CN111505034A - X-ray diffraction enhanced imaging method based on iterative algorithm - Google Patents

X-ray diffraction enhanced imaging method based on iterative algorithm Download PDF

Info

Publication number
CN111505034A
CN111505034A CN202010361992.6A CN202010361992A CN111505034A CN 111505034 A CN111505034 A CN 111505034A CN 202010361992 A CN202010361992 A CN 202010361992A CN 111505034 A CN111505034 A CN 111505034A
Authority
CN
China
Prior art keywords
imaged object
signal
formula
detector
projection data
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN202010361992.6A
Other languages
Chinese (zh)
Other versions
CN111505034B (en
Inventor
王志立
陈恒
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hefei University of Technology
Original Assignee
Hefei University of Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hefei University of Technology filed Critical Hefei University of Technology
Priority to CN202010361992.6A priority Critical patent/CN111505034B/en
Publication of CN111505034A publication Critical patent/CN111505034A/en
Application granted granted Critical
Publication of CN111505034B publication Critical patent/CN111505034B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • 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
    • G01N23/20—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 using diffraction of the radiation by the materials, e.g. for investigating crystal structure; by using scattering of the radiation by the materials, e.g. for investigating non-crystalline materials; by using reflection of the radiation by the materials
    • G01N23/207—Diffractometry using detectors, e.g. using a probe in a central position and one or more displaceable detectors in circumferential positions

Abstract

The invention discloses an X-ray diffraction enhanced imaging method based on an iterative algorithm, which is applied to a diffraction enhanced imaging system formed by sequentially arranging an X-ray source, a monochromatic crystal, an analysis crystal and a detector along the propagation direction of the X-ray, wherein the X-ray is incident to the surface of the monochromatic crystal to be diffracted, the emergent monochromatic collimated X-ray is incident to the surface of the analysis crystal to be diffracted after penetrating through an imaged object, the intensity of the emergent X-ray is detected and recorded by the detector after the emergent X-ray is incident to the detector, the normal line of the diffraction surface of the analysis crystal is taken as a rotating shaft, and the detector is utilized to record the projection data of the analysis crystal at three different angular positions, so that the projection data recorded by the detector is processed by the proposed iterative algorithm to obtain the absorption, refraction and scattering signals of the imaged object. The invention can solve the problem of accurately extracting the refraction signal and the scattering signal of the imaged object when the bias of the light intensity curve is not zero.

Description

X-ray diffraction enhanced imaging method based on iterative algorithm
Technical Field
The invention relates to the field of X-ray imaging methods, in particular to an X-ray diffraction enhanced imaging method based on an iterative algorithm.
Background
Through the continuous development of more than 100 years, the X-ray imaging technology is widely applied to the fields of clinical medical diagnosis and treatment, public safety inspection, material science and the like. For objects containing heavy metal elements, a good imaging effect can be obtained by utilizing an X-ray absorption contrast imaging technology. However, for objects composed mainly of low atomic number elements, such as organic composite materials and human soft tissues, the attenuation of X-rays is very weak, and the quality of images obtained by using the absorption contrast imaging technique is poor. To overcome this limitation, scientists have continued to develop a series of multi-mode X-ray imaging methods as a powerful complement to conventional absorption contrast imaging techniques. The new imaging methods can utilize phase shift signals and scattering signals when X-rays pass through an object to form image contrast, and can obtain good image quality when a weakly absorbing object is imaged. The diffraction enhanced imaging method is characterized in that the tiny change of the X-ray propagation direction caused by the change of the refractive index in an object is screened out by utilizing the selectivity of crystal diffraction on the angle of incident X-rays. The diffraction enhanced imaging method can simultaneously acquire absorption, refraction and scattering signals of an imaged object, has the advantages of high spatial resolution, high sensitivity and the like, and is increasingly widely applied to the fields of breast/joint imaging, three-dimensional space structure research of porous composite materials and the like.
Currently, the X-ray diffraction enhanced imaging method generally adopts a multi-pattern statistical method to perform data acquisition of multi-pattern imaging and extraction of absorption, refraction and scattering signals of an imaged object. The multi-graph statistical method requires: the normal of the diffraction surface of the analysis crystal is taken as a rotating shaft, angular position stepping scanning is carried out on the analysis crystal, dozens of projection images are collected, so that the data collection time is long, and the experiment efficiency is reduced; multiple (typically tens of experimental) exposures of the imaged object increase the risk of radiation damage to the imaged object. More importantly, when the bias of the light intensity curve is not zero, the multi-graph statistical method cannot accurately extract the refraction signal and the scattering signal of the imaged object. These limitations hinder the popularization and application of X-ray diffraction enhanced imaging in the fields of dynamic multi-mode imaging, porous material quantitative characterization, and the like. Therefore, developing a new diffraction enhanced imaging method, overcoming the limitations of the multi-image statistical method requiring analyzing the step scanning of the crystal angle position, the multiple exposure of the imaged object and the deviation of the light intensity curve to zero, has become one of the problems to be solved in the process of promoting the practical application of the X-ray diffraction enhanced imaging method.
Disclosure of Invention
The invention provides an X-ray diffraction enhanced imaging method based on an iterative algorithm in order to avoid the defects of the existing imaging method, so that the complicated angular position step scanning of an analysis crystal can be abandoned, and the X-ray diffraction enhanced imaging process is simplified; the absorption, refraction and scattering signals of the imaged object can be acquired simultaneously only by exposing the imaged object for three times, so that the risk of radiation damage is reduced; when the bias of the light intensity curve is not zero, the refraction signal and the scattering signal of the imaged object can be accurately extracted, so that a new way is provided for realizing rapid, accurate and low-radiation-damage X-ray diffraction enhanced imaging.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention relates to an X-ray diffraction enhanced imaging method based on an iterative algorithm, which is characterized in that the method is applied to a diffraction enhanced imaging system, wherein the diffraction enhanced imaging system takes the propagation direction of X-rays as the Z-axis direction, and the X-ray source, a monochromatic crystal, an analysis crystal and a detector are sequentially arranged along the Z-axis direction; the X-ray diffraction enhanced imaging method comprises the following steps:
step 1, setting relevant positions of all devices to meet the following requirements: d is more than 01＜d3＜d4Wherein d is1The relative distance between the monochromatic crystal and the X-ray source along the Z-axis, d3For the relative distance of the analysis crystal from the X-ray source in the Z-axis direction, d4The relative distance between the detector and the X-ray source along the Z-axis direction;
step 2, obtaining background projection data:
step 2.1, taking the normal of the diffraction surface of the analysis crystal as a rotating shaft;
step 2.2, setting a first angular position of the analysis crystal along the rotating shaft as theta1(ii) a After the X-ray source is started, first background projection data I are acquired by the detector according to an exposure time length t11；
Step 2.3, setting a second angular position of the analysis crystal along the rotating shaft as theta2；
Acquiring second background projection data I according to exposure time t2 by the detector2；
Step 2.4, setting a third angular position of the analysis crystal along the rotating shaft as theta3；
Acquiring third background projection data I according to exposure time t3 by using the detector3Then, the X-ray source is turned off;
step 3, acquiring projection data of the imaged object:
3.1, placing the imaged object in the middle of the monochromatic crystal and the analysis crystal along the Z-axis direction; and the relative distance between the imaged object and the X-ray source along the Z-axis direction is recorded as d2And satisfy d1＜d2＜d3；
Step 3.2, setting the first angular position of the analysis crystal along the rotating shaft as theta1；
After the X-ray source is started, acquiring first projection data I 'of the imaged object by utilizing the detector according to the exposure time length t 1'1；
Step 3.3, setting the second angular position of the analysis crystal along the rotating shaft as theta2(ii) a Acquiring second projection data I 'of the imaged object according to exposure duration t2 by utilizing the detector'2；
Step 3.4, setting the third angular position of the analysis crystal along the rotating shaft as theta3(ii) a Acquiring third projection data I 'of the imaged object according to exposure duration t3 by utilizing the detector'3Then, the X-ray source is turned off;
and 4, extracting an absorption signal T of the imaged object based on an iterative algorithm:
step 4.1, defining the iteration number as k, and initializing k to be 1;
obtaining an absorption signal T under the kth iteration by using the formula (1)k：
Figure BDA0002475308290000031
Step 4.2, extracting an absorption signal T of the imaged object under the (k + 1) th iteration by using the formula (2)k+1：
Figure BDA0002475308290000032
In the formula (2), the reaction mixture is,
Figure BDA0002475308290000033
represents the offset correction after the kth iteration and has:
Figure BDA0002475308290000034
in formula (3), c is the bias of the light intensity curve of the diffraction enhanced imaging system, and c is more than 0;
step 4.3, judge | Tk+1-Tk|＜1If yes, the iteration is ended, and the final absorption signal T is obtainedk+1Otherwise, after assigning k +1 to k, returning to the step 4.2; wherein the content of the first and second substances,1is a given threshold value;
step 5, extracting a refraction signal theta of the imaged object (5) based on an iterative algorithmR：
Step 5.1, initializing k to be 1;
obtaining a refraction signal under the k iteration by using the formula (4)
Figure BDA0002475308290000035
Figure BDA0002475308290000041
Step 5.2, extracting the refraction signal of the imaged object under the (k + 1) th iteration by using the formula (5)
Figure BDA0002475308290000042
Figure BDA0002475308290000043
Step 5.3, judgment
Figure BDA0002475308290000044
Whether the signal is true or not, if so, the iteration is ended to obtain a refraction signal
Figure BDA0002475308290000045
Otherwise, after k +1 is assigned to k, returning to the step 5.2 for execution; wherein the content of the first and second substances,2another given threshold;
step 6, extracting the scattering signal of the imaged object based on an iterative algorithm
Figure BDA0002475308290000046
Step 6.1, initializing k to 1;
obtaining a scattering signal at the kth iteration by using the formula (6)
Figure BDA0002475308290000047
Figure BDA0002475308290000048
Step 6.2, extracting a scattering signal of the imaged object under the (k + 1) th iteration by using the formula (7)
Figure BDA0002475308290000049
Figure BDA00024753082900000410
Step 6.3, judgment
Figure BDA00024753082900000411
Whether the scattering signal is established or not, if so, the iteration is ended to obtain the scattering signal
Figure BDA00024753082900000412
Otherwise, after k +1 is assigned to k, returning to the step 6.2 for execution; wherein the content of the first and second substances,3a third given threshold;
based on absorption signal T and refraction signal theta of the imaged objectRScattering signal
Figure BDA00024753082900000413
As a result of the diffraction enhanced imaging method.
The X-ray diffraction enhanced imaging method is also characterized in that:
first projection data I 'of the imaged object'1Satisfies formula (3.1):
Figure BDA0002475308290000051
in the formula (3.1), σrIs the angular width of the light intensity curve of the diffraction enhanced imaging system;
second projection data l 'of the imaged object'2Satisfies formula (3.2):
Figure BDA0002475308290000052
third projection data l 'of the imaged object'3Satisfies formula (3.3):
Figure BDA0002475308290000053
compared with the prior art, the invention has the beneficial effects that:
1. the invention provides an X-ray diffraction enhanced imaging method based on an iterative algorithm by utilizing the Gaussian function approximation of a light intensity curve, and realizes the accurate extraction of refraction signals and scattering signals of an imaged object when the bias of the light intensity curve is not zero. The limitation that a multi-graph statistical method requires analysis of step scanning of the crystal angular position is overcome, and the data acquisition process of diffraction enhanced imaging is simplified; the limitation that a multi-image statistical method requires multiple exposures on an imaged object is overcome, and the radiation damage risk is reduced; the method solves the limitation that the multi-graph statistical method can not accurately extract the refraction signal and the scattering signal of the imaged object when the bias of the light intensity curve is not zero, and realizes the fast, accurate and low-radiation-damage X-ray diffraction enhanced imaging;
2. compared with the existing multi-image statistical method, the method has the advantages that when the projection data are obtained, the analysis crystal is sequentially fixed at the three determined angular positions, the angle step scanning of the analysis crystal is abandoned, and the data acquisition process of diffraction enhanced imaging is simplified;
3. compared with the existing multi-image statistical method, the method can quantitatively extract the absorption, refraction and scattering signals of the imaged object by only exposing the imaged object for 3 times and recording 3 pieces of projection image data, thereby avoiding multiple exposure of the imaged object and reducing the risk of radiation damage;
4. compared with the existing multi-image statistical method, the method utilizes the iterative algorithm to correct the non-zero offset of the light intensity curve, can accurately and quantitatively extract the refraction signal and the scattering signal of the imaged object, and realizes the quantitative accuracy of refraction imaging and dark field imaging;
drawings
FIG. 1 is a schematic view of an X-ray diffraction enhanced imaging apparatus according to the present invention;
FIG. 2 is a graph of light intensity in the prior art;
FIG. 3 is a graph illustrating the result of the absorption signal of the imaged object;
FIG. 4 shows the result of extracting the refraction signal of the imaged object according to the present invention;
FIG. 5 shows the result of extracting the scattering signal of the imaged object according to the present invention;
reference numbers in the figures: 1, an X-ray source; 2, a monochromatic crystal; 3 analyzing the crystal; 4, a detector; 5 an imaged object.
Detailed Description
In the present embodiment, referring to fig. 1, an X-ray diffraction enhanced imaging system composed of an X-ray source 1, a monochromatic crystal 2, an analytical crystal 3, and a detector 4 is provided; as shown in fig. 1, the X-ray propagation direction is taken as the Z-axis direction; the X-ray source 1, the monochromatic crystal 2, the imaged object 5, the analysis crystal 3 and the detector 4 are sequentially arranged along the Z-axis direction; the iterative algorithm-based X-ray diffraction enhanced imaging method comprises the following steps:
step 1, setting relevant positions of all devices to meet the following requirements: d is more than 01＜d3＜d4Wherein d is1Is the relative distance between the monochromatic crystal 2 and the X-ray source 1 along the Z-axis, d3For analyzing the relative distance between the crystal 3 and the X-ray source 1 along the Z-axis; d4The relative distance between the detector 4 and the X-ray source 1 along the Z-axis direction;
step 2, obtaining background projection data:
step 2.1, taking the normal of the diffraction surface of the analysis crystal 3 as a rotating shaft;
step 2.2, setting the first angular position of the analysis crystal 3 along the rotating shaft as theta1；
After the X-ray source 1 is activated, first background projection data I are acquired with the detector 4 for an exposure time period t11；
Step 2.3, setting the second angular position of the analysis crystal 3 along the rotating shaft as theta2(ii) a Acquiring second background projection data I with the detector 4 with an exposure time duration t22；
Step 2.4, setting a third angular position of the analysis crystal 3 along the rotating shaft as theta3(ii) a Third background projection data I are acquired with the detector 4 with an exposure time duration t33Then, the X-ray source 1 is turned off;
for exposure time periods t1, t2, t 3: when the X-ray source 1 is a synchrotron radiation X-ray source, the typical value of the exposure time is 1-10 milliseconds; when the X-ray source 1 is a conventional X-ray source, a typical value of the exposure time is ten seconds to hundreds of seconds according to different power of the X-ray source;
size relationship of t1, t2, t 3: when the angular position theta1The corresponding intensity profile (as shown in FIG. 2) has a value greater than the angular position θ2At the value of the corresponding intensity curve, t1<t 2. Otherwise, t1>t 2. And so on.
Step 3, acquiring projection data of the imaged object:
3.1, placing an imaged object 5 between the monochromatic crystal 2 and the analysis crystal 3 along the Z-axis direction; and the relative distance between the imaged object 5 and the X-ray source 1 along the Z-axis is recorded as d2And satisfy d1＜d2＜d3；
Step 3.2, setting the first angular position of the analysis crystal 3 along the rotating shaft as theta1；
After the X-ray source 1 is activated, first projection data I of the imaged object 5 are acquired with the detector 4 according to an exposure time period t11′；
Step 3.3, setting the second angular position of the analytical crystal 3 along the rotation axis as theta2(ii) a Second projection data l 'of the imaged object 5 are acquired with the detector 4 at exposure time period t 2'2；
Step 3.4, setting the third angular position of the analysis crystal 3 along the rotating shaft as theta3(ii) a Third projection data I 'of the imaged object 5 are acquired with the detector 4 at exposure time period t 3'3Then, the X-ray source 1 is turned off;
wherein the acquired first projection data I 'of the imaged object 5'1Satisfies formula (3.1):
Figure BDA0002475308290000071
in the formula (3.1), T is an absorption signal of the imaged object 5; thetaRIs a refractive signal of the imaged object 5;
Figure BDA0002475308290000072
is the scatter signal of the imaged object 5; c is the bias of the light intensity curve of the diffraction enhanced imaging system, and c is more than 0; sigmarIs the angular width of the light intensity curve of the diffraction enhanced imaging system.
Second projection data I 'of acquired imaged object 5'2Satisfies formula (3.2):
Figure BDA0002475308290000073
third projection data of the imaged object 5 is acquiredI′3Satisfies formula (3.3):
Figure BDA0002475308290000074
and 4, extracting an absorption signal T of the imaged object 5 based on an iterative algorithm:
step 4.1, defining the iteration number as k, and initializing k to be 1;
obtaining an absorption signal T under the kth iteration by using the formula (1)k：
Figure BDA0002475308290000081
Step 4.2, extracting an absorption signal T of the imaged object 5 under the k +1 th iteration by using the formula (2)k+1：
Figure BDA0002475308290000082
In the formula (2), the reaction mixture is,
Figure BDA0002475308290000083
represents the offset correction after the kth iteration and has:
Figure BDA0002475308290000084
in formula (3), c is the bias of the light intensity curve of the diffraction enhanced imaging system, and c is more than 0;
step 4.3, judgment
Figure BDA0002475308290000085
If yes, the iteration is ended, and the final absorption signal T is obtainedk+1Otherwise, after assigning k +1 to k, returning to the step 4.2; wherein the content of the first and second substances,1is a given threshold value;
obtained according to formula (3.1), formula (3.2), formula (3.3):
Figure BDA0002475308290000086
first consider the case where the bias of the intensity curve is zero, i.e., c is 0. Obtained by using the formula (4.1):
Figure BDA0002475308290000091
obtained by using the formula (4.2):
Figure BDA0002475308290000092
obtained by using the formula (4.3):
Figure BDA0002475308290000093
Figure BDA0002475308290000094
the compound is obtained by using the formulas (4.4) and (4.5):
Figure BDA0002475308290000101
the compound is obtained by using the formulas (4.2) and (4.6):
Figure BDA0002475308290000102
that is, when c is 0, the absorption signal of the object can be extracted by equation (4.7).
In the case where the bias of the intensity curve is not zero (as shown in fig. 2), i.e. c > 0, a comparison of equations (4.1) and (4.2) may find a key issue as to how to correct for non-zero bias. The invention proposes to correct the non-zero offset by an iterative algorithm based on equation (4.7). Taking an equation (4.7) as an iteration initial value of k ═ 1, and extracting an absorption signal of the imaged object by using an iterative algorithm shown in an equation (2);
result T when the k +1 th iterationk+1The node of the k iterationFruit TkSatisfy | Tk+1-Tk|＜1When so, the iteration ends. By Tk+1As a result of the extraction of the absorption signal of the imaged object. Threshold value1Typical values of (A) are 1E-12 to 1E-8.
Step 5, extracting refraction signal theta of the imaged object 5 based on an iterative algorithmR：
Step 5.1, initializing k to be 1;
obtaining a refraction signal under the k iteration by using the formula (4)
Figure BDA0002475308290000111
Figure BDA0002475308290000112
Step 5.2, extracting the refraction signal of the imaged object 5 under the k +1 th iteration by using the formula (5)
Figure BDA0002475308290000113
Figure BDA0002475308290000114
Step 5.3, judgment
Figure BDA0002475308290000115
Whether the signal is true or not, if so, the iteration is ended to obtain a refraction signal
Figure BDA0002475308290000116
Otherwise, after k +1 is assigned to k, returning to the step 5.2 for execution; wherein the content of the first and second substances,2another given threshold;
obtained according to formula (3.1), formula (3.2), formula (3.3):
Figure BDA0002475308290000117
first consider the case where the bias of the intensity curve is zero, i.e., c is 0. Obtained by using the formula (5.1):
Figure BDA0002475308290000118
obtained by using the formula (5.2):
Figure BDA0002475308290000121
obtained by the formula (5.3)
Figure BDA0002475308290000122
Figure BDA0002475308290000123
The compound is obtained by using the formulas (5.4) and (5.5):
Figure BDA0002475308290000124
that is, when c is 0, the refractive signal of the object can be extracted by equation (5.6).
In the case where the bias of the intensity curve is not zero (as shown in fig. 2), i.e. c > 0, a comparison of equations (5.1) and (5.2) may find a key issue as to how to correct for non-zero bias. The invention proposes to correct the non-zero offset by an iterative algorithm based on equation (5.6). Taking equation (5.6) as an iteration initial value of k ═ 1, and extracting a refraction signal of the imaged object by using an iterative algorithm shown in equation (4);
when the result of the (k + 1) th iteration
Figure BDA0002475308290000125
And the result of the k-th iteration
Figure BDA0002475308290000126
Satisfy the requirement of
Figure BDA0002475308290000127
When so, the iteration ends. To be provided with
Figure BDA0002475308290000128
As a result of the extraction of the refraction signal of the imaged object. Threshold value2Typical values of (A) are 1E-16 to 1E-12.
Step 6, extracting the scattering signal of the imaged object 5 based on an iterative algorithm
Figure BDA0002475308290000129
Step 6.1, initializing k to 1;
obtaining a scattering signal at the kth iteration by using the formula (6)
Figure BDA0002475308290000131
Figure BDA0002475308290000132
Step 6.2, extracting a scattering signal of the imaged object 5 under the (k + 1) th iteration by using the formula (7)
Figure BDA0002475308290000133
Figure BDA0002475308290000134
Step 6.3, judgment
Figure BDA0002475308290000135
Whether the scattering signal is established or not, if so, the iteration is ended to obtain the scattering signal
Figure BDA0002475308290000136
Otherwise, after k +1 is assigned to k, returning to the step 6.2 for execution; wherein the content of the first and second substances,3a third given threshold;
obtained according to formula (3.1), formula (3.2), formula (3.3):
Figure BDA0002475308290000137
first consider the case where the bias of the intensity curve is zero, i.e., c is 0. Obtained by using the formula (6.1):
Figure BDA0002475308290000138
obtained by using the formula (6.2):
Figure BDA0002475308290000141
obtained by using the formula (6.3):
Figure BDA0002475308290000142
obtained by using the formula (6.4):
Figure BDA0002475308290000143
that is, when c is 0, the scattering signal of the object to be imaged can be extracted using equation (6.5).
When the bias of the intensity curve is not zero (as shown in fig. 2), i.e. c > 0, we find out how to correct the non-zero bias as a key issue comparing equation (6.1) and equation (6.2). The invention proposes to correct the non-zero offset by an iterative algorithm based on equation (6.5). Taking equation (6.5) as an iteration initial value of k ═ 1, and extracting a scattering signal of the imaged object by using an iterative algorithm shown in equation (7);
when the result of the (k + 1) th iteration
Figure BDA0002475308290000144
And the result of the k-th iteration
Figure BDA0002475308290000145
Satisfy the requirement of
Figure BDA0002475308290000146
When so, the iteration ends. To be provided with
Figure BDA0002475308290000147
As a result of the extraction of the scatter signal of the imaged object. Threshold value3Typical values of (A) are 1E-20 to 1E-16.
Fig. 3 shows the result of extracting the absorption signal of the imaged object 5. The result of the new method provided by the invention is in good agreement with the theoretical predicted value. Fig. 4 shows the extraction result of the refraction signal of the imaged object 5. The result of the method is consistent with the theoretical predicted value within the experimental error range, while the result of the existing method obviously deviates from the theoretical predicted value and is inaccurate; fig. 5 shows the extraction result of the scattering signal of the imaged object 5. The result of the invention is consistent with the theoretical predicted value, while the result of the existing method is completely inconsistent with the theoretical predicted value and is wrong. These results demonstrate the feasibility of the X-ray diffraction enhanced imaging method proposed by the present invention.
Based on the absorption signal T and the refraction signal theta of the imaged object 5RScattering signal
Figure BDA0002475308290000148
As a result of the diffraction enhanced imaging method.

Claims (2)

1. An X-ray diffraction enhanced imaging method based on an iterative algorithm is characterized by being applied to a diffraction enhanced imaging system, wherein the diffraction enhanced imaging system takes the propagation direction of X-rays as the Z axial direction, and is sequentially provided with an X-ray source (1), a monochromatic crystal (2), an analysis crystal (3) and a detector (4) along the Z axial direction; the X-ray diffraction enhanced imaging method comprises the following steps:
step 1, setting relevant positions of all devices to meet the following requirements: d is more than 01＜d3＜d4Wherein d is1Is the relative distance between the monochromatic crystal (2) and the X-ray source (1) along the Z-axis, d3The relative distance between the analysis crystal (3) and the X-ray source (1) along the Z-axis, d4The relative distance between the detector (4) and the X-ray source (1) along the Z-axis direction;
step 2, obtaining background projection data:
step 2.1, taking the normal of the diffraction surface of the analysis crystal (3) as a rotating shaft;
step 2.2, setting a first angular position of the analysis crystal (3) along the rotating shaft as theta1(ii) a After the X-ray source (1) is started, first background projection data I are acquired by the detector (4) according to an exposure time length t11；
Step 2.3, setting a second angular position of the analysis crystal (3) along the rotating shaft as theta2；
Acquiring second background projection data I with the detector (4) for an exposure time period t22；
Step 2.4, setting a third angular position of the analysis crystal (3) along the rotating shaft as theta3；
Acquiring third background projection data I with the detector (4) for an exposure time period t33Thereafter, the X-ray source (1) is switched off;
step 3, acquiring projection data of the imaged object:
3.1, placing the imaged object (5) between the monochromatic crystal (2) and the analysis crystal (3) along the Z-axis direction; and the relative distance between the imaged object (5) and the X-ray source (1) along the Z-axis direction is recorded as d2And satisfy d1＜d2＜d3；
Step 3.2, setting a first angular position of the analysis crystal (3) along the rotating shaft as theta1；
Acquiring first projection data l 'of the imaged object (5) according to the exposure time duration t1 by utilizing the detector (4) after the X-ray source (1) is started'1；
Step 3.3, setting the second angular position of the analysis crystal (3) along the rotating shaft as theta2(ii) a Acquiring second projection data l 'of the imaged object (5) with the detector (4) according to an exposure time period t 2'2；
Step 3.4, setting the third angular position of the analysis crystal (3) along the rotating shaft as theta3(ii) a Acquiring third projection data l 'of the imaged object (5) with the detector (4) according to an exposure time period t 3'3Then, the valve is closedAn X-ray source (1);
and 4, extracting an absorption signal T of the imaged object (5) based on an iterative algorithm:
step 4.1, defining the iteration number as k, and initializing k to be 1;
obtaining an absorption signal T under the kth iteration by using the formula (1)k：
Figure FDA0002475308280000021
Step 4.2, extracting an absorption signal T of the imaged object (5) under the k +1 th iteration by using the formula (2)k+1：
Figure FDA0002475308280000022
In the formula (2), the reaction mixture is,
Figure FDA0002475308280000023
represents the offset correction after the kth iteration and has:
Figure FDA0002475308280000024
in formula (3), c is the bias of the light intensity curve of the diffraction enhanced imaging system, and c is more than 0;
step 4.3, judge | Tk+1-Tk|＜1If yes, the iteration is ended, and the final absorption signal T is obtainedk+1Otherwise, after assigning k +1 to k, returning to the step 4.2; wherein the content of the first and second substances,1is a given threshold value;
step 5, extracting a refraction signal theta of the imaged object (5) based on an iterative algorithmR：
Step 5.1, initializing k to be 1;
obtaining a refraction signal under the k iteration by using the formula (4)
Figure FDA0002475308280000025
Figure FDA0002475308280000026
Step 5.2, extracting a refraction signal of the imaged object (5) under the k +1 th iteration by using the formula (5)
Figure FDA0002475308280000031
Figure FDA0002475308280000032
Step 5.3, judgment
Figure FDA0002475308280000033
Whether the signal is true or not, if so, the iteration is ended to obtain a refraction signal
Figure FDA0002475308280000034
Otherwise, after k +1 is assigned to k, returning to the step 5.2 for execution; wherein the content of the first and second substances,2another given threshold;
step 6, extracting the scattering signal of the imaged object (5) based on an iterative algorithm
Figure FDA0002475308280000035
Step 6.1, initializing k to 1;
obtaining a scattering signal at the kth iteration by using the formula (6)
Figure FDA0002475308280000036
Figure FDA0002475308280000037
Step 6.2, extracting a scattering signal of the imaged object (5) under the k +1 th iteration by using the formula (7)
Figure FDA0002475308280000038
Figure FDA0002475308280000039
Step 6.3, judgment
Figure FDA00024753082800000310
Whether the scattering signal is established or not, if so, the iteration is ended to obtain the scattering signal
Figure FDA00024753082800000311
Otherwise, after k +1 is assigned to k, returning to the step 6.2 for execution; wherein the content of the first and second substances,3a third given threshold;
using the absorption signal T and the refraction signal theta of the imaged object (5)RScattering signal
Figure FDA00024753082800000312
As a result of the diffraction enhanced imaging method.
2. The X-ray diffraction enhanced imaging method as set forth in claim 1, wherein:
first projection data I 'of the imaged object (5)'1Satisfies formula (3.1):
Figure FDA0002475308280000041
in the formula (3.1), σrIs the angular width of the light intensity curve of the diffraction enhanced imaging system;
second projection data l 'of the imaged object (5)'2Satisfies formula (3.2):
Figure FDA0002475308280000042
third projection data I 'of the imaged object (5)'3Satisfy the formula(3.3)：
Figure FDA0002475308280000043
CN202010361992.6A 2020-04-30 2020-04-30 X-ray diffraction enhanced imaging method based on iterative algorithm Active CN111505034B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202010361992.6A CN111505034B (en) 2020-04-30 2020-04-30 X-ray diffraction enhanced imaging method based on iterative algorithm

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202010361992.6A CN111505034B (en) 2020-04-30 2020-04-30 X-ray diffraction enhanced imaging method based on iterative algorithm

Publications (2)

Publication Number Publication Date
CN111505034A true CN111505034A (en) 2020-08-07
CN111505034B CN111505034B (en) 2022-03-29

Family

ID=71867973

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202010361992.6A Active CN111505034B (en) 2020-04-30 2020-04-30 X-ray diffraction enhanced imaging method based on iterative algorithm

Country Status (1)

Country Link
CN (1) CN111505034B (en)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040258202A1 (en) * 2003-06-17 2004-12-23 Wernick Miles N. Imaging method based on attenuation, refraction and ultra-small-angle scattering of x-rays
US20050129169A1 (en) * 2001-11-05 2005-06-16 Donnelly Edwin F. Phase-contrast enhanced computed tomography
CN104132953A (en) * 2014-08-01 2014-11-05 中国科学技术大学 Dual-energy X-ray phase-contrast imaging device and implementation method thereof
CN104569002A (en) * 2013-10-23 2015-04-29 北京纳米维景科技有限公司 X-ray phase contrast imaging system based on photon counting, X-ray phase contrast imaging method realized by the system, and key equipment of X-ray phase contrast imaging method
CN107764846A (en) * 2017-10-20 2018-03-06 重庆大学 A kind of the CL imaging systems and analysis method of orthogonal straight lines scanning
CN108645879A (en) * 2018-05-07 2018-10-12 中国科学院高能物理研究所 A kind of diffraction enhanced imaging method of synchrotron radiation

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050129169A1 (en) * 2001-11-05 2005-06-16 Donnelly Edwin F. Phase-contrast enhanced computed tomography
US20040258202A1 (en) * 2003-06-17 2004-12-23 Wernick Miles N. Imaging method based on attenuation, refraction and ultra-small-angle scattering of x-rays
CN104569002A (en) * 2013-10-23 2015-04-29 北京纳米维景科技有限公司 X-ray phase contrast imaging system based on photon counting, X-ray phase contrast imaging method realized by the system, and key equipment of X-ray phase contrast imaging method
CN104132953A (en) * 2014-08-01 2014-11-05 中国科学技术大学 Dual-energy X-ray phase-contrast imaging device and implementation method thereof
CN107764846A (en) * 2017-10-20 2018-03-06 重庆大学 A kind of the CL imaging systems and analysis method of orthogonal straight lines scanning
CN108645879A (en) * 2018-05-07 2018-10-12 中国科学院高能物理研究所 A kind of diffraction enhanced imaging method of synchrotron radiation

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
JOVAN G. BRANKOV等: "Physical Model of Image Formation in", 《IEEE》 *
ORIOL CAUDEVILLA等: "Machine learning based parametric image estimation", 《IEEE》 *

Also Published As

Publication number Publication date
CN111505034B (en) 2022-03-29

Similar Documents

Publication Publication Date Title
US9795350B2 (en) Material differentiation with phase contrast imaging
Cagnoni et al. A Medium Survey of the Hard X-Ray Sky with the ASCA Gas Imaging Spectrometer: The (2-10 keV) Number Counts Relationship
CN108896584B (en) Single exposure X-ray dark field imaging method based on double-detector grating interferometer
KR101179540B1 (en) Method for analyzing the Internal Density of Material using a X-ray Computerized Tomography
Kaestner et al. Recent developments in neutron imaging with applications for porous media research
CN110133012B (en) Single exposure multimode X-ray imaging method based on three-detector grating interferometer
EP1672361B1 (en) X-ray diffraction microscope and x-ray diffraction measurement method using x-ray diffraction microscope
JP2848751B2 (en) Elemental analysis method
CN113063809B (en) X-ray grating interferometer imaging method based on Hough transform method
McLeod et al. The galaxy UV luminosity function at z≃ 11 from a suite of public JWST ERS, ERO, and Cycle-1 programs
CN111505034B (en) X-ray diffraction enhanced imaging method based on iterative algorithm
CN111795980B (en) X-ray boundary illumination imaging method based on pixel-by-pixel Gaussian function fitting method
Kottler et al. Phase contrast X‐ray imaging of large samples using an incoherent laboratory source
JP2009175065A (en) Simultaneous three-dimensional distribution-visualization observation-measurement method of a plurality of elements by neutron prompt gamma-ray analysis, and device thereof
Gürsoy et al. Depth-resolved Laue microdiffraction with coded apertures
CN111595877B (en) Multi-contrast image extraction method for X-ray diffraction enhanced imaging
KR102229895B1 (en) Radiation camera including a pluraligy of coded apertures and method for analyzing nuclides using the radiation carmera
Takeuchi et al. Differential Phase‐Contrast Scanning X‐Ray Microscope For Observation Of Low‐Z element Specimen
Kaestner et al. Recent developments in neutron imaging with applications for porous media research
McLeod et al. The galaxy UV luminosity function at $\mathbf {z\simeq 11} $ from a suite of public JWST ERS, ERO and Cycle-1 programs
CN111649704A (en) X-ray-based pearl layer thickness measuring device and measuring method
CN113805216B (en) Substance decomposition method for one-time exposure X-ray phase propagation imaging
CN113607761B (en) Novel X-ray multi-mode imaging method based on grating interferometer
Yu et al. Size characterization of x-ray tube source with sphere encoded imaging method
Kochikov et al. A new software for processing the radial symmetric diffractograms

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant