CN1240948A - Method for obtaining image by tomography system - Google Patents
Method for obtaining image by tomography system Download PDFInfo
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- CN1240948A CN1240948A CN 99104171 CN99104171A CN1240948A CN 1240948 A CN1240948 A CN 1240948A CN 99104171 CN99104171 CN 99104171 CN 99104171 A CN99104171 A CN 99104171A CN 1240948 A CN1240948 A CN 1240948A
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Abstract
The invention provides an image acquiring method for a tomogram photographing system, which can obtain a tomographic image of an object to be measured at the required height by calculation without vertically moving it and irradiating it with additional radiation rays. This image acquiring method comprises the steps of obtaining a virtual transmission image corresponding to a tomographic surface at an arbitrary height above or below the standard tomographic surface by drawing a diagram to obtain a center D of the transmission image, obtained from the diagram, by a formula, and obtaining a new tomographic image with respect to the tomographic surface at the arbitrary height by synthesizing and averaging the transmission images so that the centers and the center D overlap each other.
Description
The present invention relates to a kind of tomography system that is used for Non-Destructive Testing, relate to the method for in predetermined limit height, obtaining each cross-sectional image of object specifically.
Prove that now tomography is very useful in the Non-Destructive Testing field of welding position.For example, on printed circuit board (PCB), be difficult to the naked eye check the state (whether soldered securely fixing) of welding position to determine this element.In this case, can utilize tomography system to obtain the cross-sectional image of this object.
Be used to obtain object to be detected cross-sectional image tomography system as shown in Figure 1.
As shown in Figure 1, tomography system comprises XYZ-platform 10, scanning X-ray tube 20, image amplifier 30, view selector 40 and camera 50.Object to be detected 1 is placed on XYZ one platform 10.Scanning X-ray tube 20 with the X-ray irradiation to the object 1 that is loaded on the XYZ-platform 10.The X-ray that image amplifier 30 will pass object 1 is converted to visual light.View selector 40 is selected the cross-sectional image in the cross section that requires detection from a plurality of cross-sectional images that the imaging plane at image amplifier 30 projects.Camera 50 will become electric signal from the image transitions that view selector 40 receives.
Though it is not shown in the drawings, tomography system can also comprise the drive part that is used for mobile XYZ-platform, be used to control the control section of deflection coil, and the display that is electrically connected with camera 50 by computing machine, wherein deflection coil is used for the X-ray that radiates from scanning X-ray tube 20 is carried out deflection.
The testing process of tomography system is described below.
At first, the object 1 that needs are detected fixedly is loaded on the XYZ-platform 10.Then, move back and forth XYZ-platform 10 up and down, the depth of section that detects up to the needs of object 1 is placed on the focussing plane.
Afterwards, radiate the X-ray, and shine on the object 1 on the XYZ-platform 10 from scanning X-ray tube 20.The x-ray irradiation that radiates from the end of scanning X-ray tube 20 is on object 1, and when scanning X-ray tube 20 concerned with object 1 keeping parallelism, the X-ray was radiated on the object 1 with being rotated.
Being radiated at X-ray on the object 1 passes object 1 and focuses in the imaging plane of image amplifier 30 form with transfer image acquisition.Then, view selector 40 just from these images, select need and the image of selecting is transferred to camera 50.Camera 50 sends to display with image, on display the form of these images with an image is shown.
Below with reference to Fig. 2 the method for the cross-sectional image that obtains object 1 is described in more detail.
Fig. 2 explains the view adopt tomography system as shown in Figure 1 to obtain the ultimate principle of cross-sectional image.Fig. 2 is the sectional view that the central axis C about tomography system of this system intercepts.Although the X-ray is actually at X-beam Plane of rotation (2-1) and go up rotates, and under the description of schematic sectional view Fig. 2, only show two positions of central axis C and X-ray.
When the X-ray when the position RS of X-beam Plane of rotation (2-1) radiates out and shines the object 1 that is positioned on the sectional plane (2-2), go up the formation transfer image acquisition on the perspective imaging plane of image amplifier 30 (2-3), be RS (2-4), its position RS with X-beam Plane of rotation (2-1) becomes the diagonal line relation.With above similar, position-RS from X-beam Plane of rotation (2-1) radiates out when the X-ray, object 1 transfer image acquisition appears on the transmission imaging plane of image amplifier 30 (2-3), promptly-RS (2-5), its position-RS with X-beam Plane of rotation (2-1) becomes the diagonal line relation.
So on the perspective imaging plane, formed about object the image RS (2-4) of the central point (O) of sectional plane (2-2) and-RS (2-5) so that the transfer image acquisition RS (2-4) of central point (O) and-RS (2-5) is overlapped.Composograph RS (2-4) and-RS (2-5) is by average (divided by 2), thereby obtain object in the cross section cross-sectional image of (2-2).
Simultaneously, for obtain similar RS as shown in Figure 2 and-the RS image of 180 degree (180 °) at interval, can obtain more heterogeneous and cross-sectional image by following step, promptly, again image be synthesized with average by obtaining a plurality of transfer image acquisitions from a plurality of angle radiation X-rays.Like this, the cross-sectional image of object 1 on cross section (2-2) then clearly shows, and the cross-sectional image of other plane (being higher or lower than cross section (2-2)) is just erased simultaneously.
Therefore, when obtaining object behind the cross-sectional image in a cross section,, just the another one cross section of object need be adjusted to sectional plane once more, and use the x-ray irradiation object again if the user need obtain the image in different cross section on the object.If the user need detect the welded condition of a plurality of electronic components of the upside that is installed in printed circuit board (PCB) respectively and downside, for example, he at first will be installed in the welding portion of electronic component of a side of printed circuit board (PCB) and adjust to the sectional plane of system, and obtain the cross-sectional image of this welding portion; Afterwards, the user must readjust the sectional plane of system with the welding portion of electronic component that is installed in an other side of printed circuit board (PCB), and obtains its cross-sectional image.As mentioned above, in order to obtain different cross-sectional image with classic method, object must be adjusted to the sectional plane of system repeatedly through moving up or down.This means onerous toil and more normal shooting time.And in order to obtain cross-sectional image from each cross section, the X-ray must shine object repeatedly.
The present invention be directed to that the problems referred to above propose, therefore the method that the purpose of this invention is to provide a kind of cross-sectional image of each cross section that in predetermined altitude range, obtains object to be detected, do not need to shine object repeatedly with the X-ray, do not need to make progress repeatedly, adjust object downwards yet, and only need calculate the cross-sectional image data that before obtain by tomography system.
The object of the present invention is achieved like this, promptly provides a kind of and obtain the method for image by tomography system, comprises the steps:
A) cross section of adjustment object to be detected is so that the cross section is positioned on the focussing plane of tomography system;
B) at least two the position irradiating objects of X-ray on the circumference of scanning X-ray tube that generate from scanning X-ray tube;
C) by synthesizing at least two transfer image acquisitions that on the imaging plane of image amplifier, converge out,, and composograph is averaged, thereby acquisition is with reference to the cross-sectional image of sectional plane so that it is overlapped each other about its central point;
D) by the structure figure line, obtain hypothetical transition image,, obtain the central point D of hypothetical transition image by the structure figure line about upside in the predetermined altitude range of reference sectional plane and following side plane; With
E) by in the central point D of overlapping hypothetical transition image, synthetic hypothetical transition image, and average synthetic hypothetical transition image, thereby obtain object in the cross section on the predetermined altitude the new cross-sectional image on new sectional plane.
Herein, central point D be from center distance R i and apart from dRi with obtain, wherein Ri promptly is the centre distance of the transfer image acquisition corresponding with the reference sectional plane, dRi amplifies with the corresponding distance of the height change of the sectional plane of object, also be that central point D can obtain from formula Ti+dRi, wherein Ri can be obtained by formula-Rs * Hi/Ho, and dRi can be obtained by formula-Rs (Hi+dH)/(Ho-dH)-Ri.
' Rs ' in the above-mentioned formula, ' Ho ', ' Hi ' is the input value of the optical system of tomography system, more specifically say, ' Rs ' is the distance of X-ray irradiation position on X-ray Plane of rotation, ' Ho ' is the distance from X-ray Plane of rotation to sectional plane, and ' Hi ' is the distance from sectional plane to the perspective imaging plane.And ' dH ' is the height from the reference sectional plane to new sectional plane.
The present invention also comprises the following steps, f) adjusts hypothetical transition size of images R
2, its size with the reference cross-sectional image that obtains after step d) is equated.Can pass through formula R herein,
2=R
1* (Ho-dH)/Ho obtains.
Thus, in case obtained the cross-sectional image in the cross section in preset range, then other cross-sectional image in its upper and lower cross section can obtain by calculating, and does not therefore need mobile object, or crosses object with radiation exposure repeatedly.As a result, testing process can be carried out easily at high speed.
With reference to the accompanying drawing description of preferred embodiments, can make above-mentioned purpose of the present invention and advantage more obvious by following.In the accompanying drawing:
Fig. 1 is the skeleton view of traditional tomography system;
Fig. 2 explains the view adopt system as shown in Figure 1 to obtain the ultimate principle of cross-sectional image;
Fig. 3 explains the view that obtains the method for cross-sectional image according to the present invention;
Fig. 4 explains to utilize the method according to this invention to obtain the maximum view of cross-sectional image.
As indicated above, in conventional art,, must obtain the picture centre of the sectional plane of this object in order to obtain the cross-sectional image of object to be detected.Subsequently, obtained two images about picture centre (when the X-ray when radiate two positions of X-ray beam Plane of rotation, above-mentioned situation can appear; But the X-ray also can radiate from the position of different numbers), and these two images are synthesized and average.
The ultimate principle of obtaining cross-sectional image according to the present invention, obtained from as shown in Figure 3 structure figure line object after the hypothetical transition cross-sectional image of a cross section of predetermined altitude at sectional plane, by obtaining the new center D of transfer image acquisition, thereby obtain new cross-sectional image in other cross section of object predetermined altitude from the cross-sectional image of previous acquisition, like this needn't mobile object, also needn't use the x-ray irradiation object again.
Below with reference to Fig. 3 said process is described in more detail.
As shown in Figure 3, the picture centre of sectional plane (2-2) is point ' E ', and this point is ' Ri ' with the distance of the center C of X-beam Plane of rotation (2-1), and wherein sectional plane (2-2) is ' Ho ' with the distance of X-beam Plane of rotation (2-1).Similarly, the image center of the sectional plane B that need obtain is D, and this point is ' Ri+dRi ' with the distance of the center C of X-beam Plane of rotation (2-1), and wherein the distance of sectional plane B and X-beam Plane of rotation (2-1) is ' Ho-dH '.Thus, when the image on the left side of perspective imaging plane (2-3) and the right about the synthetic also mean time of D point (this point be ' Ri+dRi ' with the distance of the center C of X-beam Plane of rotation (2-1)), just obtained the cross-sectional image in another cross section of object.
Describe the method that is used to obtain new image center D below in detail.
In Fig. 3, Ho: Hi=-Rs: Ri (1)
From formula (1), make m=Hi/Ho, because triangle ABO is similar with OCD, formula (1) can be write as following form:
(Ho-dH)∶(Hi+dH)＝-Rs∶(Ri+dRi)。
Rearrange formula about dRi:
dRi＝-Rs(Hi+dH)/(Ho-dH)-Ri，
And with m substitution formula,
dRi＝-Rs[(Hi+dH)/(Ho-dH)-m] (2)
As shown in Figure 3, ' D ' equals Ri+dRi apart from the distance of center C, and therefore ' Ri ' can obtain from formula 1, and when with four value substitution formula cited below (2), just can obtain the value of ' dRi '.
' Rs ' in the above-mentioned formula, ' Ho ', ' Hi ' is the input value of the optical system of tomography system, wherein, ' Rs ' is the distance that goes up X-ray irradiation position at X-ray Plane of rotation (2-1), ' Ho ' is the distance from X-ray Plane of rotation (2-1) to sectional plane (2-2), and ' Hi ' is the distance from sectional plane (2-2) to perspective imaging plane (2-3).' dH ' is the height from reference sectional plane (2-2) to the new sectional plane B of object.In addition, ' Ri ' is to the distance with reference to the picture centre E of the transfer image acquisition of sectional plane (2-2) from X-ray Plane of rotation (2-1) center C, ' dRi ' is the distance from the center E of transfer image acquisition to new center D, and this value is exaggerated about the height of the variation of sectional plane.
In case from above-mentioned formula, obtain the center ' D ' of transfer image acquisition, then, can obtain the new cross-sectional image on the predetermined altitude by the transfer image acquisition on left side and right side is synthetic and average about new images center ' D '.
And, as shown in Figure 3, the image scaled of the image on reference sectional plane (2-2) is (Hi+Ho)/Ho, then projects on the perspective imaging plane (2-3) with following ratio with the image of reference sectional plane (2-2) at a distance of the sectional plane B of the object of ' dH ' simultaneously:
In the image scaled of dH=(Hi+Ho)/(Ho-dH)
Because dH＞0, so the size of projects images (transfer image acquisition) will be greater than the size of the transfer image acquisition of reference sectional plane (2-2).Therefore, by following formula, can make consistent with ratio with reference to the transfer image acquisition of sectional plane (2-2) with the image scaled of the transfer image acquisition of the sectional plane B that leaves this distance with reference to sectional plane (2-2).
R
2＝R
1×(Ho-dH)/Ho (3)
Wherein, the R in the formula (3)
1It is size with reference to the transfer image acquisition of sectional plane (2-2), Ho is that X-ray Plane of rotation (2-1) is to the distance with reference to sectional plane (2-2), dH is new cross section B to the height with reference to sectional plane (2-2), is the cross-sectional image of cross section B and the user need obtain.
By with the image scaled adjustment of the cross-sectional image in new cross section and unified on the image scaled of the cross-sectional image that had before obtained (above-mentioned transfer image acquisition with reference to sectional plane), two different cross sections of object can fully compare.
Simultaneously, said method can not obtain the cross-sectional image in all cross sections of object.In other words, when calculating the cross-sectional image that obtains with reference to the cross section of sectional plane upside and downside by the cross-sectional image data that the reference sectional plane is obtained, exist limit height.
For from formula (2), solving dH,
dH×(-Rs)+Hi(-Rs)＝Ho(Ri+dRi)-dH(Ri+dRi)
dH(-Rs+Ri+dRi)＝Ho(Ri+dRi)-Hi×(-Rs)
dH＝[Ho(Ri+dRi)-Hi×(-Rs)]/(-Rs+Ri+dRi)
With reference to above-mentioned formula and Fig. 4, when ' dH ' is maximal value on the occasion of (+), ' dRi ' be one on the occasion of, corresponding with half of camera view.When ' dH ' was the maximal value of negative value (-), ' dRi ' was a negative value, and be corresponding with half of camera view.By this method, the user can needn't test thus to estimating by the limit that the synthesized reference cross-sectional image obtains each cross-sectional image of object, has avoided error simultaneously.
As mentioned above, being used in according to the present invention obtains the method for object cross-sectional image, after obtaining with reference to the sectional plane image,, can accurately obtain the image in other cross section in the object predetermined altitude limit rapidly by the data of reference sectional plane image are calculated by classic method.Therefore, detected object needn't move and adjust repeatedly, and also irradiating object repeatedly of X-ray.
According to the present invention, after predetermined cross-sectional has obtained with reference to cross-sectional image, needn't mobile object, also needn't use the x-ray irradiation object repeatedly, just can obtain the cross-sectional image in predetermined upside downside limit height.Therefore, testing just becomes simply, and is exposed to may also reduce under the ray.
Although in conjunction with the preferred embodiments the present invention is described in detail, it will be understood by those skilled in the art that under the spirit and scope that do not exceed the claims qualification, can do various modifications to form of the present invention and details.
Claims (2)
1. one kind is obtained the method for image by tomography system, comprises the following steps:
A) cross section of adjustment object to be detected is so that this cross section is positioned on the focussing plane of tomography system;
B) at least two the position irradiating objects of X-ray on the circumference of scanning X-ray tube that generate from scanning X-ray tube;
C) by synthesizing at least two transfer image acquisitions on the imaging plane of image amplifier, assembling out, and it is overlapped each other about its central point, and composograph is averaged, thereby obtain cross-sectional image with reference to sectional plane;
D) by the structure figure line, obtain hypothetical transition image,, obtain the central point D of hypothetical transition image by the structure figure line about upside in the predetermined altitude range of reference sectional plane and following lateral section; With
E) by in the central point D of overlapping hypothetical transition image, synthetic hypothetical transition image, and average synthetic hypothetical transition image, thereby obtain object in a cross section on the predetermined altitude the new cross-sectional image on new sectional plane,
Ri＝-Rs×Hi/Ho (1)
dRi＝-Rs(Hi+dH)/(Ho-dH)-Ri (2)
D＝Ri+dRi (3)
Wherein, Rs is the distance of the X-ray irradiation position on X-ray Plane of rotation, and Ho is the distance from X-ray Plane of rotation to the reference sectional plane, and Hi is the distance from the reference sectional plane to the perspective imaging plane; DH is the height from the reference sectional plane to the new sectional plane of object; Ri is the distance from X-ray Plane of rotation center to the picture centre of the transfer image acquisition of reference sectional plane, and dRi is the distance from the picture centre of transfer image acquisition to the new images center, and this value is exaggerated about the height of the variation of reference sectional plane.
2. the method for claim 1 is characterized in that, also comprises step f), adjusts hypothetical transition size of images R by following formula (4)
2, make its size equate that formula (4) is with the reference cross-sectional image that after step d), obtains
R
2＝R
1×(Ho-dH)/Ho (4)
R wherein
1Be the size with reference to the transfer image acquisition of sectional plane, Ho is that X-ray Plane of rotation arrives the distance with reference to sectional plane, and dH is that new cross section B is to the height with reference to sectional plane.
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| CN 99104171 CN1240948A (en) | 1998-07-03 | 1999-03-22 | Method for obtaining image by tomography system |
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| CN 99104171 CN1240948A (en) | 1998-07-03 | 1999-03-22 | Method for obtaining image by tomography system |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100465629C (en) * | 2000-12-06 | 2009-03-04 | 泰拉丁公司 | Off-center tomosynthesis |
| CN1969761B (en) * | 2005-07-13 | 2010-09-29 | 美国西门子医疗解决公司 | 4-dimensional digital tomosynthesis and its applications in radiation therapy |
| CN101686817B (en) * | 2007-06-29 | 2011-06-15 | 株式会社岛津制作所 | Radiation imaging apparatus |
| CN1854723B (en) * | 2005-04-29 | 2011-07-13 | 依科视朗国际射线有限公司 | Method for automatic defect recognition in testpieces by means of an X-ray examination unit |
| CN108387524A (en) * | 2018-01-22 | 2018-08-10 | 青岛理工大学 | A kind of heterogeneous material serial section image acquisition methods |
-
1999
- 1999-03-22 CN CN 99104171 patent/CN1240948A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100465629C (en) * | 2000-12-06 | 2009-03-04 | 泰拉丁公司 | Off-center tomosynthesis |
| CN1854723B (en) * | 2005-04-29 | 2011-07-13 | 依科视朗国际射线有限公司 | Method for automatic defect recognition in testpieces by means of an X-ray examination unit |
| CN1969761B (en) * | 2005-07-13 | 2010-09-29 | 美国西门子医疗解决公司 | 4-dimensional digital tomosynthesis and its applications in radiation therapy |
| CN101686817B (en) * | 2007-06-29 | 2011-06-15 | 株式会社岛津制作所 | Radiation imaging apparatus |
| CN108387524A (en) * | 2018-01-22 | 2018-08-10 | 青岛理工大学 | A kind of heterogeneous material serial section image acquisition methods |
| CN108387524B (en) * | 2018-01-22 | 2020-06-05 | 青岛理工大学 | Method for acquiring continuous section images of multiphase material |
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