CN203763103U - Geometric correction device of detector of cone beam CT (computed Tomography) system - Google Patents
Geometric correction device of detector of cone beam CT (computed Tomography) system Download PDFInfo
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- CN203763103U CN203763103U CN201420006024.3U CN201420006024U CN203763103U CN 203763103 U CN203763103 U CN 203763103U CN 201420006024 U CN201420006024 U CN 201420006024U CN 203763103 U CN203763103 U CN 203763103U
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Abstract
The utility model discloses a geometric correction device of a detector of a cone beam CT (computed Tomography) system. The correction device comprises a correction plate, an adjusting table, the detector, an X ray source device and an X ray source table, wherein the X ray source table and an adjusting table are respectively arranged at both ends, the X ray source device is arranged on the X ray source table, the bottom of the detector is arranged on the horizontal surface of the adjusting table, the correction plate is positioned between the X ray source device and the detector and is arranged on the surface of the adjusting table, the correction plate is provided with a plurality of through holes to form a through hole array, each through hole is in a circle shape, and the through holes are same in size, and are parallel in the axial direction. The correction device has the advantages that by adopting the correction plate provided with the through hole array, the detector of the cone beam CT system can be effectively subjected to geometric correction, the calculation is completely not needed, the geometric position of the detector is firstly corrected, and then the position of the rotary table is corrected; the operation is simple and rapid.
Description
Technical field
This utility model relates to biomedical imaging field, is specifically related to a kind of correcting unit for cone-beam CT system detector geometric position.
Background technology
Electronic computer x-ray tomography technology CT(Computed Tomography), at present bringing into play very important effect in nucleus medical image, especially in multi-modality imaging field, CT provides structural information and correction for attenuation information for other mode.Can say so, the reconstruction precision of CT has determined image reconstruction effect and the image syncretizing effect of other mode to a great extent.At present, 3 D pyramidal CT generally adopts FDK(Feldkamp) analytic reconstruction algorithm, but the three-dimensional reconstruction effect of FDK algorithm is very responsive to the geometric parameter of 3 D pyramidal CT system, it requires the relative geometry position of radiographic source, detector and turntable in perfect condition, be that radiographic source central ray is vertically injected detector center, the coplanar perpendicular quadrature of rotating shaft and central ray.Therefore 3 D pyramidal CT being carried out to geometric correction has very important significance.
Traditional geometric correction method is broadly divided into asynchronous correction, and nonlinear least square method synchronous correction.So-called asynchronous correction, is exactly that each step is only proofreaied and correct one or several parameter, and synchronous correction is exactly all parameters of disposable correction.
The people such as Yi Sun have proposed a kind of method of asynchronous correction in " A Calibration Method for Misaligned Scanner Geometry in Cone-beam Computed Tomography " literary composition: four identical high density balls are placed in to four summits of square poly (methyl methacrylate) plate, then just can obtain the projected position of four balls on detector.By the relative geometry position relation between four projections, can calculate successively the various geometrical offset parameters of detector.But this method is all calculated based on other parameter ideal situations in each step, and the very difficult realization of the operation requirements having, such as the symmetrical centre that requires radiographic source central ray vertical sand shooting to four points.And the method need to be measured radiographic source to the distance of detector, and in fact because ray source focus position cannot be determined and is difficult to obtain this parameter.
The people such as Smekal have proposed a kind of method of inlaying two circle steel balls on low density material in " Accurate technique for complete geometric calibration of cone-beam computed tomography system ".On a cylinder, inlay upper and lower two-layer steel ball, and each 12 up and down, on circumference, being uniformly distributed, the relative position between steel ball is known, and the relative position of the projection centre by it on detector carries out geometric parameter correction.Yet in the method, the corresponding relation of projection and former steel ball is easy to obscure.
Patent CN202104929U has improved said method, has added again one or more positioning balls between two-layer steel ball, makes the corresponding relation of projection and former steel ball clearer and more definite, and the method is easier on calculating simultaneously.But the precision of these two kinds of methods is subject to the interference of several factors, such as the certainty of measurement etc. of proofreading and correct the machining accuracy of imitative body used, relative position between steel ball.
All asynchronous bearing calibrations, need to measure radiographic source and to rotating shaft or correction, imitate the distance of body to distance and the radiographic source of detector, and these distance parameters are not only difficult to measure, and have inevitably introduced measurement error.
BJ University of Aeronautics & Astronautics provides a kind of method of synchronous correction in Non-linear least square estimation of geometrical parameters for Cone-beam three dimensional computed tomography.On turntable, place a steel ball, through 360 degree rotations, obtain the projection of this steel ball under all angles.By extract the projection centre under each angle and set up projection centre and geometric parameter between functional relationship, can to geometric parameter, carry out matching estimation by nonlinear least square method, thereby reach the disposable object that solves all geometric parameters.The method has been carried out too much hypothesis in formulation process, and if detector is without rotating in face, without face external rotation, rotating shaft non-angular error, only has offset error etc., thereby for practical situation inapplicable.
Utility model content
In order to overcome problems of the prior art, this utility model provides the array hole device of a kind of Fast Correction cone-beam CT system detector geometric position.It is more simple that this device and method is compared other geometric correction schemes, can very fast and effeciently realize the geometric correction of detector, for follow-up rotating shaft, proofreaies and correct and lay the groundwork.
The purpose of this utility model is to provide a kind of correcting unit for cone-beam CT system detector geometric position.
Cone-beam CT system detector geometric correction device of the present utility model comprises: correcting plate, regulating platform, detector, x-ray source device and x-ray source platform; Wherein, the test surface of detector is vertical with bottom surface; Correcting plate is tabular, positive parallel with the back side, and perpendicular to bottom surface; Regulating platform comprises adjusting device and is arranged on the table top of the level in adjusting device; X-ray source platform and regulating platform lay respectively at two ends, and x-ray source device is positioned on x-ray source platform; The bottom surface of detector is placed on the table top of level of regulating platform, and correcting plate is being placed between x-ray source device and detector on the table top of regulating platform; On correcting plate, be provided with a plurality of through holes and form via-hole array, through hole be circle, each through hole measure-alike, and axially parallel.
Regulating platform can move along three mutually perpendicular axis, and can rotate around three mutually perpendicular axis.X-ray source platform can move along three mutually perpendicular axis, and can rotate around three mutually perpendicular axis, thereby adjusts x-ray source device with respect to the position of detector.
In x-ray source device, from x-ray focus transmitting cone-beam x-ray, central ray along continuous straight runs, be radiated on correcting plate, the through hole that ray sees through correcting plate projects on detector, projection of shape by through hole on detector judges that the position of ray on detector is offset and the angular deflection of detector self, thereby realizes the Fast Correction of CT detector.
The via-hole array of correcting plate is included in the centre bore at center, and comprises main horizontal line mutually perpendicular and that comprise centre bore and main vertically row.The main horizontal line of behavior at centre bore place, centre bore place classify main vertically row as, main horizontal line and main vertically row are orthogonal, hole centered by the intersection of main horizontal line and main vertically row; Main horizontal line is parallel to bottom surface, and main vertically row are perpendicular to bottom surface.The distribution of via-hole array is symmetrical.The distribution mode of other through holes on correcting plate is not limit, and can be circular array, can be square array yet, and the number of its through hole is not limit yet, and the number of through hole is more, and correction accuracy is higher.The thickness of correcting plate is directly proportional to the diameter of through hole, and the linear attenuation coefficient of correcting plate and the thickness of plate are inversely proportional to, for convenience of processing and can observing the obvious deformation of through hole projection, and the general aluminium sheet that is greater than 10mm thickness that adopts, through-hole diameter is 1mm.
The turntable that further comprises of the present utility model, turntable is between regulating platform and x-ray source platform, and turntable comprises base and table top, and the table top of turntable is parallel to central ray, and base can move and can rotate around vertical axes at horizontal plane.When the central ray sending when x-ray source device incides the center of test surface perpendicular to test surface, complete after the geometric correction of detector, remove correcting plate, adjustable stem is placed on turntable, projection according to adjustable stem on test surface, adjust the position of turntable, thus make the rotating shaft of turntable and the center of x-ray focus and test surface coplanar, and x-ray focus is vertical with rotating shaft with the line of centres of test surface.
Cone-beam CT system detector geometric correction method of the present utility model, comprises the following steps:
1) detector is placed on the table top of regulating platform, correcting plate is close to test surface and is placed on regulating platform;
2) in x-ray source device, from x-ray focus transmitting cone-beam x-ray, be radiated on correcting plate, the via-hole array that ray sees through correcting plate projects on detector, on detector, form projected array, according to projected array, adjust the relative position of correcting plate and detector, make the projection speckle of centre bore be positioned at the center of test surface, thus the center superposition of the center of centre bore and test surface;
3) relative position of correcting plate and detector remains unchanged, by adjusting regulating platform, regulate level and the vertical position of detector and correcting plate, make main horizontal line projection speckle major axis all vertically, and the major axis of the main vertically projection speckle of row all vertically, thereby central ray incides the center of test surface;
4) regulate the outer angular deviation of face of detector, by adjusting regulating platform, regulate detector around the anglec of rotation of trunnion axis and vertical axes, the circle that the projection speckle that makes centre bore is standard, and this standard circular reached maximum, and now central ray incides the center of test surface perpendicular to test surface.
Cone-beam CT system detector geometric correction method of the present utility model, can also be by comprising the following steps realization:
1) detector is placed on the table top of regulating platform, correcting plate is placed on regulating platform between x-ray source device and detector;
2) in x-ray source device, from x-ray focus transmitting cone-beam x-ray, be radiated on correcting plate, the via-hole array that ray sees through correcting plate projects on detector, on detector, form projected array, according to projected array, adjust the relative position of correcting plate and detector, make the projection speckle of main horizontal line be positioned at the central row of detector array, and the main vertically projection speckle of row is positioned at the central series of detector array, thereby seeing through the center of centre bore, central ray is radiated on detector;
3) relative position of correcting plate and detector remains unchanged, adjust regulating platform, regulate the outer angular deviation of face of detector, the projection speckle that makes centre bore is that standard is maximum circular, and whether equate to come auxiliary judgment by observing the major axis of main horizontal line or the main projection speckle being vertically listed as, thereby central ray is perpendicular to test surface;
4) obtain the projection coordinate of central ray on test surface, according to projection coordinate's value, calculate the side-play amount of central ray on test surface, adjust regulating platform, make the coordinate of central ray be positioned at the center of test surface, now central ray incides the center of test surface perpendicular to test surface.
Geometric correction method of the present utility model further comprises the adjusting of turntable position, when the central ray sending when x-ray source device incides the center of test surface perpendicular to test surface, complete after the geometric correction of detector, remove correcting plate, adjustable stem is placed on turntable, projection according to adjustable stem on test surface, adjust the position of turntable, thereby make the rotating shaft of turntable and the center of x-ray focus and test surface coplanar, and x-ray focus is vertical with rotating shaft with the line of centres of test surface.
Advantage of the present utility model:
This utility model adopts the correcting plate that is provided with via-hole array, can fast and effeciently to the detector of cone-beam CT system, carry out geometric correction, does not need to calculate fast and easy completely.This utility model adopts correcting plate, first the geometric position of detector is proofreaied and correct, and then proofreaies and correct the position of turntable, simple to operate quick.
Accompanying drawing explanation
Fig. 1 is the structural representation of an embodiment of cone-beam CT system detector geometric correction device of the present utility model;
Fig. 2 is the principle schematic of cone-beam CT system detector geometric correction device of the present utility model;
Fig. 3 is the schematic diagram of the geometric error situation of several detectors, wherein, be (a) and (b) test surface in the projection of xz plane, (c) be (d) test surface in the projection of xy plane, be (e) that test surface is in the projection of yz plane;
Fig. 4 is the structural representation of the correcting plate of cone-beam CT system detector geometric correction device of the present utility model;
Fig. 5 is the schematic diagram of the projected array of cone-beam CT system detector geometric correction device of the present utility model;
Fig. 6 is the structural representation that cone-beam CT system detector geometric correction device of the present utility model regulates turntable;
Fig. 7 is the schematic diagram of the horizontal departure of turntable, wherein, (a) is the situation that adjustable stem is vertically placed, (b) for adjustable stem does not have the situation of vertically placing.
The specific embodiment
Below in conjunction with accompanying drawing, by embodiment, this utility model is described further.
As shown in Figure 1, the cone-beam CT system detector geometric correction device of the present embodiment comprises: correcting plate 1, detector 4, regulating platform 5, x-ray source device 6 and x-ray source platform 7; Wherein, the test surface of detector 4 is vertical with bottom surface; Regulating platform 5 comprises adjusting device and is arranged on the table top of the level in adjusting device; X-ray source platform 7 and regulating platform 5 lay respectively at two ends, and the bottom surface of detector 4 is placed on the table top of level of regulating platform 5, and correcting plate 1 is placed on the table top of regulating platform 5 between x-ray source device 6 and detector 4.Regulating platform 5, x-ray source platform 7 and turntable are arranged on optical table 10.Between regulating platform 5 and x-ray source platform 7, be turntable, turntable comprises the table top 82 of base 81 and level.
As shown in Figure 2, S represents light source, and central ray is propagated along X-axis, and XYZ coordinate system is the space coordinates of setting up with central ray and rotating shaft, and O is initial point.UV coordinate system is the plane coordinate system of setting up with the central row of actual detector and central series, and ideally, this plane parallel is in YOZ, and O
2be positioned in X-axis, U is parallel to Y, and V is parallel to Z.Detector to be adjusted is positioned at VO
2u plane, O
2imaging center for detector to be adjusted.
In the present embodiment, the material of correcting plate adopts aluminium sheet, through hole be distributed as 7 * 7 square array.
Fig. 3 is the schematic diagram of the geometric error situation of several detectors.Wherein, be (a) and (b) detector in the projection of XOZ plane, as shown in Figure 4 (a), detector rotates θ around U axle; As shown in Figure 4 (b), the imaging center O of detector
2apart from differ Δ V along V wheelbase from O.Figure (c) and (d) be detector in the projection of XOY plane, as shown in Figure 4 (c), detector rotates β around V axle; As shown in Fig. 4 (d), the imaging center O of detector
2apart from differ Δ U along U wheelbase from O.As shown in Fig. 4 (e), detector rotates η around X-axis, for the skew of this geometric position, because cone-beam x-ray is symmetrical about central ray projected position on the impact of parallel hole array projection, in projected array, without Observable, change, can regulate by other means.
As shown in Figure 4, correcting plate 1 is tabular, and front 101 is parallel with the back side 102, and perpendicular to bottom surface 103.On correcting plate 1, be provided with a plurality of through holes 2, form via-hole array, through hole 2 be circle, each through hole measure-alike, and axially parallel.The distribution of through hole is included in the centre bore 201 at center, and the distribution of through hole comprises main horizontal line 203 mutually perpendicular and that comprise centre bore and main vertical row 202.The main horizontal line 203 of behavior at centre bore 201 places, centre bore 201 places classify main vertical row 202 as, main horizontal line 203 and main vertical row 202 are orthogonal, hole 201 centered by the intersection of main horizontal line 203 and main vertical row 202; Main horizontal line 203 is parallel to bottom surface 103, and main vertical row 202 are perpendicular to bottom surface 103.The distribution of through hole is symmetrical.In the present embodiment, adopt the aluminium sheet of 10mm thickness, through-hole diameter is 1mm.
Light source S launches cone-beam x-ray, is radiated on correcting plate 1, and the through hole 2 that ray sees through correcting plate 1 projects on detector, form projected array 3, as shown in Figure 5, the projection speckle 301 of centre bore 201, main horizontal line forms projection speckle 303, and main vertically row form projection speckle 302.Shown in Fig. 5 is whole system projected array ideally, the long axis direction of projection speckle 303 is vertical, projection speckle 302 long axis direction levels, projection speckle 301 is that standard is maximum circular, final object is exactly to make the projection of correcting plate 1 reach effect as shown in Figure 5, and the correction of that detector has just completed.Initial in the situation that, the projection speckle of the shape of projection speckle 302,301,303 and periphery is similar.
The cone-beam CT system detector geometric correction method of the present embodiment, comprises the following steps:
1) detector 4 is placed on the table top of regulating platform 5, correcting plate 1 is placed on regulating platform 5, between x-ray source device 6 and detector 4 and be close to test surface, the bottom surface 103 of correcting plate is positioned at the table top of the level of regulating platform 5, front 101 and the test surface UO of correcting plate
2v is parallel, and centre bore 201 is in the center O of test surface
2near.
2) x-ray source device transmitting cone-beam x-ray, be radiated on correcting plate 1, the through hole that ray sees through correcting plate projects on detector, form projected array 3, according to the projection of centre bore 201, form the position of projection speckle 301, along U axle, V direction of principal axis, regulate correcting plate respectively, by horizontal sliding correcting plate on regulating platform 5, regulate correcting plate along the displacement of U axle, and regulate correcting plate along the displacement of V axle by pad is set between correcting plate 1 and regulating platform 5, make the center O of projection Ban301 center and test surface
2overlap.For example,, when projection speckle 301 is at plane UO
2in the time of in first quartile in V, according to its center and U axle, V wheelbase from, regulate correcting unit to-V ,-U direction, to move respective distance respectively with respect to detector, again viewed in projection projection speckle 301 positions, continue to regulate, until projection speckle 301 drops on the center O of test surface
2.Now, the central shaft of centre bore 201 is crossed the center O of test surface
2.Other situations in like manner regulate.
3) correcting plate 1 remains unchanged with the relative position of detector 4, regulates level and the vertical position of detector 4 and correcting plate 1 by adjusting regulating platform 5, makes central ray be positioned at the center of test surface:
The offset deviation of detector respectively as in Fig. 3 along U direction of principal axis displacement Y, detector along V direction of principal axis displacement Z.The projection speckle of finding major axis level in projected array 3 is capable, and the vertical projection speckle row of major axis, in a width projection kind, can only find only a line and only string.According to a line projection speckle of major axis level and the vertical string projection speckle of major axis, respectively along U axle and V direction of principal axis adjusting detector, make the major axis difference level of the projection speckle 302 of the vertical row of master and the projection speckle of main horizontal line with vertical.For example, when the projection speckle of major axis level is positioned at projection speckle 302 right side, spacing according to itself and projection speckle 302 along U axle, be that detector is along U direction of principal axis displacement Y, regulate detector to move respective distance along U direction, viewed in projection projection speckle 302 shapes, continue to regulate, until the long axis horizontal direction of projection speckle 302 again; In like manner regulate detector along V direction of principal axis position, make the long axis vertical direction of projection speckle 303.Now, central ray is by 201 dozens of center O at test surface of centre bore
2.Other situations in like manner regulate.
Need explanation, because the outer corner of test surface also can exert an influence to projected array 3, as detector in Fig. 2 can cause projected array 3 to produce the compression of V direction of principal axis around U axle rotation angle θ, and detector can cause projected array 3 to produce the compression of U direction of principal axis around V axle anglec of rotation β, but above compression effectiveness does not play a decisive role to each projection speckle long axis direction, separate to the adjusting of the outer corner of the displacement dough-making powder of detector.
4) regulate the outer angular deviation of face of detector, the maximum that the projection speckle 301 that makes centre bore is standard is circular, and the major axis size of the projection speckle 303 of main horizontal line is symmetry equivalent about the projection speckle column direction of centre bore; Same, the major axis size of the main vertically projection speckle 302 of row is symmetry equivalent in the row direction about the projection speckle institute of centre bore; Simultaneously the long axis direction of other projection speckles and size are symmetrical about the projection speckle place row and column axis of orientation of centre bore, and distribute about the centrosymmetry of the projection speckle of centre bore, and now central ray is perpendicular to test surface, and projected array 3 as shown in Figure 5.
Embodiment above, when the geometric position of correcting detection face, first makes central ray be positioned at the center of test surface, and rear adjusting central ray is vertical with test surface.Proofread and correct the geometric position of test surface, can also make it vertical with test surface by first correction center ray, and rear adjusting central ray incides the center of test surface.And, can also further to the rotating shaft of turntable, regulate, concrete bearing calibration comprises the following steps:
1) detector 4 is placed on the table top of regulating platform 5, correcting plate 1 is placed on regulating platform 5 between x-ray source device 6 and detector 4, correcting plate 1 can have certain distance between detector 4, do not need to be close to test surface, the bottom surface 103 of correcting plate is positioned at the table top of the level of regulating platform, front 101 and the test surface UO of correcting plate
2v is parallel, and centre bore 201 is in the center O of test surface
2near.
2) regulate detector displacement, make central ray pass centre bore 201 and impinge perpendicularly on test surface:
The projection speckle of finding major axis level in projected array 3 is capable, and the vertical projection speckle row of major axis, in a width projection, can only find only a line and only string.According to a line projection speckle of major axis level and the vertical string projection speckle of major axis, regulate detector respectively along U axle and V direction of principal axis, the major axis that makes the main vertically projection speckle 302 of row and the projection speckle 303 of main horizontal line is level and vertically respectively.For example, when the projection speckle of major axis level is positioned at projection speckle 302 right side, spacing according to itself and projection speckle 302 along U axle, be that detector is along U direction of principal axis displacement Y, regulate detector to move respective distance along U direction, viewed in projection projection speckle 302 shapes, continue to regulate, until the long axis horizontal direction of projection speckle 302 again; In like manner regulate detector along V direction of principal axis position, make the long axis vertical direction of projection speckle 303, now, central ray is by 201 dozens of center O 2 at test surface of centre bore.Other situations in like manner regulate.
3) regulate the outer angular deviation of face of detector, make central ray perpendicular to test surface:
The outer angular deviation of the face of detector be respectively in Fig. 3 detector around U axle rotation angle θ, detector around V axle anglec of rotation β.Observe the shape of projection speckle 301, if its long axis direction along U axle or V direction of principal axis, regulates detector around U axle or V Shaft angle, make projection speckle 301 for the maximum circle of standard.Meanwhile, whether the major axis that can be positioned on central row or central series about the projection speckle of projection speckle 301 symmetric positions by observation equate, come auxiliary judgment to regulate after the outer angle of face of detector whether adjusted complete.
For example, when the long axis direction of projection speckle 301 is along U axle, show that detector exists around U axle rotation angle θ, whether now observe projection speckle 304 and 305 major axis about projection speckle 301 symmetries on central series equates, if the major axis of projection speckle 304 is greater than projection speckle 305 major axis, show that angle θ is produced around the rotation of U axle in the counterclockwise direction by detector, regulate along clockwise direction detector to rotate suitable angle around U axle, whether again observe the long axis direction of projection speckle 301 and the major axis of projection speckle 304 and 305 equates, if the major axis of projection speckle 304 is less than the major axis of projection speckle 305, regulate in the counterclockwise direction detector to rotate suitable angle around U axle.So repeatedly, until projection speckle 301 is standard circular, and the major axis of projection speckle 304 and 305 equates.Now detector regulates complete around U axle anglec of rotation θ.In like manner regulate detector around V axle anglec of rotation β.Other situations in like manner regulate.
Need explanation, because the outer corner of test surface also can exert an influence to projected array 3, as detector in Fig. 2 can cause projected array 3 to produce the compression of V direction of principal axis around U axle rotation angle θ, and detector can cause projected array 3 to produce the compression of U direction of principal axis around V axle anglec of rotation β, but above compression effectiveness does not play a decisive role to each projection speckle long axis direction, separate to the adjusting of the outer corner of the displacement dough-making powder of detector.
4) regulate detector, make central ray vertically inject the center of test surface:
By step 3, can obtain the projection coordinate of central ray on detector 4, the center that calculates central ray and detector 4 according to this projection coordinate's value is at U, side-play amount in V direction, adjusts regulating platform to regulate the position of detector, makes central ray vertically inject detector center.For example, in the time of in the first quartile of projection speckle 301 in plane UOV, according to its center and U axle, V wheelbase from, regulate detector to V, U direction, to move respective distance respectively, now, central ray is vertically injected the center of test surface, and projected array 3 as shown in Figure 5.
5) more than, having adjusted central ray incides behind the center of test surface perpendicular to test surface, remove correcting plate, adjustable stem 9 is placed on the optional position of table top 82 of level of turntable, turntable rotates a circle, thereby on test surface, obtain the projection that adjustable stem 9 rotates a circle, be projected as about vertical axisymmetric tetragon, tetragonal axis of symmetry is exactly the projection of rotating shaft, by the distance at the projection of rotating shaft and the center of test surface, adjust the base 81 of turntable, thereby the rotating shaft of turntable is adjusted on central ray.In two kinds of situation:
(a) adjustable stem is vertically placed on the table top 82 of level, by allowing turntable rotate a circle, obtains the multi-angle projection of adjustable stem 9, is a rectangle, as shown in Figure 7 (a).By searching, be projected in distance V axle distance farthest in U direction, for example adjustable stem 9 is 50 pixel sizes at U positive direction maximum distance, negative direction at U is 30 pixels apart from V axle maximum distance, we just can learn that rotating shaft has cheap error along Y-axis positive direction like this, then regulate the base 81 of turntable to make its opposite direction along Y-axis move (50-30)/4*pixel_size.Wherein pixel_size is the pixel size of detector, as detector pixel size 74.8um. repeated trials can be adjusted to ideal position turntable 2～3 times.
(b) if adjustable stem 9 is not placed vertically, its projection just as shown in Figure 7 (b) shows, is an isosceles trapezoid.The two ends farthest of isosceles trapezoid are the straight lines tilting, but bearing calibration is substantially the same, we are by finding apart from V axle straight line farthest, then draw their axis of symmetry, so just can calculate offset U, then regulate turntable adjustable base system to make the mobile U/4 of its opposite direction along Y-axis, repeated trials can be adjusted to ideal position rotating shaft 2～3 times.
Finally it should be noted that, the object of publicizing and implementing mode is to help further to understand this utility model, but it will be appreciated by those skilled in the art that: within not departing from the spirit and scope of this utility model and appended claim, various substitutions and modifications are all possible.Therefore, this utility model should not be limited to the disclosed content of embodiment, and the scope that the claimed scope of this utility model defines with claims is as the criterion.
Claims (7)
1. a cone-beam CT system detector geometric correction device, is characterized in that, described correcting unit comprises: correcting plate (1), detector (4), regulating platform (5), x-ray source device (6) and x-ray source platform (7); Wherein, the test surface of described detector (4) is vertical with bottom surface; Described correcting plate (1) is tabular, positive parallel with the back side, and perpendicular to bottom surface; Described regulating platform (5) comprises adjusting device and is arranged on the table top of the level in adjusting device; Described x-ray source platform (7) and regulating platform lay respectively at two ends, and described x-ray source device (6) is positioned on x-ray source platform (7); The bottom surface of described detector (4) is placed on the table top of level of regulating platform (5), and correcting plate (1) is positioned between x-ray source device (6) and detector (4) and is placed on the table top of regulating platform (5); On described correcting plate (1), be provided with a plurality of through holes (2), form via-hole array, through hole (2) be circle, each through hole measure-alike, and axially parallel.
2. correcting unit as claimed in claim 1, it is characterized in that, the via-hole array of described correcting plate is included in the centre bore (201) at center, and comprises mutually perpendicular and main horizontal line that comprise centre bore (203) and main vertically row (202); The main horizontal line of behavior at described centre bore (201) place, centre bore place classify main vertically row as, main horizontal line and main vertically row are orthogonal, hole centered by the intersection of main horizontal line and main vertically row; Described main horizontal line (203) is parallel to bottom surface (103), and described master is vertically listed as (202) perpendicular to bottom surface (103).
3. correcting unit as claimed in claim 1, is characterized in that, the thickness of described correcting plate (1) is directly proportional to the diameter of through hole.
4. correcting unit as claimed in claim 1, is characterized in that, the linear attenuation coefficient of described correcting plate (1) and the thickness of plate are inversely proportional to.
5. correcting unit as claimed in claim 1, is characterized in that, described regulating platform (5) moves along three mutually perpendicular axis, and rotates around three mutually perpendicular axis.
6. correcting unit as claimed in claim 1, is characterized in that, described x-ray source platform (7) moves along three mutually perpendicular axis, and rotates around three mutually perpendicular axis.
7. correcting unit as claimed in claim 1, is characterized in that, further comprises turntable, and described turntable is positioned between regulating platform (5) and x-ray source platform (7), and described turntable comprises base (81) and table top (82).
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|---|---|---|---|
| CN201420006024.3U CN203763103U (en) | 2014-01-06 | 2014-01-06 | Geometric correction device of detector of cone beam CT (computed Tomography) system |
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| CN201420006024.3U CN203763103U (en) | 2014-01-06 | 2014-01-06 | Geometric correction device of detector of cone beam CT (computed Tomography) system |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103735282A (en) * | 2014-01-06 | 2014-04-23 | 北京大学 | Device and method for geometric correction of detector of cone-beam CT (computed tomography) system |
| CN106447637A (en) * | 2016-09-30 | 2017-02-22 | 北京纳米维景科技有限公司 | Splicing detector geometry correction body model and correction method thereof |
| CN106880374A (en) * | 2017-03-27 | 2017-06-23 | 东北大学 | Power spectrum CT imaging methods and power spectrum CT imaging systems |
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2014
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103735282A (en) * | 2014-01-06 | 2014-04-23 | 北京大学 | Device and method for geometric correction of detector of cone-beam CT (computed tomography) system |
| CN106447637A (en) * | 2016-09-30 | 2017-02-22 | 北京纳米维景科技有限公司 | Splicing detector geometry correction body model and correction method thereof |
| CN106447637B (en) * | 2016-09-30 | 2019-03-15 | 北京纳米维景科技有限公司 | A kind of splicing detector geometric correction body mould and bearing calibration |
| CN106880374A (en) * | 2017-03-27 | 2017-06-23 | 东北大学 | Power spectrum CT imaging methods and power spectrum CT imaging systems |
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