CN108680589A - X-ray grating differential phase contrast 3 D cone-beam computer tomography method based on transversion malposition grating and device - Google Patents
X-ray grating differential phase contrast 3 D cone-beam computer tomography method based on transversion malposition grating and device Download PDFInfo
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- 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
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- G01N23/041—Phase-contrast imaging, e.g. using grating interferometers
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- 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
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- G01N2223/00—Investigating materials by wave or particle radiation
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- G01N2223/04—Investigating materials by wave or particle radiation by transmission and measuring absorption
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- G01N2223/40—Imaging
- G01N2223/401—Imaging image processing
Abstract
The X-ray grating differential phase contrast 3 D cone-beam computer tomography method and device, this method that the invention discloses a kind of based on transversion malposition grating include：Talbot Lau 3 D cone-beam tomography structures are arranged with transversion malposition absorption grating；The two-dimensional intensity image sequence after X-ray passes through object is obtained with above structure；X-ray absorption contrast, differential phase contrast and scattering three kinds of image sequences of contrast are isolated from collected two-dimensional intensity image with Fourier analysis method；Image reconstruction acquisition three kinds of contrast CT sectioning images of object are carried out to three kinds of contrast image sequences respectively using contrast, differential phase contrast and scattering contrast filter back-projection reconstruction algorithm is absorbed.The present invention is not necessarily to carry out stepping to absorption grating, can be obtained three kinds of contrast CT sectioning images in CT scan method of the tradition based on X-ray attenuation, greatly reduces imaging time, reduce imaging dosage, improve system imaging efficiency and stability.
Description
Technical field
The present invention relates to X ray computer chromatography imaging technique field more particularly to a kind of X based on transversion malposition grating
Radial grating differential phase contrast 3 D cone-beam computer tomography method and device.
Background technology
In X ray computer tomography (Computed Tomography, abbreviation CT) system, x-ray source sends out X
Ray passes through a certain region of object to be detected, the detector for being positioned over radiographic source opposite to be connect in respective angles from different perspectives
It receives.Then, according to the different degrees of decaying of each angle ray, operation is carried out using certain algorithm for reconstructing and computer, is rebuild
Go out the ray line attenuation coefficient distribution map image that object is scanned region, to realize reconstructing image from projection, nondestructively again
The features such as existing Media density, ingredient and the structural form of object in the area.
CT technology of the tradition based on X-ray attenuation principle is only capable of obtaining the absorption contrast image of internal structure of body, to low
Atomic number material structure sample is difficult to obtain high-contrast image.In recent years, phase contrast imaging technology, which is suggested, improves this
A little low decaying samples at image contrast.Such as, Yuan Qing habits etc., synchrotron radiation applications diffraction enhanced imaging peak position are imaged CT researchs,
Chinese Physics C,vol.29.No.10,pp:1023-1026,2005 realizes a kind of diffraction enhanced imaging phase contrast imaging side
Method；Pfeiffer F etc., Phase retrieval differential phase-contrast imaging with low-
Brilliance x-ray sources, Nature Physics, vol.2, no.4, pp.258-261,2006, it is proposed that a kind of
Differential phase contrast method based on grating；Zanette I etc., Speckle-based x-ray phase-contrast imaging
Using a grating interferometer, Physical review letter, vol.112, no.25,2014 are proposed
A kind of speckle phase contrast imaging technology.Among these, the differential phase contrast method based on grating can use common X-ray tube to realize, have
Important Project application prospect has obtained extensive research.
But the existing differential phase contrast method based on grating is all based on greatly the conventional method of absorption grating translation step, imaging
Time is long, and dosage is big, and stability is low, inefficient, constrains its further engineer application.
Currently, not yet finding that the X-ray grating differential phase contrast 3 D cone-beam based on transversion malposition absorption grating calculates
Machine laminated imaging device.
Invention content
The present invention provides a kind of X-ray grating difference based on transversion malposition grating to overcome the deficiencies of existing technologies
Phase contrast 3 D cone-beam computer tomography method and device.
The technical solution adopted by the present invention is：A kind of X-ray grating differential phase contrast three based on transversion malposition grating
Gated cone-beam computed tomography method is tieed up, is included the following steps：
Step 1 obtains X-ray across object with the Talbort-Lau three-dimensionals chromatography imaging arrangement based on transversion malposition grating
Two-dimensional projection image sequence after body；The two-dimensional projection image sequence is affiliated detector during object axially rotates
Periodically acquisition X-ray passes through the two-dimensional projection after object, and object described in a width is collected in a collection period
Two-dimensional projection image；
Step 2 isolates X-ray absorption contrast, difference phase to two-dimensional projection image sequence progress Fourier transformation
Position contrast and scattering three kinds of contrast images of contrast；
Step 3, using absorb contrast, differential phase contrast and scattering contrast filter back-projection reconstruction algorithm respectively to three kinds
Contrast two-dimensional image sequence carries out image reconstruction, obtains the object absorption contrast, phase contrast and scattering three kinds of CT of contrast and cuts
Picture.
Further, the transversion malposition absorption grating arranges Talbot-Lau imaging arrangements, including：
It includes six parts that the Talbot-Lau imaging arrangements light path, which has altogether,：X-ray source, source grating G0, test object,
Phase grating G1, absorption grating G2, detector；
The Talbot-Lau imaging arrangements light path parameter should meet following formula (1)-(4)：
kg1=2g2, (2)
g0=g2L/d, (3)
s<g2L/2d, (4)
Wherein, d indicates the distance between phase grating G1 and absorption grating G2；K=(L+d)/L is amplification ratio, and L is source light
Grid G0 and the direct distances of phase grating G1；M indicates m rank score Talbot distances；g1For the period of phase grating G1, λ is
The wavelength of X-ray used, g2For the period of absorption grating G2, g0For the period of source grating G0, s is in source grating in each period
The lower width for allowing X-ray transparent；
The transversion malposition absorption grating refers to absorption grating G2 in the Talbot-Lau imaging arrangements light path,
There is lateral periodicity dislocation in the relative position for visiting member with detector so that laterally multiple adjacent detectors visit the intensity that member obtains
Signal can be equivalent to a detector in conventional imaging method and visit the strength signal that member is obtained at multiple and different positions；
Member is visited for 4 laterally adjacent detectors, is respectively labeled as p1、p2、p3、p4, each to visit member px(x=1,2,3,4)
Width is w, in transversion malposition absorption grating, corresponds to the grating gp that one section of length is wx, each section of grating gpxScreen periods be
g2, adjacent detector visits the corresponding grating of member, and there is the alternate position spikes that distance is f, such as adjacent detector to visit member p1And p2It is corresponding
Grating section gp1With gp2There is the alternate position spikes of f, wherein f=g2/ 4, gpxThe position of grating is equivalent to absorption grating and is being moved to x
When position, the position that adjacent 4 detectors visit the corresponding each section of absorption grating of member is variant, mutually staggers distance f, referred to as
Transversion malposition grating, detector visit member pxThe X-ray intensity signal value of acquisition is that absorption grating G2 is collected when being moved to position x
Intensity value.
Further, step 1 further includes：
In the Talbot-Lau imaging arrangements, when turntable does not place object, turntable is along rotation center uniform rotation
360 degree, and imaging area is covered by cone-beam in rotation process, and two-dimensional projection image is acquired by detector；
In the Talbot-Lau imaging arrangements, when turntable places object, turntable is along rotation center uniform rotation 360
Degree, and imaging area is covered by cone-beam in rotation process, and two-dimensional projection image is acquired by detector.
Further, further include：
Image analysis is carried out to the two-dimensional projection image sequence according to formula (5)-(14) and obtains three kinds of contrast two dimensions
Projection image sequence：
I1(x, z, θ)=I (x-1, z, θ), (5)
I2(x, z, θ)=I (x, z, θ), (6)
I3(x, z, θ)=I (x+1, z, θ), (7)
I4(x, z, θ)=I (x+2, z, θ), (8)
Phase (x, z, θ)=φs(x,z,θ)-φr(x,z,θ), (13)
Wherein, x is the abscissa of two-dimension projection point；Z is the ordinate of two-dimension projection point, θ two-dimension projections thus
As place projection angle；I (x, z, θ) is intensity value of the two-dimension projection midpoint (x, z) in projection angle θ；I1(x,z,θ)、I2
(x,z,θ)、I3(x,z,θ)、I4(x, z, θ) indicates point (x, z) in 4 different intensity values of projection angle θ, simulation biography respectively
System grating differential phase contrast image midpoint (x, z) is strong when absorption grating is in 4 different stepping positions in projection angle θ
Angle value；M indicates the number of different intensity value in a point (x, z), M=4；a0(x, z, θ) is point (x, z) in projection angle θ
The sinusoidal mean value that fits of 4 different intensity values；a1(x, z, θ) be point (x, z) at 4 of projection angle θ not
The sinusoidal amplitude size that same intensity value fits；φ (x, z, θ) is that point (x, z) is different at 4 of projection angle θ
The sinusoidal phase value that intensity value fits；Indicate a when projection angle θ does not put test object0(x,
Z, θ) value,Indicate a when projection angle θ places test object0(x, z, θ) value；It indicates
Projection angle θ does not put a when test object1(x, z, θ) value,It indicates when projection angle θ places test object
A1(x, z, θ) value；φr(x, z, θ) indicates φ (x, z, θ) value when projection angle θ does not put test object, φs(x,z,θ)
Indicate φ (x, z, θ) value when projection angle θ places test object；Abs (x, z, θ) is to be absorbed in projection angle θ points (x, z)
The value of contrast；Phase (x, z, θ) is the value in projection angle θ point (x, z) differential phase contrast；Dark (x, z, θ) is to project
Angle, θ point (x, z) scatters the value of contrast imaging.
Further, right respectively using contrast, differential phase contrast and scattering contrast filter back-projection reconstruction algorithm is absorbed
Three kinds of contrast two-dimensional image sequences carry out image reconstruction, obtain the object and absorb contrast, phase contrast and three kinds of contrast of scattering
CT sectioning images, including：
Image analysis is carried out to the two-dimensional projection image sequence according to formula (15)-(17) and obtains three kinds of contrast two dimensions
Projection image sequence：
Wherein, a (x, y, z), p (x, y, z) and d (x, y, z) are respectively the absorption contrast sectioning image rebuild, phase contrast
Sectioning image and scattering contrast sectioning image；Abs (s, v, θ), phase (s, v, θ) and dark (s, v, θ) indicate projected angle respectively
Absorption contrast, differential phase contrast under θ and scattering contrast two-dimensional projection, s, v are pixel and radiographic source on detector respectively
Line and the intersecting point coordinate of dummy detector that is placed at rotary shaft；ξ is the angle of ray and central ray；D is ray
Distance of the source to virtual detector plane；Y ' is the distance for rebuilding image pixel point to virtual detector plane；ha(s)、hp(s)
And hd(s) it is respectively the filter for absorbing contrast, differential phase contrast and scattering contrast two-dimensional projection, is defined as formula
(18)-(19)：
ha(s)=| s |, (18)
hd(s)=| s |, (20)
Another aspect of the present invention is to provide a kind of X-ray grating differential phase contrast three based on transversion malposition grating
Gated cone-beam computed tomography device is tieed up, including：
Acquisition module, for obtaining the collected two-dimensional projection image sequence of detector, the two-dimensional projection image sequence
It is object axially in rotation process, is obtained after the ray projection of the excessively described object of detector periodicity acquisition of transmission
Multiple two-dimensional projection images, and the two-dimensional projection image of sampling period one object of correspondence；
Computing module obtains absorption contrast, difference phase for carrying out Fourier transformation to the two-dimensional projection image sequence
Position contrast and scattering contrast two-dimensional projection sequence；It is filtered using contrast, differential phase contrast and scattering three kinds of contrasts of contrast are absorbed
Three kinds of contrast two-dimensional projection sequences of anti-algorithm for reconstructing pair are rebuild to obtain three dimensional CT sectioning image.
Further, the transversion malposition absorption grating arranges Talbot-Lau imaging arrangements, including：
It includes six parts that the Talbot-Lau imaging arrangements light path, which has altogether,：X-ray source, source grating G0, test object,
Phase grating G1, absorption grating G2, detector；
The Talbot-Lau imaging arrangements light path parameter should meet following formula (1)-(4)：
kg1=2g2, (2)
g0=g2L/d, (3)
s<g2L/2d, (4)
Wherein, d indicates the distance between phase grating G1 and absorption grating G2；K=(L+d)/L is amplification ratio, and L is source light
Grid G0 and the direct distances of phase grating G1；M indicates m rank score Talbot distances；g1For the period of phase grating G1, λ is
The wavelength of X-ray used, g2For the period of absorption grating G2, g0For the period of source grating G0, s is in source grating in each period
The lower width for allowing X-ray transparent；
The transversion malposition absorption grating refers to absorption grating G2 in the Talbot-Lau imaging arrangements light path,
There is lateral periodicity dislocation in the relative position for visiting member with detector so that laterally multiple adjacent detectors visit the intensity that member obtains
Signal can be equivalent to a detector in conventional imaging method and visit the strength signal that member is obtained at multiple and different positions；
Member is visited for 4 laterally adjacent detectors, is respectively labeled as p1、p2、p3、p4, each to visit member px(x=1,2,3,4)
Width is w, in transversion malposition absorption grating, corresponds to the grating gp that one section of length is wx, each section of grating gpxScreen periods be
g2, adjacent detector visits the corresponding grating of member, and there is the alternate position spikes that distance is f, such as adjacent detector to visit member p1And p2It is corresponding
Grating section gp1With gp2There is the alternate position spikes of f, wherein f=g2/ 4, gpxThe position of grating is equivalent to absorption grating and is being moved to x
When position, the position that adjacent 4 detectors visit the corresponding each section of absorption grating of member is variant, mutually staggers distance f, referred to as
Transversion malposition grating, detector visit member pxThe X-ray intensity signal value of acquisition is that absorption grating G2 is collected when being moved to position x
Intensity value.
Further, acquisition module further includes：
In the Talbot-Lau imaging arrangements, when turntable does not place object, turntable is along rotation center uniform rotation
360 degree, and imaging area is covered by cone-beam in rotation process, and two-dimensional projection image is acquired by detector；
In the Talbot-Lau imaging arrangements, when turntable places object, turntable is along rotation center uniform rotation 360
Degree, and imaging area is covered by cone-beam in rotation process, and two-dimensional projection image is acquired by detector.
Further, computing module isolates X-ray suction with Fourier analysis method from collected two-dimensional intensity image
Contrast, differential phase contrast and scattering three kinds of images of contrast are received, including：
Image analysis is carried out to the two-dimensional projection image sequence according to formula (5)-(14) and obtains three kinds of contrast two dimensions
Projection image sequence：
I1(x, z, θ)=I (x-1, z, θ), (5)
I2(x, z, θ)=I (x, z, θ), (6)
I3(x, z, θ)=I (x+1, z, θ), (7)
I4(x, z, θ)=I (x+2, z, θ), (8)
Phase (x, z, θ)=φs(x,z,θ)-φr(x,z,θ), (13)
Wherein, x is the abscissa of two-dimension projection point；Z is the ordinate of two-dimension projection point, θ two-dimension projections thus
As place projection angle；I (x, z, θ) is intensity value of the two-dimension projection midpoint (x, z) in projection angle θ；I1(x,z,θ)、I2
(x,z,θ)、I3(x,z,θ)、I4(x, z, θ) indicates point (x, z) in 4 different intensity values of projection angle θ, simulation biography respectively
System grating differential phase contrast image midpoint (x, z) is strong when absorption grating is in 4 different stepping positions in projection angle θ
Angle value；M indicates the number of different intensity value in a point (x, z), M=4；a0(x, z, θ) is point (x, z) in projection angle θ
The sinusoidal mean value that fits of 4 different intensity values；a1(x, z, θ) be point (x, z) at 4 of projection angle θ not
The sinusoidal amplitude size that same intensity value fits；φ (x, z, θ) is that point (x, z) is different at 4 of projection angle θ
The sinusoidal phase value that intensity value fits；Indicate a when projection angle θ does not put test object0(x,
Z, θ) value,Indicate a when projection angle θ places test object0(x, z, θ) value；Expression is being thrown
Shadow angle, θ does not put a when test object1(x, z, θ) value,Indicate a when projection angle θ places test object1
(x, z, θ) value；φr(x, z, θ) indicates φ (x, z, θ) value when projection angle θ does not put test object, φs(x, z, θ) is indicated
φ (x, z, θ) value when projection angle θ places test object；Abs (x, z, θ) is to absorb contrast in projection angle θ points (x, z)
Value；Phase (x, z, θ) is the value in projection angle θ point (x, z) differential phase contrast；Dark (x, z, θ) is in projection angle
θ points (x, z) scatter the value of contrast imaging.
Further, computing module is rebuild and is calculated using contrast, differential phase contrast and scattering contrast filtered back projection is absorbed
Method carries out image reconstruction to three kinds of contrast two-dimensional image sequences respectively, obtains the object and absorbs contrast, phase contrast and scattering
Three kinds of CT sectioning images of contrast, including：
Image analysis is carried out to the two-dimensional projection image sequence according to formula (15)-(17) and obtains three kinds of contrast two dimensions
Projection image sequence：
Wherein, a (x, y, z), p (x, y, z) and d (x, y, z) are respectively the absorption contrast sectioning image rebuild, phase contrast
Sectioning image and scattering contrast sectioning image；Abs (s, v, θ), phase (s, v, θ) and dark (s, v, θ) indicate projected angle respectively
Absorption contrast, differential phase contrast under θ and scattering contrast two-dimensional projection, s, v are pixel and radiographic source on detector respectively
Line and the intersecting point coordinate of dummy detector that is placed at rotary shaft；ξ is the angle of ray and central ray；D is ray
Distance of the source to virtual detector plane；Y ' is the distance for rebuilding image pixel point to virtual detector plane；ha(s)、hp(s)
And hd(s) it is respectively the filter for absorbing contrast, differential phase contrast and scattering contrast two-dimensional projection, is defined as formula
(18)-(19)：
ha(s)=| s |, (18)
hd(s)=| s |, (20)
The advantages of the present invention over the prior art are that：(1) present invention can solve repeatedly to expose under a projection angle
The problem of light reduces dose of radiation；(2) grating stepping is avoided during projection imaging under an angle, eliminates machine
The error that tool shake etc. is brought；(3) only single exposure is needed to be imaged under each angle, you can to obtain object and absorb contrast, phase
The three-dimensional tomographic image of position contrast and scattering three kinds of contrasts of contrast.
Description of the drawings
Fig. 1 is the X-ray grating differential phase contrast three-dimensional cone provided in an embodiment of the present invention based on transversion malposition grating
Beam computerized chromatography imaging method flow chart；
Fig. 2 is the X-ray grating differential phase contrast three-dimensional cone provided in an embodiment of the present invention based on transversion malposition grating
Beam computerized chromatographic imaging system schematic diagram；
Fig. 3 is the structure principle chart of novel transversion malposition absorption grating provided in an embodiment of the present invention；
Fig. 4 be the X-ray grating differential phase contrast 3 D cone-beam Computerized chromatographic based on transversion malposition absorption grating at
The two-dimensional projection image of image space method；
Fig. 5 is four width two-dimensional projection images of Traditional x-ray grating differential phase contrast imaging method；
Fig. 6 be the X-ray grating differential phase contrast 3 D cone-beam Computerized chromatographic based on transversion malposition absorption grating at
Absorption contrast, differential phase contrast and the scattering contrast image that image space method obtains；
Fig. 7 be Traditional x-ray grating differential phase contrast imaging method obtain absorption contrast, differential phase contrast and dissipate
Penetrate contrast image；
Fig. 8 is the X-ray grating differential phase contrast three provided in an embodiment of the present invention based on transversion malposition absorption grating
Tie up the CT images of gated cone-beam computed tomography method；
Fig. 9 is the CT images of Traditional x-ray grating differential phase contrast imaging method.
Figure 10 is the X-ray grating differential phase contrast three provided in an embodiment of the present invention based on transversion malposition absorption grating
Tie up the structure chart of gated cone-beam computed tomography device.
In figure：20 be x-ray source, and 21 be X-ray beam, and 22 be source grating G0, and 23 be object under test, and 24 be phase grating
G1,25 be transversion malposition absorption grating G2, and 26 be detector, and 27 be computer, and 100 be X-ray cylinder 3 D cone-beam computer
Laminated imaging device, 101 be acquisition module, and 102 be computing module.
Specific implementation mode
Below in conjunction with the accompanying drawings and specific implementation mode further illustrates the present invention.
Fig. 1 is the X-ray grating differential phase contrast three provided in an embodiment of the present invention based on transversion malposition absorption grating
Tie up gated cone-beam computed tomography method flow diagram；The embodiment of the present invention is directed to existing X-ray absorption contrast CT image-forming and X-ray
Grating differential phase contrast CT image-forming, sectioning image only have a kind of contrast or can obtain three kinds of contrasts but need a projection
The problems such as multiple exposure, dose of radiation are big under angle, imaging time is long, efficiency is low and mechanical shaking error is big, provides and is based on
The X-ray grating differential phase contrast 3 D cone-beam computer tomography method of transversion malposition absorption grating, this method are specific
Steps are as follows：
Step S101, with proposed by the present invention, the Talbort-Lau three-dimensionals based on transversion malposition grating chromatograph imaging arrangement
It obtains X-ray and passes through the two-dimensional projection image sequence after object.Two-dimensional projection's sequence is during object axially rotates,
Affiliated detector periodically acquisition X-ray passes through the two-dimensional projection after object, and a width is collected in a collection period
The two-dimensional projection image of the object.
The Talbot-Lau three-dimensionals chromatography imaging arrangement light path parameter should meet following formula (1)-(4)：
kg1=2g2, (2)
g0=g2L/d, (3)
s<g2L/2d, (4)
Wherein, d indicates the distance between phase grating G1 and absorption grating G2；K=(L+d)/L is amplification ratio, and L is source light
Grid G0 and the direct distances of phase grating G1；M indicates m rank score Talbot distances；g1For the period of phase grating G1, λ is
The wavelength of X-ray used, g2For the period of absorption grating G2, g0For the period of source grating G0, s is in source grating in each period
The lower width for allowing X-ray transparent.
Fig. 2 is the X-ray grating differential phase contrast three-dimensional cone provided in an embodiment of the present invention based on transversion malposition grating
Beam computerized chromatographic imaging system schematic diagram；As shown in Fig. 2, the X-ray grating differential phase contrast based on transversion malposition grating
3 D cone-beam computerized tomography system includes：X-ray source 20, X-ray beam 21, source grating G0 22, object under test 23, phase
Position grating G1 24, transversion malposition absorption grating G2 25, detector 26, computer 27.Wherein, detector 26, x-ray source 20 divide
It is not connect with computer 27.Computer 27 is used to control x-ray source 20 and generates intensity and the time of X-ray beam 21, and controls spy
It surveys device 26 and acquires two-dimensional intensity image.The X-ray beam 21 that x-ray source 20 produces measuring targets 23 after source grating G0 22
It is transmitted, 23 imaging area of object under test is covered by X-ray beam 21, and X-ray beam 21 is by phase grating G1 24 and transversion malposition
It is acquired by detector 26 after 25 modulated signals of absorption grating G2.After completing to acquire, computer 27 controls the stopping of detector 26 and adopts
Sample, control x-ray source 20 stop generating X-ray, the X-ray grating differential phase contrast 3 D cone-beam based on transversion malposition grating
Computerized tomography system completes a projection imaging under a projection angle.Entirely tomographic process is：Each
Under projection angle, in the Talbot-Lau three-dimensionals chromatograph imaging arrangement, object under test 23 is not placed first, computer 27 controls
The two-dimensional intensity image of the acquisition of detector 26 at this time；Object under test 23 is positioned in the Talbot-Lau imaging optical paths again,
Ensure that object is tested area and is all covered by X-ray beam 21, computer 27 controls the acquisition of detector 26 and decayed by object under test 23
X-ray afterwards believes two-dimensional intensity image；Projection angle covers 360 degree, after doing above-mentioned acquisition under each projection angle, completes one
The acquisition of secondary tomography two-dimensional projection image sequence.
Fig. 3 is the structure principle chart of novel transversion malposition absorption grating provided in an embodiment of the present invention.
Step S102, Fourier transformation is carried out to the two-dimensional projection image sequence and isolates X-ray absorption contrast, difference
Phase contrast and scattering three kinds of contrast image sequences of contrast.
The collected two-dimensional projection image sequence of detector that computer 27 obtains it carries out Fourier transformation and isolates X
Radiation absorption contrast, differential phase contrast and scattering three kinds of contrast image sequences of contrast, including：
Image analysis is carried out to the two-dimensional projection image sequence according to formula (5)-(14) and obtains three kinds of contrast two dimensions
Projection image sequence：
I1(x, z, θ)=I (x-1, z, θ), (5)
I2(x, z, θ)=I (x, z, θ), (6)
I3(x, z, θ)=I (x+1, z, θ), (7)
I4(x, z, θ)=I (x+2, z, θ), (8)
Phase (x, z, θ)=φs(x,z,θ)-φr(x,z,θ), (13)
Wherein, x is the abscissa of two-dimension projection point；Z is the ordinate of two-dimension projection point, θ two-dimension projections thus
As place projection angle；I (x, z, θ) is intensity value of the two-dimension projection midpoint (x, z) in projection angle θ；I1(x,z,θ)、I2
(x,z,θ)、I3(x,z,θ)、I4(x, z, θ) indicates point (x, z) in 4 different intensity values of projection angle θ, simulation biography respectively
System grating differential phase contrast image midpoint (x, z) is strong when absorption grating is in 4 different stepping positions in projection angle θ
Angle value；M indicates the number of different intensity value in a point (x, z), M=4；a0(x, z, θ) is point (x, z) in projection angle θ
The sinusoidal mean value that fits of 4 different intensity values；a1(x, z, θ) be point (x, z) at 4 of projection angle θ not
The sinusoidal amplitude size that same intensity value fits；φ (x, z, θ) is that point (x, z) is different at 4 of projection angle θ
The sinusoidal phase value that intensity value fits；Indicate a when projection angle θ does not put test object0(x,
Z, θ) value,Indicate a when projection angle θ places test object0(x, z, θ) value；Expression is being thrown
Shadow angle, θ does not put a when test object1(x, z, θ) value,Indicate a when projection angle θ places test object1
(x, z, θ) value；φr(x, z, θ) indicates φ (x, z, θ) value when projection angle θ does not put test object, φs(x, z, θ) is indicated
φ (x, z, θ) value when projection angle θ places test object；Abs (x, z, θ) is to absorb contrast in projection angle θ points (x, z)
Value；Phase (x, z, θ) is the value in projection angle θ point (x, z) differential phase contrast；Dark (x, z, θ) is in projection angle
θ points (x, z) scatter the value of contrast imaging.
Step S103, right respectively using contrast, differential phase contrast and scattering contrast filter back-projection reconstruction algorithm is absorbed
Three kinds of contrast two-dimensional image sequences carry out image reconstruction, obtain the object and absorb contrast, phase contrast and three kinds of contrast of scattering
CT sectioning images, including：
Image analysis is carried out to the two-dimensional projection image sequence according to formula (15)-(17) and obtains three kinds of contrast two dimensions
Projection image sequence：
Wherein, a (x, y, z), p (x, y, z) and d (x, y, z) are respectively the absorption contrast sectioning image rebuild, phase contrast
Sectioning image and scattering contrast sectioning image；Abs (s, v, θ), phase (s, v, θ) and dark (s, v, θ) indicate projected angle respectively
Absorption contrast, differential phase contrast under θ and scattering contrast two-dimensional projection, s, v are pixel and radiographic source on detector respectively
Line and the intersecting point coordinate of dummy detector that is placed at rotary shaft；ξ is the angle of ray and central ray；D is ray
Distance of the source to virtual detector plane；Y ' is the distance for rebuilding image pixel point to virtual detector plane；ha(s)、hp(s)
And hd(s) it is respectively the filter for absorbing contrast, differential phase contrast and scattering contrast two-dimensional projection, is defined as formula
(18)-(19)：
ha(s)=| s |, (18)
hd(s)=| s |, (20)
The embodiment of the present invention is served as a contrast compared to existing based on X-ray absorption contrast CT technologies and X-ray grating differential phase
Spend CT technologies, can be only imaged with single exposure under each projection angle, finally reconstruct object absorb contrast, phase contrast and
The faultage image of three kinds of contrasts of contrast is scattered, step is simple, is not necessarily to the high precision movement to absorption grating in imaging process, significantly
Imaging time is reduced, dose of radiation is reduced, improves imaging efficiency.
In order to prove that the effect of above-described embodiment, the embodiment of the present invention have carried out following experiment, experimental procedure is as follows：
(1) experiment condition is set.Source grating G0, phase grating G1, the absorption grating G2 of this experiment are to be in X-ray energy
It is designed under conditions of 28keV.The period of source grating G0 is 14 microns；The period of phase grating G1 is 3.5 microns；Absorb light
The period of grid G2 is 2.0 microns.The distance of source grating G0 and phase grating G1 are 1400 millimeters, phase grating G1 and absorption grating
The distance of G2 is 200 millimeters, corresponds to the 5th score Talbot distances (m=5).The size of two-dimensional intensity image is 307*652.
(2) according to Talbot-Lau imaging optical path parameter requests, Talbot-Lau imaging arrangements are arranged.
(3) according to setup parameter, computer controls turntable rotation, and the forward and backward projection of object under test is placed in detector acquisition
Data, and generate two-dimensional projection image sequence according to data for projection.
(4) computer is inhaled two-dimensional projection image sequence using Fourier analysis method according to above-mentioned formula (5)-(14)
Receive contrast, differential phase contrast and the separation for scattering three kinds of image sequences of contrast.
(5) computer according to above-mentioned formula (15)-(20) to the object isolated absorb contrast, differential phase contrast and
Scattering contrast image sequence carries out the faultage image that image reconstruction obtains three kinds of contrasts of the object respectively.
Fig. 4 is the X-ray grating differential phase contrast 3 D cone-beam computerized tomography system based on transversion malposition grating
The two-dimensional projection image that system obtains；Fig. 6 is that the X-ray grating differential phase contrast 3 D cone-beam based on transversion malposition grating calculates
Absorption contrast, differential phase contrast and the scattering contrast two-dimensional projection image that machine chromatographic imaging system parses；Fig. 8 be based on
The CT figures that the X-ray grating differential phase contrast 3 D cone-beam computerized tomography system reconstructing of transversion malposition grating obtains
Picture.By Fig. 4,6 and 8 it is found that the X-ray grating differential phase contrast 3 D cone-beam Computerized chromatographic based on transversion malposition grating at
As system can correctly isolate three kinds of contrast two-dimensional projection images of object, and reconstruct the tomograph of three kinds of contrasts of object
Picture.
Fig. 5 is the two-dimensional projection image obtained using Traditional x-ray grating differential phase contrast imaging method；Fig. 7 is to pass
Absorption contrast, differential phase contrast and the scattering contrast two dimension that system X-ray grating differential phase contrast imaging method parses
Projected image；Fig. 9 is the CT images that Traditional x-ray grating differential phase contrast computerized tomography system reconstructing obtains.It is logical
Crossing Fig. 5 can significantly observe, Traditional x-ray grating differential phase contrast imaging method needs to carry out 4 exposures, pole to object
Big increases imaging time and dose of radiation, significantly reduces imaging efficiency.
By Fig. 4,5,6,7,8 and 9 it is found that the embodiment of the present invention quickly correctly can carry out absorption contrast, phase to object
Contrast and scattering contrast three-dimensional imaging, only need single exposure that projection imaging process can be realized, are not required under each projection angle
The multiple exposure of traditional raster Difference Imaging method is wanted, imaging time is reduced, significantly reduces dose of radiation, reduces mechanical shaking band
The error come, improves the efficiency of three kinds of contrast imagings, process is simply easily realized.
Figure 10 is the X-ray grating differential phase contrast three-dimensional cone provided in an embodiment of the present invention based on transversion malposition grating
The structure chart of beam computerized laminated imaging device.X-ray grating provided in an embodiment of the present invention based on transversion malposition grating is poor
Point phase contrast 3 D cone-beam computer laminated imaging device can execute three kinds of contrast 3 D cone-beam Computerized chromatographics of object at
As the process flow that embodiment of the method provides, as shown in Figure 10, the X-ray grating differential phase contrast based on transversion malposition grating
3 D cone-beam computer laminated imaging device 100 includes acquisition module 101 and computing module 102, wherein acquisition module 101 is used
In the acquisition collected two-dimensional projection image sequence of detector；Computing module 102 be used for the two-dimensional projection image sequence into
Three kinds of contrast projection image sequences are isolated in row Fourier analysis, and are used three kinds of contrasts to filter anti-algorithm for reconstructing respectively and rebuild three
Kind contrast faultage image.
The embodiment of the present invention is served as a contrast compared to existing based on X-ray absorption contrast CT technologies and X-ray grating differential phase
Spend CT technologies, can be only imaged with single exposure under each projection angle, finally reconstruct object absorb contrast, phase contrast and
The faultage image of three kinds of contrasts of contrast is scattered, step is simple, is not necessarily to the high precision movement to absorption grating in imaging process, significantly
Imaging time is reduced, dose of radiation is reduced, improves imaging efficiency.
Each device is arranged by the needs of acquisition module 101 according to Talbot-Lau imaging optical path parameter requests,
Detector carries out the object under test acquisition of two-dimensional intensity image.
The Talbot-Lau imaging arrangements light path parameter should meet following formula (1)-(4)：
kg1=2g2, (2)
g0=g2L/d, (3)
s<g2L/2d, (4)
Wherein, d indicates the distance between phase grating G1 and absorption grating G2；K=(L+d)/L is amplification ratio, and L is source light
Grid G0 and the direct distances of phase grating G1；M indicates m rank score Talbot distances；g1For the period of phase grating G1, λ is
The wavelength of X-ray used, g2For the period of absorption grating G2, g0For the period of source grating G0, s is in source grating in each period
The lower width for allowing X-ray transparent.
Computing module 102 carries out image analysis to the two-dimensional projection image sequence according to formula (5)-(14) and obtains three
Kind contrast two-dimensional projection image sequence：
I1(x, z, θ)=I (x-1, z, θ), (5)
I2(x, z, θ)=I (x, z, θ), (6)
I3(x, z, θ)=I (x+1, z, θ), (7)
I4(x, z, θ)=I (x+2, z, θ), (8)
Phase (x, z, θ)=φs(x,z,θ)-φr(x,z,θ), (13)
Wherein, x is the abscissa of two-dimension projection point；Z is the ordinate of two-dimension projection point, θ two-dimension projections thus
As place projection angle；I (x, z, θ) is intensity value of the two-dimension projection midpoint (x, z) in projection angle θ；I1(x,z,θ)、I2
(x,z,θ)、I3(x,z,θ)、I4(x, z, θ) indicates point (x, z) in 4 different intensity values of projection angle θ, simulation biography respectively
System grating differential phase contrast image midpoint (x, z) is strong when absorption grating is in 4 different stepping positions in projection angle θ
Angle value；M indicates the number of different intensity value in a point (x, z), M=4；a0(x, z, θ) is point (x, z) in projection angle θ
The sinusoidal mean value that fits of 4 different intensity values；a1(x, z, θ) be point (x, z) at 4 of projection angle θ not
The sinusoidal amplitude size that same intensity value fits；φ (x, z, θ) is that point (x, z) is different at 4 of projection angle θ
The sinusoidal phase value that intensity value fits；Indicate a when projection angle θ does not put test object0(x,
Z, θ) value,Indicate a when projection angle θ places test object0(x, z, θ) value；Expression is being thrown
Shadow angle, θ does not put a when test object1(x, z, θ) value,Indicate a when projection angle θ places test object1
(x, z, θ) value；φr(x, z, θ) indicates φ (x, z, θ) value when projection angle θ does not put test object, φs(x, z, θ) is indicated
φ (x, z, θ) value when projection angle θ places test object；Abs (x, z, θ) is to absorb contrast in projection angle θ points (x, z)
Value；Phase (x, z, θ) is the value in projection angle θ point (x, z) differential phase contrast；Dark (x, z, θ) is in projection angle
θ points (x, z) scatter the value of contrast imaging.
Computing module 102 carries out image analysis to the two-dimensional projection image sequence according to formula (15)-(17) and obtains
Three kinds of contrast two-dimensional projection image sequences：
Wherein, a (x, y, z), p (x, y, z) and d (x, y, z) are respectively the absorption contrast sectioning image rebuild, phase contrast
Sectioning image and scattering contrast sectioning image；Abs (s, v, θ), phase (s, v, θ) and dark (s, v, θ) indicate projected angle respectively
Absorption contrast, differential phase contrast under θ and scattering contrast two-dimensional projection, s, v are pixel and radiographic source on detector respectively
Line and the intersecting point coordinate of dummy detector that is placed at rotary shaft；ξ is the angle of ray and central ray；D is ray
Distance of the source to virtual detector plane；Y ' is the distance for rebuilding image pixel point to virtual detector plane；ha(s)、hp(s)
And hd(s) it is respectively the filter for absorbing contrast, differential phase contrast and scattering contrast two-dimensional projection, is defined as formula
(18)-(19)：
ha(s)=| s |, (18)
hd(s)=| s |, (20)
The embodiment of the present invention is served as a contrast compared to existing based on X-ray absorption contrast CT technologies and X-ray grating differential phase
Spend CT technologies, can be only imaged with single exposure under each projection angle, finally reconstruct object absorb contrast, phase contrast and
The faultage image of three kinds of contrasts of contrast is scattered, step is simple, is not necessarily to the high precision movement to absorption grating in imaging process, significantly
Imaging time is reduced, dose of radiation is reduced, improves imaging efficiency.
X-ray grating differential phase contrast 3 D cone-beam provided in an embodiment of the present invention based on transversion malposition grating calculates
Machine laminated imaging device can be specifically used for executing the embodiment of the method that above-mentioned Fig. 1 is provided, and details are not described herein again for concrete function.
The embodiment of the present invention quickly can carry out two-dimensional projection to the absorption contrast of object, differential phase contrast and scattering contrast
Imaging, and three kinds of contrast three-dimensional tomographic images are reconstructed, only need single exposure under each projection angle, you can isolate three kinds
Contrast two-dimensional projection image, reduces imaging time, reduces dose of radiation, eliminates the error that mechanical shaking is brought, and improves
Imaging efficiency.
In conclusion the embodiment of the present invention can carry out absorption contrast, phase contrast compared to existing CT technologies to object
Degree and scattering three kinds of contrast three-dimensional tomographies of contrast；Step is simple, and single exposure is only needed under each projection angle, without more
Secondary stepping absorption grating, you can obtain three kinds of contrast two-dimensional projection images；Reduce two-dimensional projection's imaging time；Reduce radiation
Dosage；Eliminate the error that mechanical shaking is brought；Improve imaging efficiency.
In several embodiments provided by the present invention, it should be understood that disclosed device and method can pass through it
Its mode is realized.For example, the apparatus embodiments described above are merely exemplary, for example, the division of the unit, only
Only a kind of division of logic function, formula that in actual implementation, there may be another division manner, such as multiple units or component can be tied
Another system is closed or is desirably integrated into, or some features can be ignored or not executed.Another point, it is shown or discussed
Mutual coupling, direct-coupling or communication connection can be the INDIRECT COUPLING or logical by some interfaces, device or unit
Letter connection can be electrical, machinery or other forms.
The unit illustrated as separating component may or may not be physically separated, aobvious as unit
The component shown may or may not be physical unit, you can be located at a place, or may be distributed over multiple
In network element.Some or all of unit therein can be selected according to the actual needs to realize the mesh of this embodiment scheme
's.
In addition, each functional unit in each embodiment of the present invention can be integrated in a processing unit, it can also
It is that each unit physically exists alone, it can also be during two or more units be integrated in one unit.Above-mentioned integrated list
The form that hardware had both may be used in member is realized, can also be realized in the form of hardware adds SFU software functional unit.
The above-mentioned integrated unit being realized in the form of SFU software functional unit can be stored in one and computer-readable deposit
In storage media.Above-mentioned SFU software functional unit is stored in a storage medium, including some instructions are used so that a computer
It is each that equipment (can be personal computer, server or the network equipment etc.) or processor (processor) execute the present invention
The part steps of embodiment the method.And storage medium above-mentioned includes：USB flash disk, mobile hard disk, read-only memory (Read-
Only Memory, ROM), random access memory (Random Access Memory, RAM), magnetic disc or CD etc. it is various
The medium of program code can be stored.
Those skilled in the art can be understood that, for convenience and simplicity of description, only with above-mentioned each function module
Division progress for example, in practical application, can be complete by different function modules by above-mentioned function distribution as needed
At the internal structure of device being divided into different function modules, to complete all or part of the functions described above.On
The specific work process for stating the device of description, can refer to corresponding processes in the foregoing method embodiment, and details are not described herein.
Finally it should be noted that：The above embodiments are only used to illustrate the technical solution of the present invention., rather than its limitations；To the greatest extent
Present invention has been described in detail with reference to the aforementioned embodiments for pipe, it will be understood by those of ordinary skill in the art that：Its according to
So can with technical scheme described in the above embodiments is modified, either to which part or all technical features into
Row equivalent replacement；And these modifications or replacements, various embodiments of the present invention technology that it does not separate the essence of the corresponding technical solution
The range of scheme.
Claims (10)
1. a kind of X-ray grating differential phase contrast 3 D cone-beam computer tomography method based on transversion malposition grating,
It is characterised in that it includes following steps：
Step 1 obtains X-ray after object with the Talbort-Lau three-dimensionals chromatography imaging arrangement based on transversion malposition grating
Two-dimensional projection image sequence, the two-dimensional projection image sequence is during object axially rotates, and detector is periodically adopted
Collect X-ray and pass through the two-dimensional projection after object, and collects the two-dimensional projection of object described in a width in a collection period
Image；
Step 2 isolates the two-dimensional projection image sequence progress Fourier transformation X-ray absorption contrast, differential phase lining
Degree and scattering three kinds of contrast images of contrast；
Step 3, using absorb contrast, differential phase contrast and scattering contrast filter back-projection reconstruction algorithm respectively to three kinds of contrasts
Two-dimensional image sequence carries out image reconstruction, obtains the object and absorbs contrast, phase contrast and scattering three kinds of CT slice maps of contrast
Picture.
2. the X-ray grating differential phase contrast 3 D cone-beam according to claim 1 based on transversion malposition grating calculates
Machine chromatography imaging method, which is characterized in that the transversion malposition absorption grating arranges Talbot-Lau imaging arrangements, including：
It includes six parts that the Talbot-Lau imaging arrangements light path, which has altogether,：X-ray source, source grating G0, test object, phase
Grating G1, absorption grating G2, detector；
The Talbot-Lau imaging arrangements light path parameter should meet following formula (1)-(4)：
kg1=2g2, (2)
g0=g2L/d, (3)
s<g2L/2d, (4)
Wherein, d indicates the distance between phase grating G1 and absorption grating G2；K=(L+d)/L is amplification ratio, and L is source grating G0
With the direct distances of phase grating G1；M indicates m rank score Talbot distances；g1For the period of phase grating G1, λ is X used
The wavelength of ray, g2For the period of absorption grating G2, g0For the period of source grating G0, s is to allow under each period in source grating
The width of X-ray transparent；
The transversion malposition absorption grating refers to absorption grating G2 in the Talbot-Lau imaging arrangements light path, with spy
It surveys the relative position that device visits member and lateral periodicity dislocation occurs so that laterally multiple adjacent detectors visit the intensity letter that member obtains
Number, a detector in conventional imaging method can be equivalent to and visit the strength signal that member is obtained at multiple and different positions；
Member is visited for 4 laterally adjacent detectors, is respectively labeled as p1、p2、p3、p4, each to visit member px(x=1,2,3,4) width
For w the grating gp that one section of length is w is corresponded in transversion malposition absorption gratingx, each section of grating gpxScreen periods be g2, phase
Adjacent detector visits the corresponding grating of member, and there is the alternate position spikes that distance is f, such as adjacent detector to visit member p1And p2Corresponding grating section
gp1With gp2There is the alternate position spikes of f, wherein f=g2/ 4, gpxThe position of grating is equivalent to position of the absorption grating when being moved to x
It sets, the position that adjacent 4 detectors visit the corresponding each section of absorption grating of member is variant, mutually staggers distance f, referred to as laterally wrong
Position grating, detector visit member pxThe X-ray intensity signal value of acquisition is that absorption grating G2 is moved to collected intensity when the x of position
Value.
3. the X-ray grating differential phase contrast 3 D cone-beam according to claim 1 based on transversion malposition grating calculates
Machine chromatography imaging method, which is characterized in that step 1 further includes：
In the Talbot-Lau imaging arrangements, when turntable does not place object, turntable is along rotation center uniform rotation 360
Degree, and imaging area is covered by cone-beam in rotation process, and two-dimensional projection image is acquired by detector；
In the Talbot-Lau imaging arrangements, when turntable places object, turntable along 360 degree of rotation center uniform rotation,
And imaging area is covered by cone-beam in rotation process, and two-dimensional projection image is acquired by detector.
4. the X-ray grating differential phase contrast 3 D cone-beam according to claim 1 based on transversion malposition grating calculates
Machine chromatography imaging method, which is characterized in that isolate X-ray suction from collected two-dimensional intensity image with Fourier analysis method
Contrast, differential phase contrast and scattering three kinds of images of contrast are received, including：
Image analysis is carried out to the two-dimensional projection image sequence according to formula (5)-(14) and obtains three kinds of contrast two-dimensional projections
Image sequence：
I1(x, z, θ)=I (x-1, z, θ), (5)
I2(x, z, θ)=I (x, z, θ), (6)
I3(x, z, θ)=I (x+1, z, θ), (7)
I4(x, z, θ)=I (x+2, z, θ), (8)
Phase (x, z, θ)=φs(x,z,θ)-φr(x,z,θ), (13)
Wherein, x is the abscissa of two-dimension projection point；Z is the ordinate of two-dimension projection point, θ two-dimensional projection image institutes thus
In projection angle；I (x, z, θ) is intensity value of the two-dimension projection midpoint (x, z) in projection angle θ；I1(x,z,θ)、I2(x,z,
θ)、I3(x,z,θ)、I4(x, z, θ) indicates that point (x, z) in 4 different intensity values of projection angle θ, simulates traditional raster respectively
Intensity value of the differential phase contrast image midpoint (x, z) in projection angle θ when absorption grating is in 4 different stepping positions；M
Indicate the number of different intensity value in a point (x, z), M=4；a0(x, z, θ) be point (x, z) at 4 of projection angle θ not
The sinusoidal mean value that same intensity value fits；a1(x, z, θ) is 4 different intensity of the point (x, z) in projection angle θ
The sinusoidal amplitude size that value fits；φ (x, z, θ) is that 4 different intensity values of the point (x, z) in projection angle θ are quasi-
The sinusoidal phase value closed out；Indicate a when projection angle θ does not put test object0(x, z, θ) value,Indicate a when projection angle θ places test object0(x, z, θ) value；It indicates in projection angle
θ does not put a when test object1(x, z, θ) value,Indicate a when projection angle θ places test object1(x,z,
θ) value；φr(x, z, θ) indicates φ (x, z, θ) value when projection angle θ does not put test object, φs(x, z, θ) expression is projecting
Angle, θ places φ (x, z, θ) value when test object；Abs (x, z, θ) is the value that contrast is absorbed in projection angle θ points (x, z)；
Phase (x, z, θ) is the value in projection angle θ point (x, z) differential phase contrast；Dark (x, z, θ) is in projection angle θ points
(x, z) scatters the value of contrast imaging.
5. the X-ray grating differential phase contrast 3 D cone-beam according to claim 1 based on transversion malposition grating calculates
Machine chromatography imaging method, which is characterized in that rebuild and calculate using contrast, differential phase contrast and scattering contrast filtered back projection is absorbed
Method carries out image reconstruction to three kinds of contrast two-dimensional image sequences respectively, obtains the object and absorbs contrast, phase contrast and scattering
Three kinds of CT sectioning images of contrast, including：
Image analysis is carried out to the two-dimensional projection image sequence according to formula (15)-(17) and obtains three kinds of contrast two-dimensional projections
Image sequence：
Wherein, a (x, y, z), p (x, y, z) and d (x, y, z) are respectively the absorption contrast sectioning image rebuild, phase contrast slice
Image and scattering contrast sectioning image；Abs (s, v, θ), phase (s, v, θ) and dark (s, v, θ) are indicated under projected angle θ respectively
Absorption contrast, differential phase contrast and scattering contrast two-dimensional projection, s, v are the company of pixel and radiographic source on detector respectively
The intersecting point coordinate of line and the dummy detector being placed at rotary shaft；ξ is the angle of ray and central ray；D arrives for radiographic source
The distance of virtual detector plane；Y ' is the distance for rebuilding image pixel point to virtual detector plane；ha(s)、hp(s) and hd
(s) it is respectively the filter for absorbing contrast, differential phase contrast and scattering contrast two-dimensional projection, is defined as formula (18)-
(19)：
ha(s)=| s |, (18)
hd(s)=| s |, (20).
6. a kind of X-ray grating differential phase contrast 3 D cone-beam computer laminated imaging device based on transversion malposition grating,
It is characterised in that it includes：
Acquisition module, for obtaining the collected two-dimensional projection image sequence of detector, the two-dimensional projection image sequence is object
Body axially in rotation process, obtains multiple after the ray projection of the excessively described object of detector periodicity acquisition of transmission
Two-dimensional projection image, and the two-dimensional projection image of sampling period one object of correspondence；
Computing module, for being carried out to the two-dimensional projection image sequence, Fourier transformation obtains absorption contrast, differential phase serves as a contrast
Degree and scattering contrast two-dimensional projection sequence；Image weight is carried out using three kinds of contrast two-dimensional projection sequences of cone beam reconstruction algorithm pair
It builds, obtains the corresponding three dimensional CT sectioning image of the object cylinder.
7. the X-ray grating differential phase contrast 3 D cone-beam according to claim 6 based on transversion malposition grating calculates
Machine laminated imaging device, which is characterized in that the transversion malposition absorption grating arranges Talbot-Lau imaging arrangements, including：
It includes six parts that the Talbot-Lau imaging arrangements light path, which has altogether,：X-ray source, source grating G0, test object, phase
Grating G1, absorption grating G2, detector；
The Talbot-Lau imaging arrangements light path parameter should meet following formula (1)-(4)：
kg1=2g2, (2)
g0=g2L/d, (3)
s<g2L/2d, (4)
Wherein, d indicates the distance between phase grating G1 and absorption grating G2；K=(L+d)/L is amplification ratio, and L is source grating G0
With the direct distances of phase grating G1；M indicates m rank score Talbot distances；g1For the period of phase grating G1, λ is X used
The wavelength of ray, g2For the period of absorption grating G2, g0For the period of source grating G0, s is to allow under each period in source grating
The width of X-ray transparent；
The transversion malposition absorption grating refers to absorption grating G2 in the Talbot-Lau imaging arrangements light path, with spy
It surveys the relative position that device visits member and lateral periodicity dislocation occurs so that laterally multiple adjacent detectors visit the intensity letter that member obtains
Number, a detector in conventional imaging method can be equivalent to and visit the strength signal that member is obtained at multiple and different positions；
Member is visited for 4 laterally adjacent detectors, is respectively labeled as p1、p2、p3、p4, each to visit member px(x=1,2,3,4) width
For w the grating gp that one section of length is w is corresponded in transversion malposition absorption gratingx, each section of grating gpxScreen periods be g2, phase
Adjacent detector visits the corresponding grating of member, and there is the alternate position spikes that distance is f, such as adjacent detector to visit member p1And p2Corresponding grating section
gp1With gp2There is the alternate position spikes of f, wherein f=g2/ 4, gpxThe position of grating is equivalent to position of the absorption grating when being moved to x
It sets, the position that adjacent 4 detectors visit the corresponding each section of absorption grating of member is variant, mutually staggers distance f, referred to as laterally wrong
Position grating, detector visit member pxThe X-ray intensity signal value of acquisition is that absorption grating G2 is moved to collected intensity when the x of position
Value.
8. the X-ray grating differential phase contrast 3 D cone-beam according to claim 7 based on transversion malposition grating calculates
Machine laminated imaging device, which is characterized in that acquisition module further includes：
In the Talbot-Lau imaging arrangements, when turntable does not place object, turntable is along rotation center uniform rotation 360
Degree, and imaging area is covered by cone-beam in rotation process, and two-dimensional projection image is acquired by detector；
In the Talbot-Lau imaging arrangements, when turntable places object, turntable along 360 degree of rotation center uniform rotation,
And imaging area is covered by cone-beam in rotation process, and two-dimensional projection image is acquired by detector.
9. the X-ray grating differential phase contrast 3 D cone-beam according to claim 7 based on transversion malposition grating calculates
Machine laminated imaging device, which is characterized in that the computing module is with Fourier analysis method from collected two-dimensional intensity image
X-ray absorption contrast, differential phase contrast and scattering three kinds of images of contrast are isolated, including：
Image analysis is carried out to the two-dimensional projection image sequence according to formula (5)-(14) and obtains three kinds of contrast two-dimensional projections
Image sequence：
I1(x, z, θ)=I (x-1, z, θ), (5)
I2(x, z, θ)=I (x, z, θ), (6)
I3(x, z, θ)=I (x+1, z, θ), (7)
I4(x, z, θ)=I (x+2, z, θ), (8)
Phase (x, z, θ)=φs(x,z,θ)-φr(x,z,θ), (13)
Wherein, x is the abscissa of two-dimension projection point；Z is the ordinate of two-dimension projection point, θ two-dimensional projection image institutes thus
In projection angle；I (x, z, θ) is intensity value of the two-dimension projection midpoint (x, z) in projection angle θ；I1(x,z,θ)、I2(x,z,
θ)、I3(x,z,θ)、I4(x, z, θ) indicates that point (x, z) in 4 different intensity values of projection angle θ, simulates traditional raster respectively
Intensity value of the differential phase contrast image midpoint (x, z) in projection angle θ when absorption grating is in 4 different stepping positions；M
Indicate the number of different intensity value in a point (x, z), M=4；a0(x, z, θ) be point (x, z) at 4 of projection angle θ not
The sinusoidal mean value that same intensity value fits；a1(x, z, θ) is 4 different intensity of the point (x, z) in projection angle θ
The sinusoidal amplitude size that value fits；φ (x, z, θ) is that 4 different intensity values of the point (x, z) in projection angle θ are quasi-
The sinusoidal phase value closed out；Indicate a when projection angle θ does not put test object0(x, z, θ) value,Indicate a when projection angle θ places test object0(x, z, θ) value；It indicates in projection angle
θ does not put a when test object1(x, z, θ) value,Indicate a when projection angle θ places test object1(x,z,
θ) value；φr(x, z, θ) indicates φ (x, z, θ) value when projection angle θ does not put test object, φs(x, z, θ) expression is projecting
Angle, θ places φ (x, z, θ) value when test object；Abs (x, z, θ) is the value that contrast is absorbed in projection angle θ points (x, z)；
Phase (x, z, θ) is the value in projection angle θ point (x, z) differential phase contrast；Dark (x, z, θ) is in projection angle θ points
(x, z) scatters the value of contrast imaging.
10. the X-ray grating differential phase contrast 3 D cone-beam according to claim 6 based on transversion malposition grating calculates
Machine laminated imaging device, which is characterized in that the computing module is filtered using contrast, differential phase contrast and scattering contrast is absorbed
Backprojection reconstruction algorithm carries out image reconstruction to three kinds of contrast two-dimensional image sequences respectively, obtains the object and absorbs contrast, phase
Position contrast and scattering three kinds of CT sectioning images of contrast, including：
Image analysis is carried out to the two-dimensional projection image sequence according to formula (15)-(17) and obtains three kinds of contrast two-dimensional projections
Image sequence：
Wherein, a (x, y, z), p (x, y, z) and d (x, y, z) are respectively the absorption contrast sectioning image rebuild, phase contrast slice
Image and scattering contrast sectioning image；Abs (s, v, θ), phase (s, v, θ) and dark (s, v, θ) are indicated under projected angle θ respectively
Absorption contrast, differential phase contrast and scattering contrast two-dimensional projection, s, v are the company of pixel and radiographic source on detector respectively
The intersecting point coordinate of line and the dummy detector being placed at rotary shaft；ξ is the angle of ray and central ray；D arrives for radiographic source
The distance of virtual detector plane；Y ' is the distance for rebuilding image pixel point to virtual detector plane；ha(s)、hp(s) and hd
(s) it is respectively the filter for absorbing contrast, differential phase contrast and scattering contrast two-dimensional projection, is defined as formula (18)-
(19)：
ha(s)=| s |, (18)
hd(s)=| s |, (20).
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