CN101011261A - Multi-source spiral CT BPF accurate reconstruction system - Google Patents
Multi-source spiral CT BPF accurate reconstruction system Download PDFInfo
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- CN101011261A CN101011261A CN 200710037288 CN200710037288A CN101011261A CN 101011261 A CN101011261 A CN 101011261A CN 200710037288 CN200710037288 CN 200710037288 CN 200710037288 A CN200710037288 A CN 200710037288A CN 101011261 A CN101011261 A CN 101011261A
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Abstract
The invention relates to a multi-source screw CT reverse-projection filter accurate rebuilding system, which comprises a projection collecting processing system, a reverse-projection filter module, a data rearranging module and a display module, wherein, the projection collecting processing system collects the projection data and send it to the reverse-projection filter module which uses the multi-source screw CT reverse-projection filter rebuild algorism to process the projection data to obtain the rebuilt image spanning the screw PI coordinate, to be input into the data rearranging module; the data rearranging module rearranges the rebuilt image into Cartesian coordinate system, to obtain the three-dimension data, to be input into the display module; and the display module reads the three-dimension data to display tomography on the screen while it also can display the image at different sections and gray windows. The invention can realize the accurate reconstruction of 2N+1-source screw taper beam CT without additive radiation amount.
Description
Technical field
What the present invention relates to is a kind of system of technical field of image processing, particularly a kind of multi-source spiral CT BPF accurate reconstruction system.
Background technology
The operation principle of single source helical cone beam CT is such: in scanning process, x-ray source is done rotation continuously around testee, simultaneously, places the examinating couch moving linearly of testee.With the testee is that referential is observed, and the track of x-ray source is a single-screw.Helical cone beam CT is recording projection data quickly, realizes volume reconstruction, has obtained extensive use clinically.Exact reconstruction algorithm [the A.Katsevich of single source helical CT, " Improved exact FBP algorithm for spiral CT " (" improved spiral CT accurate filtering back projection algorithm "), " Advances in Applied Mathematics " (" applied mathematics progress ", 32 volume 681-697 pages or leaves) based on PI line and minimum detection window, the imaging precision height, big and the imaging precision of z axle coverage has nothing to do with pitch, is with a wide range of applications.
But though exact reconstruction algorithm has improved the coverage of z axle, acquisition speed does not increase.The x-ray source rotary speed of present single source conical beam CT is the highest can only to reach 300 milliseconds/circle, still can't satisfy dynamic imaging, especially the needs of cardiac imaging.The effective way that addresses this problem is the number that increases X-ray source, from different direction while recording projection datas, to improve the temporal resolution of imaging.
Find through literature search prior art, Chinese patent application number: 200510103153.X, name are called the patent of " processing system of reconstructing 3 D pyramidal CT image and processing method ", a kind of parallel reconstructing system that comprises many computers has been proposed, though this method can improve reconstruction speed after obtaining data for projection, but, the picking rate of projection is not improved because system still adopts single x-ray source.
Summary of the invention
The objective of the invention is to overcome deficiency of the prior art, a kind of multi-source spiral CT BPF accurate reconstruction system is provided, make it under the condition that does not increase x-ray dose, the 2N+1 that image taking speed is risen to single source situation doubly, thereby improve the temporal resolution of reconstructed image, further improve quality of reconstructed images.
The present invention is achieved by the following technical solutions, the present invention includes four modules: projection acquisition processing module, backprojection-filtration module, data rearrangement module and display module, projection acquisition processing module recording projection data, the data for projection that collects is sent into the backprojection-filtration module; The backprojection-filtration module adopts the multi-source spiral CT BPF accurate reconstruction algorithm, and above-mentioned data for projection is handled, and obtains striding the reconstructed image in the spiral PI coordinate system, and with this reconstructed image input data rearrangement module; The data rearrangement module is reset above-mentioned reconstructed image of striding in the spiral PI coordinate system in the Cartesian coordinates through interpolation of data, obtains the three-dimensional data under the Cartesian coordinate, and with this three-dimensional data input display module; Display module reads the three-dimensional data of rebuilding under the Cartesian coordinate of back, shows faultage image on screen, and can provide image in different cross section and the different gray scale windows according to customer requirements.
Described projection acquisition processing module comprises 2N+1 x-ray source and corresponding 2N+1 minimum detection window, corresponding minimum detection device window of each x-ray source wherein, respectively along 2N+1 bar helical trajectory recording projection data, the data for projection that collects is through carrying out differential to projection angle after the denoising pretreatment, and the data for projection behind the differential is sent into the backprojection-filtration module and rebuild.
Described minimum detection window is meant, a given x-ray source, a last circle spiral that is set out by this x-ray source and next circle the most intermediary two enclose the zone that spirals (or its projection) surround between spiral.
Described backprojection-filtration module is made up of two submodules: back projection's module and Hilbert filtration module, the data for projection of back projection's submodule after to differential carries out integration, the bound of integration is determined by the projection angle of striding two end points of spiral PI line, the result of back projection's submodule output is back projection's data of striding in the spiral PI coordinate system, after these back projection's data are sent into Hilbert filtering submodule, carry out limited Hilbert inverse transformation along striding spiral PI line, according to the reconstruction formula of backprojection-filtration algorithm, what at this moment obtain is the reconstructed image of striding in the spiral PI coordinate system.
The reconstructed image that described data rearrangement module will be striden in the spiral PI coordinate system is reset in the Cartesian coordinates, obtain the three-dimensional data under the Cartesian coordinate, furtherly, it is exactly the coordinate of given Cartesian coordinates mid point, obtain by this point stride spiral PI line, and then obtain the gray value of these corresponding point in striding spiral PI coordinate system.
The described spiral PI coordinate system of striding is a two-dimentional rectangular coordinate system, and an axle is for striding spiral PI line, and another root axle is the angle parameter of striding an end points of spiral PI line, and another end points of striding spiral PI line is a fixed value.
The described spiral PI line of striding is a straightway, its end points is positioned on the helix, another end points is positioned on another helix, represent these two endpoint locations angle parameter difference less than 360 the degree.
The invention has the beneficial effects as follows: multi-source spiral CT BPF accurate reconstruction system is realized the accurate reconstruction of 2N+1 source helical cone beam CT under the prerequisite that does not increase radiation dose, the imaging precision height, and z axle coverage is big.Compare with single source situation, acquisition speed of the present invention has improved 2N+1 doubly, thereby has improved the temporal resolution and the spatial resolution of dynamic object imaging, and cardiac imaging, small animal imaging are had great importance.
Description of drawings
The schematic block diagram of Fig. 1 multi-source spiral CT BPF accurate reconstruction system of the present invention
Fig. 2 three source CT radiographic sources-detector is placed sketch map
The specific embodiment
Below in conjunction with accompanying drawing embodiments of the invention are elaborated: present embodiment has provided detailed embodiment and process being to implement under the prerequisite with the technical solution of the present invention, but protection scope of the present invention is not limited to following embodiment.
As shown in Figure 1, present embodiment comprises projection acquisition processing module, backprojection-filtration module, data rearrangement module and display module, projection acquisition processing module recording projection data, and the data for projection that collects is sent into the backprojection-filtration module; The backprojection-filtration module adopts the multi-source spiral CT BPF accurate reconstruction algorithm, and these data for projection are handled, and obtains striding the reconstructed image in the spiral PI coordinate system, and with this reconstructed image input data rearrangement module; The data rearrangement module is reset the reconstructed image of striding in the spiral PI coordinate system in the Cartesian coordinates through interpolation of data, obtains the three-dimensional data under the Cartesian coordinate, and with this three-dimensional data input display module; Display module reads the three-dimensional data of rebuilding under the Cartesian coordinate of back, shows faultage image on screen.
Present embodiment adopts the scan mode of three source helical cone beam CT, the modes of emplacement of x-ray source and detector as shown in Figure 2, present embodiment is implemented according to following steps:
1, the projection acquisition processing module comprises the x-ray source that three symmetries are placed, each x-ray source offside is placed a flat-panel detector, as shown in Figure 2, the sampling number of flat-panel detector is 512 * 256, and the mouse alive of anaesthetizing is placed on the detection bed of uniform motion, and the cone beam X ray that first x-ray source sends is through collimator, after passing Mus alive, gathered by first detector, x-ray source whenever revolves to turn around gathers 1024 projections, through obtaining primary data for projection D after the denoising pretreatment
1(f, u v), obtain dD after the differential
1(t, u, v)/dt, offer the backprojection-filtration module, the cone beam X ray that second x-ray source sends is through collimator, pass Mus alive after, by second detector collection, x-ray source whenever revolves to turn around gathers 1024 projections, through obtaining primary data for projection D after the denoising pretreatment
2(t, u v), obtain dD after the differential
2(t, u, v)/dt, offer the backprojection-filtration module, the cone beam X ray that the 3rd x-ray source sends is through collimator, pass Mus alive after, by the 3rd detector collection, x-ray source whenever revolves to turn around gathers 1024 projections, through obtaining primary data for projection D after the denoising pretreatment
3(t, u v), obtain dD after the differential
3(t, u, v)/and dt, offer the backprojection-filtration module;
2, the data for projection behind the backprojection-filtration module reception differential adopts three source backprojection-filtration exact reconstruction algorithm that it is rebuild, and the backprojection-filtration module comprises back projection's module and two submodules of limited Hilbert inverse transform module:
A) back projection's module is at first carried out integration respectively to the data for projection behind above-mentioned three groups of differential, and specifically, the data for projection of first x-ray source correspondence is from t
1 MinTo t
2 MaxIntegration obtains striding the D of first of the back projection's data in the spiral PI coordinate system
1 #(x
π, t
1, t
2), described t
1 MinAnd t
2 MaxRepresent the starting point of striding spiral PI line between article one helix and the second helix and the anglec of rotation of terminating point correspondence respectively, the data for projection of second x-ray source correspondence is from t
2 MinTo t
3 MaxIntegration obtains striding the second portion D of the back projection's data in the spiral PI coordinate system
2 #(x
π, t
1, t
2), described t
2 MinAnd t
3 MaxRepresent the starting point of striding spiral PI line between second helix and the 3rd helix and the anglec of rotation of terminating point correspondence respectively, the data for projection of the 3rd x-ray source correspondence is from t
3 MinTo t
1 MaxIntegration obtains striding the third part D of the back projection's data in the spiral PI coordinate system
3 #(x
π, t
1, t
2), described t
3 MinAnd t
1 MaxRepresent the starting point of striding spiral PI line between the 3rd helix and article one helix and the anglec of rotation of terminating point correspondence respectively, foregoing three part back projection data multiply by corresponding weight coefficient η respectively
1, η
2, η
3Summation obtains striding the data D of back projection in the spiral PI coordinate system afterwards
#(x
π, t
1, t
2), send into limited Hilbert inverse transform module;
B) limited Hilbert inverse transform module with following formula from the data D of back projection
#(x
π, t
1, t
2) in solve the image reconstruction value
Obtain striding the reconstruction gray value in the spiral PI coordinate system,
L ' described in the formula and U ' represent the lower bound and the upper bound of the tight support of back projection's data respectively, and L and U represent to stride the lower bound and the upper bound of waiting to rebuild the tight support of object in the spiral PI coordinate system respectively, and C is a constant, is used to eliminate limit;
3, the data rearrangement module transforms to above-mentioned reconstruction gray value of striding in the spiral PI coordinate system in the Cartesian coordinates, obtain the three-dimensional data under the Cartesian coordinate, furtherly, given space a bit, try to achieve with two way classification and to stride spiral PI line through this point, thereby obtain this coordinate in striding spiral PI coordinate system, because the coordinate figure of at this moment obtaining may not be on the sampling grid of back projection, therefore obtain the gray value of this point with the method for three-dimensional interpolation, the three-dimensional data under this Cartesian coordinate is transfused to display module subsequently;
4, display module reads the three-dimensional data under the Cartesian coordinate that the data rearrangement module obtains, and be presented on the high-resolution medical display according to user's needs, this module is developed based on the VGL visualization tool, comprise human-computer interaction interface, select gray-scale displayed window and the cross section that needs to show by the user.
Claims (7)
1, a kind of multi-source spiral CT BPF accurate reconstruction system, comprise display module, it is characterized in that, also comprise: the projection acquisition processing module, backprojection-filtration module and data rearrangement module, projection acquisition processing module recording projection data, and the data for projection that collects sent into the backprojection-filtration module, the backprojection-filtration module adopts the multi-source spiral CT BPF accurate reconstruction algorithm, above-mentioned data for projection is handled, obtain striding the reconstructed image in the spiral PI coordinate system, and with this reconstructed image input data rearrangement module, the data rearrangement module is through interpolation of data, above-mentioned reconstructed image of striding in the spiral PI coordinate system is reset in the Cartesian coordinates, obtain the three-dimensional data under the Cartesian coordinate, and with this three-dimensional data input display module, display module reads the three-dimensional data under the above-mentioned Cartesian coordinate, shows faultage image on screen.
2, multi-source spiral CT BPF accurate reconstruction system according to claim 1, it is characterized in that, described projection acquisition processing module comprises 2N+1 x-ray source and corresponding 2N+1 minimum detection window, corresponding minimum detection device window of each x-ray source wherein, respectively along 2N+1 bar helical trajectory recording projection data, the data for projection that collects is through carrying out differential to projection angle after the denoising pretreatment, and the data for projection behind the differential is sent into the backprojection-filtration module and rebuild.
3, multi-source spiral CT BPF accurate reconstruction system according to claim 2, it is characterized in that, described minimum detection window is meant a given x-ray source, and a last circle spiral that is set out by this x-ray source and next circle the most intermediary two enclose the zone that spirals or its projection surround between spiral.
4, multi-source spiral CT BPF accurate reconstruction system according to claim 1, it is characterized in that, described backprojection-filtration module comprises two submodules: back projection's module and Hilbert filtration module, the data for projection of back projection's module after to differential carries out integration, the bound of integration is determined by the projection angle of striding two end points of spiral PI line, the result of back projection's submodule output is back projection's data of striding in the spiral PI coordinate system, after these back projection's data are sent into Hilbert filtering submodule, carry out limited Hilbert inverse transformation along striding spiral PI line, according to the reconstruction formula of backprojection-filtration algorithm, obtain striding the reconstructed image in the spiral PI coordinate system.
5, multi-source spiral CT BPF accurate reconstruction system according to claim 1, it is characterized in that, the coordinate of the given Cartesian coordinates mid point of described data rearrangement module, obtain by this point stride spiral PI line, and then obtain the gray value of these corresponding point in striding spiral PI coordinate system.
6, multi-source spiral CT BPF accurate reconstruction system according to claim 5, it is characterized in that, the described spiral PI coordinate system of striding is a two-dimentional rectangular coordinate system, an axle is for striding spiral PI line, another root axle is the angle parameter of striding an end points of spiral PI line, and another end points of striding spiral PI line is a fixed value.
7, multi-source spiral CT BPF accurate reconstruction system according to claim 6, it is characterized in that, the described spiral PI line of striding is a straightway, its end points is positioned on the helix, another end points is positioned on another helix, represent these two endpoint locations angle parameter difference less than 360 the degree.
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103630563A (en) * | 2013-12-04 | 2014-03-12 | 公安部第一研究所 | X-ray helical scanning and navigating method |
| CN104407540A (en) * | 2014-10-22 | 2015-03-11 | 中国科学院苏州生物医学工程技术研究所 | CT data acquisition system |
| CN106056541A (en) * | 2015-04-07 | 2016-10-26 | 西门子公司 | Structure-compliant noise reduction during multispectral computed tomography CT imaging |
| CN107533755A (en) * | 2015-04-14 | 2018-01-02 | 皇家飞利浦有限公司 | For improving the apparatus and method of medical image quality |
| CN110974278A (en) * | 2019-12-21 | 2020-04-10 | 电子科技大学 | DSA (digital Signal amplification) cone beam precise filtering back-projection tomography system and imaging method |
| CN111552002A (en) * | 2020-05-19 | 2020-08-18 | 重庆大学 | Three-source swing spiral CT imaging device and method for security check |
-
2007
- 2007-02-08 CN CN 200710037288 patent/CN101011261A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103630563A (en) * | 2013-12-04 | 2014-03-12 | 公安部第一研究所 | X-ray helical scanning and navigating method |
| CN104407540A (en) * | 2014-10-22 | 2015-03-11 | 中国科学院苏州生物医学工程技术研究所 | CT data acquisition system |
| CN106056541A (en) * | 2015-04-07 | 2016-10-26 | 西门子公司 | Structure-compliant noise reduction during multispectral computed tomography CT imaging |
| CN106056541B (en) * | 2015-04-07 | 2020-05-15 | 西门子公司 | Structure-adaptive noise suppression in multi-spectral CT imaging |
| CN107533755A (en) * | 2015-04-14 | 2018-01-02 | 皇家飞利浦有限公司 | For improving the apparatus and method of medical image quality |
| CN107533755B (en) * | 2015-04-14 | 2021-10-08 | 皇家飞利浦有限公司 | Apparatus and method for improving medical image quality |
| CN110974278A (en) * | 2019-12-21 | 2020-04-10 | 电子科技大学 | DSA (digital Signal amplification) cone beam precise filtering back-projection tomography system and imaging method |
| CN111552002A (en) * | 2020-05-19 | 2020-08-18 | 重庆大学 | Three-source swing spiral CT imaging device and method for security check |
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