CN102426376B - Monitoring and correction method of flat panel detector - Google Patents
Monitoring and correction method of flat panel detector Download PDFInfo
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- CN102426376B CN102426376B CN 201110230491 CN201110230491A CN102426376B CN 102426376 B CN102426376 B CN 102426376B CN 201110230491 CN201110230491 CN 201110230491 CN 201110230491 A CN201110230491 A CN 201110230491A CN 102426376 B CN102426376 B CN 102426376B
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Abstract
本发明公开了一种平板探测器的监控与校正方法，在平板探测器射线接收窗一侧安装一金属条，获取暗场图像和坏像素模板图像，采集多幅空白照射图像，合成一幅后减去暗场图像，得到图像S′(x，y)；照射被检测物体得到图像S0(x，y)；进行暗场校正得到图像S1(x，y)；进行平板探测器暗场图像波动监控的判定计算和校正计算，得到图像S2(x，y)；得到图像S3(x，y)＝ln[S′(x，y)/S2(x，y)]；利用坏像素模板图像，对图像S3(x，y)进行坏像素校正。本发明提供的方法可以监控平板探测器全使用周期中的暗场图像波动并进行简便校正，无需生成增益校正图像，并去除了常规的增益校正步骤，可直接计算得到用于后续应用的数字图像。
The invention discloses a monitoring and calibration method of a flat panel detector. A metal strip is installed on one side of the ray receiving window of the flat panel detector to obtain dark field images and bad pixel template images, collect multiple blank irradiation images, and synthesize one Subtract the dark field image to obtain the image S'(x, y); irradiate the detected object to obtain the image S 0 (x, y); perform dark field correction to obtain the image S 1 (x, y); perform flat panel dark field Judgment calculation and correction calculation of image fluctuation monitoring to obtain image S 2 (x, y); obtain image S 3 (x, y)=ln[S′(x, y)/S 2 (x, y)]; use The bad pixel template image is used to perform bad pixel correction on the image S 3 (x, y). The method provided by the present invention can monitor the fluctuation of the dark field image in the whole service cycle of the flat panel detector and perform simple correction without generating a gain correction image, and removes the conventional gain correction step, and can directly calculate and obtain a digital image for subsequent applications .
Description
Technical field
The invention belongs to the ray digital imaging field, relate to a kind of monitoring and bearing calibration.
Background technology
Flat panel detector is a kind of ray digitalized image equipment of high complexity, can be used for substituting the radial imaging of conventional film, also can be used as the image-forming block of cone-beam CT system.Due to the restriction of architectural feature and manufacturing process, there is multiple flaw in the original output image of flat panel detector, directly affect its image quality, therefore usually need to carry out necessary correction to flat panel detector.
The unfavorable factor of the flat panel detector of paying close attention at present mainly contains 3: have darkfield image, gain coefficient is inconsistent and have bad pixel, corresponding bearing calibration is respectively details in a play not acted out on stage, but told through dialogues correction, gain calibration and bad pixel correction.The output valve of flat panel detector when darkfield image refers to there is no radiation exposure, darkfield image will be added to when opening radiographic source in projected image, and can be along with the variation of transmitted intensity linear change; The output characteristics parameter of a large amount of pixels of flat panel detector has dispersiveness, thereby produces the inconsistent problem of gain coefficient; Bad pixel is the pixel to the transmitted intensity abnormal reaction, and due to the pixel enormous amount of flat panel detector, manufacturing process is complicated, thereby bad pixel is generally inevitable.The conventional bearing calibration of this 3 aspect is comparative maturity, and is extensively adopted by flat panel detector manufacturer.
When flat panel detector is in good working state, darkfield image can be stablized within the specific limits, and flat panel detector easily is subject to the impact of the many factors such as RADI, humidity corrosion, local pyrexia and component aging in long-term the use, darkfield image fluctuation by a relatively large margin may occur and show as random appearance fluctuation striped, directly causes the image after conventional method is proofreaied and correct unavailable when serious.King's hardship is stupid, the people such as Zhang Dinghua, Huang Kuidong are at " computer-aided design (CAD) and graphics journal " (2009,21 (7): proposed a kind of details in a play not acted out on stage, but told through dialogues fluctuation estimation and bearing calibration based on shadow shield in article 954-961) " bearing calibration of a kind of Cone-Beam CT middle plateform detector output image ", obtained effect preferably, but whether the method does not consider the details in a play not acted out on stage, but told through dialogues fluctuation, and the size of details in a play not acted out on stage, but told through dialogues undulate quantity, the details in a play not acted out on stage, but told through dialogues fluctuation that all images carry out is line by line without exception proofreaied and correct, and processing may cause a large amount of unnecessary calculating like this.
The original output image of flat panel detector generally also will carry out Logarithmic calculation after processing through above-mentioned correction, could for detection of judge, perhaps be used for cone-beam CT reconstruction.
Summary of the invention
There are a large amount of unnecessary calculating and the deficiency that needs to proofread and correct rear Logarithmic calculation in order to overcome prior art, the invention provides a kind of monitoring and bearing calibration of flat panel detector, fluctuate with the darkfield image that reaches in the full life cycle of monitoring flat panel detector, and simplify the purpose of flat panel detector aligning step, minimizing correction calculation amount.
The technical solution adopted for the present invention to solve the technical problems comprises the following steps:
(1) in a side of flat panel detector ray receiver window, a bonding jumper is installed, this bonding jumper is perpendicular to the details in a play not acted out on stage, but told through dialogues striped that fluctuates, and can make some column or row of flat panel detector output image obtain good alpha ray shield;
(2) choose the flat panel detector mode of operation according to the detection demand, obtain darkfield image, obtain bad template pixel image based on the method for Statistical Information Analysis according to the method for several superposed averages of routine;
(3) choose the radiation exposure parameter according to the detection demand, gather the blank irradiation image that several do not contain object to be detected, and each pixel respective pixel gray scale phase adduction of these images is average, obtain the blank irradiation of width image, the method of subtracting each other by the respective pixel gray scale again, deduct darkfield image from the blank irradiation of this width image, obtain image S ' (x, y);
(4) by selected flat panel detector mode of operation and radiation exposure parameter irradiation object to be detected, obtain image S
0(x, y);
The method of (5) subtracting each other by the respective pixel gray scale is from image S
0Deduct darkfield image in (x, y), complete details in a play not acted out on stage, but told through dialogues and proofread and correct, obtain image S
1(x, y);
(6) carry out judgement calculating and the correction calculation of flat panel detector darkfield image fluctuation monitoring, obtain image S
2(x, y); Judgement calculating and the correction calculation step of described flat panel detector darkfield image fluctuation monitoring are as follows:
A) calculate darkfield image pixel grey scale average P and grey scale variance T;
B) get T '=(1.1～1.3) T, obtain the lower limit E of darkfield image fluctuation
1The upper limit E of=P-T ' and darkfield image fluctuation
2=P+T ';
C) with image S
0In (x, y), the N of shielding row or N are capable, adopt the method for pressing row pixel grey scale progressive mean or pressing row pixel grey scale progressive mean, on average become 1 row or 1 row, are designated as
D) search
The maximal value of middle pixel grey scale
And minimum value
E) judgement: if
And
Think image S
0(x, y) is stable, need not to carry out the details in a play not acted out on stage, but told through dialogues fluctuation and proofreaies and correct; Otherwise image S
0There are the details in a play not acted out on stage, but told through dialogues unusual fluctuations in (x, y), and this moment is right
In pixel grey scale judge one by one, if i pixel grey scale
Exceed the upper limit or the lower limit of darkfield image fluctuation, establish its details in a play not acted out on stage, but told through dialogues undulate quantity
With S
1In (x, y), all pixel grey scales of the capable or i of i row all deduct
(7) press S
3(x, y)=ln[S ' (x, y)/S
2(x, y)] calculate, obtain image S
3(x, y);
(8) utilize bad template pixel image, the method for the average or interpolation of neighborhood normal pixel routinely is to image S
3(x, y) carry out bad pixel correction.
The invention has the beneficial effects as follows: the darkfield image that method provided by the invention can be monitored in the full life cycle of flat panel detector fluctuates and carries out easy correction, need not to generate gain correction image, and removed conventional gain calibration step, can directly calculate the digital picture for subsequent applications.With respect to the flat panel detector bearing calibration of routine, the invention provides a kind of more reliable and easy disposal route.
The present invention is further described below in conjunction with drawings and Examples.
Description of drawings
Fig. 1 is flat panel detector monitoring of the present invention and correcting process;
Fig. 2 is for testing the image same position gray scale comparison diagram after aluminum component adopts the inventive method and classic method correction.
Embodiment
One aluminum component is carried out X ray flat panel detector digital imagery, and x-ray source is the Y.TU450-D02 of YXLON, and flat panel detector is the PaxScan2520 of Varian, uses the inventive method and carries out monitoring and the correction of flat panel detector, carries out following steps:
(1) at the downside of flat panel detector ray receiver window, the thick leads of one 5mm is installed, this leads is perpendicular to the details in a play not acted out on stage, but told through dialogues striped that fluctuates, and can make 20 row (output image of this model flat panel detector has been made the ranks transposition with respect to its ray receiver window) of flat panel detector output image obtain good alpha ray shield;
(2) choosing the flat panel detector mode of operation according to the detection demand is the full resolution low noise, obtains darkfield image, obtains bad template pixel image based on the method for Statistical Information Analysis according to the method for several superposed averages of routine;
(3) choosing the radiation exposure parameter according to the detection demand is 170kV and 1.0mA, gather the blank irradiation image that 8 width do not contain object to be detected, and each pixel respective pixel gray scale phase adduction of these images is average, obtain the blank irradiation of width image, the method of subtracting each other by the respective pixel gray scale again, deduct darkfield image from the blank irradiation of this width image, obtain image S ' (x, y);
(4) by selected flat panel detector mode of operation and radiation exposure parameter irradiation object to be detected, obtain image S
0(x, y);
The method of (5) subtracting each other by the respective pixel gray scale is from image S
0Deduct darkfield image in (x, y), complete details in a play not acted out on stage, but told through dialogues and proofread and correct, obtain image S
1(x, y);
(6) carry out judgement calculating and the correction calculation of flat panel detector darkfield image fluctuation monitoring, obtain image S
2(x, y);
Judgement calculating and the correction calculation step of described flat panel detector darkfield image fluctuation monitoring are as follows:
A) calculate darkfield image pixel grey scale average P and grey scale variance T;
B) get T '=1.15T, obtain the lower limit E of darkfield image fluctuation
1The upper limit E of=P-T ' and darkfield image fluctuation
2=P+T ';
C) with image S
020 of shielding row in (x, y) adopt the method by row pixel grey scale progressive mean, on average become 1 row, are designated as
D) search
The maximal value of middle pixel grey scale
And minimum value
E) judgement: if
And
Think image S
0(x, y) is stable, need not to carry out the details in a play not acted out on stage, but told through dialogues fluctuation and proofreaies and correct; Otherwise image S
0There are the details in a play not acted out on stage, but told through dialogues unusual fluctuations in (x, y), and this moment is right
In pixel grey scale judge one by one, if i pixel grey scale
Exceed the upper limit or the lower limit of darkfield image fluctuation, establish its details in a play not acted out on stage, but told through dialogues undulate quantity
With S
1In (x, y), all pixel grey scales of the capable or i of i row all deduct
(7) press S
3(x, y)=ln[S ' (x, y)/S
2(x, y)] calculate, obtain image S
3(x, y);
(8) utilize bad template pixel image, the method for the average or interpolation of neighborhood normal pixel routinely is to image S
3(x, y) carry out bad pixel correction.
The experiment aluminum component that provides from Fig. 2 adopts the image same position gray scale after the inventive method and classic method are proofreaied and correct relatively can find out, the method that the present invention proposes is in the situation that possess flat panel detector details in a play not acted out on stage, but told through dialogues monitoring and omit gain calibration, the flat panel detector output image has been corrected to the level suitable with classic method, has shown that the inventive method is a kind of more reliable and easy disposal route.
Claims (1)
1. the monitoring of a flat panel detector and bearing calibration is characterized in that comprising the steps:
(1) in a side of flat panel detector ray receiver window, a bonding jumper is installed, this bonding jumper is perpendicular to the details in a play not acted out on stage, but told through dialogues striped that fluctuates, and can make some column or row of flat panel detector output image obtain good alpha ray shield;
(2) choose the flat panel detector mode of operation according to the detection demand, obtain darkfield image according to the method for several superposed averages, according to obtain bad template pixel image based on the method for Statistical Information Analysis;
(3) choose the radiation exposure parameter according to the detection demand, gather the blank irradiation image that several do not contain object to be detected, and each pixel respective pixel gray scale phase adduction of these images is average, obtain the blank irradiation of width image, the method of subtracting each other by the respective pixel gray scale again, deduct darkfield image from the blank irradiation of this width image, obtain image S ' (x, y);
(4) by selected flat panel detector mode of operation and radiation exposure parameter irradiation object to be detected, obtain image S
0(x, y);
The method of (5) subtracting each other by the respective pixel gray scale is from image S
0Deduct darkfield image in (x, y), complete details in a play not acted out on stage, but told through dialogues and proofread and correct, obtain image S
1(x, y);
(6) carry out judgement calculating and the correction calculation of flat panel detector darkfield image fluctuation monitoring, obtain image S
2(x, y); Judgement calculating and the correction calculation step of described flat panel detector darkfield image fluctuation monitoring are as follows:
A) calculate darkfield image pixel grey scale average P and grey scale variance T;
B) get T '=(1.1～1.3) T, obtain the lower limit E of darkfield image fluctuation
1The upper limit E of=P-T ' and darkfield image fluctuation
2=P+T ';
C) with image S
0In (x, y), the N of shielding row or N are capable, adopt the method for pressing row pixel grey scale progressive mean or pressing row pixel grey scale progressive mean, on average become 1 row or 1 row, are designated as
D) search
The maximal value of middle pixel grey scale
And minimum value
E) judgement: if
And
Think image S
0(x, y) is stable, need not to carry out the details in a play not acted out on stage, but told through dialogues fluctuation and proofread and correct, at this moment, image S
2(x, y) equals S
1(x, y); Otherwise image S
0There are the details in a play not acted out on stage, but told through dialogues unusual fluctuations in (x, y), and this moment is right
In pixel grey scale judge one by one, if i pixel grey scale
Exceed the upper limit or the lower limit of darkfield image fluctuation, establish its details in a play not acted out on stage, but told through dialogues undulate quantity
With S
1In (x, y), all pixel grey scales of the capable or i of i row all deduct
Obtain image S
2(x, y);
(7) press S
3(x, y)=ln[S ' (x, y)/S
2(x, y)] calculate, obtain image S
3(x, y);
(8) utilize bad template pixel image, press the method for the average or interpolation of neighborhood normal pixel to image S
3(x, y) carry out bad pixel correction.
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| CN102426376B true CN102426376B (en) | 2013-05-08 |
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| CN105982683B (en) * | 2015-02-15 | 2019-12-31 | 北京纳米维景科技有限公司 | X-ray detector comprehensive correction method capable of eliminating ray hardening influence simultaneously |
| CN106296595B (en) * | 2015-06-08 | 2019-01-01 | 上海奕瑞光电子科技股份有限公司 | A kind of flat panel detector and the method for reducing flat panel detector image ghost |
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| CN109709597B (en) * | 2018-11-13 | 2023-10-03 | 上海奕瑞光电子科技股份有限公司 | Gain correction method for flat panel detector |
| CN109712084B (en) * | 2018-12-10 | 2021-01-19 | 上海奕瑞光电子科技股份有限公司 | Image restoration method, image restoration system and flat panel detector |
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| US7302039B2 (en) * | 2005-02-24 | 2007-11-27 | Canon Kabushiki Kaisha | Radiography apparatus, radiography system, and control method thereof |
| JP5238175B2 (en) * | 2007-03-23 | 2013-07-17 | 株式会社日立メディコ | X-ray diagnostic imaging equipment |
| CN101126724B (en) * | 2007-09-30 | 2011-01-05 | 西北工业大学 | Cone-beam CT system plate detector image anti-interference calibration method |
| JP2009219691A (en) * | 2008-03-17 | 2009-10-01 | Fujifilm Corp | Radiographing apparatus and image defect discriminating method |
| CN101509879B (en) * | 2009-03-17 | 2011-04-13 | 西北工业大学 | CT rapid batch scanning and correcting method |
| CN101510298B (en) * | 2009-03-17 | 2010-12-29 | 西北工业大学 | Synthesis correction method for CT pseudo-shadow |
| CN101975965B (en) * | 2010-10-27 | 2012-07-25 | 江苏康众数字医疗设备有限公司 | Flat panel detector and temperature calibration method and image correction method thereof |
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