CN104698016B - A kind of interlaced helical industry CT scan imaging method of multiple translation - Google Patents
A kind of interlaced helical industry CT scan imaging method of multiple translation Download PDFInfo
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- CN104698016B CN104698016B CN201510137023.1A CN201510137023A CN104698016B CN 104698016 B CN104698016 B CN 104698016B CN 201510137023 A CN201510137023 A CN 201510137023A CN 104698016 B CN104698016 B CN 104698016B
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Abstract
The present invention relates to a kind of interlaced helical industry CT scan imaging method of multiple translation, belongs to CT scan technical field.The method loading turntable during scanning carries out single direction rotation always, and turntable only needs to, along the direction transverse translation parallel to detector, without the need for radial motion, realize interlaced helix scan by the axial back and forth movement of radiographic source and detector in helical scanning gap twice.The interlaced helical industry CT scan imaging method of a kind of multiple translation that the present invention is provided, suitable for III for CT large-size workpieces high accuracy rapid three dimensional imaging, the method realizes high accuracy rapid three dimensional imaging for linear array detector CT system using existing III, scanning process need not enter row detector physics interpolation, on the premise of accuracy of detection is ensured, CT system structure is simplified, CT system manufacturing cost is reduced, and is effectively raised detection efficiency.
Description
Technical field
The invention belongs to CT scan technical field, is related to a kind of interlaced helical industry CT of multiple translation and is scanned into image space
Method.
Background technology
Be limited to the volume and cost of detector, at present the main layout of large-scale high energy ICT equipment be still II generations,
In III generations or II+III generations, detector is substantially linear array detector, seldom has planar array detector.Therefore detection efficiency is relatively low,
That what is detected is relatively costly.High energy CT is to reduce the crosstalk between detector, typically will be first passed through into before detector in ray
One " tunnel type " collimator carries out ray collimation, due to all having needed corresponding collimator per 1 detector cells, visitor
Unit length detector quantity is caused in sight few, single detector high cost, large-scale integrated cannot be carried out.Do not increasing spy
In the case of surveying density, it is the spatial resolution for improving CT, conventional method is to carry out physics interpolation (in scanning process, to lead to
The swing of detector or the movement of object are crossed, Multiple-Scan data are obtained, these data are combined into into a fan-beam number then
According to).If detection zone is not a tomography, but certain scope, conventional method is successively to scan, due to testing cost
Relation, interfloor distance are generally large.Between two-layer scanning, accelerator needs to stop beam (because the life-span of accelerator is that have
Limit, the life-span of its core component was at 500～800 hours or so), thus detection efficiency is relatively low.
The content of the invention
In view of this, it is an object of the invention to provide a kind of interlaced helical industry CT of multiple translation is scanned into image space
Method, the method is in the case of the spatial resolution for ensureing CT, it is possible to increase detection efficiency, reduces testing cost.
To reach above-mentioned purpose, the present invention provides following technical scheme：
A kind of interlaced helical industry CT scan imaging method of multiple translation, the method are comprised the following steps：
S1：Workpiece for measurement is placed on scanning turntable, requires to be fixed workpiece for measurement according to detection；
S2：Require to arrange the visual field size of CT scan, detecting distance and imaging size detection parameter according to detection；According to inspection
Survey pitch and scanning turntable translation step pitch that parameter request calculates CT scan；
S3：According to detector size, imaging size, sampling time, determine that radiographic source, detector are synchronized with the movement speed and examine
Survey platform rotary speed；
S4：By radiographic source, the bottom of detector synchronizing moving to the region of object to be scanned, while carrying out radiographic source, visiting
Survey device to be synchronized with the movement and scanning turntable rotary motion；
S5：First time helical scanning is completed after radiographic source, detector are synchronized with the movement beyond detection range；Stop ray
Source, detector are synchronized with the movement, and scanning turntable is translated a step pitch, need not stop the rotary motion of turntable in translation motion；
S6：The workpiece for measurement that scan again that radiographic source, detector is synchronized with the movement round about completes second spiral and sweeps
Retouch；
S7：Repeat S5, S6, until scanning turntable translation N-1 steps, complete whole helical scanning；N is true according to detection parameter
Surely need to do n times helical scanning；
S8：Rearrangement is entered to the data for projection that S4 and S6 are collected；
S9：Data after resetting to S8 carry out CT image reconstructions using iterative reconstruction algorithm.
Further, it is described scanning turntable translation step pitch be,
Wherein, radiuses of the R for curved detector, the angle of two adjacent detector units is △ γ.
Further, the method that data for projection enters rearrangement in the S8 is that the projection angle range for rebuilding layer is limited in one
In less scope, it is 12 ° -18 ° that accelerator CT rebuilds the projection angle range of layer, and bulb machine CT rebuilds the projection angle range of layer and is
30 ° -40 °, CT image reconstructions are carried out using finite angle method for reconstructing.
Further, the S9 carries out CT image reconstructions using iterative reconstruction algorithm, concretely comprises the following steps：Using TV regularization sides
Then all results are superimposed, then stack result are corrected to each spiral reconstruction by method；Introduce during algorithm is realized
Prior information；Quick reconstruction is realized using purpose parallel acceleration algorithm.
The beneficial effects of the present invention is：The interlaced helical industry CT scanning imagery of a kind of multiple translation that the present invention is provided
Method, is transformed to the scan mode of existing three generations's linear array spiral CT machine, eliminates detector physics interpolation structure, to sweep
Retouch stage translation and image interpolation is realized to substitute, reduce the hardware cost of CT machines；Continuously rotate, visit using object under test in scanning
Survey device and interlaced helix scan path is realized with the radiographic source mode of being synchronized with the movement, improve scan efficiency, reduce CT testing costs；
Image reconstruction combines priori, reconstruction quality height, good resolution using TV method of regularizations.
Description of the drawings
In order that the object, technical solutions and advantages of the present invention are clearer, below in conjunction with accompanying drawing the present invention is made into
The detailed description of one step, wherein：
Flow charts of the Fig. 1 for the method for the invention；
Fig. 2 is spiral three-dimensional schematic diagram twice；
Fig. 3 is spiral three-dimensional top view twice；
Fig. 4 is the translation schematic diagram of four physics interpolation.
Specific embodiment
Below in conjunction with accompanying drawing, the preferred embodiments of the present invention are described in detail.
The interlaced helical industry CT scan imaging method of a kind of multiple translation that the present invention is provided, the flow process of the method is as schemed
Shown in 1.Radiographic source and detector are equivalent to around turntable rotate counterclockwise, similarly, thing as Objects around A turntable turns clockwise
Body is equivalent to radiographic source around turntable rotate counterclockwise and detector turns clockwise around turntable, for convenience of description for the sake of, below
Description all assumes that object is maintained static, and radiographic source and detector are rotated around turntable, while assuming that radiographic source and detector edge turn
Platform axial translation.Following narration illustrates the scanning theory of interlaced helical with No. 4 turntable translations.Methods described include with
Lower step：
S1：Workpiece for measurement is placed on scanning turntable, requires necessary being fixed against to be carried out to workpiece according to detection
There is change in location in rotation and translation in workpiece；
S2：Require that arranging the visual field size of CT scan, the distance in source to object center of rotation, center of rotation arrives according to detection
The detection parameter such as distance and imaging size of detector, calculates CT scan according to detection parameter request (i.e. imaging space resolution)
Pitch and scanning turntable translation step pitch；
Fig. 2 is structure and its top view for the first time with second helical scanning, when Fig. 3 is 4 helical scanning, in starting
The schematic diagram of beam corresponding to a probe unit in the top view of angle or end angle.
The angle of two adjacent detector units of hypothesis is △ γ, then each translation distance of radiographic source and detector (is swept
Retouch the step pitch of turntable translation) be
The distance is determined by the number of times for translating.Radiuses of the wherein R for curved detector.
S3：According to detector size, imaging size sampling time, determine that radiographic source, detector are synchronized with the movement speed and examine
Survey platform rotary speed；
S4：By radiographic source, the bottom of detector synchronizing moving to the region to be measured for scanning object, radiographic source is opened；Wait to penetrate
It is synchronized with the movement and scanning turntable rotary motion while carrying out radiographic source, detector after line source goes out Shu Wending；
S5：First time helical scanning is completed after radiographic source, detector are synchronized with the movement beyond detection range, stops ray
Source, detector are synchronized with the movement, and scanning turntable is translated a step pitch, need not be stopped the rotary motion of turntable and protect in translation motion
Hold radiographic source opening；
S6：The workpiece for measurement that scan again that radiographic source, detector is synchronized with the movement round about completes second spiral and sweeps
Retouch；
S7：Repeat S5, S6, until scanning turntable translation N-1 steps, complete whole helical scanning；N is true according to detection parameter
Surely need to do n times helical scanning；
Assume that region to be detected is time-limited cylinder, rectangular coordinate system as shown in Figure 1 is set up with its center
O-xyz, according to Fig. 2 and Fig. 3, the scanning process of interlaced helical is described as follows：In detection process, radiographic source and detector are first
First translate to the negative semiaxis of y-axis along the direction parallel to y-axisThen radiographic source and detector turn clockwise around object,
Radiographic source and detector moving up along the direction parallel to z-axis, obtains first time helical scanning simultaneously；Radiographic source and detection
Device continues to be rotated in a clockwise direction, and radiographic source and detector translate △ to the positive axis of y-axis along the direction parallel to y-axis again
D as shown in figure 4, and then radiographic source and detector moving down along the direction parallel to z-axis, obtain second helical scanning；
Similar fashion carries out third time and the 4th helical scanning according to this.
S8：Rearrangement is entered to the data for projection that S4 and S6 are collected；
Data for projection enters the method for rearrangement：The projection angle range for rebuilding layer is limited in a less scope,
It is 12 ° -18 ° that accelerator CT rebuilds the projection angle range of layer, and it is 30 ° -40 ° that bulb machine CT rebuilds the projection angle range of layer, and not
It is traditional 180 ° or 360 °, CT image reconstructions is carried out using finite angle method for reconstructing.
S9：Data after resetting to S8 carry out CT image reconstructions using iterative reconstruction algorithm.
Iterative reconstruction algorithm carries out CT image reconstructions, concretely comprises the following steps：Using TV regularization methods to each spiral reconstruction,
Then all results are superimposed, then stack result is corrected；Prior information is introduced during algorithm is realized；Using parallel
Accelerating algorithm realizes quick reconstruction.
From the description above process, in detection process, it is contemplated that some specific detection objects, such as solid-rocket
Electromotor etc., can only rotate around a direction, and radiographic source and detector are rotated clockwise around object all the time, radiographic source and spy
Surveying device is needing to do a translational motion twice between helical scanning, by radiographic source and detector along parallel to turret axis
Direction upper and lower translation defines interlaced helical structure.In the image reconstruction stage, as a result of improved algorithm for reconstructing, it is only necessary to
Know the direction of initial angle, sweep length, pitch and the axial translation of each rotation, it is contemplated that in most cases, turntable is
Radial translation is unable to, the method for the invention does not need turntable radial translation, it is not required that turntable was returned to before scanning in next time
Original position, more crucially accelerator only need to switch at the beginning and end of scanning once, centre need not stop beam,
So as to improve detection efficiency, testing cost has been saved.Meanwhile, this scan mode does not need detector to carry out physics interpolation,
The frame for movement and control algolithm of CT system are simplified, the cost of CT system is effectively reduced.
Finally illustrate, preferred embodiment above is only unrestricted to illustrate technical scheme, although logical
Cross above preferred embodiment to be described in detail the present invention, it is to be understood by those skilled in the art that can be
Various changes are made to which in form and in details, without departing from claims of the present invention limited range.
Claims (4)
1. the interlaced helical industry CT scan imaging method of a kind of multiple translation, it is characterised in that：The method is comprised the following steps：
S1：Workpiece for measurement is placed on scanning turntable, requires to be fixed workpiece for measurement according to detection；
S2：Require to arrange the visual field size of CT scan, detecting distance and imaging size detection parameter according to detection；According to detection ginseng
Number requires the pitch for calculating CT scan and scanning turntable translation step pitch；
S3：According to detector size, imaging size, sampling time, determine that radiographic source, detector are synchronized with the movement speed and detect flat
Platform rotary speed；
S4：By radiographic source, the bottom of detector synchronizing moving to the region of object to be scanned, while carrying out radiographic source, detector
It is synchronized with the movement and scanning turntable rotary motion；
S5：First time helical scanning is completed after radiographic source, detector are synchronized with the movement beyond detection range；Stopping radiographic source,
Detector is synchronized with the movement, and scanning turntable is translated a step pitch, need not stop the rotary motion of turntable in translation motion；
S6：By radiographic source, detector be synchronized with the movement round about again scan workpiece for measurement complete second helical scanning；
S7：Repeat S5, S6, until scanning turntable translation N-1 steps, complete whole helical scanning；N is according to detection parameter determination need
Do n times helical scanning；
S8：Rearrangement is entered to the data for projection that S4 and S6 are collected；
S9：Data after resetting to S8 carry out CT image reconstructions using iterative reconstruction algorithm.
2. the interlaced helical industry CT scan imaging method of a kind of multiple translation according to claim 1, it is characterised in that：
It is described scanning turntable translation step pitch be,
Wherein, radiuses of the R for curved detector, the angle of two adjacent detector units is △ γ.
3. the interlaced helical industry CT scan imaging method of a kind of multiple translation according to claim 1, it is characterised in that：
The method that data for projection enters rearrangement in the S8 is that the projection angle range for rebuilding layer is limited in less scope, is accelerated
It is 12 ° -18 ° that device CT rebuilds the projection angle range of layer, and it is 30 ° -40 ° that bulb machine CT rebuilds the projection angle range of layer, using limited
Angle method for reconstructing carries out CT image reconstructions.
4. the interlaced helical industry CT scan imaging method of a kind of multiple translation according to claim 1, it is characterised in that：
The S9 carries out CT image reconstructions using iterative reconstruction algorithm, concretely comprises the following steps：Using TV regularization methods to each spiral weight
Build, then all results are superimposed, then stack result is corrected；Prior information is introduced during algorithm is realized；Using
Purpose parallel acceleration algorithm is realized rebuilding.
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| CN105136823B (en) * | 2015-07-07 | 2017-12-05 | 重庆大学 | CT partial sweep imaging methods outside large diameter pipeline wall |
| CN105445300A (en) * | 2015-12-16 | 2016-03-30 | 天津三英精密仪器有限公司 | Full-field rod-shaped sample CT scanning device |
| CN106691488B (en) * | 2017-01-25 | 2019-10-18 | 重庆大学 | CT scan imaging method and system |
| CN107764846B (en) * | 2017-10-20 | 2020-04-14 | 重庆大学 | Orthogonal linear scanning CL imaging system and analysis method |
| CN115113289B (en) * | 2021-07-07 | 2024-04-26 | 同方威视技术股份有限公司 | Inspection system and method |
| CN114713518B (en) * | 2022-03-15 | 2024-05-14 | 江苏纳唯信息技术有限公司 | Intelligent flaw detection method for inner wall of industrial pipe fitting based on image analysis |
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