CN101987021A - Scattering correction method of CT system and CT system - Google Patents
Scattering correction method of CT system and CT system Download PDFInfo
- Publication number
- CN101987021A CN101987021A CN2010105741628A CN201010574162A CN101987021A CN 101987021 A CN101987021 A CN 101987021A CN 2010105741628 A CN2010105741628 A CN 2010105741628A CN 201010574162 A CN201010574162 A CN 201010574162A CN 101987021 A CN101987021 A CN 101987021A
- Authority
- CN
- China
- Prior art keywords
- image
- scattering
- scatter
- intensity
- projection
- 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
Links
- 238000012937 correction Methods 0.000 title claims abstract description 164
- 238000000034 method Methods 0.000 title claims abstract description 39
- 238000009826 distribution Methods 0.000 claims abstract description 59
- 238000012545 processing Methods 0.000 claims abstract description 13
- 239000011324 bead Substances 0.000 claims description 41
- 238000004422 calculation algorithm Methods 0.000 claims description 17
- 230000002068 genetic effect Effects 0.000 claims description 13
- 230000001915 proofreading effect Effects 0.000 claims description 11
- 239000012141 concentrate Substances 0.000 claims description 5
- 230000008569 process Effects 0.000 description 10
- 230000000694 effects Effects 0.000 description 8
- 230000008859 change Effects 0.000 description 7
- 238000003384 imaging method Methods 0.000 description 6
- 238000013459 approach Methods 0.000 description 4
- 239000004744 fabric Substances 0.000 description 4
- 230000000007 visual effect Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 229920001617 Vinyon Polymers 0.000 description 2
- 239000011358 absorbing material Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000002591 computed tomography Methods 0.000 description 1
- 238000013170 computed tomography imaging Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 238000003325 tomography Methods 0.000 description 1
Images
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
- A61B6/42—Arrangements for detecting radiation specially adapted for radiation diagnosis
- A61B6/4291—Arrangements for detecting radiation specially adapted for radiation diagnosis the detector being combined with a grid or grating
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
- A61B6/48—Diagnostic techniques
- A61B6/483—Diagnostic techniques involving scattered radiation
Landscapes
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Medical Informatics (AREA)
- Pathology (AREA)
- Heart & Thoracic Surgery (AREA)
- High Energy & Nuclear Physics (AREA)
- Physics & Mathematics (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Optics & Photonics (AREA)
- Veterinary Medicine (AREA)
- Radiology & Medical Imaging (AREA)
- Biomedical Technology (AREA)
- Biophysics (AREA)
- Molecular Biology (AREA)
- Surgery (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Toxicology (AREA)
- Apparatus For Radiation Diagnosis (AREA)
Abstract
A scattering correction method of a CT system includes the following steps: obtaining a light field image; placing a scattering corrector between an object to be scanned and a detector for performing equal-angle cycle scanning to obtain a damped projection image; respectively performing the equal-angle cycle scanning on the object to be scanned and the scattering corrector to obtain a projection image collection and a scattering correction image; generating a scattering strength distribution graph according to the light field image, the scattering corrector image and the damped projection image; and obtaining a corrected projection image collection according to difference between the projection image collection and the scattering strength distribution graph. In the scattering correction method of the CT system and the CT system, influence on the scattering is removed through placing the scattering corrector between the object to be scanned and the detector, so that processing time and processed data quantity are greatly reduced, and efficiency and precision are effectively improved.
Description
[technical field]
The present invention relates to a kind of simulation imaging technology, the scatter correction method and the CT system of especially a kind of CT system.
[background technology]
CT imaging technique (computed tomography, electronic computer x-ray tomography technology) has treatment position is carried out X line perspective, takes the photograph the multi-functional of sheet and volume imaging, using the CT system to carry out in the radioparent imaging process, the X ray that arrives detector comprises two kinds of compositions, i.e. initial ray and scattered ray.Initial ray produces signal and then generates image, and scattered ray produces noise and image artifacts, for example pseudo-shadow of cup-shaped and jail-bar artifacts, thus reduced the contrast of projected image, cause the CT value inaccuracy of rebuilding.Adopt linear array detector in the fan-shaped beam CT system, only be subjected to unidimensional diffuse transmission influence, can not produce a large amount of scattered ray, collimator is installed just can be reached extraordinary scattering inhibition effect, but cone-beam CT system makes that owing to the detector employing is planar array detector scattering is a Two dimensional Distribution, the irradiation of accepting scattered ray is much bigger, therefore must manage to eliminate the influence of scattering.
In cone-beam CT system, because scattering is Two dimensional Distribution, single hardware corrected or software correction method all is difficult to reach ideal effect, therefore the hybrid-correction method that hardware combines with software occurred, and present bearing calibration has following three kinds:
(1) frequency modulating method.Frequency modulating method is that a grid with different penetrance is placed between scanned object and the detector.Point-blank primary photon has different frequency response characteristics with scattered photon for manipulator, be that the direct projection photon is modulated to high-frequency signal, and scattered photon is modulated to low frequency signal, utilizes non-linear frequency domain filter that the scattering composition is separated from the frequency spectrum of projected image again.The method has the simple advantage of scatter correction equipment, but for different scanned objects and different imaging precisions, needs to adjust suitable mesh spacing.
(2) elementary modulator approach.In elementary modulator approach, need to make a correcting sheet.Be evenly to be covered with square protuberance on the aluminium sheet of 2mm at a slice thickness, the protuberance length of side is 2mm, and spacing is 2mm, and thickness is 1mm.Correcting sheet is positioned between radiographic source and the scanned object as modulating coder.The process of elementary modulator approach can be divided into following a few step: the primary ray that is sent by radiographic source is corrected sheet " modulating-coding ", passes scanned object again.On frequency domain, be detected the transmitted ray that device receives and have encoding information, scattered ray is a low-frequency noise, with high pass filter to projection filtering, with the influence of deduction scattering, very high but elementary modulator approach requires in the application process of reality, be not easy to realize.
In addition, gather air projected image and beam attenuation grid projected image after can also setting sweep parameter, object to be detected is carried out circular scanning, gather the projection image set I and the scanned object II of band beam attenuation grid and object to be detected, calculate the projected position at each prill center in the beam attenuation grid, projected image among employing beam attenuation grid bearing calibration calculating and the projection image set I is the scattered field distributed image one to one, projection image set I is deducted projection image set III after corresponding scattered field distributed image obtains scatter correction, reconstruct the sequence section sequence behind the scatter correction by FBP (Filtered Back Projection filters back projection) algorithm thus.In the method, the beam attenuation grid is placed between radiographic source and the scanned object, near scanned object,, cause emergent light spectrum to change because emergent light at first passes the beam attenuation grid.In addition, for same scanned object, scan twice, double sweep time, and the data volume of processing has also increased by one times, and efficient is very low.
[summary of the invention]
Based on this, be necessary to provide a kind of scatter correction method of the CT system that raises the efficiency.
In addition, also be necessary to provide a kind of CT system that raises the efficiency.
The scatter correction method of a kind of CT system may further comprise the steps: obtain bright-field image; Scattering correction device is positioned between scanned object and the detector, carries out equal angles circular scanning and obtain the projected image of decaying; Respectively scanned object and scattering correction device are carried out equal angles circular scanning and obtain projection image set and scatter correction image; Generate scatter intensity distribution figure according to described bright-field image, scatter correction image and decay projected image; Projection image set after difference by described projection image set and scatter intensity distribution figure obtains proofreading and correct.
Preferably, described scattering correction device is to embed bead in thin plate, and the absorptance of described thin plate is less than the absorptance of described bead.
Preferably, described bead is the chessboard distribution in described thin plate.
Preferably, described step according to described bright-field image, scatter correction image and decay projected image generation scatter intensity distribution figure is: the centre coordinate that obtains each projection circle by genetic algorithm from the scatter correction image; From bright-field image, obtain and the corresponding initial ray intensity of described each projection circle, and from the scatter correction image, obtain and corresponding transmitted intensity and the gauged total transmitted intensity that passes behind the scattering correction device of described each projection circle; From the concentrated total transmitted intensity of object that obtains of projected image; By described initial ray intensity, pass the scattering value that transmitted intensity, gauged total transmitted intensity and the total transmitted intensity of object behind the scattering correction device obtain decaying in the projected image and distribute; Described scattering value distributed carry out two-dimensional interpolation and the angle interpolation obtains scatter intensity distribution figure.
Also comprise after the step of the projection image set after preferably, described difference by described projection image set and scatter intensity distribution figure obtains proofreading and correct: the projection image set after the described correction is carried out image reconstruction.
A kind of CT system, at least comprise: scan module, be used to obtain bright-field image, to scanned object and place scattering correction device between described scanned object and the detector to carry out equal angles scanning to obtain the projected image of decaying, and respectively scanned object and scattering correction device are carried out equal angles circular scanning and obtain projection image set and scatter correction image; Processing module is used for generating scatter intensity distribution figure according to described bright-field image, scatter correction image and decay projected image; Correction module, the projection image set after being used for difference by described projection image set and scatter intensity distribution figure and obtaining proofreading and correct.
Preferably, described scattering correction device is to embed bead in thin plate, and the absorptance of described thin plate is less than the absorptance of described bead.
Preferably, described bead is the chessboard distribution in described thin plate.
Preferably, described processing module comprises: the position acquiring unit is used for obtaining the round centre coordinate of each projection by genetic algorithm from the scatter correction image; The intensity acquiring unit, be used for obtaining and the corresponding initial ray intensity of described each projection circle from bright-field image, and from the scatter correction image, obtain and corresponding transmitted intensity and the gauged total transmitted intensity that passes behind the scattering correction device of described each projection circle, concentrate from projected image and obtain the total transmitted intensity of object; Computing unit is used for by described initial ray intensity, passes transmitted intensity, gauged total transmitted intensity and the total transmitted intensity of object behind the scattering correction device obtain the decaying scattering value of projected image and distribute; Interpolating unit is used for two-dimensional interpolation and angle interpolation are carried out in described scattering value distribution, obtains scatter intensity distribution figure.
Preferably, also comprise: rebuild module, be used for the projection image set after the described correction is carried out image reconstruction.In the scatter correction method and CT system of above-mentioned CT system,, reduced the data volume of sweep time and processing widely, improved efficient and precision effectively by scattering correction device being placed the influence of eliminating scattering between scanned object and the detector.
The scatter correction method and the scattering correction device in the CT system of above-mentioned CT system are simple in structure, cheap for manufacturing cost, are easy to realize and be applicable to scanned object qualitative change environment very.
[description of drawings]
Fig. 1 is the scatter correction method of CT system among the embodiment;
Fig. 2 is the sketch map of a scattering correction device among the embodiment;
Fig. 3 is the flow chart that generates scatter intensity distribution figure among the embodiment according to bright-field image, scatter correction image and decay projected image;
Fig. 4 is the sketch map of scanning bright field among the embodiment;
Fig. 5 is the sketch map of placing scanned object among the embodiment and adding scattering correction device;
Fig. 6 is the sketch map that only scans scanned object among the embodiment;
Fig. 7 is the sketch map that only scans scattering correction device among the embodiment;
Fig. 8 is the detailed block diagram of CT system among the embodiment;
Fig. 9 is the sketch map of processing module among the embodiment.
[specific embodiment]
Fig. 1 shows the scatter correction method of CT system among the embodiment, may further comprise the steps:
In step S10, obtain bright-field image.In the present embodiment, do not place any object in the scanning field of view, the scanning bright field obtains bright-field image.Do not place scanned object in the imaging viewing field, and open light source and scan the image that obtains and be this field picture.
In step S20, scattering correction device is positioned between scanned object and the detector, carry out equal angles circular scanning and obtain the projected image of decaying.In the present embodiment, as shown in Figure 2, (scattercorrection device is to embed bead in thin plate SCD) to scattering correction device, and the absorptance of thin plate is less than the absorptance of bead.Bead is chessboard and distributes in thin plate.The big I of scattering correction device is between scanned object and detector, and is easier for making in the actual operation, and the size of scattering correction device and the consistent size of detector can be satisfied the demand, and promptly is preferably in the scope of 50mm*50mm～500mm*500mm.Thickness for scattering correction device must guarantee so just bead can be fixed greater than the little radius of a ball, so the thickness of scattering correction device is preferably in the scope of 1mm～50mm.In specific embodiment, select for use size to be 50mm*50mm, thickness is the scattering correction device of 1mm～5mm.Among another embodiment, bead also can adopt other distribution mode, and its diameter depends on practical situation, and for example, for present industry and Medical CT system, the parameter of bead is: the diameter range value is 0.5mm～20mm; The hole depth value range is 0.25mm～10mm; OC value range is 1mm～40mm.In a preferred embodiment, the diameter range value is 0.5mm～1.5mm; The hole depth value range is 0.25mm～1mm; OC value range is 1mm～4mm.Thin plate is preferably the vinyon plate, but also can adopt the material of other low absorptance, for example hardboard, veneer etc., and bead is preferably prill, but also can be other high absorbing material, for example shot.
Passing scanned object at X ray enters in the process of detector, if ray does not react with scanned object, then this ray can be called initial ray, if reaction has taken place, mainly owing to Compton effect produces, this ray can be called scattered ray when then the X ray energy range was 0.1～1MeV.Therefore, the ray that is absorbed on detector is made up of two parts, be initial ray and scattered ray, for industry CT and Medical CT, energy range is produced by Compton effect mostly at the scattered ray of 0kv～450kv, and energy range also exists scattered ray at the low power range system of 20kv～90kv in the cone-beam CT system, eliminates the influence of scattered ray in scanning process by the effect of scattering correction device.
For the position of scattering correction device, scattering correction device has four positions to place in the visual field: (1) scattering correction device is positioned over the position near light source; (2) scattering correction device is positioned between scanned object and the detector position near scanned object; (3) scattering correction device is positioned between scanned object and the detector position near scanned object; (4) scattering correction device is positioned between scanned object and the detector near position of detector.For position (1) and position (2), along the direction of propagation of ray, before scattering correction device was positioned over scanned object, this moment, ray at first passed scattering correction device, and scatter distributions does not also form; For position (4), because scattering correction device is close to detector, the bead in the scattering correction device can absorb initial ray and scattered ray, thereby can change the intensity distributions of scattering; Has only position (3) after ray passes scanned object, scatter distributions forms, and passes scattering correction device this moment again, absorbs initial ray by bead, promptly do not change the ray of direction as yet, thus in the relevant position on the detector resulting be exactly scattered ray and the decay after initial ray.Hence one can see that, in scanning process, scattering correction device is positioned between scanned object and the detector, and as far as possible near scanned object.
Because the spatial variations of scatter intensity distribution is little, even therefore increase scanning angle at interval, scatter intensity distribution changes still little, only need carry out equal angles circular scanning 60 times after having added scattering correction device, obtains 60 width of cloth images and gets final product.
In step S30, respectively scanned object and scattering correction device are carried out equal angles scanning and obtain projection image set and scatter correction image.In the present embodiment, only in the visual field, place scanned object, scanned object is carried out equal angles circular scanning at interval 360 times, obtain the projection image set, remove scanned object then, only place scattering correction device and scan, obtain the scatter correction image.
In step S40, generate scatter intensity distribution figure according to bright-field image, scatter correction image and decay projected image.In the present embodiment, extraction data from bright-field image, scatter correction image and decay projected image respectively, and generate scatter intensity distribution figure by genetic algorithm and Lambert's law, to be used for correcting orthographic projection image's collection.
In a specific embodiment, as shown in Figure 3, the step that generates scatter intensity distribution figure according to bright-field image, scatter correction image and decay projected image is:
In step S401, from the scatter correction image, obtain the centre coordinate of each projection circle by genetic algorithm.In the present embodiment, by obtaining a series of bead projection circular image in the scatter correction image, thereby obtain the centre coordinate of each projection circle by genetic algorithm, for example, can use the Matlab coding, adopt genetic algorithm, in the projection circle, find a bit and a radius, make each point arrive the distance of this point and the quadratic sum minimum of the difference of radius, can obtain the centre coordinate of each projection circle in the scatter correction image.
In step S402, from bright-field image, obtain and the corresponding initial ray intensity of each projection circle, and from the scatter correction image, obtain and the corresponding transmitted intensity that passes behind the scattering correction device of each projection circle, from the decay projected image, obtain gauged total transmitted intensity.In the present embodiment, as shown in Figure 4, can from bright-field image, measure the initial ray intensity I of the corresponding point of each projection circle centre coordinate respectively
0,, from the scatter correction image, passed the transmitted intensity I behind the scattering correction device accordingly according to the centre coordinate of each projection circle
3, as shown in Figure 5, in the decay projected image, measure gauged total transmitted intensity D
1Gauged total transmitted intensity D
1It is received total transmitted intensity on the detector when placing scattering correction device between scanned object and the detector.
In step S403, from the concentrated total transmitted intensity of object that obtains of projected image.In the present embodiment, as shown in Figure 6, concentrate the total transmitted intensity D of the measured object that obtains at projected image
2Be only to place scanned object, the total transmitted intensity that receives on the detector when scanned object is carried out equal angles interval scan 360 times.
In step S404, by initial ray intensity, pass the scattering value that transmitted intensity, gauged total transmitted intensity and the total transmitted intensity of object behind the scattering correction device obtain decaying in the projected image and distribute.In the present embodiment,, as shown in Figs. 5 to 7, can obtain formula (1), can obtain formula (2) and formula (3), can obtain formula (4) by Fig. 7 by Fig. 5 by Fig. 6 according to Lambert's law:
I
2＝D
1-S……(3)
Wherein, μ
1Be the linear attenuation coefficient of scanned object, μ
2Be the linear attenuation coefficient of bead in the scattering correction device, l
1For passing the path of scanned object, l
2Be the diameter of bead, S is a scattered ray intensity, I
1For passing the transmitted intensity of scanned object, I
2For passing the transmitted intensity of bead.
Bringing formula (1) into (2) gets:
By formula (2)
Bringing formula (2) into formula (5) gets:
Obtain to obtain the scattered ray strength S of each projection circle in the decay projected image by formula (6), and then obtain the scattering value distribution of each bead in all decay projected images.
In step S405, scattering value distributed carry out two-dimensional interpolation and the angle interpolation obtains scatter intensity distribution figure.In the present embodiment, because the scattered ray Strength Space changes slowly, spatial frequency is lower, and each width of cloth image in therefore can distributing to scattering value carries out two-dimensional interpolation, obtains and the identical scatter intensity distribution figure of projected image quantity that decays.Carry out angle interpolation by the point through same location of pixels among the scatter intensity distribution figure behind the two-dimensional interpolation this moment, obtains one group and be total to and the corresponding scatter intensity distribution figure of projection image set.
In step S50, the projection image set after the difference by projection image set and scatter intensity distribution figure obtains proofreading and correct.In the present embodiment, deduct scatter intensity distribution figure successively with the projection image set and just obtained the image after the correction.
In other embodiments, the scatter correction method of above-mentioned CT system has also comprised the step of the projection image set after proofreading and correct being carried out image reconstruction.In the present embodiment, can use BPF algorithm (BackprojectionFiltration, backprojection-filtration type algorithm for reconstructing) and carry out image reconstruction.
In addition, also be necessary to provide a kind of CT system that has used above-mentioned scatter correction method, as shown in Figure 8, this system comprises scan module 10, processing module 20 and correction module 30 at least.
Passing scanned object at X ray enters in the process of detector, if ray does not react with scanned object, then this ray can be called initial ray, if reaction has taken place, mainly owing to Compton effect produces, this ray can be called scattered ray when then the X ray energy range was 0.1～1MeV.Therefore, the ray that is absorbed on detector is made up of two parts, be initial ray and scattered ray, for industry CT and Medical CT, energy range is produced by Compton effect mostly at the scattered ray of 0kv～450kv, and energy range also exists scattered ray at the low power range system of 20kv～90kv in the Cone-Beam CT, eliminates the influence of scattered ray in scanning process by the effect of scattering correction device.
For the position of scattering correction device, scattering correction device has four positions to place in the visual field: (1) scattering correction device is positioned over the position near light source; (2) scattering correction device is positioned between scanned object and the detector position near scanned object; (3) scattering correction device is positioned between scanned object and the detector position near scanned object; (4) scattering correction device is positioned between scanned object and the detector near position of detector.For position (1) and position (2), along the direction of propagation of ray, before scattering correction device was positioned over scanned object, this moment, ray at first passed scattering correction device, and scatter distributions does not also form; For position (4), because scattering correction device is close to detector, the bead in the scattering correction device can absorb initial ray and scattered ray, thereby can change the intensity distributions of scattering; Has only position (3) after ray passes scanned object, scatter distributions forms, and passes scattering correction device this moment again, absorbs initial ray by bead, promptly do not change the ray of direction as yet, thus in the relevant position on the detector resulting be exactly scattered ray and the decay after initial ray.Hence one can see that, in scanning process, scattering correction device is positioned between scanned object and the detector, and as far as possible near scanned object.
Do not place any object in the scanning field of view, scan module 10 scanning bright fields obtain bright-field image.Because the spatial variations of scatter intensity distribution is little, even therefore increase scanning angle at interval, scatter intensity distribution changes still little, added scattering correction device after 10 needs of scan module carry out equal angles circular scanning 60 times, obtain 60 width of cloth images and get final product.
Only place scanned object in the visual field, 10 pairs of scanned objects of scan module carry out equal angles circular scanning at interval 360 times, obtain the projection image set, remove scanned object then, only place scattering correction device and scan, and obtain the scatter correction image.
In a specific embodiment, as shown in Figure 9, processing module 20 comprises position acquiring unit 201, intensity acquiring unit 202, computing unit 203 and interpolating unit 204.
I
2＝D
1-S……(3)
Wherein, μ
1Be the linear attenuation coefficient of scanned object, μ
2Be the linear attenuation coefficient of bead in the scattering correction device, l
1For passing the path of scanned object, l
2Be the diameter of bead, S is a scattered ray intensity, I
1For passing the transmitted intensity of scanned object, I
2For passing the transmitted intensity of bead.
Bringing formula (1) into (2) gets:
By formula (2)
Bringing formula (2) into formula (5) gets:
Obtain to obtain the scattered ray strength S of each projection circle in the decay projected image by formula (6), and then obtain the scattering value distribution of each bead in all decay projected images.
Interpolating unit 204 is used for scattering value distributed and carries out two-dimensional interpolation and angle interpolation, obtains scatter intensity distribution figure.In the present embodiment, because the scattered ray Strength Space changes slowly, spatial frequency is lower, so interpolating unit 204 each width of cloth image in can distributing to scattering value carry out two-dimensional interpolation, obtains and the identical scatter intensity distribution figure of projected image quantity that decays.Carry out angle interpolation by the point through same location of pixels among the scatter intensity distribution figure behind the two-dimensional interpolation this moment, obtains one group and be total to and the corresponding scatter intensity distribution figure of projection image set.
In other embodiments, above-mentioned CT system has also comprised the reconstruction module, and this reconstruction module is used for the projection image set after proofreading and correct is carried out image reconstruction.In the present embodiment, the reconstruction module can be used the BPF algorithm and carry out image reconstruction.
Set forth the scatter correction method of above-mentioned CT system and the application process of CT system below in conjunction with a detailed embodiment.Among this embodiment, can obtain a series of bead projection circular image by the scatter correction image, and adopt genetic algorithm in the projection circle, to find a bit and a radius R, and make each point arrive the distance of this point and the quadratic sum minimum of the difference of R, can obtain each projection circle centre coordinate (u in the scatter correction image
i, v
i).
In bright-field image, can measure (u respectively
i, v
i) the initial ray intensity I of corresponding point
0Value, in the scatter correction image, can measure with (u
i, v
i) corresponding I
3Value.Can calculate by formula (4)
Concentrate measurement (u respectively at decay projected image and projected image
i, v
u) gauged total transmitted intensity D of corresponding point
1With the total transmitted intensity D of object
2, the scattering value that can be drawn in the decay projected image by formula (6) distributes.
Two-dimensional interpolation is carried out in distribution to scattering value, thereby must obtain scatter intensity distribution figure by the angle interpolation.The difference of projection image set and scatter intensity distribution figure is the projection image set after the correction.
For example, suppose to obtain a projection circle centre coordinate for (800,500), in bright-field image, measure I by the scatter correction image calculation
0Be 10000. in the scatter correction image, to obtain I
3Be 5000, then get by formula (4)
In the decay projected image, obtain the D of (800,500) position
1Be 2000, obtain the D of (800,500) position by the projection image set
2Be 3000, then can obtain the scattered ray intensity of (800,500) position by formula (6)
And then obtain scattering value and distribute.
The scatter correction method of above-mentioned CT system and the detector in the CT system adopt planar array detector.
In the scatter correction method and CT system of above-mentioned CT system,, reduced the data volume of sweep time and processing widely, improved efficient and precision effectively by scattering correction device being placed the influence of eliminating scattering between scanned object and the detector.
The scatter correction method and the scattering correction device in the CT system of above-mentioned CT system are simple in structure, cheap for manufacturing cost, are easy to realize and be applicable to scanned object qualitative change environment very.
The above embodiment has only expressed several embodiment of the present invention, and it describes comparatively concrete and detailed, but can not therefore be interpreted as the restriction to claim of the present invention.Should be pointed out that for the person of ordinary skill of the art without departing from the inventive concept of the premise, can also make some distortion and improvement, these all belong to protection scope of the present invention.Therefore, the protection domain of patent of the present invention should be as the criterion with claims.
Claims (10)
1. the scatter correction method of a CT system may further comprise the steps:
Obtain bright-field image;
Scattering correction device is positioned between scanned object and the detector, carries out equal angles circular scanning and obtain the projected image of decaying;
Respectively scanned object and scattering correction device are carried out equal angles circular scanning and obtain projection image set and scatter correction image;
Generate scatter intensity distribution figure according to described bright-field image, scatter correction image and decay projected image;
Projection image set after difference by described projection image set and scatter intensity distribution figure obtains proofreading and correct.
2. the scatter correction method of CT according to claim 1 system is characterized in that described scattering correction device is to embed bead in thin plate, and the absorptance of described thin plate is less than the absorptance of described bead.
3. the scatter correction method of CT according to claim 2 system is characterized in that, described bead is chessboard and distributes in described thin plate.
4. the scatter correction method of CT according to claim 1 system is characterized in that, the described step that generates scatter intensity distribution figure according to described bright-field image, scatter correction image and decay projected image is:
From the scatter correction image, obtain the centre coordinate of each projection circle by genetic algorithm;
From bright-field image, obtain and the corresponding initial ray intensity of described each projection circle, and from the scatter correction image, obtain and corresponding transmitted intensity and the gauged total transmitted intensity that passes behind the scattering correction device of described each projection circle;
From the concentrated total transmitted intensity of object that obtains of projected image;
By described initial ray intensity, pass the scattering value that transmitted intensity, gauged total transmitted intensity and the total transmitted intensity of object behind the scattering correction device obtain decaying in the projected image and distribute;
Described scattering value distributed carry out two-dimensional interpolation and the angle interpolation obtains scatter intensity distribution figure.
5. the scatter correction method of CT according to claim 1 system is characterized in that, also comprises after the step of the projection image set after described difference by described projection image set and scatter intensity distribution figure obtains proofreading and correct:
Projection image set after the described correction is carried out image reconstruction.
6. a CT system is characterized in that, comprises at least:
Scan module, be used to obtain bright-field image, to scanned object and place scattering correction device between described scanned object and the detector to carry out equal angles scanning to obtain the projected image of decaying, and respectively scanned object and scattering correction device are carried out equal angles circular scanning and obtain projection image set and scatter correction image;
Processing module is used for generating scatter intensity distribution figure according to described bright-field image, scatter correction image and decay projected image;
Correction module, the projection image set after being used for difference by described projection image set and scatter intensity distribution figure and obtaining proofreading and correct.
7. CT according to claim 6 system is characterized in that described scattering correction device is to embed bead in thin plate, and the absorptance of described thin plate is less than the absorptance of described bead.
8. CT according to claim 7 system is characterized in that, described bead is chessboard and distributes in described thin plate.
9. CT according to claim 6 system is characterized in that described processing module comprises:
The position acquiring unit is used for obtaining the round centre coordinate of each projection by genetic algorithm from the scatter correction image;
The intensity acquiring unit, be used for obtaining and the corresponding initial ray intensity of described each projection circle from bright-field image, and from the scatter correction image, obtain and corresponding transmitted intensity and the gauged total transmitted intensity that passes behind the scattering correction device of described each projection circle, concentrate from projected image and obtain the total transmitted intensity of object;
Computing unit is used for by described initial ray intensity, passes transmitted intensity, gauged total transmitted intensity and the total transmitted intensity of object behind the scattering correction device obtain the decaying scattering value of projected image and distribute;
Interpolating unit is used for two-dimensional interpolation and angle interpolation are carried out in described scattering value distribution, obtains scatter intensity distribution figure.
10. CT according to claim 6 system is characterized in that, also comprises:
Rebuild module, be used for the projection image set after the described correction is carried out image reconstruction.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201010574162A CN101987021B (en) | 2010-12-06 | 2010-12-06 | Scattering correction method of CT system and CT system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201010574162A CN101987021B (en) | 2010-12-06 | 2010-12-06 | Scattering correction method of CT system and CT system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101987021A true CN101987021A (en) | 2011-03-23 |
| CN101987021B CN101987021B (en) | 2012-10-17 |
Family
ID=43743949
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201010574162A Active CN101987021B (en) | 2010-12-06 | 2010-12-06 | Scattering correction method of CT system and CT system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN101987021B (en) |
Cited By (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103987320A (en) * | 2011-12-12 | 2014-08-13 | 株式会社日立医疗器械 | X-ray ct device and method for correcting scattered x-rays |
| CN104783819A (en) * | 2014-08-27 | 2015-07-22 | 上海联影医疗科技有限公司 | Scatter correction method and device |
| CN106618625A (en) * | 2017-02-08 | 2017-05-10 | 李宝生 | Digital X-ray photography system based on attenuating plate |
| CN107049349A (en) * | 2017-02-06 | 2017-08-18 | 李宝生 | A kind of conical beam CT imaging system based on attenuating plate |
| CN107831463A (en) * | 2016-09-16 | 2018-03-23 | 通用电气公司 | For the PET MRI systems and its method and its surface coils of imaging to image objects |
| CN108013888A (en) * | 2016-11-04 | 2018-05-11 | 西门子保健有限责任公司 | Scattering radiation compensation for medical imaging devices |
| CN108078580A (en) * | 2016-11-21 | 2018-05-29 | 通用电气公司 | Radiological imaging method and its system |
| CN108109183A (en) * | 2016-11-25 | 2018-06-01 | 上海东软医疗科技有限公司 | Beam hardening correction method and device |
| CN108776322A (en) * | 2018-02-26 | 2018-11-09 | 奕瑞新材料科技（太仓）有限公司 | Radiographic source localization method |
| CN108903964A (en) * | 2018-07-09 | 2018-11-30 | 广州华端科技有限公司 | The scatter correction method and device of computed tomography image |
| CN111096761A (en) * | 2018-10-29 | 2020-05-05 | 上海西门子医疗器械有限公司 | Method, device and related equipment for correcting wedge filter scattering |
| US10722205B2 (en) | 2016-11-07 | 2020-07-28 | Shenzhen Institutes Of Advanced Technology | Method and apparatus for optimizing blocking grating for cone beam CT image scattering correction |
| CN111526796A (en) * | 2017-12-29 | 2020-08-11 | 上海联影医疗科技有限公司 | System and method for image scatter correction |
| CN111588997A (en) * | 2020-05-18 | 2020-08-28 | 上海联影医疗科技有限公司 | Method, device and equipment for determining scattering quantity and storage medium |
| CN113237903A (en) * | 2021-06-15 | 2021-08-10 | 清华大学 | Double-layer flat panel detector cone-beam CT-based scattering correction method and device |
| WO2021258785A1 (en) * | 2020-06-22 | 2021-12-30 | Shanghai United Imaging Healthcare Co., Ltd. | Systems and methods for x-ray imaging |
| CN116531015A (en) * | 2023-07-04 | 2023-08-04 | 中国科学院深圳先进技术研究院 | Image reconstruction method, device, electronic equipment and storage medium |
| CN116563413A (en) * | 2023-07-04 | 2023-08-08 | 中国科学院深圳先进技术研究院 | Correction parameter determining method, image reconstructing method, device, equipment and medium |
| WO2023179227A1 (en) * | 2022-03-25 | 2023-09-28 | 康达洲际医疗器械有限公司 | Cone beam computed tomography method and system based on scattering recognition |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2770935B2 (en) * | 1991-03-15 | 1998-07-02 | 株式会社日立メディコ | CT device |
| US20080056549A1 (en) * | 2006-08-29 | 2008-03-06 | Siemens Medical Solutions Usa, Inc. | System and Method for Reducing Circular Artifacts in Tomographic Imaging |
| CN101158653A (en) * | 2007-11-16 | 2008-04-09 | 西北工业大学 | Diffuse transmission measuring and correcting method of cone-beam CT system |
| CN101566590A (en) * | 2009-04-20 | 2009-10-28 | 西北工业大学 | Scattering intensity distribution acquiring method in digital radiograph of planar array detector |
-
2010
- 2010-12-06 CN CN201010574162A patent/CN101987021B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2770935B2 (en) * | 1991-03-15 | 1998-07-02 | 株式会社日立メディコ | CT device |
| US20080056549A1 (en) * | 2006-08-29 | 2008-03-06 | Siemens Medical Solutions Usa, Inc. | System and Method for Reducing Circular Artifacts in Tomographic Imaging |
| CN101158653A (en) * | 2007-11-16 | 2008-04-09 | 西北工业大学 | Diffuse transmission measuring and correcting method of cone-beam CT system |
| CN101566590A (en) * | 2009-04-20 | 2009-10-28 | 西北工业大学 | Scattering intensity distribution acquiring method in digital radiograph of planar array detector |
Cited By (30)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103987320A (en) * | 2011-12-12 | 2014-08-13 | 株式会社日立医疗器械 | X-ray ct device and method for correcting scattered x-rays |
| US9307949B2 (en) | 2011-12-12 | 2016-04-12 | Hitachi Medical Corporation | X-ray CT device and method for correcting scattered X-rays |
| CN103987320B (en) * | 2011-12-12 | 2016-04-13 | 株式会社日立医疗器械 | X-ray ct device and the bearing calibration of scattering x-ray |
| CN104783819A (en) * | 2014-08-27 | 2015-07-22 | 上海联影医疗科技有限公司 | Scatter correction method and device |
| CN107831463A (en) * | 2016-09-16 | 2018-03-23 | 通用电气公司 | For the PET MRI systems and its method and its surface coils of imaging to image objects |
| CN108013888A (en) * | 2016-11-04 | 2018-05-11 | 西门子保健有限责任公司 | Scattering radiation compensation for medical imaging devices |
| US11134904B2 (en) | 2016-11-04 | 2021-10-05 | Siemens Healthcare Gmbh | Scattered radiation compensation for a medical imaging appliance |
| US10722205B2 (en) | 2016-11-07 | 2020-07-28 | Shenzhen Institutes Of Advanced Technology | Method and apparatus for optimizing blocking grating for cone beam CT image scattering correction |
| CN108078580A (en) * | 2016-11-21 | 2018-05-29 | 通用电气公司 | Radiological imaging method and its system |
| CN108078580B (en) * | 2016-11-21 | 2021-06-18 | 通用电气公司 | Radiation imaging method and system thereof |
| CN108109183A (en) * | 2016-11-25 | 2018-06-01 | 上海东软医疗科技有限公司 | Beam hardening correction method and device |
| CN107049349A (en) * | 2017-02-06 | 2017-08-18 | 李宝生 | A kind of conical beam CT imaging system based on attenuating plate |
| CN106618625A (en) * | 2017-02-08 | 2017-05-10 | 李宝生 | Digital X-ray photography system based on attenuating plate |
| CN111526796A (en) * | 2017-12-29 | 2020-08-11 | 上海联影医疗科技有限公司 | System and method for image scatter correction |
| CN111526796B (en) * | 2017-12-29 | 2023-08-25 | 上海联影医疗科技股份有限公司 | System and method for image scatter correction |
| CN108776322B (en) * | 2018-02-26 | 2020-10-16 | 张岚 | Ray source positioning method |
| CN108776322A (en) * | 2018-02-26 | 2018-11-09 | 奕瑞新材料科技（太仓）有限公司 | Radiographic source localization method |
| CN108903964A (en) * | 2018-07-09 | 2018-11-30 | 广州华端科技有限公司 | The scatter correction method and device of computed tomography image |
| CN111096761A (en) * | 2018-10-29 | 2020-05-05 | 上海西门子医疗器械有限公司 | Method, device and related equipment for correcting wedge filter scattering |
| CN111096761B (en) * | 2018-10-29 | 2024-03-08 | 上海西门子医疗器械有限公司 | Method, device and related equipment for correcting scattering of wedge-shaped filter |
| CN111588997A (en) * | 2020-05-18 | 2020-08-28 | 上海联影医疗科技有限公司 | Method, device and equipment for determining scattering quantity and storage medium |
| CN111588997B (en) * | 2020-05-18 | 2022-07-12 | 上海联影医疗科技股份有限公司 | Method, device and equipment for determining scattering quantity and storage medium |
| WO2021258785A1 (en) * | 2020-06-22 | 2021-12-30 | Shanghai United Imaging Healthcare Co., Ltd. | Systems and methods for x-ray imaging |
| CN113237903A (en) * | 2021-06-15 | 2021-08-10 | 清华大学 | Double-layer flat panel detector cone-beam CT-based scattering correction method and device |
| CN113237903B (en) * | 2021-06-15 | 2022-06-10 | 清华大学 | Double-layer flat panel detector cone-beam CT-based scattering correction method and device |
| WO2023179227A1 (en) * | 2022-03-25 | 2023-09-28 | 康达洲际医疗器械有限公司 | Cone beam computed tomography method and system based on scattering recognition |
| CN116563413A (en) * | 2023-07-04 | 2023-08-08 | 中国科学院深圳先进技术研究院 | Correction parameter determining method, image reconstructing method, device, equipment and medium |
| CN116531015A (en) * | 2023-07-04 | 2023-08-04 | 中国科学院深圳先进技术研究院 | Image reconstruction method, device, electronic equipment and storage medium |
| CN116531015B (en) * | 2023-07-04 | 2023-10-03 | 中国科学院深圳先进技术研究院 | Image reconstruction method, device, electronic equipment and storage medium |
| CN116563413B (en) * | 2023-07-04 | 2024-04-09 | 中国科学院深圳先进技术研究院 | Correction parameter determining method, image reconstructing method, device, equipment and medium |
Also Published As
| Publication number | Publication date |
|---|---|
| CN101987021B (en) | 2012-10-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101987021B (en) | Scattering correction method of CT system and CT system | |
| CN101158653B (en) | Diffuse transmission measuring and correcting method of cone-beam CT system | |
| Maltz et al. | Algorithm for X-ray scatter, beam-hardening, and beam profile correction in diagnostic (kilovoltage) and treatment (megavoltage) cone beam CT | |
| CN101416073B (en) | Dynamic optimization of the signal-to-noise ratio of dual-energy attenuation data for reconstructing images | |
| CN108109183B (en) | Beam hardening correction method and device | |
| CN102715914B (en) | G-shaped arm X-ray machine, three-dimensional image generating method and device for G-shaped arm X-ray machine | |
| US20130121475A1 (en) | Anti-scatter grid or collimator | |
| EP1151322B1 (en) | X-ray imaging apparatus and method with scatter correction | |
| DE102015226693A1 (en) | CT detection method and CT device | |
| CN100358471C (en) | Radiation computer tomography apparatus and tomography image forming method | |
| Oliveira et al. | Comparison among tomographic reconstruction with limited data | |
| CN104161536A (en) | Cone beam CT scatter correction method and device based on complementary gratings | |
| CN101566590B (en) | Scattering intensity distribution acquiring method in digital radiograph of planar array detector | |
| CN102456227A (en) | Reconstruction method and device for CT (computerized tomography) image | |
| WO2011011014A1 (en) | X-ray scattering imaging | |
| Yu et al. | Local ROI reconstruction via generalized FBP and BPF algorithms along more flexible curves | |
| Berggren et al. | Characterization of photon‐counting multislit breast tomosynthesis | |
| CN103767723A (en) | Cone beam CT three-dimensional digital imaging method based on C-shaped arm | |
| CN103489206A (en) | Hybrid filtering method based on fan-beam X-ray CT filtering back-projection resetting | |
| Stonestrom et al. | Scatter considerations in fan beam computerized tomographic systems | |
| El-Mohri et al. | Optimization of the performance of segmented scintillators for radiotherapy imaging through novel binning techniques | |
| Wei et al. | Evaluation of quantitative, efficient image reconstruction for VersaPET, a compact PET system | |
| Jirasek | Considerations for x-ray CT polymer gel dosimetry | |
| Baer et al. | Scatter correction methods in dimensional CT | |
| McKee et al. | Accurate attenuation correction for a 3D PET system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant |