CN111399072A - X-ray projection optimized imaging method and system - Google Patents
X-ray projection optimized imaging method and system Download PDFInfo
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- CN111399072A CN111399072A CN202010211038.9A CN202010211038A CN111399072A CN 111399072 A CN111399072 A CN 111399072A CN 202010211038 A CN202010211038 A CN 202010211038A CN 111399072 A CN111399072 A CN 111399072A
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- 238000003384 imaging method Methods 0.000 title claims description 52
- 238000012937 correction Methods 0.000 claims abstract description 8
- 238000012935 Averaging Methods 0.000 claims abstract description 6
- 238000000034 method Methods 0.000 claims description 17
- 230000001360 synchronised effect Effects 0.000 claims description 6
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- 238000005259 measurement Methods 0.000 description 5
- 230000005855 radiation Effects 0.000 description 4
- 238000005457 optimization Methods 0.000 description 3
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Abstract
A ray source and a detector which are arranged at two sides of a measured object are arranged to carry out micro-motion shooting around the measured object and obtain a plurality of projection images, and then the plurality of projection images are subjected to plane reconstruction and superposition averaging to obtain an optimized projection image with corrected magnification. The invention obtains the projection image with clear boundary and capable of accurately measuring by using the distance from a smaller ray source to a detector and multiple times of projection irradiation and a magnification correction algorithm.
Description
Technical Field
The invention relates to a technology in the field of image processing, in particular to an X-ray projection optimization imaging method and system.
Background
The current X-ray two-dimensional projection imaging is generally a cone beam imaging mode, that is, a point light source emits X-rays to irradiate the surface of a flat panel detector. In cone beam imaging, if the distance from the light source to the detector is fixed, the closer the object is to the detector, the smaller the magnification. Due to the fact that the magnification of different positions is different in object imaging, the magnification of projection images at different positions is different, and accurate measurement cannot be conducted. To solve this problem of inaccurate measurements, it is desirable to use a parallel beam X-ray imaging modality, i.e. a magnification that is constant at any location. However, this type of imaging cannot be realized in practical products, and the existing X-ray devices usually achieve similar magnification uniformity by increasing the distance from the focal point of the radiation source to the detector and placing the object to be imaged close to the detector.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides an X-ray projection optimization imaging method and system, which can obtain a projection image with clear boundary and capable of being accurately measured by using a small distance from a ray source to a detector and multiple times of projection irradiation and a magnification correction algorithm, namely realize the consistency of the magnification at any position.
The invention is realized by the following technical scheme:
the invention relates to an X-ray projection optimization imaging method, which comprises the steps of carrying out micro-motion shooting around a measured object by arranging a ray source and a detector which are positioned at two sides of the measured object, obtaining a plurality of projection images, and then carrying out plane reconstruction and superposition averaging on the plurality of projection images to obtain an optimized projection image with corrected magnification.
The micro-motion shooting is as follows: controlling the ray source and the detector to synchronously move in a small range around the central position of an imaging object, wherein the moving range can be a space angle of-6 degrees; carrying out exposure shooting simultaneously in the motion process; the method specifically comprises the following steps: controlling the radiation source and the detector to synchronously clockwise or anticlockwise rotate in a circular manner within-6 degrees in a plane with a measured object as a circle center, and simultaneously, synchronously rotating or linearly moving the radiation source and the detector in a direction vertical to the plane of the circle center by taking the center of the imaged object of the template as a rotating center, wherein the moving range is matched with the rotating range of the plane of the circle center; and exposure shooting is carried out simultaneously in the process of movement.
The radius between the ray source and the circle center is 400 mm-600 mm.
The radius between the detector and the circle center is 200 mm-300 mm.
The plane reconstruction means that: firstly, a reconstruction plane, namely a plane Si perpendicular to a 90-degree X-ray path is determined, and the process of plane reconstruction is to back-project acquired projection images Pj of different angles to each reconstruction plane Si, namely Si ═ Si + bp (Pj), wherein: BP is a back-projection procedure, i.e. the signals acquired by each pixel of the detector are mapped to corresponding positions of the reconstruction plane Si according to the X-ray propagation path.
In the planar reconstruction, preferably, the filtering process is performed on a plurality of images obtained by the micro-motion shooting before the reconstruction.
The superposition average is as follows: and correspondingly accumulating the obtained reconstructed images on the multiple Si planes according to respective pixels and then carrying out arithmetic average.
Technical effects
The invention integrally solves the problem of inaccurate image measurement caused by different imaging magnifications at different positions of the cone beam; compared with the prior art, the method can obviously reduce the distance from a large ray source to a detector required in the prior scheme, saves equipment space, improves measurement precision, and does not have the problem of conical beam amplification imaging.
Drawings
FIG. 1 is a schematic view of the process of the present invention;
FIG. 2 is a schematic plan reconstruction diagram;
FIG. 3 is a schematic diagram comparing the principle of the embodiment with the prior art;
in the figure: (a) x-ray parallel beam imaging (a), (b) long-distance cone-beam imaging, and (c) short-distance cone-beam imaging;
FIG. 4 is a schematic diagram illustrating the effects of the embodiment;
in the figure: (a) a parallel beam X-ray projection image of a hollow cube; (b) is a short-distance cone-beam imaging result; (c1) for rotation around the object in the horizontal plane (one dimension), the 5 projection data angles are 84 °, 87 °, 90 °, 93 °, and 96 °, respectively; (c2) as a result of the (c1) -based data acquisition, but with high-pass filtering of each projection image followed by back-projection, the sharp edges of the object edges are improved; (d1) in order to rotate around an object on a horizontal plane (one dimension) and translate in a vertical direction (a second dimension) in cooperation with a detector, 5 projection data angles are respectively 84 degrees, 87 degrees, 90 degrees, 93 degrees and 96 degrees, and corresponding detector translation ranges are-3 cm, -1.5cm, 0cm, 1.5cm and 3cm to obtain simulated parallel beam projections;
FIG. 5 is a schematic diagram of an embodiment.
Detailed Description
This embodiment takes X-ray imaging of a hollow cube as an example, and as can be seen from fig. 3, (a) the projected image of the hollow cube is sharp-edged due to parallel beam imaging; in contrast, (c) the front and back faces of the cube are not magnified to the same scale due to the magnification of the cone beam, resulting in blurred edges in the image, making it difficult to measure the size of the cube from plot (c). In all practical cone-beam X-ray imaging, the source of the radiation is usually far from the object, as shown in diagram (b), in order to be able to obtain accurate measurement data. In diagram (b), the distance from the source to the center of the object is 1.6 meters, and the distance from the center of the object to the detector is 0.2 meters; in view (c), the source is 0.6 meters from the center of the object, which is 0.2 meters from the detector.
The method of fig. 3(b) has the significant drawback that the overall X-ray imaging system is bulky.
As shown in fig. 2, the present embodiment includes the following steps:
step 1) carrying out micro-motion shooting around a measured object by controlling a ray source and a detector and obtaining projection data P under each rotation anglei；
Step 2) as shown in fig. 2, the object to be measured is divided into a plurality of imaging planes SiIn order to simulate 90-degree parallel beam imaging, each imaging plane S is different in distance from a ray source and a detector under the 90-degree projection orientationiWith respective corresponding magnification ratios for the projection data PjPerforming back projection to SiAnd (4) a plane.
Step 3) back-projecting the corrected image to an imaging plane SiThe method specifically comprises the following steps: according to any X-ray in the cone beam of FIG. 2 passing through the imaging plane SiEventually reaching the detector Pj,(x,y)The position (x, y), wherein j is the jth projection data, is calculated according to the imaging geometrical relationship under the corresponding deflection projection angle of the micro-motion shooting, and the (x, y) position of the detector is in the imaging plane SiIs (x) ati,yi) Correspondingly, realize the imaging plane SiBack projection of (2):
step 4) mixing allThe image planes being subjected to a superposition averaging to obtain simulated parallel beam projections, i.e.
Wherein N is the number of imaging planes.
As shown in fig. 5, a system for implementing the method includes: synchronous rotation shooting unit, plane reconstruction unit, stack correction unit, wherein: the synchronous rotation shooting unit respectively controls the ray source and the detector to carry out micro-motion shooting around a measured object and obtain a plurality of projection images, the synchronous rotation shooting unit outputs rotation phase information and the projection images to the plane reconstruction unit, the plane reconstruction unit is connected with the rotation shooting unit and transmits projection image information of different positions, the superposition correction unit is connected with the plane reconstruction unit, and data of all imaging planes are superposed and averaged.
As shown in fig. 4, for the simulated parallel beam projection obtained using the above method, it can be seen that the edge blurring effect of the image is greatly improved, but the blurring correction in one direction is due to the other direction. It can be seen from the figure that the edge blurring effect of the image is greatly improved compared to (b) and (c), and the blurring correction effect is good in both directions. FIG. 4(d2) is based on the data acquisition of FIG. 4(d1), but with the sharpness of the object edges improved as a result of high pass filtering each projection image, followed by back projection.
The foregoing embodiments may be modified in many different ways by those skilled in the art without departing from the spirit and scope of the invention, which is defined by the appended claims and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Claims (8)
1. An optimized X-ray projection imaging method is characterized in that after a plurality of projection images are obtained by performing micro-motion shooting around a measured object by arranging a ray source and a detector which are positioned at two sides of the measured object, plane reconstruction and superposition averaging are performed on the plurality of projection images, and the optimized projection images with corrected magnification are obtained.
2. The optimized X-ray projection imaging method as claimed in claim 1, wherein said micro-motion photographing is: controlling the ray source and the detector to synchronously move in a small range around the central position of an imaging object, wherein the moving range can be a space angle of-6 degrees; and exposure shooting is carried out simultaneously in the process of movement.
3. The optimized X-ray projection imaging method as claimed in claim 1, wherein the radius between the source and the center of the circle is 400 mm-600 mm; the radius between the detector and the circle center is 200 mm-300 mm.
4. The optimized X-ray projection imaging method as claimed in claim 1, wherein said planar reconstruction is performed by: firstly, a reconstruction plane, namely a plane Si perpendicular to a 90-degree X-ray path is determined, and the process of plane reconstruction is to back-project acquired projection images Pj of different angles to each reconstruction plane Si, namely Si ═ Si + bp (Pj), wherein: BP is a back-projection procedure, i.e. the signals acquired by each pixel of the detector are mapped to corresponding positions of the reconstruction plane Si according to the X-ray propagation path.
5. The optimized X-ray projection imaging method as claimed in claim 1 or 4, wherein the planar reconstruction is performed by filtering the plurality of images obtained by the micro-motion shooting, preferably before the reconstruction.
6. The X-ray projection optimized imaging method as claimed in claim 1, wherein the superposition averaging is: and correspondingly accumulating the obtained reconstructed images on the multiple Si planes according to respective pixels and then carrying out arithmetic average.
7. The X-ray projection optimized imaging method as claimed in any one of claims 1 to 6, which comprises the following steps:
step 1) carrying out micro-motion shooting around a measured object by controlling a ray source and a detector and obtaining each rotationProjection data P at a turning anglei；
Step 2) dividing the object to be measured into a plurality of imaging planes SiIn order to simulate 90-degree parallel beam imaging, each imaging plane S is different in distance from a ray source and a detector under the 90-degree projection orientationiWith respective corresponding magnification ratios for the projection data PjPerforming back projection to SiA plane;
step 3) back-projecting the corrected image to an imaging plane SiThe method specifically comprises the following steps: according to any X-ray in the cone beam of FIG. 2 passing through the imaging plane SiEventually reaching the detector Pj,(x,y)The position (x, y), wherein j is the jth projection data, is calculated according to the imaging geometrical relationship under the corresponding deflection projection angle of the micro-motion shooting, and the (x, y) position of the detector is in the imaging plane SiIs (x) ati,yi) Correspondingly, realize the imaging plane SiBack projection of (2):
step 4) performing superposition averaging on all imaging planes to obtain simulated parallel beam projection, namely
Wherein N is the number of imaging planes.
8. An X-ray projection optimized imaging system for carrying out the method of any of the preceding claims, comprising: synchronous rotation shooting unit, plane reconstruction unit, stack correction unit, wherein: the synchronous rotation shooting unit respectively controls the ray source and the detector to carry out micro-motion shooting around a measured object and obtain a plurality of projection images, the synchronous rotation shooting unit outputs rotation phase information and the projection images to the plane reconstruction unit, the plane reconstruction unit is connected with the rotation shooting unit and transmits projection image information of different positions, the superposition correction unit is connected with the plane reconstruction unit, and data of all imaging planes are superposed and averaged.
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| CN102150036A (en) * | 2008-09-10 | 2011-08-10 | 欧姆龙株式会社 | X-ray inspection device and method for X-ray inspection |
| CN104274201A (en) * | 2014-10-10 | 2015-01-14 | 深圳先进技术研究院 | Method, system and equipment for tomography of mammary gland and image acquisition and processing method |
| CN107831180A (en) * | 2016-09-14 | 2018-03-23 | 奚岩 | X ray in situ imaging method and system |
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Patent Citations (8)
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| US20090147920A1 (en) * | 2005-09-26 | 2009-06-11 | The Regents Of The University Of California | Isotopic imaging via nuclear resonance fluorescence with laser-based thomson radiation |
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Effective date of registration: 20230427 Address after: Factory Building 2, Science Park, No. 777 Kangyuan Road, Chengyang Street, Xiangcheng District, Suzhou City, Jiangsu Province, 215000 Applicant after: Suzhou Qiying Medical Technology Co.,Ltd. Address before: Room 105, building 3, 1500 Kangwei Road, Pudong New Area, Shanghai, 201315 Applicant before: Shanghai Luying Information Technology Co.,Ltd. |
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