CN115363607B - X-ray imaging device and method for imaging using the same - Google Patents
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Abstract
本申请公开了X射线成像设备及使用X射线成像设备进行成像的方法。X射线成像设备包括：扫描测量射源，发射X射线以照射至关于投照体对称面大致对称的投照体；散射测量组件，包括散射测量射源；探测器；转动机构，绕竖直平面中的转动轴围绕投照体转动，其中，扫描测量射源和散射测量射源设置为在水平面上沿着同一圆周轨迹转动；以及计算组件，配置以根据扫描测量射源在圆周轨迹上的第一位置处的扫描测量数据与散射测量射源在圆周轨迹上的第二位置处的散射测量数据进行计算、以获得第一位置处的散射校正扫描数据，其中，第一位置和投照体对称面之间的角度与第二位置和投照体对称面之间的角度大小相等且方向相反。
The present application discloses an X-ray imaging device and a method for imaging using the X-ray imaging device. The X-ray imaging device includes: a scanning measurement source, emitting X-rays to irradiate an illuminant that is roughly symmetrical about the symmetry plane of the illuminant; a scattering measurement component, including a scattering measurement source; a detector; a rotation mechanism, rotating around the illuminant around a rotation axis in a vertical plane, wherein the scanning measurement source and the scattering measurement source are arranged to rotate along the same circular trajectory on a horizontal plane; and a calculation component, configured to calculate based on the scanning measurement data of the scanning measurement source at a first position on the circular trajectory and the scattering measurement data of the scattering measurement source at a second position on the circular trajectory to obtain scattering-corrected scanning data at the first position, wherein the angle between the first position and the symmetry plane of the illuminant is equal in magnitude and opposite in direction to the angle between the second position and the symmetry plane of the illuminant.
Description
Technical Field
The present application relates to the field of imaging, and more particularly to an X-ray imaging apparatus and a method of imaging using the same.
Background
Imaging techniques, including for example X-ray imaging, CT (Computed Tomography ) and the like, have been widely used in numerous fields, especially in the field of medical examinations, for the generation of ask oneself. For example, oral CT may reflect tissue conditions from a three-dimensional perspective, and may detect lesions that are not detected by the projection angle of an oral X-ray film, or that are finer.
Scattering is a problem that needs to be considered in imaging techniques. Because conventional CT reconstruction theory assumes that x-rays propagate along straight lines, the detected radiation intensities decay exponentially with the path integral. Scattered photons deviate from the direction of the incident beam and cannot be modeled in the conventional CT reconstruction theory, thus becoming an error source for CT image reconstruction.
Disclosure of Invention
In view of at least one of the above technical problems, the present application provides an X-ray imaging apparatus and a method of imaging using the same. The application relates to the following technical scheme:
Technical solution 1. An X-ray imaging apparatus includes:
a scanning measurement source configured to emit X-rays for irradiation to an illuminant, wherein the illuminant is substantially symmetrical about an illuminant symmetry plane;
A scatterometry assembly configured to measure scatter through the projectile, wherein the scatterometry assembly comprises a scatterometry source configured to emit X-rays to impinge upon the projectile so as to measure scatter through the projectile;
a detector configured to detect X-rays emitted by the scanning measurement source to obtain scanning measurement data of the scanning measurement source, and to detect X-rays emitted by the scatterometry source to obtain scatterometry data;
A rotation mechanism configured to rotate the scanning measurement source, the detector, and the scatterometry device about an axis of rotation in a vertical plane about a projectile, wherein the scanning measurement source and the scatterometry source are disposed to rotate along a same circumferential trajectory in a horizontal plane, an
A calculation component configured to calculate, based on the scan measurement data of the scan measurement source at a first location on the circumferential track and the scatter measurement data of the scatter measurement source at a second location on the circumferential track, scatter correction scan data at the first location, wherein an angle between the first location and the plane of symmetry of the projectile is equal in magnitude and opposite in direction to an angle between the second location and the plane of symmetry of the projectile.
The X-ray imaging apparatus according to claim 1, wherein the calculation component is further configured to calculate an illuminant symmetry plane, comprising:
reconstructing the scan measurement data to obtain a reconstructed volume of the projection volume;
the center of gravity of the reconstruction is calculated by,
Wherein, G represents the sum of pixel values of all pixel points of the reconstruction body, G i represents the pixel value of the ith pixel point, x i represents the x component of the ith pixel point, yi represents the y component of the ith pixel point, and z i represents the z component of the ith pixel point;
Determining a plane passing through the center of gravity of the reconstruction, and calculating the plane of symmetry of the reconstruction for all planes passing through the center of gravity of the reconstruction by the following formula
Wherein f (x i,yi,zi) denotes the pixel value of the ith pixel point, f (x i',yi',zi ') denotes the pixel value of the pixel point of the ith pixel point symmetrical about the determined plane, N denotes the total number of pixel points of the whole object for (x i',yi',zi'),f(xi',yi',zi') outside the reconstruction volume equal to zero, wherein i=1 to N/2, and
And determining the symmetry plane of the projection body according to the symmetry plane of the reconstruction body.
An X-ray imaging apparatus according to claim 1 or 2, wherein the calculating means calculates, from the scan measurement data of the scan measurement source at a first position on the circumferential track and the scatter measurement data of the scatter measurement source at a second position on the circumferential track, to obtain scatter correction scan data at the first position, comprises:
a computing component that computes scatter data of the scanning measurement source at a first location on the circumferential track from scatter measurement data of the scatter measurement source at a second location on the circumferential track, and
A calculation component subtracts the scatter data of the scanning measurement source at the first location on the circumferential track from the scan measurement data of the scanning measurement source at the first location on the circumferential track to obtain scatter corrected scan data at the first location.
An X-ray imaging apparatus as set forth in claim 3, wherein the calculating means calculates the scatter data of the scanning measurement source at the first position on the circumferential track from the scatter measurement data of the scatter measurement source at the second position on the circumferential track comprises:
The computing component determines a third location, wherein the third location is symmetrical with the second location about the projection body symmetry plane;
A computing component inverts the scatterometry data of the scatterometry source at the second location on the circumferential track about a vertical central axis of the detector to obtain scatterometry data at a third location;
A calculation component calculates scatter data for the scanning measurement source at a first location on the circumferential track based on the first location, the third location, and the scatter measurement data at the third location.
Technical solution the X-ray imaging apparatus of claim 4, wherein the calculating means calculates the scatter data of the scanning measurement source at the first position on the circumferential trajectory based on the scatter measurement data at the first position, the third position, and the third position comprises:
Calculation is based on the following
Wherein SAD A represents the distance from the first position to the plane parallel to the detector surface where the rotation axis is located, AID represents the distance from the rotation axis to the detector surface, SAD B represents the distance from the third position to the plane parallel to the detector surface where the rotation axis is located, F represents the corrected scatter data, F represents the scatter data corresponding to the third position, x represents the horizontal coordinate on the detector corresponding to the third position, deltax represents the difference between the distance from the first position to the rotation axis and the distance from the third position to the rotation axis, and y represents the vertical coordinate on the detector corresponding to the third position.
Technical solution the X-ray imaging apparatus according to claim 1, wherein the scatterometry assembly further comprises:
a beam blocker includes a plurality of lead strips disposed between the scatterometry source and the projectile.
Technical solution the X-ray imaging apparatus according to claim 1, wherein the scanning measurement source and the scatterometry source are disposed symmetrically about a plane containing the rotation axis and perpendicular to the detector surface.
Technical solution claim 8, a method of imaging a projection object with an X-ray imaging apparatus, wherein the projection object is substantially symmetrical about a plane of symmetry of the projection object, the X-ray imaging apparatus comprising a scanning measurement source, a scatterometry assembly, a detector, a rotation mechanism, and a calculation assembly, wherein the scatterometry assembly is configured to measure scatter through the projection object, the scatterometry assembly comprises a scatterometry source configured to emit X-rays to the projection object to measure scatter through the projection object, the rotation mechanism is configured to rotate the scanning measurement source, the detector, and the scatterometry device about the projection object about an axis of rotation in a vertical plane, wherein the scanning measurement source and the scatterometry source are disposed to rotate along a same circumferential trajectory in a horizontal plane, and wherein the method comprises:
Placing a projection body;
emitting X-rays by a scanning measurement source to irradiate an irradiation body;
Emitting X-rays by a scatterometry source to illuminate an projectile;
Detecting X-rays emitted by the scanning measurement source by a detector to obtain scanning measurement data of the scanning measurement source and detecting X-rays emitted by the scatterometry source to obtain scatterometry data, and
And calculating by a calculating component according to the scanning measurement data of the scanning measurement source at the first position on the circumferential track and the scattering measurement data of the scattering measurement source at the second position on the circumferential track, so as to obtain scattering correction scanning data at the first position, wherein the angle between the first position and the symmetrical plane of the projection body is equal to the angle between the second position and the symmetrical plane of the projection body in size and opposite in direction.
The method of claim 8, further comprising calculating, by the calculation component, a projection symmetry plane, comprising:
reconstructing the scan measurement data to obtain a reconstructed volume of the projection volume;
the center of gravity of the reconstruction is calculated by,
Wherein, G represents the sum of pixel values of all pixel points of the reconstruction body, G i represents the pixel value of the ith pixel point, x i represents the x component of the ith pixel point, y i represents the y component of the ith pixel point, and z i represents the z component of the ith pixel point;
Determining a plane passing through the center of gravity of the reconstruction, and calculating the plane of symmetry of the reconstruction for all planes passing through the center of gravity of the reconstruction by the following formula
Wherein f (x i,yi,zi) denotes the pixel value of the ith pixel point, f (x i',yi',zi ') denotes the pixel value of the pixel point of the ith pixel point symmetrical about the determined plane, N denotes the total number of pixel points of the whole object for (x i',yi',zi'),f(xi',yi',zi') outside the reconstruction volume equal to zero, wherein i=1 to N/2, and
And determining the symmetry plane of the projection body according to the symmetry plane of the reconstruction body.
The method of claim 8 or 9, wherein calculating, by a calculation component, from the scan measurement data of the scan measurement source at a first location on the circumferential track and the scatter measurement data of the scatter measurement source at a second location on the circumferential track to obtain scatter corrected scan data at the first location comprises:
Calculating scatter data of the scanning measurement source at a first location on the circumferential track from scatter measurement data of the scatter measurement source at a second location on the circumferential track, and
Subtracting the scatter data of the scanning measurement source at the first position on the circumferential track from the scan measurement data of the scanning measurement source at the first position on the circumferential track to obtain scatter corrected scan data at the first position.
The method of claim 11, wherein calculating the scatter data for the scan measurement source at the first location on the circumferential track from the scatter measurement data for the scatter measurement source at the second location on the circumferential track comprises:
determining a third position, wherein the third position is symmetrical with the second position about the plane of symmetry of the projectile;
Flipping the scatterometry data of the scatterometry source at the second location on the circumferential track about a vertical central axis of the detector to obtain scatterometry data at a third location;
scatter data of the scanning measurement source at a first location on the circumferential trajectory is calculated based on the scatter measurement data at the first location, the third location, and the third location.
The method of claim 11, wherein calculating the scatter data of the scanning measurement source at the first location on the circumferential track based on the scatter measurement data at the first location, the third location, and the third location comprises:
Calculation is based on the following
Wherein SAD A represents the distance from the first position to the plane parallel to the detector surface where the rotation axis is located, AID represents the distance from the rotation axis to the detector surface, SAD B represents the distance from the third position to the plane parallel to the detector surface where the rotation axis is located, F represents the corrected scatter data, F represents the scatter data corresponding to the third position, x represents the horizontal coordinate on the detector corresponding to the third position, deltax represents the difference between the distance from the first position to the rotation axis and the distance from the third position to the rotation axis, and y represents the vertical coordinate on the detector corresponding to the third position.
Technical solution 13. A method of obtaining scatter-corrected scan data, comprising:
Obtaining scan measurement data of an illuminant, wherein the illuminant is substantially symmetrical about an illuminant symmetry plane;
Obtaining scatterometry data of the projectile, and
And calculating according to the scanning measurement data at the first position and the scattering measurement data at the second position to obtain scattering correction scanning data at the first position, wherein the first position and the second position are symmetrical about the symmetry plane of the projection body.
The method of claim 14, further comprising calculating a plane of symmetry of the projectile, comprising:
reconstructing the scan measurement data to obtain a reconstructed volume of the projection volume;
the center of gravity of the reconstruction is calculated by,
Wherein, G represents the sum of pixel values of all pixel points of the reconstruction body, G i represents the pixel value of the ith pixel point, x i represents the x component of the ith pixel point, y i represents the y component of the ith pixel point, and z i represents the z component of the ith pixel point;
Determining a plane passing through the center of gravity of the reconstruction, and calculating the plane of symmetry of the reconstruction for all planes passing through the center of gravity of the reconstruction by the following formula
Wherein f (x i,yi,zi) denotes the pixel value of the ith pixel point, f (x i',yi',zi) denotes the pixel value of the pixel point symmetrical to the ith pixel point about the determined plane, N denotes the total number of pixel points of the whole object for (x i',yi',zi'),f(xi',yi',zi') outside the reconstruction volume equal to zero, wherein i=1 to N/2, and
And determining the symmetry plane of the projection body according to the symmetry plane of the reconstruction body.
The method of claim 13 or 14, wherein calculating from the scan measurement data at the first location and the scatter measurement data at the second location to obtain scatter corrected scan data at the first location comprises:
Calculating scatter data at the first location from the scatter measurement data at the second location, and
The scatter data at the first location is subtracted from the scan measurement data at the first location to obtain scatter corrected scan data at the first location.
The method of claim 16, wherein calculating the scatter data at the first location from the scatter measurement data at the second location comprises:
determining a third position, wherein the third position is symmetrical with the second position about the plane of symmetry of the projectile;
Flipping the scatterometry data at the second location about a central axis of a detector from which the scatterometry data was obtained to obtain scatterometry data at a third location, wherein the central axis of the detector is substantially parallel or contained with the plane of symmetry of the projection object;
Scatter data at the first location is calculated based on the first location, the third location, and the scatter measurement data at the third location.
17. The method of claim 16, wherein calculating the scatter data at the first location based on the scatter measurement data at the first location, the third location, and the third location comprises:
Calculation is based on the following
Wherein SAD A represents the distance from the first position to the plane parallel to the detector surface where the rotation axis is located, AID represents the distance from the rotation axis to the detector surface, SAD B represents the distance from the third position to the plane parallel to the detector surface where the rotation axis is located, F represents the corrected scatter data, F represents the scatter data corresponding to the third position, x represents the horizontal coordinate on the detector corresponding to the third position, deltax represents the difference between the distance from the first position to the rotation axis and the distance from the third position to the rotation axis, and y represents the vertical coordinate on the detector corresponding to the third position.
Technical solution an X-ray imaging apparatus includes:
a scanning measurement source configured to emit X-rays for irradiation to an illuminant, wherein the illuminant is substantially symmetrical about an illuminant symmetry plane;
A scatter measurement assembly configured to measure scatter through the projectile;
A detector configured to detect X-rays emitted by the scanning measurement source to obtain scanning measurement data of the scanning measurement source, and to detect X-rays emitted by the scatterometry assembly to obtain scatterometry data;
a rotation mechanism configured to rotate the scanning measurement source, the detector, and the scatterometry device about an axis of rotation in a vertical plane about the projectile, and
And a calculation component configured to calculate from the scan measurement data at the first location and the scatter measurement data at the second location to obtain scatter corrected scan data at the first location, wherein the first location and the second location are symmetrical about an illuminant symmetry plane.
Claim 19 the X-ray imaging apparatus of claim 18, wherein the scatterometry assembly comprises:
A scatterometry source configured to emit X-rays for irradiation to the projectile so as to measure scatter through the projectile
Technical solution the X-ray imaging apparatus of claim 19, wherein the scatterometry assembly further comprises:
a beam blocker includes a plurality of lead strips disposed between the scatterometry source and the projectile.
The X-ray imaging apparatus according to claim 19 or 20, wherein the scanning measurement source and the scatterometry source are disposed on both sides of a plane containing the rotational axis and perpendicular to the detector surface.
Technical solution the X-ray imaging apparatus of claim 21, wherein the scanning measurement source and the scatterometry source are disposed symmetrically about a plane containing the rotational axis and perpendicular to the detector surface.
The X-ray imaging apparatus of claim 21, wherein the scan measurement source and the scatterometry source are disposed at an acute angle to a plane containing the axis of rotation and perpendicular to the detector surface.
The X-ray imaging apparatus according to claim 19 or 20, wherein the scanning measurement source and the scatterometry source are the same source.
The X-ray imaging apparatus according to claim 24, wherein the scanning measurement source is disposed through a plane containing the rotation axis and perpendicular to the detector surface.
Technical solution the X-ray imaging apparatus according to claim 18, further comprising:
and the positioning auxiliary tool is configured for positioning the projection body.
The X-ray imaging apparatus of claim 27, wherein the positioning aid comprises a dental tray.
By utilizing the characteristic that the projection body is substantially symmetrical with respect to the projection body symmetry plane, the X-ray imaging apparatus and method according to the exemplary embodiment of the present application can obtain scan measurement data corrected for scattering, that is, corrected for scattering.
Drawings
The above and other aspects, features and advantages of the present application will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:
fig. 1 is a schematic view of an X-ray imaging apparatus according to an exemplary embodiment of the present application.
Fig. 2 shows a schematic perspective view of the X-ray imaging apparatus according to an exemplary embodiment of the application in fig. 1, with the rotation mechanism and the calculation assembly and the beam blocker in the scatterometry assembly removed (only the scatterometry source in the scatterometry assembly is shown), fig. 2 shows the scan measurement source and the trajectory of movement of the scatterometry source (circular dashed line).
Fig. 3 shows a top view of the X-ray imaging apparatus of fig. 2 according to an exemplary embodiment of the present application.
Fig. 4 shows a top view of an X-ray imaging apparatus according to an exemplary embodiment of the application when the scanning measurement source is in a first position and when the scatterometry source is in a second position.
Fig. 5A shows a perspective view of a scatterometry assembly of an X-ray imaging device of an exemplary embodiment of the present application, and fig. 5B shows a front view of the scatterometry assembly of the X-ray imaging device of an exemplary embodiment of the present application.
Fig. 6 shows a case where the calculated third position does not coincide with the first position, since the plane of symmetry of the projectile does not contain the rotation axis and is perpendicular to the detector surface, according to an exemplary embodiment of the application. Fig. 7 shows a schematic view of a first position, a third position, a plane parallel to the detector surface where the rotation axis lies, and a spatial relationship of the detector surface according to an exemplary embodiment of the application.
Detailed Description
The present application will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments are shown. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the application to those skilled in the art. Like reference numerals refer to like elements throughout the specification and all drawings.
It will be understood that when an element is referred to as being "on" another element, it can be directly on the other element or intervening elements may be present therebetween. In contrast, when an element is referred to as being directly on another element, there are no intervening elements present.
It will be understood that, although the terms "first," "second," "third," etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings herein.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well as "at least one" unless the context clearly indicates otherwise. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.
Further, spatially relative terms such as "under" or "on" and "over" and the like may be used herein to describe one element's relationship to another element as illustrated in the figures. It will be understood that relative terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures. For example, if the device in one of the figures is turned over, elements described as "below" other elements would then be oriented "above" the other elements. The exemplary terms "below" or "beneath" can, therefore, encompass both an orientation of above and below.
As used herein, "about" or "approximately" includes the stated values as well as averages over a range of acceptable deviations for a particular value as determined by one of ordinary skill in the art in view of the ongoing measurements and errors associated with the particular amount of measurements (i.e., limitations of the measurement system).
As used herein, "scan measurement data at a location" means data that a scan measurement source at a location emits X-rays and is measured by a detector, which includes both scan data and scatter data.
As used herein, "scatterometry data at a location" refers to data measured by a scatterometry component and detector at a location.
As used herein, "scatter data at a location" means scatter data extrapolated from data of scatter measurement data at a location, which is included in the "scan measurement data" described above.
As used herein, "scatter corrected scan data" means scan measurement data after the scatter data is removed, i.e., the scan measurement data is scatter corrected.
As used herein, "angle between a source and a plane" refers to the angle between the centerline of the source and the plane.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Fig. 1 shows a schematic perspective view of an X-ray imaging apparatus 1000 according to an exemplary embodiment of the present application.
As shown in FIG. 1, an X-ray imaging apparatus 1000 includes a scanning measurement source 100, a scatterometry assembly 200, a detector 300, a rotation mechanism 400, and a computing assembly 500.
The scanning measurement source 100 is configured to emit X-rays to illuminate an illuminant, wherein the illuminant is substantially symmetrical about an illuminant symmetry plane, in certain exemplary embodiments the X-ray imaging device may be, for example, CBCT, the illuminant may be, for example, a human head, and in certain exemplary embodiments the X-ray imaging device may be, for example, CT, the illuminant may be, for example, a human chest. It should be noted that the scope of the present application is not limited in this respect and includes any X-ray imaging apparatus suitable for use with any generally symmetrical projection subject.
The scatterometry assembly 200 is configured to measure scatter through the projectile, wherein the scatterometry assembly 200 comprises a scatterometry source 210, the scatterometry source 210 configured to emit X-rays to impinge upon the projectile to measure scatter through the projectile. In some exemplary embodiments according to the present application, as shown in FIG. 1, scatterometry assembly 200 further comprises a beam stop 220 (described in detail below with reference to FIGS. 5A, 5B).
Fig. 2 shows a schematic perspective view of the X-ray imaging apparatus of fig. 1 with the rotation mechanism 400 and the calculation assembly 500 and the beam blocker 220 in the scatterometry assembly 200 removed (only the scatterometry source 210 in the scatterometry assembly 200 is shown), and fig. 2 shows the trajectory of movement of the scan measurement source 100 and the scatterometry source 210 (circular dashed line). Fig. 3 shows a top view of the X-ray imaging apparatus of fig. 2 according to an exemplary embodiment of the present application.
The detector 300 is configured to detect X-rays emitted by the scanning measurement source 100 to obtain scanning measurement data of the scanning measurement source 100 and to detect X-rays emitted by the scatterometry source 210 to obtain scatterometry data. In certain exemplary embodiments, the detector 300 may be a two-dimensional planar detector. For example, detector 300 may be a flat panel detector.
The rotation mechanism 400 is configured to rotate the scanning measurement source 100, the detector 300, and the scatterometry device about an axis of rotation in a vertical plane about the projectile, wherein the scanning measurement source 100 and the scatterometry source 210 are disposed to rotate along a same circumferential trajectory in a horizontal plane, the rotation mechanism 400 shown in FIG. 1 is merely exemplary and the application is not limited thereto, and in other embodiments the rotation mechanism 400 may take any other suitable form, such as a floor-standing rotation mechanism. It should be noted that spatial terms such as "vertical", "horizontal" and the like are used herein for the sake of clarity and convenience of description only, and are expressed in terms of spatial relative positional relationships, not limited to "vertical", "horizontal", etc. in a conventional sense, and may also be referred to as "vertical", "horizontal" in some exemplary embodiments, for example, as "horizontal", "vertical" in other exemplary embodiments. Those skilled in the art will appreciate that the rotational axis of the rotational mechanism 400 is oriented perpendicular to the plane in which the scanning measurement source 100 and the scatterometry source 210 rotate about the projectile and parallel to the plane in which the surface of the detector 300 is located. For clarity and convenience of description, in the present exemplary embodiment, a direction in which the rotation axis of the rotation mechanism 400 is located is referred to as a vertical direction, a plane in which the scanning measurement source 100 and the scatterometry source 210 rotate around the projection object is referred to as a horizontal plane, an intersection point of the rotation axis of the rotation mechanism 400 and the horizontal plane in which the scanning measurement source 100 and the scatterometry source 210 rotate around the projection object is referred to as a rotation center (see fig. 3, rotation center O), and the scanning measurement source 100 and the scatterometry source 210 are disposed at the same distance from the rotation center, i.e., a center of a circle. In certain exemplary embodiments according to the present application, the scanning measurement source 100 and the scatterometry source 210 are disposed symmetrically about a plane containing the axis of rotation and perpendicular to the surface of the detector 300. In other words, the line of the scan measurement source 100 and the scatterometry source 210 is parallel to the detector 300 surface, or in a horizontal plane, the line of the midpoint of the line of the scan measurement source 100 and the scatterometry source 210 and the center of rotation (i.e., the center of the circle) is perpendicular to the detector 300 surface. It should be noted that the scope of the present application is not limited in this respect, and that the scanning measurement source 100 and the scatterometry source 210 may be disposed so as not to be symmetrical about a plane that includes the axis of rotation and is perpendicular to the surface of the detector 300.
In some exemplary embodiments according to the present application, the scanning measurement source 100 and the scatterometry source 210 alternately emit X-rays to avoid interference with each other.
Fig. 4 shows a top view of an X-ray imaging apparatus according to an exemplary embodiment of the application when the scanning measurement source is in a first position and when the scatterometry source is in a second position. The calculation component 500 is configured to calculate, based on the scan measurement data of the scan measurement source 100 at a first position P1 on the circumferential track and the scatter measurement data of the scatter measurement source 210 at a second position P2 on the circumferential track, scatter correction scan data at the first position P1, wherein an angle (- θ angle) between the first position P1 and the plane of symmetry of the projectile is equal in magnitude and opposite in direction to an angle (θ angle) between the second position P2 and the plane of symmetry of the projectile. Those skilled in the art will appreciate that the angles to which each of the images obtained by the present X-ray imaging apparatus correspond are known so that reconstruction can be performed.
In some exemplary embodiments according to the present application the X-ray imaging apparatus further comprises a positioning aid configured for positioning the projection object. For example, the positioning aid may be a dental tray. Theoretically, by means of a projection positioning aid, such as a dental tray, etc., and/or by means of an operator's setup, the projection symmetry plane of the projection can be made to comprise the rotation axis and be perpendicular to the surface of the detector 300, where the projection symmetry plane of the projection is set at 0 degrees, whereby the angle of rotation about the clockwise direction is + (or-) and the corresponding angle of rotation about the counterclockwise direction is- (or+). Thus, on the horizontal plane, the intersection line (which becomes the center intersection line) of the plane of symmetry of the projection body and the horizontal plane passes through the rotation center O, that is, the circle center, and the angle at which the center intersection line is located is 0 degrees, so that the angle of rotation around the clockwise direction is + (or-), and the corresponding angle of rotation around the counterclockwise direction is- (or+). As shown, the angle between the first position P1 and the plane of symmetry of the projectile (i.e., the angle of the first position P1 with respect to the center line of intersection on a horizontal plane) is- θ, and the angle between the second position P2 and the plane of symmetry of the projectile (i.e., the angle of the second position P2 with respect to the center line of intersection on a horizontal plane) is θ, that is, the angle between the first position P1 and the plane of symmetry of the projectile is equal in magnitude and opposite in direction to the angle between the second position P2 and the plane of symmetry of the projectile.
In general, since the projectile is substantially symmetrical about the plane of projectile symmetry, the scatter of the scanning measurement source 100 at the first position P1 (-angle θ) and the scatter of the scattering source at the second position P2 (angle θ) are substantially symmetrical. In other words, the effect of scatter experienced by the scanning measurement source 100 when scanning at the first position P1 (-angle θ) can be estimated from the scatterometry data of the second position P2 (angle θ) scatterometry source. Therefore, by utilizing the characteristic that the projection body is substantially symmetrical about the projection body symmetry plane, the X-ray imaging apparatus according to the exemplary embodiment of the present application can obtain scan measurement data corrected for scattering, that is, correct for scattering.
Fig. 5A shows a perspective view of a scatterometry assembly of an X-ray imaging device of an exemplary embodiment of the present application, and fig. 5B shows a front view of the scatterometry assembly of the X-ray imaging device of an exemplary embodiment of the present application.
As shown in fig. 5A, 5B, beam blocker 220 includes a plurality of lead strips 221-225 disposed between scatterometry source 210 and the projectile. Scatterometry source 210 emits X-rays through the plurality of lead strips 221-225 and the projectile to detector 300, enabling scatterometry data to be calculated. It should be noted that the scope of the present application is not limited in this respect, and the scatterometry assembly 200 according to an exemplary embodiment of the present application may be any existing scatterometry device capable of measuring scatterometry data.
In an ideal case, i.e. by means of a projection positioning aid such as a dental tray or the like and/or by means of an operator setting, the projection symmetry plane of the projection contains the rotation axis and is perpendicular to the detector 300 surface, or the position of the projection symmetry plane produces negligible errors. However, in actual operation, a large error may be formed. At this time, it is necessary to calculate the plane of symmetry of the projectile.
In some exemplary embodiments according to the present application, the computing component 500 is further configured to calculate a projection volume symmetry plane, including:
reconstructing the scan measurement data to obtain a reconstructed volume of the projection volume;
the center of gravity of the reconstruction is calculated by,
Wherein, G represents the sum of pixel values of all pixel points of the reconstruction body, G i represents the pixel value of the ith pixel point, x i represents the x component of the ith pixel point, y i represents the y component of the ith pixel point, and z i represents the z component of the ith pixel point;
Determining a plane passing through the center of gravity of the reconstruction, and calculating the plane of symmetry of the reconstruction for all planes passing through the center of gravity of the reconstruction by the following formula
Wherein f (x i,yi,zi) denotes the pixel value of the ith pixel point, f (x i',yi',zi ') denotes the pixel value of the pixel point of the ith pixel point symmetrical about the determined plane, N denotes the total number of pixel points of the whole object for (x i',yi',zi'),f(xi',yi',zi') outside the reconstruction volume equal to zero, wherein i=1 to N/2, and
And determining the symmetry plane of the projection body according to the symmetry plane of the reconstruction body.
Those skilled in the art will recognize from the foregoing that the above approach is a way of violence solving to determine the optimal solution, which has the advantage of being computationally simple. In the actual operation, 2000 faces may be selected for calculation at equal angular intervals, for example, from which an optimal solution is determined.
It will be appreciated by those skilled in the art that the xyz coordinate system utilized in the above method is for descriptive purposes only and is not intended to be limiting in any way.
It should also be noted that the scope of the present application is not limited in this regard and encompasses any other possible method that may be used to determine the plane of symmetry of an illuminant.
In some exemplary embodiments according to the present application, the computing component 500 computes scatter correction scan data at a first position P1 of the scanning measurement source 100 on the circumferential track from the scan measurement data at the first position P1 of the scanning measurement source 100 on the circumferential track and the scatter measurement data at a second position P2 of the scatter measurement source 210 on the circumferential track to obtain scatter correction scan data at the first position P1 includes the computing component 500 computing scatter data at the first position P1 of the scanning measurement source 100 on the circumferential track from the scatter measurement data at the second position P2 of the scatter measurement source 210 on the circumferential track and the computing component 500 subtracting the scatter data at the first position P1 of the scanning measurement source 100 on the circumferential track from the scan measurement data at the first position P1 of the scanning measurement source 100 to obtain scatter correction scan data at the first position P1.
In some exemplary embodiments according to the present application, the calculation assembly 500 calculates scatter data for the scanning measurement source 100 at a first position P1 on the circumferential track from scatter measurement data for the scatter measurement source 210 at a second position P2 on the circumferential track includes the calculation assembly 500 determining a third position, wherein the third position is symmetrical with the second position P2 about the plane of symmetry of the projectile, the calculation assembly 500 flipping scatter measurement data for the scatter measurement source 210 at the second position P2 on the circumferential track about a vertical central axis of the probe 300 to obtain scatter measurement data at the third position, and the calculation assembly 500 calculating scatter data for the scanning measurement source 100 at the first position P1 on the circumferential track based on the first position P1, the third position, and the scatter measurement data at the third position.
In general, since the source at the second position P2 and the detector 300 are mirror symmetric with respect to the plane of symmetry of the scanned object, the scatter data at the third position can be calculated from the scatter measurement data at the second position P2. Specifically, the direction parallel to the plane of the circumferential track is referred to as a horizontal direction, and the calculation component 500 turns the scatterometry data of the scatterometry source 210 at the second position P2 on the circumferential track left and right in the horizontal direction, so as to obtain the scatterometry data at the third position.
It should be noted that, in an ideal case, that is, by an auxiliary positioning tool such as a dental tray, or by setting by an operator, the symmetrical surface of the projection object includes the rotation axis and is perpendicular to the surface of the detector 300, where the first position P1 and the second position P2 are symmetrical with respect to the symmetrical plane of the projection object, and thus the third position coincides with the first position P1.
However, in some cases, the plane of symmetry of the projection does not include the rotation axis and is perpendicular to the surface of the detector 300, where the first position P1 and the second position P2 are not symmetrical about the plane of symmetry of the projection, and the third position is not coincident with the first position P1, where it is necessary to calculate the scattering data of the scanning measurement source 100 at the first position P1. Fig. 6 illustrates a case where the third position is not coincident with the first position according to an exemplary embodiment of the present application. As shown in fig. 6, since the plane of symmetry of the projectile (the dashed line through the projectile in fig. 6) does not include a rotational axis (including the center of rotation O in fig. 6) and is perpendicular to the surface of the detector 300, the first position P1 of the measurement source 100 on the circumferential trajectory and the second position P2 of the scatterometry source 210 on the circumferential trajectory are not symmetrical about the plane of symmetry of the projectile, and the third position P3 is not coincident with the first position P1.
In some exemplary embodiments according to the present application, calculating the scatter data at the first position P1 of the scanning measurement source 100 on the circumferential trajectory based on the scatter measurement data at the first position P1, the third position P3, and the third position P3 includes:
Calculation is based on the following
Fig. 7 shows a schematic view of a first position, a third position, a plane parallel to the detector surface where the rotation axis lies, and a spatial relationship of the detector surface according to an exemplary embodiment of the application. As shown in fig. 7, SAD A denotes a distance from the first position P1 to a plane parallel to the surface of the detector 300 where the rotation axis is located, AID denotes a distance from the rotation axis to the surface of the detector 300, SAD B denotes a distance from the third position P3 to a plane parallel to the surface of the detector 300 where the rotation axis is located, F denotes corrected scattering data, F denotes scattering data corresponding to the third position P3, x denotes a horizontal coordinate on the detector 300 corresponding to the third position P3, Δx denotes a difference between the distance from the first position P1 to the rotation axis and the distance from the third position P3 to the rotation axis, and y denotes a vertical coordinate on the detector 300 corresponding to the third position P3.
In some exemplary embodiments according to the present application, the scanning measurement source 100 and the scatterometry source 210 are disposed on either side of a plane containing the axis of rotation and perpendicular to the surface of the detector 300.
In certain exemplary embodiments according to the present application, the scanning measurement source 100 and the scatterometry source 210 are disposed symmetrically about a plane containing the axis of rotation and perpendicular to the surface of the detector 300.
In certain exemplary embodiments according to the present application, the scanning measurement source 100 and the scatterometry source 210 are disposed at an acute angle to a plane containing the axis of rotation and perpendicular to the surface of the detector 300. For example, in some embodiments, the scanning measurement source 100 and the scatterometry source 210 are disposed at an angle of less than 30 degrees from a plane containing the axis of rotation and perpendicular to the surface of the detector 300.
In some exemplary embodiments according to the present application, the scanning measurement source 100 is the same source as the scatterometry source 210. It should be noted that according to this exemplary embodiment, each angle needs to be scanned twice (once with beam blocker 220, source as scatterometry source 210; and the other time with beam blocker 220 removed, as scanning measurement source 100).
In some exemplary embodiments according to the present application, the scanning measurement source 100 (i.e., the scatterometry source 210) is disposed through a plane that contains the axis of rotation and is perpendicular to the surface of the detector 300. In other words, the centerline of the scanning measurement source 100 (i.e., the scatterometry source 210) is perpendicular to the plane of the surface of the detector 300 and perpendicular to and intersects the axis of rotation.
According to another aspect of the present application, there is provided a method of imaging a subject with an X-ray imaging apparatus, for example, the X-ray imaging apparatus 1000. Wherein the projectile is substantially symmetrical about a plane of projectile symmetry. Referring to fig. 1-5 b, an X-ray imaging apparatus includes a scanning measurement source 100, a scatterometry assembly 200, a detector 300, a rotation mechanism 400, and a calculation assembly 500, wherein the scatterometry assembly 200 is configured to measure scatter through an object, the scatterometry assembly 200 includes a scatterometry source 210 configured to emit X-rays to the object to measure scatter through the object, and the rotation mechanism 400 is configured to rotate the scanning measurement source 100, the detector 300, and the scatterometry device about an axis of rotation in a vertical plane about the object, wherein the scanning measurement source 100 and the scatterometry source 210 are disposed to rotate on a horizontal plane along a same circumferential trajectory. The method includes placing an illuminant, emitting X-rays by the scanning measurement source 100 to illuminate the illuminant, emitting X-rays by the scatterometry source 210 to illuminate the illuminant, detecting the X-rays emitted by the scanning measurement source 100 by the detector 300 to obtain scan measurement data of the scanning measurement source 100, and detecting the X-rays emitted by the scatterometry source 210 to obtain scatterometry data, and calculating, by the calculation component 500, from the scan measurement data of the scanning measurement source 100 at a first position P1 on a circumferential track and the scatter measurement data of the scatterometry source 210 at a second position P2 on the circumferential track, to obtain scatter correction scan data at the first position P1, wherein an angle between the first position P1 and the plane of symmetry of the illuminant is equal in magnitude and opposite in direction to an angle between the second position P2 and the plane of symmetry of the illuminant.
As previously described, since the projectile is substantially symmetrical about the plane of projectile symmetry, the scatter of the scanning measurement source 100 at the first position P1 (-angle θ) and the scatter of the scattering source at the second position P2 (angle θ) are substantially symmetrical. In other words, the effect of scatter experienced by the scanning measurement source 100 when scanning at the first position P1 (-angle θ) can be estimated from the scatterometry data of the second position P2 (angle θ) scatterometry source. Therefore, by utilizing the characteristic that the projection object is substantially symmetrical about the plane of symmetry of the projection object, the method of imaging the projection object using the X-ray imaging apparatus according to the exemplary embodiment of the present application can obtain scan measurement data corrected for scattering, that is, corrected for scattering.
As will be appreciated by those skilled in the art, since the method of imaging an object with an X-ray imaging device generally corresponds to the X-ray imaging device described hereinbefore with reference to fig. 1-7, the repetition is not repeated here and hereinafter for the sake of brevity.
In some exemplary embodiments according to the present application, the method further comprises calculating, by the calculation component 500, a projection symmetry plane, comprising:
reconstructing the scan measurement data to obtain a reconstructed volume of the projection volume;
the center of gravity of the reconstruction is calculated by,
Wherein, G represents the sum of pixel values of all pixel points of the reconstruction body, G i represents the pixel value of the ith pixel point, x i represents the x component of the ith pixel point, y i represents the y component of the ith pixel point, and z i represents the z component of the ith pixel point;
Determining a plane passing through the center of gravity of the reconstruction, and calculating the plane of symmetry of the reconstruction for all planes passing through the center of gravity of the reconstruction by the following formula
Wherein f (x i,yi,zi) denotes the pixel value of the ith pixel point, f (x i',yi',zi ') denotes the pixel value of the pixel point of the ith pixel point symmetrical about the determined plane, N denotes the total number of pixel points of the whole object for (x i',yi',zi'),f(xi',yi',zi') outside the reconstruction volume equal to zero, wherein i=1 to N/2, and
And determining the symmetry plane of the projection body according to the symmetry plane of the reconstruction body.
In some exemplary embodiments according to the present application, calculating, by the calculation component 500, from the scan measurement data of the scan measurement source 100 at the first position P1 on the circumferential track and the scatter measurement data of the scatter measurement source 210 at the second position P2 on the circumferential track to obtain scatter correction scan data at the first position P1 includes calculating scatter data of the scan measurement source 100 at the first position P1 on the circumferential track from the scatter measurement data of the scatter measurement source 210 at the second position P2 on the circumferential track, and subtracting the scatter data of the scan measurement source 100 at the first position P1 on the circumferential track from the scan measurement data of the scan measurement source 100 at the first position P1 on the circumferential track to obtain scatter correction scan data at the first position P1.
In some exemplary embodiments according to the present application, calculating scatter data for the scanning measurement source 100 at a first position P1 on the circumferential track from scatter measurement data for the scatter measurement source 210 at a second position P2 on the circumferential track includes determining a third position, wherein the third position is symmetrical with respect to the second position P2 about the plane of symmetry of the projector, flipping scatter measurement data for the scatter measurement source 210 at the second position P2 on the circumferential track about a vertical central axis of the detector 300 to obtain scatter measurement data at the third position, and calculating scatter data for the scanning measurement source 100 at the first position P1 on the circumferential track based on the scatter measurement data at the first position P1, the third position, and the third position.
In some exemplary embodiments according to the application, calculating the scatter data of the scanning measurement source 100 at the first position P1 on the circumferential trajectory based on the scatter measurement data at the first position P1, the third position and the third position comprises:
Calculation is based on the following
Wherein SAD A represents the distance from the first position P1 to the plane parallel to the surface of the detector 300 where the rotation axis is located, AID represents the distance from the rotation axis to the surface of the detector 300, SAD B represents the distance from the third position to the plane parallel to the surface of the detector 300 where the rotation axis is located, F represents the corrected scatter data, F represents the scatter data corresponding to the third position, x represents the horizontal coordinate on the detector 300 corresponding to the third position, Δx represents the difference between the distance from the first position P1 to the rotation axis and the distance from the third position to the rotation axis, and y represents the vertical coordinate on the detector 300 corresponding to the third position.
According to another aspect of the present application, there is provided a method of obtaining scatter corrected scan data comprising obtaining scan measurement data of an illuminant, wherein the illuminant is substantially symmetric about an illuminant plane of symmetry, obtaining scatter measurement data of the illuminant, and calculating from the scan measurement data at a first location and the scatter measurement data at a second location to obtain scatter corrected scan data at the first location, wherein the first location and the second location are symmetric about the illuminant plane of symmetry.
It can be seen that the foregoing method of imaging a projection volume with an X-ray imaging apparatus is one exemplary embodiment of a method of obtaining scatter correction scan data in accordance with the present aspect. It should be noted that the scan measurement data of the obtained projection object and/or the scatter measurement data of the obtained projection object according to the present aspect may be obtained by any means, and are not limited to being obtained by imaging the projection object with the aforementioned X-ray imaging apparatus. For example, scan measurement data of an obtained projection and/or scatter measurement data of an obtained projection according to the present aspect may be obtained by two or more devices.
With the method of this aspect, since the projectile is substantially symmetrical about the projectile symmetry plane, the scatterometry data at the first location is substantially symmetrical with the scatterometry data at the second location. Therefore, by utilizing the characteristic that the projection body is substantially symmetrical about the projection body symmetry plane, the method of obtaining scatter-corrected scan data according to the exemplary embodiment of the present application can obtain scatter-corrected scan measurement data, that is, correct for scatter.
Since the method of obtaining scatter correction scan data according to the present aspect substantially corresponds to the X-ray imaging apparatus and the method of imaging an object with the X-ray imaging apparatus described hereinbefore with reference to fig. 1 to 7, repeated matters are not repeated here and hereinafter for the sake of brevity.
In some exemplary embodiments according to the present application, the method further comprises calculating a plane of symmetry of the projectile, comprising:
reconstructing the scan measurement data to obtain a reconstructed volume of the projection volume;
the center of gravity of the reconstruction is calculated by,
Wherein, G represents the sum of pixel values of all pixel points of the reconstruction body, G i represents the pixel value of the ith pixel point, x i represents the x component of the ith pixel point, y i represents the y component of the ith pixel point, and z i represents the z component of the ith pixel point;
Determining a plane passing through the center of gravity of the reconstruction, and calculating the plane of symmetry of the reconstruction for all planes passing through the center of gravity of the reconstruction by the following formula
Wherein f (x i,yi,zi) denotes the pixel value of the ith pixel point, f (x i',yi',zi ') denotes the pixel value of the pixel point of the ith pixel point symmetrical about the determined plane, N denotes the total number of pixel points of the whole object for (x i',yi',zi'),f(xi',yi',zi') outside the reconstruction volume equal to zero, wherein i=1 to N/2, and
And determining the symmetry plane of the projection body according to the symmetry plane of the reconstruction body.
In some exemplary embodiments according to the present application, calculating from the scan measurement data at the first location and the scatter measurement data at the second location to obtain scatter correction scan data at the first location includes calculating scatter data at the first location from the scatter measurement data at the second location and subtracting the scatter data at the first location from the scan measurement data at the first location to obtain scatter correction scan data at the first location.
In some exemplary embodiments according to the present application, calculating scatter data at a first location from scatter measurement data at a second location includes determining a third location, wherein the third location is symmetrical with respect to the second location about an illuminant symmetry plane, flipping scatter measurement data at the second location about a central axis of a detector that obtained scatter measurement data to obtain scatter measurement data at the third location, wherein the central axis of the detector is substantially parallel to or included in the illuminant symmetry plane, and calculating scatter data at the first location based on the scatter measurement data at the first location, the third location, and the third location.
In some exemplary embodiments according to the present application, calculating scatter data at the first location based on the scatter measurement data at the first location, the third location, and the third location comprises:
Calculation is based on the following
Wherein SAD A represents the distance from the first position to the plane parallel to the detector surface where the rotation axis is located, AID represents the distance from the rotation axis to the detector surface, SAD B represents the distance from the third position to the plane parallel to the detector surface where the rotation axis is located, F represents the corrected scatter data, F represents the scatter data corresponding to the third position, x represents the horizontal coordinate on the detector corresponding to the third position, deltax represents the difference between the distance from the first position to the rotation axis and the distance from the third position to the rotation axis, and y represents the vertical coordinate on the detector corresponding to the third position.
According to yet another aspect of the present application, there is provided an X-ray imaging apparatus comprising a scan measurement source configured to emit X-rays for irradiation to an irradiator, wherein the irradiator is substantially symmetrical about a plane of symmetry of the irradiator, a scatter measurement assembly configured to measure scatter passing through the irradiator, a detector configured to detect X-rays emitted by the scan measurement source to obtain scan measurement data of the scan measurement source, and to detect X-rays emitted by the scatter measurement assembly to obtain scatter measurement data, a rotation mechanism configured to rotate the scan measurement source, the detector and the scatter measurement device about an axis of rotation in a vertical plane about the irradiator, and a calculation assembly configured to calculate scatter correction scan data at a first location from the scan measurement data at the first location and the scatter measurement data at a second location, wherein the first location and the second location are symmetrical about the plane of symmetry of the irradiator.
With the X-ray imaging apparatus of the present aspect, since the projection body is substantially symmetrical with respect to the plane of symmetry of the projection body, the scatter data at the first position and the scatter measurement data at the second position are substantially symmetrical. Therefore, by utilizing the characteristic that the projection body is substantially symmetrical about the projection body symmetry plane, the X-ray imaging apparatus according to the exemplary embodiment of the present application can obtain scan measurement data corrected for scattering, that is, correct for scattering.
Since the X-ray imaging apparatus according to the present aspect corresponds substantially to the X-ray imaging apparatus described hereinbefore with reference to fig. 1 to 7, repeated matters are not repeated here and hereinafter for the sake of brevity.
In certain exemplary embodiments according to the present application, the scatterometry assembly comprises a scatterometry source configured to emit X-rays to impinge upon the projectile so as to measure scatter through the projectile.
In some exemplary embodiments according to the application, the scatterometry assembly further comprises a beam blocker comprising a plurality of lead strips disposed between the scatterometry source and the projectile.
In certain exemplary embodiments according to the present application, the scanning measurement source and the scatterometry source are disposed on opposite sides of a plane containing the axis of rotation and perpendicular to the detector surface.
In certain exemplary embodiments according to the present application, the scanning measurement source and the scatterometry source are disposed symmetrically about a plane containing the axis of rotation and perpendicular to the detector surface.
In certain exemplary embodiments according to the present application, the scan measurement source and the scatter measurement source are disposed at an acute angle to a plane containing the axis of rotation and perpendicular to the detector surface.
In certain exemplary embodiments according to the present application, the scanning measurement source and the scatterometry source are the same source. It should be noted that according to this exemplary embodiment, each angle needs to be scanned twice (once with the beam blocker, the source being the scatterometry source; and the beam blocker being removed another time as the scanned metrology source).
In certain exemplary embodiments according to the present application, the scanning measurement source is disposed through a plane containing the axis of rotation and perpendicular to the detector surface.
In some exemplary embodiments according to the present application, the X-ray imaging apparatus further comprises a positioning aid configured to position the projection object.
In certain exemplary embodiments according to the present application, the positioning aid comprises a dental tray.
While certain exemplary embodiments and examples have been described herein, other embodiments and modifications will be apparent from the above description. Various changes and modifications may be made to the embodiments of the application by those skilled in the art without departing from the teachings of the application. Accordingly, the inventive concept is not to be limited to the embodiments but is to be defined by the appended claims and the wide range of obvious modifications and equivalent arrangements.
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