CN103961125A - CT (Computed Tomography) value correcting method for cone-beam CT - Google Patents
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- 210000000988 bone and bone Anatomy 0.000 claims abstract description 58
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- 230000005540 biological transmission Effects 0.000 claims description 25
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- 238000006243 chemical reaction Methods 0.000 claims description 3
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- 210000001519 tissue Anatomy 0.000 description 5
- 208000034189 Sclerosis Diseases 0.000 description 4
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- 238000007689 inspection Methods 0.000 description 1
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Abstract
The invention discloses a CT (Computed Tomography) value correcting method for cone-beam CT. The CT value correcting method comprises the following steps: scanning air, a water phantom and a bone tissue body phantom under different scanning conditions to respectively obtain projection data; reestablishing an image; removing noise and artifacts by adopting a polynomial fitting method based on a template image; selecting a plurality of interested regions and calculating a mean value of an attenuation coefficient and a standard deviation of the attenuation coefficient; obtaining the value range of the attenuation coefficient and taking the attenuation coefficient of maximum occurrence probability; fitting the attenuation coefficients of the air, the water phantom and the bone tissue body phantom under the different scanning conditions with corresponding ideal CT values to obtain respective fitting curves; performing CT scanning and image reestablishment on a scanned material; obtaining a CT value image according to a material attenuation coefficient image and a fitting curve and finishing the CT value correction. According to the CT value correcting method disclosed by the invention, image noise and artifact can be effectively reduced, the reestablished image of single material reaches the uniformity to the great degree, the precision of the attenuation coefficient of the material becomes higher and further high accuracy for the fitting of the curve of the CT value and the material attenuation coefficient is realized.
Description
Technical field
The present invention relates to technical field of medical instruments, be specifically related to a kind of CT value correcting method for Cone-Beam CT.
Background technology
CT examination is being indispensable inspection method aspect formulation operation plan and setting radiological dose, correct CT diagnoses the lesion information that will provide by the CT photo of high-quality just can conclude, and therefore the control of the CT quality of image is just become to the problem of very paying close attention to.Aspect analysis CT image, can effectively understand the change of tissue density by measuring CT value.If CT value is not accurate enough, very easily cause erroneous judgement, cause operative failure.And in radioactivity RT treatment, CT value is the reference that radiological dose is provided as doctor, CT value is larger, and the radiological dose of requirement is just larger, otherwise CT value is less, and the radiological dose of requirement is just less.If CT value is not accurate enough, the accuracy of the radiological dose adopting when having a strong impact on doctor to patient's radiotherapy, and then affect therapeutic outcome.
Therefore, a kind of bearing calibration of the CT value that is applicable to CT image, will bring great convenience for doctor analyzes accurately focus structure and formulates operation plan.
X-ray body layer scanning means is made up of x-ray bulb and detector two large divisions, is arranged on respectively the both sides that are scanned tissue, and direction is relative.Due to the various tissues of human body (comprise normal and abnormal structure) to the absorption of x-ray not etc., so the X ray of same intensity is through remaining X ray inhomogeneous after human body, CT utilizes this characteristic, be scanned after tissue when the x-ray of bulb generation passes, the residual ray that sees through tissue is detected device and receives.The x-ray receiving is converted into the signal of telecommunication by it, then by the series of computation of computer, just can be converted into the CT image that can be understood by doctor changes in microstructure.
The single pass of object refers to that x-ray source and detector rotate a circle and obtains one group of projected image in different angles, in existing Image Reconstruction Technology, the method for normal application filtered back projection reconstructs the faultage image of some width materials, the image pixel representative now reconstructing be the attenuation measurements of material.Using formula (1) can be converted into the attenuation measurements of material CT value or Hounsfield (Hounsfield is called for short Hu), can find out that by formula (1) definition of CT value is the standard attenuation quotient u with water
was benchmark, if the attenuation quotient of certain material is u, the corresponding CT value of voxel of this material is:
For correct understanding inside of human body organizational structure variable density, conventionally specify that the desirable CT value of air is-1000HU, the desirable CT value of water is 0HU, the desirable CT value of compact bone is+1000HU.Can be found out by formula (1), the CT value of arbitrary material should be linear with the X ray attenuation quotient of this material.In existing technology, the linear equation shown in normal employing formula (2) is proofreaied and correct CT value:
Wherein, u
xfor the pad value of certain pixel of the image rebuild.
The method flow of correcting CT value of the prior art as shown in Figure 1, comprises following steps:
Step 1, under various different scanning conditions, scan respectively air, water and body mould, different scanning condition comprises voltage, electric current, scanning bed thickness, die body size etc.Data under different scanning condition are carried out to image reconstruction and obtain respectively air, water, the attenuation quotient of body mould.Obtain desirable CT value under different scanning condition and the matched curve of attenuation quotient according to formula (2), and then solve (the k obtaining under each condition of scanning
i, b
i), wherein i represents a certain condition of scanning.Desirable CT value is according to statutory regulation: the CT value of air is-1000HU, and the CT value of water is 0HU, and the CT value of compact bone is+1000HU.
Step 2, under a certain condition of scanning, obtain the raw projections data of scanning object.
Step 3, original data for projection is carried out to pretreatment, obtain the data for projection after proofreading and correct.
Step 4, carry out image reconstruction for pretreated data, obtain image pixel value, obtain the u of a certain material
x, according to (the k obtaining in step 1
i, b
i) and u
xcarry out computing, obtain the CT value of each pixel in image.
The acquisition methods of Chinese patent [CN101336828A] <CT value file and device > propose a kind of method of CT value being carried out secondary correction on the basis of existing CT value correcting method, as shown in Figure 2, aligning step is as follows:
Step 1, under the different conditions of scanning, scanning at least three kinds of unlike materials die body.
Step 2, adopt the bearing calibration of above-mentioned existing CT value, the actual test CT value of the die body that calculates various unlike materials under different scanning condition, obtains the set of actual test CT value.
Step 3, under various different scanning conditions, set up the corresponding relation of the actual test CT value CT value desirable with it of various material die bodys, this corresponding relation is as obtaining the correction file that is scanned the CT value that object should have under certain condition of scanning.
Step 4, under a certain condition of scanning, obtain the raw projections data of material.
Step 5, original data for projection is carried out to pretreatment, obtain the data for projection after proofreading and correct.
Step 6, carry out image reconstruction for pretreated data, obtain image pixel value, utilize the CT value after existing CT value correcting method is proofreaied and correct for the first time.
Step 7, according to the correction file in step 3, the CT value of obtaining in the 6th step is carried out to second-order correction, obtain more approaching the corrected value of desirable CT value.
By finding out the analysis of above method:
1, in existing CT value correcting method, in step 1, the data under different scanning condition are carried out to the attenuation quotient of image reconstruction acquisition different material, but in the faultage image of the homogeneous substance reconstructing in practical situation, the attenuation quotient of material is also inhomogeneous, for example scan uniform water mould, but the attenuation quotient of the water mould image reconstructing inhomogeneous, conventional method is to choose certain region of water mould image now, the standard attenuation quotient using the meansigma methods in this region as water.But for the CT of low dosage, such as oral cavity CT, the reconstruction image of water mould has very large noise, if simply the meansigma methods of water mould image is had to very large error as the pad value of water.
2, in the acquisition methods of Chinese patent [CN101336828A] <CT value file and device >, need to scan many kinds of substance, and need to know the desirable CT value of every kind of scanning substances.The corresponding relation of setting up actual test CT value CT value desirable with it under various different scanning conditions, needs to set up many bar states curve in practical operation, process is complicated and time-consuming.
Summary of the invention
The deficiency existing for prior art, the invention provides a kind of CT value method for correcting image for Cone-Beam CT.
Technical scheme of the present invention is:
For a CT value method for correcting image for Cone-Beam CT, comprise the steps:
Step 1: set cone-beam CT scan condition, comprise electric current, voltage and bed thickness;
Step 2: scan air, water mould and osseous tissue body mould under different scanning condition, obtain respectively the data for projection of air, water mould and osseous tissue body mould;
Step 3: adopt FDK method respectively the data for projection of air, water mould and osseous tissue body mould to be carried out to image reconstruction, obtain the attenuation coefficient images of air, water mould and osseous tissue body mould, have noise and artifact in this image;
Step 4: adopt the polynomial fitting method based on template image, the attenuation coefficient images of the attenuation coefficient images to water mould and osseous tissue body mould is removed noise and artifact, obtain the attenuation coefficient images of the water mould of removing noise and artifact or the attenuation coefficient images of osseous tissue body mould, concrete steps are as follows:
Step 4.1: adopt K-Means clustering method that the attenuation coefficient images of water mould or osseous tissue body mould is divided into die body part and background parts, background parts pixel value is made as to 0, creates and the die body image size and shape of water mould or the osseous tissue body mould template image that all identical pixel value is 1;
Step 4.2: respectively the die body image of water mould or osseous tissue body mould and corresponding template image are carried out to Radon conversion, obtain heterogeneous x ray data for projection and corresponding transmission of radiation object thickness data;
Step 4.3: utilize multinomial to carry out matching to heterogeneous x ray data for projection and corresponding transmission of radiation object thickness data, obtain the relation between heterogeneous x ray data for projection and corresponding transmission of radiation object thickness data, obtain the matched curve of heterogeneous x ray data for projection and corresponding transmission of radiation object thickness data;
Step 4.4: in the matched curve of heterogeneous x ray data for projection and corresponding transmission of radiation object thickness data, the point that abscissa is zero excessively does tangent line, and this tangent slope is as homogeneous X-ray data for projection;
Step 4.5: according to heterogeneous x ray data for projection, lead to the equivalent transmission of radiation object thickness data while obtaining heterogeneous x ray projection, and then according to these equivalence transmission of radiation object thickness data, obtain equivalent homogeneous X-ray data for projection by the tangent line described in step 4.4;
Step 4.6: equivalent homogeneous X-ray data for projection is carried out to image reconstruction, obtain the attenuation coefficient images of the water mould of removing noise and artifact or the attenuation coefficient images of osseous tissue body mould;
Step 5: removing in noise and pseudo-movie queen's water mode attenuation coefficient image and the attenuation coefficient images of osseous tissue body mould, choose some area-of-interests, area-of-interest is calculated to attenuation quotient average and attenuation quotient standard deviation;
Step 6: calculate attenuation quotient average and attenuation quotient standard deviation and obtain the span of attenuation quotient according to area-of-interest, take out the attenuation quotient of existing maximum probability as the attenuation quotient of the water mould under the current condition of scanning or osseous tissue body mould in this span;
Step 7: air, water mould, the attenuation quotient of osseous tissue body mould under different scanning condition are carried out to matching with corresponding desirable CT value, obtain respectively matched curve;
Step 8: carry out CT scan and obtain the data for projection of this material being scanned material, and this data for projection is carried out to image reconstruction, obtain the attenuation coefficient images of this material under the current condition of scanning;
Step 9: the matched curve that the attenuation coefficient images according to this material under the current condition of scanning and step 7 obtain, obtain the CT value image of this material, complete CT value and proofread and correct.
Beneficial effect:
The technical problem to be solved in the present invention mainly contains: aspect the pretreatment of rebuilding image, adopt sclerosis artifact and noise in the polynomial fitting method correcting image based on template image, obtain material attenuation quotient accurately, and then the accurate relation curve between matching CT value and material attenuation quotient.CT value method for correcting image for Cone-Beam CT of the present invention, based on the bearing calibration of existing CT value, for the material attenuation coefficient images after rebuilding, one is proposed more reasonable, the image processing method that precision is higher, the method can effectively reduce picture noise and artifact, and greatly the reconstruction image that makes one matter of degree reaches homogenization.Make the attenuation quotient precision of material higher, so more accurate in the time of the curve of matching CT value and material attenuation quotient.The polynomial fitting method of employing wherein based on template image can reduce picture noise effectively, overcomes in existing whole body CT correction and needs die body accurately to put the defect in center of rotation.Effectively correcting CT value, to ensure accuracy and the reasonability of CT value, improves referential and the picture quality of CT value.
Brief description of the drawings
Fig. 1 is the method flow diagram of correcting CT value of the prior art;
Fig. 2 is the method flow diagram that CT value is carried out to secondary correction of the prior art;
Fig. 3 is the CT value correcting method flow chart for Cone-Beam CT of the specific embodiment of the present invention;
Fig. 4 is the water mode attenuation coefficient image reconstructing of the specific embodiment of the present invention;
Fig. 5 is the attenuation coefficient images of the removal noise of the specific embodiment of the present invention and the water mould of artifact;
Fig. 6 is the geometrical relationship schematic diagram between die body, detector and radiographic source;
Fig. 7 is the central row Data Comparison curve chart that the attenuation coefficient images of the specific embodiment of the present invention water mould is removed noise and artifact front and back;
Fig. 8 be the specific embodiment of the present invention homogeneous X-ray beam and, relation curve comparison diagram between heterogeneous x ray beam and the penetration thickness corresponding with it;
Fig. 9 is the relation curve comparison diagram between attenuation quotient and the CT value of CT value correcting method of CT value correcting method of the prior art and the specific embodiment of the present invention;
Figure 10 is that the specific embodiment of the present invention adopts the polynomial fitting method based on template image, and the attenuation coefficient images of the attenuation coefficient images to water mould or osseous tissue body mould is removed the flow chart of noise and artifact.
Detailed description of the invention
Below in conjunction with accompanying drawing, specific embodiment of the invention is elaborated.
Present embodiment is that the CT value method for correcting image for Cone-Beam CT is applied to oral cavity Cone-Beam CT, as shown in Figure 3, for the CT value correcting method of Cone-Beam CT, comprises the steps:
Step 1: set cone-beam CT scan condition, comprise electric current, voltage and bed thickness;
The applied oral cavity of present embodiment Cone-Beam CT, the conventional condition of scanning has two groups (1 groups and 2 groups), and 1 group is 1 mA, 55 kV, bed thickness is 0.126 mm, 2 groups is 2 mA, 60 kV, bed thickness is 0.126 mm.
Step 2: scan air, water mould and osseous tissue body mould under different scanning condition, obtain respectively the data for projection of air, water mould and osseous tissue body mould;
Reconstruction matrix 512 × 512, scan vision scope is 65mm, scans respectively air, water mould and osseous tissue body mould.Water mould is inner filling water, diameter 52mm, the cylindrical container of height 85mm.Osseous tissue body mould is at diameter 52mm, in the hydrostatic column of height 85mm, places compact bone tissue.When scanning, respectively water mould and osseous tissue body mould are placed within sweep of the eye, adopt 1 group of condition of scanning die body to be scanned to the data for projection that obtains air, water mould and osseous tissue body mould.
Step 3: respectively the data for projection of air, water mould and osseous tissue body mould is carried out to image reconstruction, obtain the attenuation coefficient images of air, water mould and osseous tissue body mould, have noise and artifact in this image;
Present embodiment adopts FDK method respectively the data for projection of air, water mould and osseous tissue body mould to be carried out to image reconstruction, FDK algorithm is a kind of approximate reconstruction algorithm based on circular orbit scan, by Feldkamp, Davis andKress (1984) proposes.
Due to beam hardening phenomenon, in the attenuation coefficient images reconstructing, beyond the attenuation coefficient images of deacration, all inevitably there will be sclerosis artifact, on image, show as middle gray scale slightly high and spread to surrounding gradually.The generation of " sclerosis " artifact can affect the uniformity of material pad value in image greatly, and the calculating of follow-up pad value is brought to very large error.
As shown in Figure 4, in the water mode attenuation coefficient image reconstructing, contain comparatively significantly picture noise and sclerosis artifact.
Step 4: adopt the polynomial fitting method based on template image, the attenuation coefficient images of the attenuation coefficient images to water mould and osseous tissue body mould is removed noise and artifact, obtains the attenuation coefficient images of the water mould of removing noise and artifact or the attenuation coefficient images of osseous tissue body mould;
Traditional fitting of a polynomial bearing calibration need to be positioned over die body the center of rotation of CT system accurately, could be according to the die body shown in Fig. 6, and detector, the geometrical relationship between radiographic source calculates the corresponding relation between data for projection and object penetration thickness.This kind of method has strict requirement for the placement of die body, and in present embodiment, adopt the polynomial fitting method based on template image, do not need die body accurately to put in the center of rotation of CT system, just can obtain the attenuation coefficient images of the water mould of removing noise and artifact or the attenuation coefficient images of osseous tissue body mould.
Adopt the polynomial fitting method based on template image, the attenuation coefficient images of the attenuation coefficient images to water mould and osseous tissue body mould is removed noise and artifact, and as shown in figure 10, concrete steps are as follows for flow process:
Step 4.1: adopt K-Means clustering method that the attenuation coefficient images of water mould or osseous tissue body mould is divided into die body part and background parts, background parts pixel value is made as to 0, creates and the die body image size and shape of water mould or the osseous tissue body mould template image that all identical pixel value is 1;
Step 4.2: the die body image to water mould or osseous tissue body mould and corresponding template image carry out Radon conversion respectively, obtains heterogeneous x ray data for projection and corresponding transmission of radiation object thickness data;
Step 4.3: utilize multinomial to carry out matching to heterogeneous x ray data for projection and corresponding transmission of radiation object thickness data, obtain the relation between heterogeneous x ray data for projection p (x) and corresponding transmission of radiation object thickness data x, as shown in Equation (3), obtain the matched curve of heterogeneous x ray data for projection and corresponding transmission of radiation object thickness data;
p(x)=a
nx
n+a
n-1x
n-1+…+a
1x（3）
Wherein, a
1... a
n-1, a
nbe multinomial coefficient, n is polynomial order.
Step 4.4: in the matched curve of heterogeneous x ray data for projection and corresponding transmission of radiation object thickness data, the point that abscissa is zero excessively does tangent line, and this tangent line is as the relation curve between homogeneous X-ray data for projection and transmission of radiation object thickness;
Easily knew by the fundamental property of derivative that abscissa was that the tangent slope of zero point is a
1, the relation curve using this tangent line as homogeneous X-ray data for projection and between transmission of radiation object thickness, tangent function as shown in Equation (4):
p′(x)=a
1x（4）
Wherein, p ' was (x) that abscissa is the tangent line of zero point;
Step 4.5: according to heterogeneous x ray data for projection, equivalent transmission of radiation object thickness data while obtaining heterogeneous x ray projection, and then according to these equivalence transmission of radiation object thickness data, obtain equivalent homogeneous X-ray data for projection by the tangent line described in step 4.4;
According to the heterogeneous x ray data for projection formula (3) obtaining, try to achieve equivalent transmission of radiation object thickness data
, then will
substitution formula (4), obtains equivalent monochromatic projection data, wherein
for the inverse function of function (3).
Step 4.6: equivalent homogeneous X-ray data for projection is carried out to image reconstruction, obtain the attenuation coefficient images of the water mould of removing noise and artifact or the attenuation coefficient images of osseous tissue body mould, the attenuation coefficient images of the water mould of removal noise and artifact as shown in Figure 5, noise and artifact are effectively removed, as shown in Figure 7, the uniformity of the pad value of water mould obtains raising clearly to central row Data Comparison curve before and after attenuation coefficient images removal noise and the artifact of water mould.
Step 5: removing in noise and pseudo-movie queen's water mode attenuation coefficient image and the attenuation coefficient images of osseous tissue body mould, choose some area-of-interests, area-of-interest is calculated to attenuation quotient average and attenuation quotient standard deviation;
In air attenuation coefficient image, the attenuation quotient average m of the area-of-interest of choosing
a=0.72, standard deviation S
a=1.6, the attenuation quotient average m of water
b=27.81, standard deviation S
b=2.3, the attenuation quotient average m of osseous tissue body mould
c=105.4, standard deviation S
c=2.1.
Step 6: calculate attenuation quotient average and attenuation quotient standard deviation and obtain the span of attenuation quotient according to area-of-interest, take out the attenuation quotient of existing maximum probability as the attenuation quotient of the water mould under the current condition of scanning or osseous tissue body mould in this span;
In attenuation coefficient images, the average of selected area-of-interest is m
wwith standard deviation be S
w, the span of established standards pad value is [m
w-3S
w, m
w+ 3S
w], in this span, to analyze, the attenuation quotient of selected probability of occurrence maximum is as the attenuation quotient of the water mould under the current condition of scanning or osseous tissue body mould.
The span of setting the pad value of water mould and osseous tissue body mould is respectively [m
b-3S
b, m
b+ 3S
b], [m
c-3S
c, m
c+ 3S
c].In span, analyze, the attenuation quotient of selected probability of occurrence maximum is as the attenuation quotient of this kind of material under this condition of scanning, and wherein the standard attenuation quotient of water is m
nw=26.72, the standard attenuation quotient of osseous tissue body mould is m
b=106.2.
Step 7: air, water mould, the attenuation quotient of osseous tissue body mould under different scanning condition are carried out to matching with corresponding desirable CT value, obtain respectively matched curve;
Attenuation quotient according to the different material obtaining (air, water mould, osseous tissue body mould) under different scanning condition and corresponding desirable CT value, simulate the linear relationship curve of the attenuation quotient of desirable CT value and material according to formula (5), solve (the k obtaining under each group condition of scanning
i, b
i).
Wherein, u
xfor the attenuation quotient of certain pixel of the image rebuild, k
i, b
ifor the parameter of linear equation, i represents a certain condition of scanning.
Simulate the linear relationship curve of the attenuation quotient of desirable CT value and material according to formula (5), solve and obtain (the k before correction under first group of condition of scanning
1c, b
1c)=(35.956 ,-1000), (k after correction
1, b
1)=(37.0971 ,-1000).
Relation curve between attenuation quotient and the CT value of the CT value correcting method of CT value correcting method of the prior art and the specific embodiment of the present invention contrasts as shown in Figure 9.
Step 8: carry out CT scan and obtain the data for projection of this material being scanned material, and this data for projection is carried out to image reconstruction, obtain the attenuation coefficient images of this material under the current condition of scanning;
Step 9: the matched curve that the attenuation coefficient images according to this material under the current condition of scanning and step 7 obtain, obtain the CT value image of this material, complete CT value and proofread and correct.
Application this method is carried out in CT value trimming process, homogeneous X-ray beam and, relation curve between heterogeneous x ray beam and the penetration thickness corresponding with it contrasts as shown in Figure 8.
Claims (2)
1. for a CT value correcting method for Cone-Beam CT, it is characterized in that: comprise the steps:
Step 1: set cone-beam CT scan condition, comprise electric current, voltage and bed thickness;
Step 2: scan air, water mould and osseous tissue body mould under different scanning condition, obtain respectively the data for projection of air, water mould and osseous tissue body mould;
Step 3: respectively the data for projection of air, water mould and osseous tissue body mould is carried out to image reconstruction, obtain the attenuation coefficient images of air, water mould and osseous tissue body mould, have noise and artifact in this image;
Step 4: adopt the polynomial fitting method based on template image, the attenuation coefficient images of the attenuation coefficient images to water mould and osseous tissue body mould is removed noise and artifact, obtain the attenuation coefficient images of the water mould of removing noise and artifact or the attenuation coefficient images of osseous tissue body mould, concrete steps are as follows:
Step 4.1: adopt K-Means clustering method that the attenuation coefficient images of water mould or osseous tissue body mould is divided into die body part and background parts, background parts pixel value is made as to 0, creates and the die body image size and shape of water mould or the osseous tissue body mould template image that all identical pixel value is 1;
Step 4.2: respectively the die body image of water mould or osseous tissue body mould and corresponding template image are carried out to Radon conversion, obtain heterogeneous x ray data for projection and corresponding transmission of radiation object thickness data;
Step 4.3: utilize multinomial to carry out matching to heterogeneous x ray data for projection and corresponding transmission of radiation object thickness data, obtain the relation between heterogeneous x ray data for projection and corresponding transmission of radiation object thickness data, obtain the matched curve of heterogeneous x ray data for projection and corresponding transmission of radiation object thickness data;
Step 4.4: in the matched curve of heterogeneous x ray data for projection and corresponding transmission of radiation object thickness data, the point that abscissa is zero excessively does tangent line, and this tangent line is as the relation curve between homogeneous X-ray data for projection and transmission of radiation object thickness data;
Step 4.5: according to heterogeneous x ray data for projection, equivalent transmission of radiation object thickness data while obtaining heterogeneous x ray projection, and then according to these equivalence transmission of radiation object thickness data, obtain equivalent homogeneous X-ray data for projection by the tangent line described in step 4.4;
Step 4.6: equivalent homogeneous X-ray data for projection is carried out to image reconstruction, obtain the attenuation coefficient images of the water mould of removing noise and artifact or the attenuation coefficient images of osseous tissue body mould;
Step 5: removing in noise and pseudo-movie queen's water mode attenuation coefficient image and the attenuation coefficient images of osseous tissue body mould, choose some area-of-interests, area-of-interest is calculated to attenuation quotient average and attenuation quotient standard deviation;
Step 6: calculate attenuation quotient average and attenuation quotient standard deviation and obtain the span of attenuation quotient according to area-of-interest, take out the attenuation quotient of existing maximum probability as the attenuation quotient of the water mould under the current condition of scanning or osseous tissue body mould in this span;
Step 7: air, water mould, the attenuation quotient of osseous tissue body mould under different scanning condition are carried out to matching with corresponding desirable CT value, obtain respectively matched curve;
Step 8: carry out CT scan and obtain the data for projection of this material being scanned material, and this data for projection is carried out to image reconstruction, obtain the attenuation coefficient images of this material under the current condition of scanning;
Step 9: the matched curve that the attenuation coefficient images according to this material under the current condition of scanning and step 7 obtain, obtain the CT value image of this material, complete CT value and proofread and correct.
2. the CT value correcting method for Cone-Beam CT according to claim 1, is characterized in that: described in step 3, respectively the data for projection of air, water mould and osseous tissue body mould is carried out to image reconstruction, adopt FDK method to carry out.
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| CN105869130A (en) * | 2016-04-20 | 2016-08-17 | 广州华端科技有限公司 | CT system geometric correction effect verification method and device |
| CN105982683A (en) * | 2015-02-15 | 2016-10-05 | 北京纳米维景科技有限公司 | Comprehensive X-ray detector correction method achieving ray hardening influence elimination simultaneously |
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| CN116188326A (en) * | 2023-04-19 | 2023-05-30 | 赛诺威盛科技(北京)股份有限公司 | CT system noise power spectrum correction method |
| 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 |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101336828A (en) * | 2007-07-06 | 2009-01-07 | Ge医疗系统环球技术有限公司 | Acquisition method and device of CT value correction paper |
| JP4540947B2 (en) * | 2003-08-04 | 2010-09-08 | 株式会社日立メディコ | X-ray CT system |
| US20100239146A1 (en) * | 2009-03-18 | 2010-09-23 | Kabushiki Kaisha Toshiba | X-ray computed tomography scanner, data processing device, and data processing method |
| US20110129057A1 (en) * | 2009-11-30 | 2011-06-02 | Toshiba Medical Systems Corporation | Method for determing a correction function for correcting computed tomographic numbers of a small target object in a ct image |
| CN102327126A (en) * | 2011-07-22 | 2012-01-25 | 李宝生 | Method for correcting individual computed tomography (CT) value in cone beam CT image for calculation of radio treatment dose |
| CN102496175A (en) * | 2011-12-22 | 2012-06-13 | 中国科学院高能物理研究所 | Method for creating attenuation image of measured object based on computer tomography CT and apparatus thereof |
-
2013
- 2013-01-31 CN CN201310039298.2A patent/CN103961125B/en not_active Expired - Fee Related
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4540947B2 (en) * | 2003-08-04 | 2010-09-08 | 株式会社日立メディコ | X-ray CT system |
| CN101336828A (en) * | 2007-07-06 | 2009-01-07 | Ge医疗系统环球技术有限公司 | Acquisition method and device of CT value correction paper |
| US20100239146A1 (en) * | 2009-03-18 | 2010-09-23 | Kabushiki Kaisha Toshiba | X-ray computed tomography scanner, data processing device, and data processing method |
| US20110129057A1 (en) * | 2009-11-30 | 2011-06-02 | Toshiba Medical Systems Corporation | Method for determing a correction function for correcting computed tomographic numbers of a small target object in a ct image |
| CN102327126A (en) * | 2011-07-22 | 2012-01-25 | 李宝生 | Method for correcting individual computed tomography (CT) value in cone beam CT image for calculation of radio treatment dose |
| CN102496175A (en) * | 2011-12-22 | 2012-06-13 | 中国科学院高能物理研究所 | Method for creating attenuation image of measured object based on computer tomography CT and apparatus thereof |
Non-Patent Citations (2)
| Title |
|---|
| 兰永树等: "影响CT值测量的因素及对策的探讨", 《实用放射学杂志》 * |
| 祁振宇等: "放射计划CT值的校准检测及其影响因素分析", 《癌症》 * |
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