suitable, but Another energy segment may be ideal.
  • a common feature of the radiation non-destructive testing system disclosed in the prior art is that only one type of ray source and one type of detector are usually used, that is, the ray source alone uses an X-ray machine, an X-ray illuminator or a ⁇ -ray source.
  • the detector uses only one of the area array detector and the line array detector. It is difficult to obtain multiple energy segments and high stability at the same time.
  • the advantages of different types of detectors are difficult to fully exert, and the defect resolution capability is limited. It is difficult to obtain a wide-energy range detection effect, and its limitations and deficiencies are described as follows:
  • the ray energy range is narrow, and the object suitable for detection is limited. In general, the higher the ray energy, the stronger the penetration ability, but the higher ray energy does not necessarily lead to higher detection accuracy. Low ray energy will result in insufficient penetrating power; ray energy is too high, and penetration ability is enhanced, but the ray attenuation is too small, which will reduce the contrast sensitivity of the imaging system and affect the imaging quality. For different sizes of workpieces and different sizes of defects in the workpiece, it is necessary to use different energy ray detection, or, for a certain energy ray, there is an optimum thickness measurement range.
  • the optimum detection thickness of a 450kV X-ray machine is about 2.3cm equivalent iron thickness
  • the optimum detection thickness of a ⁇ )-60 ⁇ -ray source is about 4.7cm equivalent iron thickness, and the best detection thickness of a 15MeV X-ray accelerator.
  • Detection systems using different sources can achieve the highest detection accuracy in the vicinity of their optimum detection thickness, and the detection effect is the best, and the deviation from this range will reduce the detection capability. Therefore, the detection system using a single ray source is limited by the ray energy range, and the range of objects suitable for detection is narrow, and the defect resolution capability is limited. This is also an important reason why industrial CT systems often need to be customized according to the detection object.
  • any kind of radiation source has its advantages and disadvantages for radiation imaging.
  • the specific performances are as follows: (i) The X-ray machine source has a small focus size. The radiation intensity is high, and high spatial resolution can be achieved, but the ray energy is low, the energy spectrum is continuous spectrum, the penetration ability is not strong, and the beam hardening is problematic, and the workpiece with small mass thickness is well detected. The effect, but the requirement for fine quantitative detection is difficult to meet the requirements of large thickness, high stability, and the size of the defect; (ii) X-ray accelerator has high ray energy, high strength, and can penetrate thicker workpieces.
  • the target is large, the spatial distribution of ray intensity and energy is large, the forward momentum is large, and the X-ray output stability is poor, and the energy spectrum is also a continuous spectrum.
  • the same beam hardening problem can be detected, and the mass thickness can be detected.
  • Workpieces but spatial resolution, detection sensitivity, and measurement stability are all limited.
  • the X-ray beam angle of the accelerator is small, to detect a large-sized workpiece, the space occupied by the detection system is large, the mechanical structure is also complicated, and the radiation protection requirements are also high; ( ⁇ ) ⁇ -ray source, For example, Co-60, whose ray intensity is gradually weakened by a fixed half-life, is determined and calculatable at any time.
  • the spatial distribution of its intensity is isotropic, and the gamma ray produced is 1.17 MeV and 1.33 MeV.
  • ⁇ ray basically no radiation hardening problem, strong penetrating ability, equivalent to 4MeV accelerator, and especially suitable for detecting small changes in mass thickness of workpieces in a long period of time, but also there are large target sizes of radiation sources, ray intensity Lower deficiencies.
  • the use of any of these sources alone has its limitations, if used in combination, in particular by combining a gamma source such as Co-60 with an X-ray machine. With it, it can make up for their own shortcomings, so that the combined detection system can achieve maximum performance.
  • the technical problem to be solved by the invention is to overcome the deficiencies of the existing radiation imaging detection system using a single ray source and a single detector working mode, and realize multi-energy segment and multi-mode combined detection of the workpiece on an integrated miniaturized system. To meet the detection requirements of high detection resolution, high detection sensitivity, strong radiation penetration and good long-term stability.
  • the present invention provides a combined radiation non-destructive testing method, and a combined radiation non-destructive testing system using the same, the method and system comprising a gamma ray source and an X ray source, and a line Multi-energy segment, multi-detection mode, high resolution, high precision, high stability on a combined ray non-destructive testing system of array detectors and area array detectors through various combinations of different ray sources and different detectors Non-destructive testing of DR/CT rays.
  • the combined radiation non-destructive testing method of the present invention is specifically: Rays through the workpiece, and converted into a digital signal and then process the signals, obtained using a workpiece detector containing solid line; Jog detector array detector, gas detector line ⁇ ⁇ array probe's surface, by switching different
  • the radiation source and the detector comprise different detection units for performing DR scanning imaging or tomographic CT imaging or cone beam CT imaging of the workpiece; the combined radiation source and combined detector, and the workpiece turntable are mounted on the same rigid base on.
  • the ray outlet of the combined ray source is provided with a front collimator that collimates the ray into a fan beam or a cone beam
  • the ray entrance of the combined detector is provided with a rear collimator
  • the injecting detector is a solid line array detector or a gas line array detector
  • the rear collimator collimates the beam into a small beam of light corresponding to the height and quantity of the detector unit, and the collimation slit width is less than The width of the detector unit; when performing DR imaging, the rear collimator can peristalize along the width direction of the detector unit, and acquire a set of projection data once per peristal motion, and the distance per peristalsis is the collimation slit width.
  • a combined radiation non-destructive testing system using the above method comprises: a rigid base on which a radiation source bracket, a workpiece turntable, and a detector bracket are arranged in sequence;
  • the radiation source bracket is provided with a gamma ray source and a combined radiation source of an X-ray source, and a switching mechanism for moving different radiation sources in the combined radiation source into a working position, and a mechanism for up-and-down, front-rear, left-right, and rotational operations on the moved radiation source;
  • a combined detector including a solid line array detector, a gas line array detector and an area array detector, and a switching mechanism for moving different detectors in the combined detector into the working position, and The detector performs upper and lower, front, back, left and right and rotation operations;
  • the radiation source bracket is provided with a front collimator capable of collimating the radiation output from the radiation source into a fan beam or a cone beam, and the detector bracket is provided with a pair of rays a post collimator for further
  • the width of the collimating slit is 1/2, 1/3 or 1/4 of the width of the detector unit.
  • the gamma ray source is a Co-60, Cs-137 or Ir-192 radioisotope gamma ray source.
  • the X-ray source is a small focus X-ray machine, a micro focus X-ray machine, and/or an X-ray line accelerator.
  • the area array detector is an amorphous silicon, amorphous selenium or CMOS area array detector.
  • the gas line array detector is a gas-filled ionization chamber, a multi-wire proportional chamber or a Geiger count pipeline array detector.
  • the solid line array detector is a solid scintillator line array detector or a semiconductor line array detector.
  • the scintillator of the solid scintillator linear array detector is Nal, Csl, CdW0 4 , LaBr 3 or LaCl 3 .
  • the multi-energy segment, multi-mode and high-precision combined radiation non-destructive testing method and system of the invention have good detection effect on the workpiece to be inspected and its internal defects, and can achieve high spatial resolution and density resolution.
  • the rate can also detect the small mass thickness variation of the internal region of interest of the workpiece over a long period of time.
  • the detection system of the invention has a wide range of energy sources, and can include medium and high energy gamma ray sources (radiation energy from several hundred keV to several thousand keV), and medium and low energy X-ray sources (radiation energy from tens of keV to several Hundred keV), can comprehensively utilize the advantages of multi-energy segments and different attribute rayes, and is suitable for detecting workpieces with a larger thickness range, which can achieve more powerful functions and achieve a combination of solid line array detectors, forming different ray sources - detection
  • the device detection unit can perform fast three-dimensional cone beam CT stereo imaging detection with different resolutions, or perform two-dimensional scanning DR or two-dimensional tomographic CT fine non-destructive detection on key areas, and fully utilize the advantages of various imaging detectors; Different kinds of ray sources and different types of detectors are integrated into one whole through clever structural design.
  • the detection system of the invention has the advantages of compact structure, small volume, small floor space, strong adaptability to the thickness, shape and size of the workpiece, high defect detection precision, powerful function and high cost performance, and is particularly suitable for detecting objects with large differences and detection requirements.
  • High application sites can meet a variety of high-precision and complex inspection requirements in the defense, aerospace, industrial and scientific research sectors.
  • Figure 1 is a perspective view of a combined radiation non-destructive testing system of the present invention.
  • Figure 2 is a structural view of the collimator slot of the line detector and the collimator of the rear collimator, and a partial enlarged view of the creep direction of the rear collimator.
  • Figure 3 is a side cross-sectional view of the gamma ray source. detailed description
  • the combined radiation non-destructive testing system of the present invention comprises: a pedestal 5 and a horn 14 at the bottom thereof; a ray source holder 10 and a detector holder 1 vertically fixed on the pedestal; a source frame 12 that is raised or lowered and positioned and positioned; a detector frame 7 that can be lifted or translated and positioned along the detector holder 1; an X-ray source 9 and a gamma-ray source 13 fixed to the source frame 12; An area array detector 6, a solid line array detector 2 and a gas line array detector 4 on the detector frame 7, a workpiece turntable 15 and a workpiece holder 8 thereon; and a front collimator 11 of the radiation source and Rear collimator 3 of the line detector.
  • the workpiece turret 15 can be rotated and raised, or can be translated in parallel or perpendicular to the direction in which the source is connected to the detector.
  • the source and detector can be moved up or down with their respective racks and positioned to the specified position.
  • the X-ray source 9 and the ray exit of the gamma ray source 13 are respectively provided with a front collimator 11 made of a lead alloy, a tungsten alloy or a depleted uranium material, and a horizontal horn slit is provided inside the front collimator 11
  • the square taper opening can be switched by horizontal shifting, and the ray is collimated into a fan beam or a square cone beam, which are used for line array detector or area array detector imaging, respectively.
  • the back line collimator 3 is respectively mounted on the ray entrance sides of the solid line array detector 2 and the gas line array detector 4 for further collimating the fan-shaped rays entering the line array detector to correspond to the detector unit.
  • the square-shaped area other than the active area of the area array detector 6 ie, the square area composed of the sensitive material for detecting X or ⁇ -rays
  • the base 5 is made of a monolithic cast iron, stone or steel frame that provides both rigid support and shock absorption as well as a reference surface for the entire inspection system installation and adjustment.
  • the horn 14 is used to adjust the pedestal 5 to a horizontal state, typically 4, 6, or 8, distributed in the middle of the four corners or four sides of the lower surface of the pedestal 5.
  • the detection system of the invention comprises an area array detector and a line array detector, respectively, and an X-ray Combination of line source or gamma ray source for DR imaging and CT imaging, its working modes include: Area Array Detector DR Imaging: Lift or translate selected ray source and area array detectors to a set position, so that the source center and The center of the area array detector is located at the same horizontal plane, and the workpiece is completely contained in the imaging area of the area array detector; the front collimator is horizontally displaced to the position of the tapered opening, and the source shutter is opened, and the radiation passes through the front collimator 11 The straight cone beam is received by the area array detector 6 after penetrating the workpiece to obtain a two-dimensional DR projection image.
  • Array detector CT imaging lifting or translating selected ray source and area array detectors to a set position, so that the center of the ray source and the center of the area array detector are at the same horizontal plane, and the workpiece is completely contained in the imaging area of the area array detector.
  • the front collimator is horizontally displaced to the conical opening position, the ray source shutter is opened, the workpiece turret is rotated 360 degrees at the set rotation speed, and one frame of projection image is acquired every one step, and all projection data is acquired.
  • a three-dimensional cone beam CT image of the workpiece is obtained.
  • Line Array Detector DR imaging can be achieved in two ways:
  • the gas line array detector or the solid line array detector has a circular arc structure and is composed of a plurality of detector units 21, and the detector unit 21 faces the end face of the radiation source (ie, the ray entrance window) along the first
  • the circular arc lines 24 are evenly arranged closely.
  • the first circular arc line 24 is centered on the source of the radiation source (ie, the target of the X-ray source or the source of the gamma ray source), and the distance from the ray entrance window to the source of the ray source is a radius.
  • the height and width of the detector unit 21 refer to the ray entrance window.
  • the height and width, the product of the width and height is the pixel value of the line detector.
  • the number of detector units 21 is such that the length of the first circular arc line 24 formed by the ray entrance window and the sector formed by the source of the ray source can cover each section to be detected of the workpiece to be inspected, and preferably 8 Integer multiple.
  • the width of the ray entrance window of each detector unit 21 in the direction of the arc should meet the detection resolution requirements of the detection system of the present invention.
  • the center line of the length direction of each detector unit 21 i.e., parallel to the direction of the ray is directed to the source of the source.
  • the rear collimator 3 of the line array detector is also a circular arc-shaped structure, and the second circular arc line 25 is also centered on the source of the ray source, and its radius is slightly smaller than the radius of the first circular arc line 24.
  • the rear collimator 3 is a spacer 23 made of a rectangular tungsten alloy sheet uniformly arranged in parallel along the second circular arc line 25, and is used for accurately fixing the spacer 23, made of copper or a lead alloy or a tungsten alloy.
  • Two parallel plywoods (not shown in Fig. 2) are constructed.
  • a plurality of collimating slits 22 are formed between the spacer 23 and the splint to further collimate the rays before entering the detector into a plurality of small beams.
  • the height of the collimating slit 22 is the distance between the two splints, and the width is the distance between the adjacent two sheets of the separator 23.
  • the height of the collimating slit 22 is equal to or slightly larger than the height of the detector unit 21, and the width is 1/2, 1/3 or 1/4 of the width of the detector unit 21, and the number is the same as the number of the detector units 21.
  • the rear collimator 3 can wriggle in both directions along the second circular arc line 25, and a set of projection data is acquired every time the peristalsis is performed, and the distance per peristaltic motion is the width of the collimating slit 22.
  • the spatial resolution of the DR imaging is 1/2, 1/3 or 1/4 of the width of the detector unit 21, which further improves the detection resolution of the detection system of the present invention.
  • Line Array CT Imaging Lift the selected source and line detector to the set position so that the center of the source and the center of the line detector are at the same horizontal plane (detection surface), and the workpiece turret 15 is raised to the set position.
  • the part to be inspected of the workpiece is located on the detection plane; the front collimator is displaced to the slit position, the radiation source is turned on, the workpiece turntable 15 is rotated 360 degrees at the set rotation speed, and a set of projection data is acquired every time a constant angle is rotated, all After the data acquisition is completed, data processing and image reconstruction are performed to obtain a CT tomographic image of the detected part of the workpiece to be tested.
  • the gamma ray source includes a shield 36 made of a lead alloy, a tungsten alloy or depleted uranium having a ray inlet 37 and a ray outlet 38 therein; one of which can be in the shield 36
  • the relatively rotating rotary shutter 35 has its axis of rotation horizontally disposed with its interior selectively illuminating the radiation inlet 37 and the ray outlet 38 in the shield 36 as it rotates Or a disconnected connecting passage 39, which is flared from the ray inlet 37 to the ray outlet 38, and together with the ray inlet 37 and the ray outlet 38 of the shield 36 form a ray-shaped ray channel.
  • the gamma ray is fanned or cone shaped; and a source 34 is located at the beginning of the ray inlet 37.
  • the invention organically integrates the X-ray source and the ⁇ -ray source into an integrated miniaturized detection system, and the different radiation sources and detectors can be combined by the lifting or translating of the radiation source and the detector to form up to two There are more than a dozen detection modes, and different detection modes are suitable for detecting defects of different objects, types and sizes, and satisfying different detection requirements.
  • the 450kV X-ray machine has a small target point (up to 0.4mm) and high radiation intensity (the dose rate at 1 meter from the target point can reach several hundred mGy/ Min ), for workpieces with equivalent mass thickness less than 60mm iron, high spatial resolution can be achieved (for example, up to 4.41p/mm with area array detectors);
  • Co-60 gamma ray source has high ray energy (average energy) 1.25MeV), its ray penetration ability is equivalent to that of 4MeV accelerator. It is suitable for detecting workpieces with equivalent mass thickness of 30 ⁇ 130mm iron, which can achieve density resolution of 0.1%.
  • ⁇ -ray source ray output intensity stability It can also be used with ⁇ -ray source ray output intensity stability. The distance between any two points inside the workpiece is measured, and a small change in the mass thickness of any local area inside the workpiece over a long period of time is detected. If you choose a microfocus X-ray machine, you can increase the detection resolution of your system to the order of a few microns.
  • a Co-60 ⁇ -ray source and a 450 keV small-focus X-ray machine are used.
  • the detector uses an area array detector, a scintillator solid line array detector and a gas-filled ion chamber gas line array detector.
  • the Co-60 source used was about 3.7 TBq (100 Curie)
  • the 450 keV X-ray machine had a focus size of 0.4 mm
  • the maximum tube current was 3.3 mA.
  • the imaging area of the area array detector is 409.6 ⁇ 409.6mm 2
  • the pixel size is 0.2 x 0.2mm 2
  • the solid line array detector uses CdW0 4 crystal as the scintillator.
  • the pixel size is 0.4 X 5 X 30mm 3 0 gas line array detector is inflated. Ionization chamber, with helium as working medium, inflation pressure 3.5MPa.
  • the gamma ray source shielding container and the front and rear collimators are each made of a tungsten alloy having a density greater than 18 g/cm 3 . Lifting of the source and detector racks or The position measurement is realized by a rotary encoder and a grating scale, and the repeat positioning accuracy is less than ⁇ ; the minimum rotation step of the workpiece turntable is 15 ⁇ , and the repeat positioning accuracy is less than 2 ⁇ .
  • the overall size of the entire inspection system is 2.5m 1.8m 2.2m (length x width x height) and weighs about 5 tons.
  • the detection of the small gap change of the gap and the thickness of the mass and the detection task such as the bubble detection are decomposed, and the detection system of different parameters and different detection methods are completed.
  • the "Co-60 source + large pixel gas line array detector DR scanning imaging" method is used to detect the small gap change of the workpiece stop gap and the mass thickness.
  • the large pixel detector has a strong output signal and small statistical fluctuations, which is conducive to the detection of mass thickness variations.
  • Co-60 source ray intensity can be stable for a long time, the cylinder is easy to operate, and the reliability is high.
  • the gas detector has small leakage current, high stability, low temperature drift and radiation resistance.
  • the combination of the two DR scanning systems has high measurement accuracy and stable performance for a long time, which is very suitable for the detection of small gaps in the gap and mass thickness.
  • the internal bubble detection of the workpiece is realized by the "X-ray machine + small pixel solid line array detector CT tomography" method.
  • CT tomography can obtain the density distribution of the object to be examined, can detect fine defects, and can accurately locate the defects, which is the best means to detect bubbling and falling off.
  • the detection system of this embodiment uses two kinds of radiation sources (Co-60 and 450kV X-ray machines) and three kinds of detectors (small pixel solid line array detector, large pixel gas line array detector and micro pixel area array detector). , combined to take full advantage of the advantages of different sources and different detectors to better meet the testing requirements.
  • the X-ray machine has high radiation intensity and small source focus size, which is beneficial to improve the resolution of the imaging system.
  • Cobalt-60 source has good single-energy, no beam hardening problem, and high ray energy and stronger penetrating ability, which can detect objects with higher mass and thickness.
  • the small pixel solid line array detector can better shield the scattered lines, and the detection efficiency is higher, and a clearer image can be obtained.
  • the micro pixel area array detector has smaller pixel size, can achieve higher spatial resolution, and has one scan. A three-dimensional image of the object is obtained, and the imaging is faster.
  • the above two kinds of ray sources and three kinds of detectors are integrated into the same detection platform, and the upper and lower shift layout and the componentized and modular design mode are adopted, and the switching combination of different ray sources and different detectors is realized, which will be different.
  • the detection methods are organically combined to form a comprehensive detection system.

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Abstract

一种组合式射线无损检测方法及系统，该方法及系统将γ射线源（13）和X射线源（9）与固体线阵探测器（2）、气体线阵探测器（4）及面阵探测器（6）分别借助射线源支架（10）和探测器支架（1）集成在一个刚性基座（5）上，通过不同射线源与不同探测器的组合，分别进行DR扫描成像和断层或锥束CT成像，实现对工件的多能量段、多模式组合的高精度射线无损检测，能同时满足高检测分辨率、高探测灵敏度、较强的射线穿透能力和良好的长期稳定性等检测要求。

Description

组合式射线无损检测方法及系统 技术领域
本发明涉及一种组合式射线无损检测方法及系统， 特別涉及一种采 用 γ射线源和 X射线源， 以及线阵探测器和面阵探测器， 能以多种射线源 -探测器组合方式对工件进行高精度 DR/CT辐射成像检测的组合式射线 无损检测方法及系统， 属于射线无损检测技术领域， 可应用于国防、 航 空航天、 工业和科研等领域的精细无损检测。
背景技术
DR ( Digital Radiography , 数字辐射成像） 和 CT ( Computed Tomography, 计算机断层成像）技术是医学和工业领域常用的射线无损 检测技术。 现有的射线无损检测系统往往性能单一， 主要针对某一类工 件或缺陷进行检测， 其性能指标如： 反差灵敏度、 空间分辨率、 穿透能 力和长期稳定性等， 多是单项突出而难于兼顾。
根据所使用的射线源不同， 射线无损检测系统分为高能系统和中低 能系统。 高能系统通常采用 X射线加速器作为射线源， 中低能系统通常 采用 X光机或放射性同位素作为射线源。 对于不同的射线源， 由于射线 能量不同， 强度不同， 靶点尺寸不同， 输出稳定性不同， 造成所适用的 检测工件厚度范围、 缺陷分辨能力等检测指标也不同。 另一方面， 用于 辐射成像的探测器也有多种， 其探测效率、 探测灵敏度、 像素尺寸、 成 像速度、 抗辐照性和环境适应性等各有不同。 而且， 探测性能跟入射射 线能量也有很大关系， 即使同一种探测器， 对不同能量段的 Χ/γ射线， 其 信号响应特性也存在显著差別， 对某一能量段的射线不适合， 而对另一 能量段则可能很理想。 然而， 现有技术中公开的射线无损检测系统存在 一个共同的特点， 就是通常只使用一种射线源和一种探测器， 即： 射线 源只单独使用 X光机、 X射线加速器或 γ射线源中的一种， 探测器只使用 面阵探测器和线阵探测器中的一种， 多个能量段与高稳定性难于同时获 得， 不同类型探测器的优势难于充分发挥， 缺陷分辨能力受限， 难于获 得宽能量范围的探测效果， 其局限性和不足具体描述如下：
1、 射线能量范围窄， 适于检测的对象受到限制 一般来讲， 射线能量越高， 穿透能力越强， 但更高的射线能量并不 一定带来更高的检测精度。 射线能量偏低， 会导致穿透能力不足； 射线 能量过高， 穿透能力增强， 但是射线衰减过少， 会降低成像系统的反差 灵敏度， 影响成像质量。 对于不同大小的工件和工件内不同尺寸的缺陷， 需要用不同能量的射线检测， 或者说， 对一定能量的射线， 存在一个最 佳厚度测量范围。 例如， 450kV X光机的最佳检测厚度约为 2.3cm等效 铁厚度， Ο)-60 γ射线源的最佳检测厚度约为 4.7cm等效铁厚度， 15MeV X 射线加速器的最佳检测厚度约为 8cm等效铁厚度， 等等。 使用不同射线 源的检测系统在其最佳检测厚度附近能获得最高的检测精度， 检测效果 最好， 而偏离这个范围， 其检测能力就会下降。 因此， 采用单个射线源 的检测系统， 受射线能量范围限制， 其适于检测的对象范围较窄， 缺陷 分辨能力有限，这也是工业 CT系统往往需要根据检测对象进行定制的重 要原因。
2、 不能综合利用不同类型射线源的优点最大限度提高检测能力 任何一种射线源用于辐射成像都有其优点， 也有其不足， 具体表现 在： （i)X 光机射线源焦点尺寸小， 射线强度高， 可以实现很高的空间分 辨率， 但是射线能量较低， 能谱是连续谱， 存在穿透能力不强和射线束 硬化等问题， 对于质量厚度较小的工件有很好的检测效果， 而对于质量 厚度较大、 稳定性要求很高， 和缺陷的尺寸需要精细定量检测的要求就 难于满足； （ii)X射线加速器的射线能量高， 强度大， 可以穿透较厚的工 件， 但是靶点大， 射线强度及能量的空间分布差异大， 前沖性大， 且 X 射线输出稳定性较差， 能谱也是连续谱， 同样存在射线束硬化问题， 能 检测质量厚度较大的工件， 但空间分辨率、 检测灵敏度和测量稳定性等 都受到限制。 另外， 由于加速器的 X射线束张角小， 要检测较大尺寸的 工件， 检测系统占用的空间就较大， 机械结构也很复杂， 而且辐射防护 要求也很高； （ίϋ)γ射线源， 如 Co-60, 其射线强度以固定的半衰期逐渐减 弱， 在任意时刻都是确定且可计算出的， 其强度的空间分布各向同性， 其产生的 γ射线为 1.17MeV和 1.33MeV的单能 γ射线， 基本不存在射线硬 化问题， 穿透能力较强， 与 4MeV加速器相当， 而且特別适合检测工件 在较长时期内质量厚度的微小变化， 但也存在射线源靶点尺寸较大、 射 线强度较低的不足。 这几种射线源中的任何一种单独使用都有其局限性， 如果将它们结合使用， 尤其是将例如 Co-60 的 γ射线源与 X光机结合使 用， 就能弥补各自的不足， 使组合式检测系统能发挥出最大效能。
3、 不能充分发挥各种探测器的优点， 最大限度地提高检测能力 不同类型探测器具有不同的特点， 各有优点也各有局限性， 具体表 现在： （i)面阵探测器： 空间分辨率高， 可达 μιη级， 成像速度快， 但灵敏 体厚度仅有 0.2 ~ 0.5mm, 探测效率低， 次级电子串扰难于消除， 对于低 能射线的探测比较合适； （ii)固体线阵探测器： 灵敏体厚度可达 cm级， 探测效率高， 检测灵敏度高， 但空间分辨率难于做到 μιη级， 需要逐行扫 描， 成像速度慢， 而且易受辐照、 环境温湿度等因素影响， 长期稳定性 较差； （iii)气体线阵探测器： 性能稳定， 环境适应性强， 耐辐照， 但探测 器单元的尺寸难于做小， 空间分辨率受到较大限制。 因此， 对于不同的 射线能量和不同的缺陷， 需要用不同类型的探测器才能获得最佳检测效 果， 单一类型的探测器难于胜任复杂的检测要求。
4、 无法同时满足灵敏度高、 穿透能力强和长期稳定性好的检测需求 在某些特殊领域， 检测对象质量厚度较大（相当于几厘米铁）， 而检 测精度要求又非常高： 要分辨出细微的 （μιη级）裂缝、 脱落、 鼓泡等缺 陷， 能发现较长时期（数月， 甚至数年） 内发生的 0.1 %的微小质量厚度 变化等。 这种情况对于空间分辨率、 检测灵敏度和长期稳定性等指标的 要求都很高， 是现有辐射成像检测系统难于实现的。 发明内容
本发明要解决的技术问题是克服现有辐射成像检测系统采用单一射 线源和单一探测器工作模式的不足， 在一套集成的小型化系统上， 实现 对工件的多能量段、 多模式组合检测， 以同时满足高检测分辨率、 高探 测灵敏度、 较强的射线穿透能力和良好的长期稳定性等检测要求。
为解决上述技术问题，本发明提出了一种组合式射线无损检测方法， 以及应用该方法的一种组合式射线无损检测系统， 该方法及系统在一个 包括 γ射线源和 X射线源，以及线阵探测器和面阵探测器的组合式射线无 损检测系统上， 通过不同射线源与不同探测器的多种组合， 实现多能量 段、 多检测模式、 高分辨率、 高精度、 高稳定性的 DR/CT射线无损检测。
本发明的组合式射线无损检测方法， 具体为： 过工件的射线， 并转换成数字信号， 然后对信号进行处理， 得到工件的 探测器采用 含固体线;阵探测器、 气体线 ^探测器^面阵探 器的 合 式探测器， 通过切换不同的射线源和探测器组成不同的检测单元， 实现 对工件的 DR扫描成像或断层 CT成像或锥束 CT成像； 所述组合式射线 源和组合式探测器， 以及工件转台均安装在同一刚性基座上。
进一步， 所述组合式射线源的射线出口设置有前准直器， 该前准直 器将射线准直成扇形束或锥形束， 所述组合式探测器的射线入口设置有 后准直器； 当切入的探测器为固体线阵探测器或气体线阵探测器时， 所 述后准直器将射线准直成与探测器单元高度、 数量相当的小射线束， 其 准直缝宽度小于所述探测器单元宽度； 在进行 DR成像时， 所述后准直 器可沿探测器单元宽度方向蠕动， 每蠕动一次获取一组投影数据， 每次 蠕动的距离为准直缝宽度。
一种应用上述方法的组合式射线无损检测系统， 包括： 一个刚性基 座， 基座上依次间隔排列有射线源支架、 工件转台、 探测器支架； 射线 源支架上设置有包^ γ射线源和 X射线源的组合式射线源，以及用于将组 合式射线源中的不同射线源移入工作位置的切换机构， 和对移入的射线 源进行上下、 前后、 左右和旋转操作的机构； 探测器支架上设置有包含 固体线阵探测器、 气体线阵探测器和面阵探测器的组合式探测器， 以及 用于将组合式探测器中的不同探测器移入工作位置的切换机构， 和对移 入的探测器进行上下、 前后、 左右和旋转操作的机构； 射线源支架上设 置有能够将射线源输出的射线准直成扇形束或锥形束的前准直器， 探测 器支架上设置有对射线做进一步准直处理的后准直器； 所述气体线阵探 测器和所述固体线阵探测器均为圓弧形结构， 当其被移入工作位置上后， 探测器上各探测器单元的射线入射窗沿着以处于工作位置上的射线源的 源心为圓心的圓弧均匀紧密排列， 且每个探测器单元的中心线均通过所 述圓心， 与气体线阵探测器或固体线阵探测器相配的后准直器同样为以 处于工作位置上的射线源的源心为圓心的圓弧形结构， 该后准直器的准 直缝可将所述扇形射线束准直成与探测器上的各探测器单元一一对应的 小射线束， 并且准直缝的宽度小于探测器单元的宽度； 在进行 DR成像 时， 所述后准直器紧邻所述气体线阵探测器或固体线阵探测器， 且可沿 探测器单元的排列方向蠕动， 每次蠕动的距离为准直缝的宽度。 进一步， 所述准直缝的宽度为探测器单元宽度的 1/2、 1/3或 1/4。 进一步， 所述 γ射线源是 Co-60、 Cs-137或 Ir-192放射性同位素 γ射线 源。
进一步， 所述 X射线源是小焦点 X光机、 微焦点 X光机和 /或 X射 线加速器。
进一步， 所述面阵探测器是非晶硅、 非晶硒或 CMOS面阵探测器。 进一步， 所述气体线阵探测器是充气电离室、 多丝正比室或盖格计 数管线阵探测器。
进一步， 所述固体线阵探测器是固体闪烁体线阵探测器或半导体线 阵探测器。
进一步， 所述固体闪烁体线阵探测器的闪烁体是 Nal、 Csl、 CdW04、 LaBr3或 LaCl3。
实践证明， 本发明的多能量段、 多模式、 高精度组合式射线无损检 测方法及系统对于被检工件及其内部缺陷具有很好的检测效果， 既可以 达到很高的空间分辨率和密度分辨率， 又可以对工件内部感兴趣区在长 时期内的微小质量厚度变化进行检测。
本发明检测系统的射线源能量范围宽， 既可包含中高能的 γ射线源 (射线能量从几百 keV〜几千 keV ), 又包含中低能的 X射线源（射线能 量从几十 keV〜几百 keV ), 可以综合利用多能量段、 不同属性射线的优 点， 适于检测的工件质量厚度范围更大， 可以实现更强大的功能和达到 固体线阵探测器组合， 构成不同的射线源 -探测器检测单元， 既可以进行 不同解析度的快速三维锥束 CT立体成像检测，也可以对重点区域进行二 维扫描 DR或二维断层 CT精细无损检测，充分发挥各种成像探测器的优 势； 将不同种类射线源和不同类型探测器通过巧妙的结构设计有机结合 为一个整体， 一套装置可以提供几种到几十种射线源 -探测器组合模式， 相当于同时拥有几套不同类型的检测系统， 既有更强的对象适应性， 又 能充分发挥不同类型射线源和探测器的特点， 达到更高的缺陷检测能力。 本发明检测系统结构紧凑， 体积小、 占地面积少， 对工件厚度、 形状和 尺寸的适应能力强， 缺陷检测精度高， 功能强大， 性价比高， 特別适用 于检测对象差异较大及检测要求较高的应用场所， 可以满足国防、 航空 航天、 工业和科研等部门的各种高精度复杂检测要求。 附图说明
图 1是本发明组合式射线无损检测系统的立体图。
图 2是线阵探测器的探测器单元和后准直器准直缝的结构形式， 以 及后准直器蠕动方向的局部放大示意图。
图 3是 γ射线源的侧视剖面图。 具体实施方式
下面结合附图， 对本发明的具体实施方式进行详细说明。
如图 1所示， 本发明组合式射线无损检测系统包括： 基座 5及其底 部的垫铁 14; 垂直固定在基座上的射线源支架 10和探测器支架 1 ; 可沿 射线源支架 10升降或平移并定位的射线源机架 12;可沿探测器支架 1升 降或平移并定位的探测器机架 7; 固定在射线源机架 12上的 X射线源 9 和 γ射线源 13； 固定在探测器机架 7上的面阵探测器 6、 固体线阵探测器 2和气体线阵探测器 4; 工件转台 15及其上的工件卡具 8; 以及射线源的 前准直器 11和线阵探测器的后准直器 3。
工件转台 15可以旋转和升降， 也可以沿平行或垂直于射线源与探测 器连线的方向平移。 射线源和探测器可以随各自机架升降或平移， 并精 确定位到指定位置。 X射线源 9和 γ射线源 13的射线出口处都分別装有前 准直器 11 , 该前准直器 11由铅合金、 钨合金或贫铀材料制成， 其内部设 有水平喇叭形狭缝和方锥形开孔， 可通过水平移位进行切换， 将射线准 直成扇形束或方锥形束， 分別用于线阵探测器或面阵探测器成像。 固体 线阵探测器 2和气体线阵探测器 4的射线入口侧都分別装有后准直器 3 , 用于将即将进入线阵探测器的扇形射线进一步准直成与探测器单元对应 的多个小射线束。 面阵探测器 6的活性区（即由用于探测 X或 γ射线的敏 感材料构成的方形区域） 以外的方框形区域用铅合金或钨合金平板屏蔽 材料覆盖（附图 1中未示出 ) , 以防止射线对面阵探测器 6的电子元器件 产生辐照损伤。 基座 5 由整体的铸铁、 石材或钢结构框架制成， 既起到 刚性支撑和减震作用， 又是整个检测系统安装和调校的基准面。 垫铁 14 用来将基座 5调节到水平状态， 一般为 4个、 6个或 8个， 分布在基座 5 下表面的四个角或四边的中间位置。
本发明的检测系统包含了面阵探测器和线阵探测器， 可分別与 X射 线源或 γ射线源组合， 进行 DR成像和 CT成像， 其工作模式包括： 面阵探测器 DR成像： 将选定射线源和面阵探测器升降或平移到设 定位置， 使得射线源中心和面阵探测器中心位于同一水平面， 且工件完 全包含在面阵探测器成像区内； 将前准直器水平移位到锥形开孔位置， 打开射线源快门， 射线经前准直器 11准直成锥形束， 穿透工件后由面阵 探测器 6接收， 获得二维 DR投影图像。
面阵探测器 CT成像：将选定射线源和面阵探测器升降或平移到设定 位置， 使得射线源中心和面阵探测器中心位于同一水平面， 且工件完全 包含在面阵探测器成像区内； 将前准直器水平移位到锥形开孔位置， 打 开射线源快门， 工件转台以设定的转速转动 360度， 每转动一个步长就 获取一帧投影图像， 全部投影数据获取完成后， 经过数据处理和图像重 建， 获得工件的三维锥束 CT图像。
线阵探测器 DR成像可以通过两种扫描方式实现：
1 )将选定射线源和线阵探测器升降或平移到设定位置， 使得射线源 中心和线阵探测器中心位于同一水平面（检测面）， 且该检测平面稍高于 工件的顶端或稍低于工件的底端（检测区外）， 将前准直器移位到狭缝位 置， 打开射线源快门， 转台 15以设定的速度托着被测工件匀速上升或下 降， 经前准直器 11准直而成的片状射线束对被测工件进行垂直扫描， 透 过工件的射线经后准直器 3准直后， 由固体线阵探测器 2或气体线阵探 测器 4接收， 并经过数据处理系统转换为 DR投影图像。
2 )将选定射线源和线阵探测器升降或平移到设定位置， 使得射线源 中心和线阵探测器中心位于同一水平面（检测面）， 且该检测平面稍高于 工件的顶端或稍低于工件的底端（检测区外）， 将前准直器移位到狭缝位 置， 打开射线源快门， 射线源和线阵探测器以设定的速度同步匀速下降 或上升，经前准直器 11准直而成的片状射线束对被测工件进行垂直扫描， 透过工件的射线经后准直器 3准直后， 由固体线阵探测器 2或气体线阵 探测器 4接收， 并经过数据处理系统转换为 DR投影图像。
如图 2所示， 气体线阵探测器或固体线阵探测器为圓弧形结构， 由 多个探测器单元 21构成， 探测器单元 21面向射线源的端面 （即射线入 射窗） 沿第一圓弧线 24均匀紧密排列， 该第一圓弧线 24以射线源源心 (即 X射线源的靶心或 γ射线源的放射源）为圓心， 以射线入射窗到射线 源源心的距离为半径。 探测器单元 21的高度和宽度就是指该射线入射窗 的高度和宽度， 该宽度与高度的乘积即该线阵探测器的像素值。 探测器 单元 21的数量应使其射线入射窗构成的第一圓弧线 24的长度与射线源 源心共同形成的扇形区能覆盖被检测工件的每个需检测的截面， 且最好 是 8的整数倍。 每个探测器单元 21的射线入射窗沿圓弧方向的宽度， 应 满足本发明检测系统的检测分辨率要求。每个探测器单元 21长度方向（即 平行于射线的方向） 的中心线均指向射线源源心。 线阵探测器的后准直 器 3也是圓弧形结构， 其第二圓弧线 25亦以射线源源心为圓心， 且其半 径略小于第一圓弧线 24的半径。 后准直器 3由沿第二圓弧线 25均匀平 行排列的、 由长方形钨合金薄片制成的隔离片 23 , 以及用于精确固定隔 离片 23、 由紫铜或铅合金或钨合金制成的上下两块平行夹板（附图 2中 未示出）构成。 隔离片 23与夹板之间形成多个准直缝 22, 将进入探测器 之前的射线进一步准直成多个小射线束。 准直缝 22的高度为两块夹板之 间的距离， 宽度为相邻两片隔离片 23之间的距离。 准直缝 22的高度等 于或略大于探测器单元 21的高度， 宽度为探测器单元 21宽度的 1/2、 1/3 或 1/4,数量与探测器单元 21的数量相同。每一片隔离片 23长度方向（即 平行于射线的方向） 的延长线都通过射线源源心， 使得每一个准直缝 22 的中心线也都通过射线源源心， 从而提高透射射线通过准直缝后进入探 测器单元的效率， 并有效阻隔散射射线， 减小相邻探测器单元 21之间的 信号串扰。 在进行线阵探测器 DR成像时， 后准直器 3可整体沿第二圓 弧线 25双方向蠕动， 每蠕动一次就获取一组投影数据， 每次蠕动的距离 为准直缝 22的宽度， 从而使 DR成像的空间分辨率达到探测器单元 21 宽度值的 1/2、 1/3或 1/4, 可进一步提高本发明检测系统的检测分辨率。
线阵探测器 CT成像： 将选定射线源和线阵探测器升降到设定位置， 使得射线源中心和线阵探测器中心位于同一水平面（检测面）， 工件转台 15升降到设定位置， 使得工件的待检部位位于检测平面； 将前准直器移 位到狭缝位置， 打开射线源， 工件转台 15以设定转速转动 360度， 每转 动一个恒定角度就获取一组投影数据， 全部数据获取完成后经过数据处 理和图像重建， 获得被测工件待检测部位的 CT断层图像。
如图 3所示， γ射线源包括一个由铅合金、 钨合金或贫铀制成的屏蔽 体 36, 其内部具有一个射线入口 37和一个射线出口 38; —个可在该屏 蔽体 36中与之相对转动的旋转快门 35 , 其旋转轴线水平布置， 其内部具 有当其转动时可选择地使展蔽体 36中射线入口 37和射线出口 38相连通 或断开的连接通道 39,该连接通道 39从射线入口 37到射线出口 38成喇 八形扩张， 与屏蔽体 36的射线入口 37和射线出口 38共同构成一个成喇 八形扩张的射线通道， 使 γ射线呈扇形束或锥形束； 以及一个位于射线入 口 37起始位置的放射源 34。
采用包括屏蔽体 36和水平布置的旋转快门 35 , 其中旋转快门 35内 部具有成喇叭形扩张的连接通道 39的 γ射线源， 由于旋转快门 35的重心 偏离其旋转轴线， 使其在不施加外力的情况下， 能靠自重产生旋转， 从 而切断射线， 使该 γ射线源具有在断电情况下自动关闭射线的固有安全性 能。
本发明将 X射线源和 γ射线源有机整合到一个集成的小型化检测系统 中， 通过射线源和探测器的升降或平移换位， 可以将不同射线源与探测 器两两组合， 形成多达十几种检测模式， 不同检测模式分別适合于检测 不同对象、 不同类型和尺寸的缺陷， 满足不同的检测要求。 以 450kV X 光机和 Co-60 γ射线源的组合为例， 450kV X光机靶点小 （可达 0.4mm ) , 辐射强度高（距靶点 1米处的剂量率可达几百 mGy/min ), 对于等效质量 厚度小于 60mm铁的工件可以达到很高的空间分辨率（例如， 与面阵探 测器配合可达 4.41p/mm ) ; Co-60 γ射线源射线能量高 （平均能量 1.25MeV ), 其射线穿透能力与 4MeV加速器相当， 适于检测等效质量厚 度 30 ~ 130mm铁的工件， 可以达到 0.1%的密度分辨率； 利用 γ射线源射 线输出强度稳定的特点， 还可以对工件内部任意两点之间的距离进行测 量， 并检测工件内部任意局部区域的质量厚度在长时间内的微小变化。 如果选用微焦点 X光机， 还可以将系统的检测分辨率提高到几个微米的 量级。
实施例 1
本实施例采用 Co-60 γ射线源和 450keV小焦点 X光机两种射线源， 探测器采用面阵探测器、 闪烁体固体线阵探测器和充气电离室气体线阵 探测器。 所用 Co-60射线源活度约 3.7TBq ( 100居里 ), 450keV X光机 焦点尺寸 0.4mm, 最大管电流 3.3mA。 面阵探测器成像区尺寸 409.6 χ 409.6mm2, 像素尺寸 0.2 x 0.2mm2, 固体线阵探测器采用 CdW04晶体作 为闪烁体， 像素尺寸 0.4 X 5 X 30mm3 0气体线阵探测器采用充气电离室， 以氙气为工作介质， 充气压力 3.5MPa。 γ射线源屏蔽容器和前、后准直器 均用密度大于 18g/cm3的钨合金制成。射线源机架和探测器机架的升降或 其位置测量采用旋转编码器和光栅尺实现， 重复定位精度小于 ΙΟμιη; 工 件转台最小旋转步长 15〃 ， 重复定位精度小于 2〃 。 整个检测系统的整 体尺寸为 2.5m 1.8m 2.2m (长 x宽 x高）， 重约 5吨。 能检测等效质量 厚度小于 130mm铁、 直径小于 φ500ιηιη的工件， 可以发现 3cm铁板后 30μιη厚的薄铁片， 可以发现不足 20μιη宽的微小裂缝或止口间隙。
本实施例将止口间隙和质量厚度微小变化的检测与鼓泡检测等检测 任务分解开， 由不同参数的探测系统和不同的检测方式完成。
本实施例采用 "Co-60源 +大像素气体线阵探测器 DR扫描成像" 方 式实现工件止口间隙和质量厚度微小变化的检测。 大像素探测器输出信 号强， 统计涨落小， 有利于质量厚度变化的检测。 Co-60源射线强度能长 时间保持稳定， 操作筒便， 可靠性高； 气体探测器漏电流小， 稳定性高， 温漂小、 耐辐照。 二者组合构成的 DR扫描系统测量精度高， 性能可长 时间保持稳定， 十分适合止口间隙和质量厚度微小变化的检测。
本实施例采用 "X光机 +小像素固体线阵探测器 CT断层成像" 方式 实现工件内部鼓泡检测。 CT断层成像能获得被检客体的密度分布， 能检 测细微缺陷， 并能对缺陷精确定位， 是检测鼓泡和脱落的最佳手段。
本实施例的检测系统采用两种射线源 （Co-60和 450kV X光机）和 三种探测器（小像素固体线阵探测器、 大像素气体线阵探测器和微像素 面阵探测器）， 组合使用以充分利用不同射线源和不同探测器的优点， 更 好地满足检测要求。 X 光机辐射强度大， 源焦点尺寸小， 有利于提高成 像系统的分辨能力。 钴 -60源单能性好， 不存在射束硬化问题， 并且射线 能量较高， 穿透能力更强， 可以检测质量厚度更大的客体。 小像素固体 线阵探测器能更好地屏蔽散射线， 探测效率更高， 能得到更加清晰的图 像； 微像素面阵探测器像素尺寸更小， 能达到更高的空间分辨率， 且一 次扫描即可获得客体的三维图像， 成像更快速。
本实施例将以上两种射线源和三种探测器集成于同一检测平台， 采 用上下移位布局和组件化、 模块化设计模式， 实现了不同射线源与不同 探测器的切换组合， 将不同的检测方式有机组合成一体， 形成了一套综 合性检测系统。
以上对本发明具体实施方式作了详细说明， 但本发明并不局限于上 述实施方式， 如可以采用小型化的 X射线加速器作为中高能 X射线源。 即使对本发明做出各种变化， 只要是基于本发明的精神实施的步骤或流 程， 以及由此构成的检测系统， 就应理解为均落在本发明保护范围内。

Claims

权利 要求
1. 一种组合式射线无损检测方法， 该方法利用射线对待检测工件进 行照射， 利用探测器接收穿过工件的射线， 并转换成数字信号， 然后通 过对所述信号进行处理， 得到工件的辐射图像， 其特征在于：
-射线源采用包^ γ射线源和 X射线源的组合式射线源， 探测器采用 包含固体线阵探测器、 气体线阵探测器和面阵探测器的组合式探测器， 通过切换不同的射线源和探测器组成不同的检测单元， 实现对工件的 DR 扫描成像或断层 CT成像或锥束 CT成像；
-所述组合式射线源和组合式探测器， 以及装卡工件的工件转台均安 装固定在同一刚性基座上。
2.根据权利要求 1所述的检测方法， 其特征在于：
-所述组合式射线源的射线输出侧设置有前准直器， 该前准直器将射 线准直成扇形束或锥形束， 所述组合式探测器的射线输入侧设置有对射 线做进一步准直处理的后准直器；
-当切入的探测器为固体线阵探测器或气体线阵探测器时， 所述后准 直器将射线准直成与探测器单元高度、 数量相当的小射线束， 其准直缝 宽度小于所述探测器单元宽度； 在进行 DR成像时， 该后准直器可沿探 测器单元宽度方向蠕动， 每蠕动一次就获取一组投影数据， 每次蠕动的 距离为准直缝宽度。
3. 一种应用权利要求 1或 2所述方法的组合式射线无损检测系统， 其特征在于， 包括：
-一个刚性基座， 基座上依次间隔排列有射线源支架、 工件转台、 探 测器支架；
-所述射线源支架上设置有包含 γ射线源和 X射线源的组合式射线源， 对移入的射线源进行上下、 前后、 左右和旋转操作的机构；
-所述探测器支架上设置有包含固体线阵探测器、 气体线阵探测器和 面阵探测器的组合式探测器， 以及用于将组合式探测器中的不同探测器 移入工作位置的切换机构， 和对移入的探测器进行上下、 前后、 左右和 旋转操作的机构；
-所述射线源支架上设置有能够将射线源输出的射线准直成扇形束或 锥形束的前准直器， 探测器支架上设置有对射线做进一步准直处理的后 准直器；
-所述气体线阵探测器和所述固体线阵探测器均为圓弧形结构， 当其 被移入工作位置上后， 探测器上各探测器单元的射线入射窗沿着以处于 工作位置上的射线源的源心为圓心的圓弧均匀紧密排列， 且每个探测器 单元的中心线均通过所述圓心， 与气体线阵探测器或固体线阵探测器相 配的后准直器同样为以处于工作位置上的射线源的源心为圓心的圓弧形 结构， 该后准直器的准直缝可将所述扇形射线束准直成与探测器上的各 探测器单元一一对应的小射线束， 并且准直缝的宽度小于探测器单元的 宽度； 在进行 DR成像时， 所述后准直器紧邻所述气体线阵探测器或固 体线阵探测器， 且可沿探测器单元排列方向蠕动， 每次蠕动的距离为准 直缝的宽度。
4.根据权利要求 3所述的检测系统， 其特征在于： 所述准直缝的宽 度为探测器单元宽度的 1/2、 1/3或 1/4。
5. 根据权利要求 3或 4所述的检测系统， 其特征在于： 所述 γ射线源 是 Co-60、 Cs-137或 Ir-192放射性同位素 γ射线源。
6. 根据权利要求 3或 4所述的检测系统， 其特征在于： 所述 X射线 源是小焦点 X光机、 微焦点 X光机和 /或 X射线加速器。
7.根据权利要求 3或 4所述的检测系统， 其特征在于： 所述面阵探 测器是非晶硅、 非晶硒或 CMOS面阵探测器。
8.根据权利要求 3或 4所述的检测系统， 其特征在于： 所述气体线 阵探测器是充气电离室、 多丝正比室或盖格计数管线阵探测器。
9.根据权利要求 3或 4所述的检测系统， 其特征在于： 所述固体线 阵探测器是固体闪烁体线阵探测器或半导体线阵探测器。
10. 根据权利要求 9所述的检测系统， 其特征在于： 所述固体闪烁体 线阵探测器的闪烁体是 Nal、 Csl、 CdW04、 LaBr3或 LaCl3。
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CN106290418A (zh) * 2016-08-31 2017-01-04 天津三英精密仪器股份有限公司 一种适合长样品的ct检测仪
CN111426710A (zh) * 2019-01-09 2020-07-17 波音公司 实时增材制造过程检查
CN109932376A (zh) * 2019-04-30 2019-06-25 王振 一种液体检测方法及装置
CN109932376B (zh) * 2019-04-30 2023-11-28 王振 一种液体检测方法及装置
CN111458357A (zh) * 2020-04-21 2020-07-28 江苏省建筑工程质量检测中心有限公司 一种装配式混凝土结构大型竖向节点施工质量的无损检测系统及检测方法
CN111982936A (zh) * 2020-08-25 2020-11-24 绍兴市特种设备检测院 一种热交换器管子-管板焊缝的x射线自动检测装置
CN111982936B (zh) * 2020-08-25 2023-10-10 绍兴市特种设备检测院 一种热交换器管子-管板焊缝的x射线自动检测装置
CN112393697A (zh) * 2020-11-09 2021-02-23 南京市计量监督检测院 一种无损测量医用鲁尔量规内尺寸的方法
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CN114280086A (zh) * 2021-11-16 2022-04-05 中国电子科技集团公司第三十八研究所 一种ct成像装置
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CN116183639A (zh) * 2021-11-26 2023-05-30 同方威视技术股份有限公司 面阵探测器、探测方法及相应的集装箱/车辆检查系统
CN114460111A (zh) * 2022-01-21 2022-05-10 上海奕瑞光电子科技股份有限公司 一种工业ct实验装置
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