CN103135121B - Line segment type module computer tomography (CT) detector and method for eliminating crosstalk - Google Patents
Line segment type module computer tomography (CT) detector and method for eliminating crosstalk Download PDFInfo
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- CN103135121B CN103135121B CN201110402463.7A CN201110402463A CN103135121B CN 103135121 B CN103135121 B CN 103135121B CN 201110402463 A CN201110402463 A CN 201110402463A CN 103135121 B CN103135121 B CN 103135121B
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Abstract
The invention relates to a computer tomography (CT) detector which comprises at least one detector module arranged in line segment type and a plurality of collimator plates, wherein each detector module comprises a plurality of pixels, and gaps are arranged between the pixels; and configuration of the plurality of collimator plates enables x ray bundles emitted by a ray tube to orient corresponding pixels of the detector module. The CT detector is characterized in that crosstalk between the pixels of the ray bundles is eliminated.
Description
Technical field
In general, the present invention relates to Medical CT and industry CT imaging field, it is more particularly related to
In the line segment shape module CT detector and method that eliminate crosstalk.
Background technology
The x-ray irradiated thereon can be converted into the signal of telecommunication by CT detectors, and it is most important part in CT devices.CT
Detector is made up of many detector modules.Conventional CT detector modules have passage on less x- directions (i.e. picture
Element), such as 16 passages, so that the pixel for making detector is preferably formed on an arc.This curved or quasi- arc is arranged
Detector have wait pel spacing.And relative to x-ray tube focus, each pixel has equal subtended angle angle.Conventional CT
The x-ray beam guide probe module that arc or quasi- curved detector surface send ray tube equipped with multiple collimator plates
Respective pixel on.These multiple collimator plates have equal subtended angle angle relative to x-ray tube focus, it is characterised in that every
The central plane of one piece of collimator plate all snaps to the center in the gap between corresponding pixel.It is logical to be usual to speak：Etc. pixel wide,
Deng subtended angle collimator CT detectors.
X-ray produces radioparent and scattered rayss after human body or object.Present CT is using radioparent (wire harness) weight
Composition as.Scattered rayss seem harmful to reconstruct image, need to eliminate.These multiple collimator plates are by Absorption, energy
Scattered x rays are reduced or eliminated, prevents scattered x rays from reaching in the pixel of module.
When the CT detectors using this arc or quasi- arc, using standard filtered back projection (FBP) image reconstruction side
Other image rebuilding methods of method or such as iterative approximation (IR) etc. carry out reconstruction image.For reduces cost, people are used in line
The CT detectors of the detector module that section shape is arranged.In the CT detectors that this line segment shape is arranged, each module is in x- directions
Upper line-like section shape, multiple line segment shape modules splice the polygonal shape of forming part.Each line segment shape Modular surface
Central point is all with x- ray tube focuses as the center of circle, on arc of the radius as D.Line segment shape module can include in the x direction many
Individual pel array (more than 32 passages, such as 64 passages or more than or equal to 128 passages).But, in this line segment shape detector mould
In block, wait pel spacing (i.e. the distance between neighbor center) not re-form and subtended angle is waited to x-ray bulb focus.Change
Sentence is talked about, and waits the x-ray beam between the collimator plate of subtended angle no longer will symmetrically be radiated in each pixel of detector module,
And some skews can be produced, produce crosstalk so as to cause x-ray beam to reach neighbor.Crosstalk can cause image to have puppet
Shadow.The central plane of the collimator plate of each grade subtended angle is by the center for no longer snapping to the gap between corresponding pixel.And understand
Producing some side-play amounts. this side-play amount is different in different channel positions.
Fig. 1 illustrates that the conventional arc or quasi- curved detector under identical x-ray tube radiation situation and line segment shape module are visited
Survey device comparison in the x direction.Wherein, label 110 represents line segment shape module detector, and it includes 5 detector modules, each
Module has 128 passages.Label 120 represents curved detector, and it includes 40 narrow modules, and each module is only logical with 16
Road.It can be seen from figure 1 that all passages in curved detector 120 are nearly all located on arc.(see Fig. 7) in curved detector, from
Detector surface to x-ray tube focus FS has nearly identical distance (being equal to the radius of arc) R.All passages all have identical
Pel spacing P and identical subtended angle Alpha, wherein Alpha=P/R.Sum it up, conventional curved detector in etc. pixel
Spacing and the geometry for waiting subtended angle.
Have unlike narrow module from above-mentioned curved detector, the Modular surface of line segment shape module detector 110 is wider
It is more flat, multiple straightways are formed, with more port numbers, generally higher than equal to 32 passages.In the detector of this line segment shape
In, the distance of different Pixel surface to FS is different.Distance of the Modular surface central point of line segment shape module detector 110 to FS
It is D, then Modular surface edge will be D/cos (theta) to the distance of FS, wherein theta is FS to module edge and FS to mould
Angle between block centre of surface.Obviously, the no longer corresponding identical subtended angle of the same pixel spacing in module, or in other words
Say, when x-ray is radiated on detector module surface with identical subtended angle degree, irradiation in the x direction no longer has identical width
Degree.
Clearer can understand above-mentioned curved detector and line segment shape module detector in the x direction not from accompanying drawing 2
Together.Label 200 represents the focus of x-ray tube.Label 290 represents collimator plate.Label 220 represents subtended angle between collimator plate
Alpha, i.e. x-ray irradiate subtended angle.Label 230 represents above-mentioned line segment shape module detector.Label 240 represents above-mentioned arc
Detector, each detector narrow module that it includes is nearly all on same arc.Label 250 represents the picture in detector module
Element.Label 260 represents the gap (kerf) between pixel.Label 270 represents the distance between two neighbor centers, i.e., as
Plain spacing P.Label 280 represents x-ray beam, and x-ray beam can not reach its neighbor.From Fig. 2 it will be clear that due to collimation
The shielding action of device plate, x-ray beam is irradiated in respective pixel, can not reach neighbor, from without cross-interference issue
Occur.
Fig. 3 further illustrates the details of line segment shape module detector x-ray irradiation in the x direction.Line taking section shape mould
Block detector has and quasi- curved detector identical pel spacing P.Label 310 represents collimator plate.Label 320 represents collimation
Subtended angle (angle between collimator plate) alpha between device plate, the x-ray for taking the subtended angle and the quasi- curved detector in Fig. 2 is shone
Penetrate the identical Alpha=P/R of subtended angle.Label 330 represents line segment shape module detector.Label 340 represents x-ray beam.Obviously, these
X-ray beam can reach neighbor, so as to produce crosstalk.From Fig. 3 it will be clear that waiting irradiation subtended angle by what collimator plate was formed
Different width will be produced in Pixel surface, cause x-ray beam to be offset to neighbor, be irradiated to adjacent shown in shadow region
Pixel, so as to produce cross-interference issue.Image is caused to have artifact.
Therefore, although existing line segment shape module CT detector can be reduced into greatly relative to arc CT detectors
This, but the cross-interference issue how eliminated in line segment shape module CT detector is the problem of urgent need to resolve in this area.
The content of the invention
According to one embodiment of present invention, the present invention relates to a kind of CT detectors, including：At least one sets in line segment shape
The detector module put, detector module includes：Multiple pixels, have gap between pixel；And multiple collimator plates, it is multiple
Collimator plate is configured in the respective pixel of the beam guide probe module of ray tube；It is a feature of the present invention that disappearing
Except beam crosstalk between the pixels.
According to one embodiment of present invention, detector includes the subtended angle collimator plate such as multiple configuration and on gap
Absorb the grid of the high density material of x-ray.By the absorption actinism of grid, beam string between the pixels is eliminated
Disturb.
According to one embodiment of present invention, the width of grid is identical.
According to one embodiment of present invention, grid has different width.According to one embodiment of present invention, grid
It is symmetricly set on the gap of pixel.
According to one embodiment of present invention, grid is asymmetric is arranged on the gap of pixel.
According to one embodiment of present invention, the width of grid is in the range of 10um to 400um.
According to one embodiment of present invention, the thickness of grid is in the range of 30um to 4mm.
According to one embodiment of present invention, only in one direction (one-dimensional x- directions) is arranged on gap grid.
According to one embodiment of present invention, grid (two dimension, x- directions and z- directions) on two intersecting directions sets
Put on gap.
According to one embodiment of present invention, grid is made up of tungsten, molybdenum or other high density materials, heavy alloy.
According to one embodiment of present invention, multiple collimator plates have wait subtended angle and have so that beam pixel it
Between do not produce the thickness of crosstalk.
According to one embodiment of present invention, the thickness of multiple collimator plates is identical.
According to one embodiment of present invention, multiple collimator plates have the thickness for differing.
According to one embodiment of present invention, the central point on detector module surface has most between the focus of ray tube
Excellent distance value, optimal distance value can be caused：The central plane of the collimator plate of each grade subtended angle is exhausted with corresponding slit centers
Side-play amount is minimized.Namely so that the maximum of multiple skew quantity sets is minimized when changing with D.So as to so that all pictures
The crosstalk of element is minimized.
According to one embodiment of present invention, CT detectors can be used used by the curved detector based on corresponding radius R
Existing standard filtered back projection FBP image rebuilding methods or iterative reconstruction approach carry out reconstruction image, and without the need for modification or school
Normal operation method.
According to one embodiment of present invention, there is different subtended angle degree, so that ray between multiple collimator plates
Beam does not produce between the pixels crosstalk.
According to one embodiment of present invention, according to the position and width calculation collimator of beam angle and the pixel
Position of the subtended angle degree and collimator plate between plate to respective pixel surface.
According to one embodiment of present invention, the edge collimator plate between two adjacent detector modules is configured to
So that edge collimator plate is formed as the symmetrical plate of its adjacent collimator plate and the edge collimator plate is adjacent collimator
Plate shape into subtended angle be significantly greater than subtended angle between other adjacent collimator plates.
According to one embodiment of present invention, a kind of method of the elimination beam crosstalk for CT detectors, CT detections
Device includes：At least one detector module arranged in line segment shape, detector module includes multiple pixels, has seam between pixel
Gap；And multiple collimator plates, multiple collimator plates are configured to the corresponding picture of the beam guide probe module of ray tube
On element；The method includes：Configuration CT detectors cause to eliminate beam crosstalk between the pixels.
According to one embodiment of present invention, the step of configuring CT detectors includes that configuration is multiple and waits subtended angle collimator plate simultaneously
The grid of the high density material for absorbing x-ray is set on gap.
According to one embodiment of present invention, the width of grid is identical.
According to one embodiment of present invention, the width of grid is equal to the thickness of collimator plate.
According to one embodiment of present invention, the width of grid is in the range of 10um to 400um.
According to one embodiment of present invention, the central point on detector module surface has most between the focus of ray tube
Excellent distance value, optimal distance value is that the central plane of the collimator plate for causing each grade subtended angle is absolute with corresponding slit centers
Minimize when side-play amount changes with D.
According to one embodiment of present invention, grid is only arranged in one direction on gap.
According to one embodiment of present invention, grid is arranged on gap on two intersecting directions.
According to one embodiment of present invention, grid is made up of tungsten, molybdenum or other high density materials.
According to one embodiment of present invention, the step of grid is arranged on gap includes：Determine width and the position of grid
Put.
According to one embodiment of present invention, the width and position for determining grid includes：Determine parameter value Ch, P, R, wherein
Ch is the total pixel number that line segment shape module has；P is the distance between neighbor center, and R is corresponding curved detector
Arc radius；Calculate the center P*n-P*Ch/2, wherein n=0,1,2 ..., Ch in gap；Between calculating collimator plate etc.
Subtended angle degree P/R；The position of the collimator plate central plane of isotonic angle of the calculating on Modular surface：D*tan(P/R*n-P/R*
Ch/2)；By cause all pixels slit centers and the center plane location of corresponding collimator plate maximum each
Minimize to determine optimal distance value Do when deviant changes with D.In being typically always the edge collimator plate on Modular surface
The position in heart face is more than the width of module, such Do so that module is always feasible with the splicing of module；In conjunction with collimator
The thickness of plate determines the position of grid and width.
According to one embodiment of present invention, the step of configuring CT detectors includes that configuration is multiple and waits subtended angle collimator plate simultaneously
Increase the thickness (thicker than or equal to 80um again than pixel gap width) of multiple collimator plates, so that beam is in pixel
Between do not produce crosstalk.
According to one embodiment of present invention, the CT detectors that multi-line section module is spliced into can be using based on corresponding parameter
Value P, the existing standard filtered back projection FBP image rebuilding methods or iterative reconstruction approach used by the curved detector of R is weighing
Image is built, and without the need for modification or correcting algorithm.
According to one embodiment of present invention, the subtended angle degree between multiple collimator plates is different, so that ray
Beam does not produce between the pixels crosstalk.
According to one embodiment of present invention, according to the subtended angle degree between beam angle calculation collimator plate.
According to one embodiment of present invention, the edge collimator plate between two adjacent detector modules is configured to
So that the edge collimator plate is formed as the symmetrical plate of its adjacent collimator plate and the edge collimator plate is adjacent standard
Straight device plate shape into subtended angle be significantly greater than subtended angle between other adjacent collimator plates.
Description of the drawings
According to appended claims, following detailed description and corresponding accompanying drawing to one or more example embodiments,
The feature and advantage of embodiments of the invention will become clear from, in accompanying drawing：
Fig. 1 illustrates the comparison in the x direction of conventional quasi- arc narrow module detector and line segment shape module detector.
Fig. 2 illustrates the details in the x direction of the conventional probes with collimator plate (isotonic angle).
Fig. 3 illustrates that the x-ray irradiation in the x direction of the line segment shape module detector with collimator plate (isotonic angle) is thin
Section.
Fig. 4 illustrates the x-ray irradiation details in the x direction of the line segment shape module detector with shielding grid.
Fig. 5 A and 5B are the details top views for shielding grid.
Fig. 6 is the details top view of scintillator pixels, 2D pel arrays.
Fig. 7 illustrates the line segment shape module of the geometry of the module array of quasi- arc narrow module and corresponding number of pixels
Schematic diagram.
Fig. 8 is the flow chart for obtaining Do values, raster width and grid positions.
Fig. 9 A and 9B are shown respectively corresponding arc or quasi- arc narrow module detector and the line segment shape mould in the present invention
The details of block detector.
Figure 10 illustrates the x-ray irradiation details in the x direction of the line segment shape module detector with thicker collimator plate.
Figure 11 illustrates that the x in the x direction of the line segment shape module detector with specially designed not grade subtended angle collimator is penetrated
Line irradiates details.
Specific embodiment
According to one embodiment of present invention, the present invention provides a kind of line segment shape for eliminating cross-interference issue of the prior art
Module CT detector.Heretofore described " line segment shape " refers to each module with line-like shape, is formed between the modules
The shape of multiple straightway splicings；" quasi- arc " refer to the module of each little pixel (for example 16 pixels) being close to or
Similar circular arc is arranged or arranged.
According to above to the description of Fig. 3 it can be seen from, between collimator plate etc. irradiation subtended angle produce on Pixel surface it is different
Width, causes x-ray beam to offset, and is irradiated to the neighbor in shadow region, so as to generate crosstalk.Thus, according to
One embodiment of the present of invention, the line segment shape module CT detector of the present invention increases on the surface of pixel and below collimator
Grid, it is inclined for shielding the above-mentioned x-ray irradiation caused because collimator plate does not have the slit centers of snap to pixels array
Move, so as to eliminate crosstalk.Meanwhile, the pixel on x directions is effectively become equidistantly after Pixel surface increases grid
With equal angular geometry.
The top in the gap that grid is placed between pixel, and grid center of a lattice is substantially aligned with the center in gap, also
It is to say, grid is symmetricly set on the gap of pixel.In an embodiment of the invention, the grid of same widths can be set.
The width of grid in the range of 10um to 400um, the preferably equal to thickness 200um of collimator plate.In another reality of the present invention
In applying example, the width of grid can be different from pixel to pixel.Being spaced in the range of 0.08mm to 2.0mm between grid,
Grid spacings can be constant, or different from pixel to pixel.The thickness of grid is in the range of 30um to 4mm.Grid
Can be made up of tungsten, molybdenum or other high density materials, heavy alloy.In one embodiment, grid is only arranged in the x direction
In Pixel surface.In other words, grid is metal band-shaped in one-dimentional structure.In another embodiment, Pixel surface x and
Z directions are respectively provided with grid.In this embodiment, grid forms the array structure of bidimensional.In an embodiment of the invention, grid
It is asymmetric to be arranged on the gap of pixel.
In one embodiment, detector includes 5 modules, and in the x direction each module has 128 passage (x sides
Pixel quantity upwards).In another embodiment, detector may include 3 modules, and in the x direction each module has 224 to lead to
Road.It will be appreciated by those skilled in the art that the module lifted of the present invention and channel number are exemplary explanation, should not be understood
For limitation of the present invention.In other words, module number is not limited to 3 or 5, and can be 1,2,4,6,7... etc., an and mould
Number of channels in block can be other values.
Fig. 4 illustrates that the line segment shape module detector with shielding grid of the invention x-ray irradiation in the x direction is thin
Section.Wherein, label 410 represents tungsten collimator plate.Label 420 represents collimator plate subtended angle (i.e. x-ray irradiation subtended angle) alpha,
Subtended angle alpha=P/R identical with the collimator plate subtended angle of the class arc module shown in Fig. 3 is taken, configuration causes multiple collimators
The subtended angle of plate is identical.Label 430 represents the position of line segment shape module detector.Label 440 represents the grid for arranging in the x direction
Lattice.Label 450 represents the beam projected from ray tube.
It will be clear that the grid that the x-ray (shown in shade) for being offset to neighbor can be added absorbs from Fig. 4,
So as to eliminate cross-interference issue.Also, pixel only receives the x-ray of the subtended angle such as corresponding for coming that free collimator plate formed.So,
Only it is suitable for the standard FBP image rebuilding method or iteration of the geometry based on isogonism of routine arc and quasi- arc CT detectors
Method for reconstructing is applied equally to the present invention, and without the need for modification or correcting algorithm or data.That is, CT detectors can be used
Existing standard filtered back projection FBP image rebuilding methods or iterative approximation used by curved detector based on corresponding radius
Method carrys out reconstruction image.For a small amount of x-ray lost in shade caused by shielding grid, can be by existing GE business
Air calibration process in algorithm for reconstructing used in industry CT is being normalized.
Fig. 5 A and 5B are the top views for shielding grid.Fig. 5 A illustrate the first example that grid is arranged.Fig. 5 B illustrate that grid sets
The second example put.Wherein, label 510 and 520 all represents grid.As described above, grid can form the multiple straight of one-dimentional structure
Line segment, as shown in Figure 5A.Compared with Fig. 5 A, Fig. 5 B increased the grid of wire-like in a z-direction, define above-mentioned 2D
The grid of structure.The width in the gap between the usual matched pixel of width of the grid on z directions, as shown in Figure 6.
Fig. 6 is the top view of the pel array of the grid with 2D structures.Picture is located at the diode array of pixel matching
Under pixel array (not shown here).Label 610 represents many pel arrays (i.e. usually said multiple passages) on x directions.
Label 620 represents many pel arrays in a z-direction.Label 630 represents the pel spacing on z directions.Label 640 represents matching
The grid of gap width.Label 650 represents the pixel in array.Label 660 represents the pel spacing on x directions.
Fig. 7 illustrates the line segment shape module of the geometry of the module array of quasi- arc narrow module and corresponding number of pixels
Schematic diagram.Label 710 represents the line segment shape module of the present invention.Label 720 represents corresponding existing quasi- arc narrow module array.
Label 730 represents the quasi- arc narrow module for including 16 passages.As shown in fig. 7, D represents the module table of line segment shape module detector
Distance of the face center to focus FS of x-ray tube；Theta angles representation module marginal surface to FS line and FS to Modular surface
Angle between the line at center；R represents the arc radius of corresponding quasi- arc narrow module detector.
According to another embodiment of the present invention, the present invention relates to a kind of central point for optimizing line segment shape Modular surface is arrived
The method apart from D of x-ray tube focus.With reference to the method that Fig. 7 illustrates present invention offer.
In existing arc or quasi- curved detector, the subtended angle alpha between collimator plate is for all pixels spacing
It is equal.Assume that pel spacing is P, then the subtended angle alpha=P/R between the collimator plate.Assume corresponding in the present embodiment
Line segment shape module detector in, line segment shape module have overall channel (i.e. pixel) count Ch.Also, the center of line segment shape module is
In 0mm.Pel spacing is identical, is also P.Take and also have between collimator plate identical subtended angle alpha=P/R, then collimator plate
Central plane will be D*tan (P/R*n-P/R*Ch/2), wherein n=0,1,2 ..., Ch in the position of Pixel surface.Line segment shape
The center in the pixel gap of module will be P*n-P*Ch/2；
The Do value related to R is obtained by being fitted D, D values are the central point of line segment type Modular surface to x-ray tube focus
Distance.Optimum Do values are when from x-ray, in the irradiation position of Modular surface, (collimator plate median plane intersects with Modular surface
Position) to gap center each deviant { [D*tan (P/R*n-P/R*Ch/2)]-(P*n-P*Ch/2) } in
The distance value of minima is obtained when the maximum of absolute value changes with D.By using this Do values, in line segment shape module detector
In have equal subtended angle x-ray response will be with the corresponding original curved detector with R value radiuses with phase
X-ray response with subtended angle is immediate.Optimum Do values cause detector the present invention detector configuration in corresponding arc
Shape detector has minimum deflection.For the line segment shape module detector with shielding grid, in this specific range, use
Raster width is little and x-ray dosage efficiency is optimum.
Grid should cover the skew in each pixel, i.e., the position intersected with Pixel surface from collimator plate face is to pixel
The distance at edge.Because the collimator plate thickness in existing curved detector covers gap, select on x directions with it is existing
There is collimator thickness identical raster width and cause grid to cover the gap of line segment shape module detector, just similar to original
Quasi- curved detector in collimator plate position, do so is convenient.Therefore, all by grid both positive offset and negative offset
Covered.
Fig. 8 is the flow chart for obtaining Do values, raster width and grid positions.In step 810, basic parameter Ch is obtained,
P, R, wherein P are pel spacings, and Ch is the overall channel number (that is, total pixel number) that line segment shape module has, and R is that corresponding arc is visited
Survey the arc radius of device.In step 820, the slit center of line segment shape module is obtained.In step 830, obtain collimator plate it
Between angle alpha.In step 840, obtain with the collimator plate central plane on the surface of the line segment shape module of D
Position.In step 850, by causing in the position of all passage slit centers and corresponding collimator plate central plane
Maximum each deviant minimum obtains Do values to be fitted D.In step 850, with reference to the thickness of collimator plate, grid is drawn
The position of grid at width and different passages in the x direction.With reference to a following example to line segment shape module detector
Discussion will be better appreciated by foregoing.
Assume in existing quasi- curved detector, pel spacing P=1.15mm；Between between pixel in the x direction
Every kerf be 0.120mm；Collimator plate thickness is 0.200mm, completely covers the width in gap, so as to reduce crosstalk and shielding
X-ray leakage in gap；Collimator plate thickness is that 0.200mm can be reduced or eliminated scattered rayss to acceptable degree.Arc
The radius of shape detector is 949.075mm；Collimator plate subtended angle is alpha=1.15/949.075=0.001212.Assume choosing
Select the line segment shape module with 128 passages (pel array on x directions).By being fitted D, we obtain Do=
947.647mm, and the minima of the peak excursion of 128 collimator plates be +/- 0.037mm (in line segment shape module two most
Outer end, collimator plate outwards exceeds 0.037mm).
In principle, it is possible to the width for selecting grid is 0.037mm and grid is placed in into pixel/seam according to its +/- skew
On gap surface.In principle, raster width can change according to the +/- skew for being calculated from pixel to pixel.But here, this
Bright easily selects unified raster width with equal to collimator plate thickness 0.200mm.And cause grid symmetrically to cover seam
Gap.So, the x-ray from +/- skew can be absorbed by the grid with unified raster width.X-ray is absorbed well
Grid thickness be 0.03mm to 4mm tungsten grid.
Fig. 9 A and 9B are shown respectively in the present example being discussed above corresponding quasi- arc narrow module detector and line segment
The details of shape module detector.Label 910 represents the collimator plate in quasi- arc narrow module detector example, and its thickness is
0.200mm.Label 920 represents collimator plate subtended angle.Label 930 represents scintillator pixels.Label 940 represents that line segment shape module is visited
The collimator plate surveyed in device example, its thickness is 0.200mm.Label 950 represents collimator plate subtended angle, 920 tables of itself and label
The collimator subtended angle size shown is identical.Label 960 represents the grid of present invention offer, and its width is 0.200mm.The table of label 970
Show scintillator pixels.Label 900 and 980 represents the gap that width is 0.120mm.Label 990 represents x-ray beam.
According to another embodiment of the present invention, the present invention is by increasing collimator plate thickness come overlay offset so that detection
There is no x-ray crosstalk in device.Increase collimator plate thickness to be intended to shield because collimator plate is without in detector pixel array
Slit centers on alignment and the x-ray irradiation skew that causes, rather than for further reducing x-ray scatter line.Usual tungsten
X-ray scatter line has just been reduced to acceptable degree when molybdenum collimator plate thickness is 0.200mm.Existing quasi- arc
Its thickness is exactly for 0.200mm in detector.For example the thickness of collimator plate is increased to into 200+37x2=274um from 200um
(the +/- 0.037mm with reference to the example being discussed above offsets).So, the x-ray from +/- skew can be increased by thickness
Degree collimator plate is absorbed.
According to another embodiment of the present invention, the thickness of the increase of collimator plate can be with difference.Its thickness increase can be with root
Obtain according to the side-play amount of the diverse location collimator plate being discussed above.As long as being by the thickness increase of collimator plate：200um is added
More than or equal to the value of its side-play amount.The crosstalk produced by skew can be just completely covered.
Figure 10 illustrates the thin of the x-ray irradiation in the x direction of the line segment shape module detector with thicker collimator plate
Section.Label 1010 represents thicker collimator plate.Label 1020 represents the subtended angle alpha between collimator plate, itself and quasi- arc
Subtended angle between the collimator plate of narrow module is identical, and configuration causes the subtended angle of multiple collimator plates identical.Label 1030 represents line
The position of section shape module detector.Label 1040 represents x-ray beam.Similarly, in conventional arc and quasi- arc CT detectors
The standard FBP image rebuilding method or iterative reconstruction approach of the geometry based on isogonism for using is equally applicable to shown in Figure 10
Detector in embodiment, and without the need for algorithm and data are modified or corrected.
According to still another embodiment of the invention, by using the different collimator plate subtended angle (angles i.e. between collimator plate
Degree) and cause there is no x-ray crosstalk in detector, as shown in figure 11.Label 1110 represents the focus of x-ray tube.Label
1120 represent the edge collimator plate between two line segment shape modules i and j.The edge collimator plate symmetrically snaps to two
The junction of line segment shape module i and j, in other words, the edge collimator plate between two adjacent detector modules is formed
For the symmetrical plate of its adjacent collimator plate.Label 1130 represents the collimator plate between non-module.Label 1140 represents collimator
Subtended angle (the i.e. x-ray irradiation subtended angle) alpha of plate.From the subtended angle between Figure 11, collimator plate be different, it is that is, accurate
Straight device plate is according to x-ray beam angle calculation in the position of Modular surface so that x-ray beam will not be crosstalked into slave module center to
Outer next pixel.According to subtended angle degree and collimation between the position and width calculation collimator plate of beam angle and pixel
Position of the device plate to respective pixel surface.Label 1150 represents the x-ray beam from x-ray tube.Without string between x-ray beam
Disturb.Label 1160 represents pixel.Label 1170 represents the edge junction of two adjacent segments shape modules.In the enforcement of the present invention
Example in, the edge collimator plate between two adjacent detector modules be formed as the symmetrical plate of its adjacent collimator plate and this
Individual edge collimator plate is adjacent the subtended angle that the subtended angle of collimator plate formation is significantly greater than between other adjacent collimator plates.
Although describing the present invention with regard to the embodiment of limited quantity, thus those skilled in the art will understand numerous repairing
Change and change.Appended claims will cover all these modifications and changes for falling within the true spirit and scope of the present invention.
Claims (32)
1. a kind of CT detectors, including：
At least one detector module arranged in line segment shape, the detector module includes：
Multiple pixels, have gap between the pixel；And multiple collimator plates, the plurality of collimator plate is configured will be caused
The x-ray beam that ray tube sends is oriented in the respective pixel of the detector module；
Characterized in that, beam crosstalk between the pixels is eliminated,
The central point on the detector module surface to having optimal distance value between the focus of the ray tube, it is described it is optimum away from
The central plane of collimator plate that each grade subtended angle is caused from value is minimized with the absolute offset values of corresponding slit centers,
The central point on the detector module surface is obtained using following steps to the optimum between the focus of the ray tube
Distance value：
Determine parameter value Ch, P, R, wherein Ch is the total pixel number that line segment shape module has；P be between neighbor center away from
From R is the arc radius of corresponding curved detector；
Calculate the center in the gap；
Calculate the angle between the collimator plate；
Calculate the position of the collimator plate central plane on the Modular surface；
By causing in all slit centers and the maximum of the position of corresponding collimator plate central plane each deviant most
Littleization is determining the optimal distance value.
2. CT detectors as claimed in claim 1, it is characterised in that the detector includes multiple collimations for waiting subtended angles configuration
The grid of the high density material of device plate and the absorption x-ray on the gap.
3. CT detectors as claimed in claim 2, it is characterised in that the width of the grid is identical.
4. CT detectors as claimed in claim 3, it is characterised in that the grid is symmetricly set on the gap.
5. CT detectors as claimed in claim 2, it is characterised in that the grid has different width.
6. CT detectors as claimed in claim 5, it is characterised in that the grid is asymmetric to be arranged on the gap.
7. CT detectors as claimed in claim 2, it is characterised in that scope of the width of the grid in 10um to 400um
It is interior.
8. CT detectors as claimed in claim 2, it is characterised in that the thickness of the grid is in the range of 30um to 4mm.
9. CT detectors as any one of claim 2 to 8, it is characterised in that the grid is only in one direction
It is arranged on the gap.
10. CT detectors as any one of claim 2 to 8, it is characterised in that the grid is two intersecting sides
Set up on the gap.
The 11. CT detectors as any one of claim 2 to 8, it is characterised in that the grid by tungsten, molybdenum or other
High density material, heavy alloy are made.
12. CT detectors as claimed in claim 1, it is characterised in that the plurality of collimator plate has grade subtended angle and has
Eliminate the thickness of beam crosstalk between the pixels.
13. CT detectors as claimed in claim 1, it is characterised in that the thickness of the plurality of collimator plate is identical.
14. CT detectors as claimed in claim 12, it is characterised in that the plurality of collimator plate has the thickness for differing
Degree.
15. CT detectors as claimed in claim 1, it is characterised in that the CT detectors can be using based on corresponding radius
Curved detector used by existing standard filtered back projection FBP image rebuilding methods or iterative reconstruction approach rebuilding figure
Picture, and without the need for modification or correcting algorithm.
16. CT detectors as claimed in claim 1, it is characterised in that there is different opening between the plurality of collimator plate
Angle, so as to eliminate crosstalk of the beam between the pixel.
17. CT detectors as claimed in claim 16, it is characterised in that according to the position of beam angle and the pixel and
Subtended angle described in width calculation between collimator plate.
18. CT detectors as claimed in claim 17, it is characterised in that the edge between two adjacent detector modules
Collimator plate is configured so that the edge collimator plate is formed as the symmetrical plate of its adjacent collimator plate and the edge is collimated
Device plate is adjacent the subtended angle that the subtended angle of collimator plate formation is significantly greater than between other adjacent collimator plates.
A kind of 19. methods of the elimination beam crosstalk for CT detectors, the CT detectors include：At least one is in line segment
The detector module that shape is arranged, the detector module includes multiple pixels, has gap between the pixel；And multiple standards
Straight device plate, the plurality of collimator plate configures the x-ray beam that ray tube will be sent and is oriented to the corresponding of the detector module
In pixel；Methods described includes：
Configure the CT detectors to eliminate beam crosstalk between the pixels,
The step of configuring the CT detectors includes configuring the subtended angle collimator plates such as multiple and absorption x being arranged on the gap penetrating
The grid of the high density material of line,
The step of grid is arranged on the gap includes：Determine width and the position of grid.
The width and position for determining the grid includes：
Determine parameter value Ch, P, R, wherein Ch is the total pixel number that line segment shape module has；P be between neighbor center away from
From R is the arc radius of corresponding curved detector；
Calculate the center in the gap；
Calculate the angle between the collimator plate；
Calculate the position of the collimator plate central plane on the Modular surface；
By causing in all slit centers and the maximum of the position of corresponding collimator plate central plane each deviant most
Littleization is determining optimal distance value；
Determine position and the width of grid with reference to the thickness of collimator plate.
20. methods as claimed in claim 19, it is characterised in that the width of the grid is identical.
21. methods as claimed in claim 19, it is characterised in that the grid has different width.
22. methods as claimed in claim 19, it is characterised in that the grid is symmetricly set on the gap.
23. methods as claimed in claim 19, it is characterised in that the width of the grid is in the range of 10um to 400um.
24. methods as claimed in claim 19, it is characterised in that the central point on the detector module surface is to the ray
There is optimal distance value between the focus of pipe, the optimal distance value cause the central plane of the collimator plate of each grade subtended angle with
The absolute offset values of corresponding slit centers are minimized.
25. methods as any one of claim 19 to 24, it is characterised in that the grid only sets in one direction
Put on the gap.
26. methods as any one of claim 19 to 24, it is characterised in that the grid is in two intersecting directions
On be arranged on the gap.
27. methods as any one of claim 19 to 24, it is characterised in that the grid is by tungsten, molybdenum or other height
Density material, heavy alloy are made.
28. methods as claimed in claim 19, it is characterised in that the step of configuring the CT detectors includes configuring multiple etc.
Subtended angle collimator plate simultaneously increases the thickness of the plurality of collimator plate, so as to eliminate beam crosstalk between the pixels.
29. methods as described in claim 19 or 28, it is characterised in that the CT detectors can be using based on corresponding radius
The all existing standard filtered back projection FBP image rebuilding methods of curved detector or iterative reconstruction approach rebuilding figure
Picture, and without the need for modification or correcting algorithm.
30. methods as claimed in claim 19, it is characterised in that the subtended angle between the plurality of collimator plate be it is different,
So as to eliminate crosstalk of the beam between the pixel.
31. methods as claimed in claim 30, it is characterised in that according to the position and width of beam angle and the pixel
Calculate the subtended angle between the collimator plate.
32. methods as claimed in claim 31, it is characterised in that the edge collimation between two adjacent detector modules
Device plate is configured so that the edge collimator plate is formed as the symmetrical plate of its adjacent collimator plate and the edge collimator plate
It is adjacent the subtended angle that the subtended angle of collimator plate formation is significantly greater than between other adjacent collimator plates.
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| CN104345070B (en) * | 2013-07-29 | 2018-03-23 | 同方威视技术股份有限公司 | Detector module, the method and ray detection system for installing detector module |
| CN104090291A (en) * | 2014-07-24 | 2014-10-08 | 重庆大学 | Collimator array and industrial CT equipment linear detector crosstalk correcting device and method |
| CN105266835A (en) * | 2014-07-25 | 2016-01-27 | Ge医疗***环球技术有限公司 | CT detector |
| JP6456854B2 (en) * | 2016-01-12 | 2019-01-23 | 株式会社日立製作所 | Radiation imaging device |
| CN108121014A (en) * | 2017-12-07 | 2018-06-05 | 公安部第三研究所 | Perspective view scatters array detection system and method |
| CN108577880B (en) * | 2018-05-18 | 2022-05-27 | 上海联影医疗科技股份有限公司 | Anti-scatter grid and CT detection system |
| CN111067555A (en) * | 2019-12-25 | 2020-04-28 | 上海联影医疗科技有限公司 | CT detector |
| CN111281406A (en) * | 2020-01-22 | 2020-06-16 | 东软医疗***股份有限公司 | Scintillator pixel array, detector submodule, module, detector and CT device |
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