Method and device for generating light source position
阅读说明：本技术 一种生成光源位置的方法和装置 (Method and device for generating light source position ) 是由 程志威 吕元媛 周少华 于 2021-07-20 设计创作，主要内容包括：本发明公开了一种生成光源位置的方法和装置,所述方法包括：控制所述光源发光,所述光源所发出的光能够照射到所述多个标定物,且能够在所述平板探测器上形成与多个标定物一一对应的多个第一投影区域；控制所述平板探测器获取多个第一投影区域的三维坐标；基于所述多个标定物之间的相对距离、以及所述多个第一投影区域的三维坐标,生成所述光源的三维坐标,其中,第一投影区域的三维坐标和光源的三维坐标均基于相同的三维坐标系。该方法能够生成光源的坐标。(The invention discloses a method and a device for generating a light source position, wherein the method comprises the following steps: controlling the light source to emit light, wherein the light emitted by the light source can irradiate the plurality of calibration objects and can form a plurality of first projection areas corresponding to the plurality of calibration objects one to one on the flat panel detector; controlling the flat panel detector to acquire three-dimensional coordinates of a plurality of first projection areas; and generating the three-dimensional coordinates of the light source based on the relative distances among the calibration objects and the three-dimensional coordinates of the first projection areas, wherein the three-dimensional coordinates of the first projection areas and the three-dimensional coordinates of the light source are based on the same three-dimensional coordinate system. The method is capable of generating coordinates of the light source.)
1. A method of generating a light source position for a tomosynthesis system, the tomosynthesis system comprising: the light source (1) and the flat panel detector (2), the light source (1) is located above the flat panel detector (2) and can move relative to the flat panel detector (2), a plurality of calibration objects (3) are arranged between the light source (1) and the flat panel detector (2), the positions of different calibration objects (3) are different, and the position of each calibration object (3) relative to the flat panel detector (2) is fixed; the method is characterized by comprising the following steps:
controlling the light source (1) to emit light, wherein the light emitted by the light source (1) can be irradiated to the plurality of calibration objects (3), and a plurality of first projection areas (21) corresponding to the plurality of calibration objects (3) one by one can be formed on the flat panel detector (2);
controlling the flat panel detector (2) to acquire three-dimensional coordinates of a plurality of first projection areas (21);
generating three-dimensional coordinates of the light source (1) based on the relative distances between the plurality of calibration objects (3) and the three-dimensional coordinates of the plurality of first projection areas (21), wherein the three-dimensional coordinates of the first projection areas (21) and the three-dimensional coordinates of the light source (1) are based on the same three-dimensional coordinate system.
2. The method of generating a light source position of claim 1,
the number of the calibration objects (3) is 4, the 4 calibration objects (3) are respectively positioned on four outer side surfaces of a square body, the four outer side surfaces are perpendicular to the flat panel detector (2), and each calibration object (3) comprises a plurality of spheres (32) arranged along a circular ring;
the "controlling the light source (1) to emit light, the light emitted by the light source (1) being capable of illuminating the plurality of calibration objects (3), and being capable of forming a plurality of first projection regions (21) on the flat panel detector (2) in one-to-one correspondence with the plurality of calibration objects (3)" specifically includes: controlling the light source (1) to emit light, wherein the emitted light can irradiate all spheres (32) in each calibration object (3), and each sphere (32) can form a second projection area (22) on the flat panel detector (2); the plurality of second projection areas (22) corresponding to each calibration object (3) are arranged along an elliptic line or a line segment;
the step of controlling the flat panel detector (2) to acquire the three-dimensional coordinates of the plurality of first projection regions (21) specifically comprises the steps of: controlling the flat panel detector (2) to obtain a projection picture, obtaining three-dimensional coordinates of a plurality of second projection areas (22) corresponding to each calibration object (3) based on the projection picture, and obtaining central points of ellipses or line segments corresponding to the plurality of second projection areas (22), wherein the three-dimensional coordinates of the first projection area (21) are the three-dimensional coordinates of the central points;
said "generating three-dimensional coordinates of said light source (1) based on the relative distances between said plurality of calibration objects (3) and the three-dimensional coordinates of said plurality of first projection areas (21)" particularly comprises: and generating the three-dimensional coordinates of the light source (1) based on the relative distances between the corresponding circle centers of the four calibration objects (3) and the three-dimensional coordinates of the central points corresponding to the four first projection areas (21).
3. The method of generating a light source position of claim 2,
an XOY plane of the three-dimensional coordinate system is a plane where the flat panel detector (2) is located, a Z axis is perpendicular to the XOY plane, and the forward direction of the Z axis is the direction of the flat panel detector (2) towards the light source (1);
the step of controlling the light source (1) to emit light specifically comprises the following steps: controlling the light source (1) to emit light, wherein the light source (1) is positioned in a space enclosed by four outer side faces;
the generating of the three-dimensional coordinates of the light source (1) based on the relative distances between the centers of circles corresponding to the four calibration objects (3) and the three-dimensional coordinates of the center point corresponding to the four first projection areas (21) specifically includes:
the four circle centers are respectively AF、AB、ALAnd ARCenter of a circle AFCorresponding elliptical line is EFOval line EFIs A 'from the center point of'F(ii) a Circle center ABCorresponding elliptical line is EBOval line EBIs A 'from the center point of'B(ii) a Circle center ALCorresponding elliptical line is ELOval line ELIs A 'from the center point of'L(ii) a Circle center ARCorresponding elliptical line is EROval line ERIs A 'from the center point of'R(ii) a Wherein A isFAnd ABAre two opposite outer side surfaces which respectively correspond to circle centers ALAnd ARThe two opposite outer side surfaces respectively correspond to circle centers, and the three-dimensional coordinate of the light source (1) is;
wherein, XlIs an elliptical line ELCenter point A 'of'LX coordinate value of (2), RlIs an elliptical line ELIs the square root of the ratio of the major axis to the minor axis, XrIs an elliptical line ERCenter point A 'of'RX coordinate value of，RrIs an elliptical line ERThe square root of the ratio of the major axis to the minor axis of (a);
wherein, YfIs an elliptical line EFCenter point A 'of'FX coordinate value of (2), RfIs an elliptical line EFSquare root of the ratio of major axis to minor axis of (a), YbIs an elliptical line EBCenter point A 'of'BX coordinate value of (2), RbIs an elliptical line EbThe square root of the ratio of the major axis to the minor axis of (a);
Z0＝AFAL·A'FA'R·A'BA'L/AFAR/(A'FA'R-A'BA'L) Wherein A isFALIs represented by AFAnd ALOf a'FA′RRepresents A'FAnd A'ROf a'BA′LRepresents A'BAnd A'LA distance between A and AFARIs represented by AFAnd ARThe distance between them.
4. The method of generating a light source position of claim,
an XOY plane of the three-dimensional coordinate system is a plane where the flat panel detector (2) is located, a Z axis is perpendicular to the XOY plane, and the forward direction of the Z axis is the direction of the flat panel detector (2) towards the light source (1);
the generating of the three-dimensional coordinates of the light source (1) based on the relative distances between the centers of circles corresponding to the four calibration objects (3) and the three-dimensional coordinates of the center point corresponding to the four first projection areas (21) specifically includes:
the four circle centers are respectively AF、AB、ALAnd ARCenter of a circle AFCorresponding elliptical line is EFOval line EFIs A 'from the center point of'F(ii) a Circle center ABCorresponding elliptical line is EBOval and ellipticalRound wire EBIs A 'from the center point of'B(ii) a Circle center ALCorresponding elliptical line is ELOval line ELIs A 'from the center point of'L(ii) a Circle center ARCorresponding elliptical line is EROval line ERIs A 'from the center point of'R(ii) a Wherein A isFAnd ABAre two opposite outer side surfaces which respectively correspond to circle centers ALAnd ARThe two opposite outer side surfaces are respectively corresponding to circle centers;
the step of controlling the light source (1) to emit light specifically comprises the following steps: controlling the light source (1) to emit light, wherein the light source (1) is positioned at the circle center AROutside the outer side surface and at the circle center AFAnd the center of a circle ABBetween the corresponding planes of the two outer side surfaces;
the three-dimensional coordinate of the light source (1) is (X)0,Y0,Z0) Wherein:
wherein, XlIs an elliptical line ELCenter point A 'of'LX coordinate value of (2), RlIs an elliptical line ELIs the square root of the ratio of the major axis to the minor axis, XrIs an elliptical line ERCenter point A 'of'RX coordinate value of (2), RrIs an elliptical line ERThe square root of the ratio of the major axis to the minor axis of (a);
wherein, YfIs an elliptical line EFCenter point A 'of'FX coordinate value of (2), RfIs an elliptical line EFSquare root of the ratio of major axis to minor axis of (a), YbIs an elliptical line EBCenter point A 'of'BX coordinate value of (2), RbIs an elliptical line EbThe square root of the ratio of the major axis to the minor axis of (a);
Z0＝AFAL·A'FA'R·A'BA'L/AFAR/(A'FA'R-A'BA'L) Wherein A isFALIs represented by AFAnd ALOf a'FA′RRepresents A'FAnd A'ROf a'BA′LRepresents A'BAnd A'LA distance between A and AFARIs represented by AFAnd ARThe distance between them.
5. The method of generating a light source position according to claim 2, wherein the "obtaining three-dimensional coordinates of the plurality of second projection regions (22) corresponding to each calibration object (3) based on the projection picture" specifically comprises:
improving the contrast of the projection picture by using a dynamic range compression algorithm, extracting the edge of the projection picture, and performing expansion processing on the edge; obtaining a plurality of outlines corresponding to each calibration object (3) from the projection picture;
the step of acquiring three-dimensional coordinates of center points of elliptical lines corresponding to the plurality of second projection regions (22) specifically includes: and fitting the plurality of profiles by using a least square method to obtain an elliptic line, and acquiring the three-dimensional coordinates of the central point of the elliptic line.
6. An apparatus for generating a light source position for a tomosynthesis system, the tomosynthesis system comprising: the light source (1) and the flat panel detector (2), the light source (1) is located above the flat panel detector (2) and can move relative to the flat panel detector (2), a plurality of calibration objects (3) are arranged between the light source (1) and the flat panel detector (2), the positions of different calibration objects (3) are different, and the position of each calibration object (3) relative to the flat panel detector (2) is fixed; the system is characterized by comprising the following modules:
the light emitting module is used for controlling the light source (1) to emit light, the light emitted by the light source (1) can be irradiated to the calibration objects (3), and a plurality of first projection areas (21) corresponding to the calibration objects (3) one by one can be formed on the flat panel detector (2);
the parameter acquisition module is used for controlling the flat panel detector (2) to acquire three-dimensional coordinates of a plurality of first projection areas (21);
a control module for generating three-dimensional coordinates of the light source (1) based on the relative distances between the plurality of calibration objects (3) and the three-dimensional coordinates of the plurality of first projection areas (21), wherein the three-dimensional coordinates of the first projection areas (21) and the three-dimensional coordinates of the light source (1) are based on the same three-dimensional coordinate system.
7. The apparatus for generating a position of a light source according to claim 1,
the number of the calibration objects (3) is 4, the 4 calibration objects (3) are respectively positioned on four outer side surfaces of a square body, the four outer side surfaces are perpendicular to the flat panel detector (2), and each calibration object (3) comprises a plurality of spheres (32) arranged along a circular ring;
the light emitting module is further configured to: controlling the light source (1) to emit light, wherein the emitted light can irradiate all spheres (32) in each calibration object (3), and each sphere (32) can form a second projection area (22) on the flat panel detector (2); the plurality of second projection areas (22) corresponding to each calibration object (3) are arranged along an elliptic line or a line segment;
the parameter acquisition module is further configured to: controlling the flat panel detector (2) to obtain a projection picture, obtaining three-dimensional coordinates of a plurality of second projection areas (22) corresponding to each calibration object (3) based on the projection picture, and obtaining central points of ellipses or line segments corresponding to the plurality of second projection areas (22), wherein the three-dimensional coordinates of the first projection area (21) are the three-dimensional coordinates of the central points;
the control module is further configured to: and generating the three-dimensional coordinates of the light source (1) based on the relative distances of the circle centers of the diameters of the circular rings corresponding to the four calibration objects and the three-dimensional coordinates of the central points corresponding to the four first projection areas (21).
8. The apparatus for generating a position of a light source according to claim 7,
an XOY plane of the three-dimensional coordinate system is a plane where the flat panel detector (2) is located, a Z axis is perpendicular to the XOY plane, and the forward direction of the Z axis is the direction of the flat panel detector (2) towards the light source (1);
the light emitting module is further configured to: controlling the light source (1) to emit light, wherein the light source (1) is positioned in a space enclosed by four outer side faces;
the parameter acquisition module is further configured to:
the four circle centers are respectively AF、AB、ALAnd ARCenter of a circle AFCorresponding elliptical line is EFOval line EFIs A 'from the center point of'F(ii) a Circle center ABCorresponding elliptical line is EBOval line EBIs A 'from the center point of'B(ii) a Circle center ALCorresponding elliptical line is ELOval line ELIs A 'from the center point of'L(ii) a Circle center ARCorresponding elliptical line is EROval line ERIs A 'from the center point of'R(ii) a Wherein A isFAnd ABAre two opposite outer side surfaces which respectively correspond to circle centers ALAnd ARThe two opposite outer side surfaces respectively correspond to circle centers, and the three-dimensional coordinate of the light source (1) is;
wherein, XlIs an elliptical line ELCenter point A 'of'LX coordinate value of (2), RlIs an elliptical line ELIs the square root of the ratio of the major axis to the minor axis, XrIs an elliptical line ERCenter point A 'of'RX coordinate value of (2), RrIs an elliptical line ERThe square root of the ratio of the major axis to the minor axis of (a);
wherein, YfIs an elliptical line EFCenter point A 'of'FX coordinate value of (2), RfIs an elliptical line EFSquare root of the ratio of major axis to minor axis of (a), YbIs an elliptical line EBCenter point A 'of'BX coordinate value of (2), RbIs an elliptical line EbThe square root of the ratio of the major axis to the minor axis of (a);
Z0＝AFAL·A'FA'R·A'BA'L/AFAR/(A'FA'R-A'BA'L) Wherein A isFALIs represented by AFAnd ALOf a'FA′RRepresents A'FAnd A'ROf a'BA′LRepresents A'BAnd A'LA distance between A and AFARIs represented by AFAnd ARThe distance between them.
9. The apparatus for generating a position of a light source according to claim 7,
an XOY plane of the three-dimensional coordinate system is a plane where the flat panel detector (2) is located, a Z axis is perpendicular to the XOY plane, and the forward direction of the Z axis is the direction of the flat panel detector (2) towards the light source (1);
the control module is further configured to:
the four circle centers are respectively AF、AB、ALAnd ARCenter of a circle AFCorresponding elliptical line is EFOval line EFIs A 'from the center point of'F(ii) a Circle center ABCorresponding elliptical line is EBOval line EBIs A 'from the center point of'B(ii) a Circle center ALCorresponding elliptical line is ELOval line ELIs A 'from the center point of'L(ii) a Circle center ARCorresponding elliptical line is EROval line ERIs A 'from the center point of'R(ii) a Wherein A isFAnd ABAre two opposite outer side surfaces which respectively correspond to circle centers ALAnd ARThe two opposite outer side surfaces are respectively corresponding to circle centers;
the step of controlling the light source (1) to emit light specifically comprises the following steps: controlling the light source (1) to emit light, wherein the light source (1) is positioned at the circle center AROn the outer side ofIs at the center of a circle AFAnd the center of a circle ABBetween the corresponding planes of the two outer side surfaces;
the three-dimensional coordinate of the light source (1) is (X)0,Y0,Z0) Wherein:
wherein, XlIs an elliptical line ELCenter point A 'of'LX coordinate value of (2), RlIs an elliptical line ELIs the square root of the ratio of the major axis to the minor axis, XrIs an elliptical line ERCenter point A 'of'RX coordinate value of (2), RrIs an elliptical line ERThe square root of the ratio of the major axis to the minor axis of (a);
wherein, YfIs an elliptical line EFCenter point A 'of'FX coordinate value of (2), RfIs an elliptical line EFSquare root of the ratio of major axis to minor axis of (a), YbIs an elliptical line EBCenter point A 'of'BX coordinate value of (2), RbIs an elliptical line EbThe square root of the ratio of the major axis to the minor axis of (a);
Z0＝AFAL·A'FA'R·A'BA'L/AFAR/(A'FA'R-A'BA'L) Wherein A isFALIs represented by AFAnd ALOf a'FA′RRepresents A'FAnd A'ROf a'BA′LRepresents A'BAnd A'LA distance between A and AFARIs represented by AFAnd ARThe distance between them.
10. The apparatus for generating a position of a light source according to claim 7, wherein the parameter obtaining module is further configured to:
improving the contrast of the projection picture by using a dynamic range compression algorithm, extracting the edge of the projection picture, and performing expansion processing on the edge; obtaining a plurality of outlines corresponding to each calibration object (3) from the projection picture;
the parameter acquisition module is further configured to: and fitting the plurality of profiles by using a least square method to obtain an elliptic line, and acquiring the three-dimensional coordinates of the central point of the elliptic line.
Technical Field
The present invention relates to the field of medical imaging, and in particular, to a method and apparatus for generating a light source position.
Background
A Tomosynthesis system (Tomosynthesis) based on a flat panel detector has a wide application in the field of medical images, and is similar to conventional CT (Computed Tomography), CBCT (Cone beam CT), and the like, and the basic principle thereof is as shown in fig. 1, when in use, a light source 1 (e.g., an X-ray tube, and the like) is located at different positions (i.e., a position a, a position B, a position C, and the like in fig. 1), and emits rays and the like to an object (e.g., a body of a patient, and the like) at each position, and the flat panel detector can project corresponding to a plurality of positions of the object, so that an original three-dimensional slice image of the object can be reconstructed according to projection data and geometric structure information. Compared with the traditional DR (direct digital Radiography) fluoroscopy, the tomosynthesis system has the advantages of higher image quality, higher contrast and the like, and in addition, the tomosynthesis system also has the advantages of simple structure, lower cost and good diagnosis effect, so that the equipment has wide application value.
Here, in the process of reconstructing the original three-dimensional slice image of the object, it is required to know the accurate three-dimensional coordinates of the light source 1 and the flat panel detector, and in practice, the flat panel detector is usually fixed, and the light source 1 is moving, and it can be understood that although the three-dimensional coordinate C1 of the light source 1 is planned in advance, there is an error between the actual three-dimensional coordinate C2 and the three-dimensional coordinate C1 of the light source 1 due to mechanical error, vibration, and the like, and the error may affect the three-dimensional slice image.
Therefore, how to obtain the actual three-dimensional coordinates of the light source 1 becomes a problem to be solved.
Disclosure of Invention
In view of the above, the present invention provides a method and apparatus for generating a position of a light source.
In order to achieve the purpose, the technical scheme of the invention is realized as follows: a method of generating a light source position for a tomosynthesis system, the tomosynthesis system comprising: the light source is positioned above the flat panel detector and can move relative to the flat panel detector, a plurality of calibration objects are arranged between the light source and the flat panel detector, the positions of different calibration objects are different, and the position of each calibration object relative to the flat panel detector is fixed; the method comprises the following steps: controlling the light source to emit light, wherein the light emitted by the light source can irradiate the plurality of calibration objects and can form a plurality of first projection areas corresponding to the plurality of calibration objects one to one on the flat panel detector; controlling the flat panel detector to acquire three-dimensional coordinates of a plurality of first projection areas; and generating the three-dimensional coordinates of the light source based on the relative distances among the calibration objects and the three-dimensional coordinates of the first projection areas, wherein the three-dimensional coordinates of the first projection areas and the three-dimensional coordinates of the light source are based on the same three-dimensional coordinate system.
Furthermore, the number of the calibration objects is 4, the 4 calibration objects are respectively positioned on four outer side surfaces of a square body, the four outer side surfaces are perpendicular to the flat panel detector, and each calibration object comprises a plurality of spheres arranged along a circular ring; the step of controlling the light source to emit light, wherein the light emitted by the light source can be irradiated to the plurality of calibration objects, and a plurality of first projection areas corresponding to the plurality of calibration objects one to one can be formed on the flat panel detector specifically includes: controlling the light source to emit light, wherein the emitted light can irradiate all spheres in each calibration object, and each sphere can form a second projection area on the flat panel detector; the plurality of second projection areas corresponding to each calibration object are arranged along an elliptic line or a line segment; the step of controlling the flat panel detector to acquire the three-dimensional coordinates of the plurality of first projection regions specifically includes: controlling the flat panel detector to obtain a projection picture, obtaining three-dimensional coordinates of a plurality of second projection areas corresponding to each calibration object based on the projection picture, and obtaining central points of elliptic lines or line segments corresponding to the plurality of second projection areas, wherein the three-dimensional coordinates of the first projection area are the three-dimensional coordinates of the central points; the "generating three-dimensional coordinates of the light source based on the relative distances between the plurality of calibration objects and the three-dimensional coordinates of the plurality of first projection regions" specifically includes: and generating the three-dimensional coordinates of the light source based on the relative distances between the corresponding circle centers of the four calibration objects and the three-dimensional coordinates of the central points corresponding to the four first projection areas.
Further, the XOY plane of the three-dimensional coordinate system is a flat panel probeThe Z axis of the plane where the detector is located is vertical to the XOY plane, and the forward direction of the Z axis is the direction of the flat panel detector towards the light source; the "controlling the light source to emit light" specifically includes: controlling the light source to emit light, wherein the light source is positioned in a space enclosed by the four outer side faces; the "generating the three-dimensional coordinates of the light source based on the relative distances between the circle centers corresponding to the four calibration objects and the three-dimensional coordinates of the center points corresponding to the four first projection areas" specifically includes: the four circle centers are respectively AF、AB、ALAnd ARCenter of a circle AFCorresponding elliptical line is EFOval line EFIs A 'from the center point of'F(ii) a Circle center ABCorresponding elliptical line is EBOval line EBIs A 'from the center point of'B(ii) a Circle center ALCorresponding elliptical line is ELOval line ELIs A 'from the center point of'L(ii) a Circle center ARCorresponding elliptical line is EROval line ERIs A 'from the center point of'R(ii) a Wherein A isFAnd ABAre two opposite outer side surfaces which respectively correspond to circle centers ALAnd ARThe two opposite outer side surfaces respectively correspond to circle centers, and the three-dimensional coordinates of the light source are as follows;wherein, XlIs an elliptical line ELCenter point A 'of'LX coordinate value of (2), RlIs an elliptical line ELIs the square root of the ratio of the major axis to the minor axis, XrIs an elliptical line ERCenter point A 'of'RX coordinate value of (2), RrIs an elliptical line ERThe square root of the ratio of the major axis to the minor axis of (a);wherein, YfIs an elliptical line EFCenter point A 'of'FX coordinate value of (2), RfIs an elliptical line EFSquare root of the ratio of major axis to minor axis of (a), YbIs an elliptical line EBCenter point A 'of'BX coordinate value of (2), RbIs an elliptical line EbLong shaft ofThe square root of the ratio to the minor axis; z0＝AFAL·A'FA'R·A'BA'L/AFAR/(A'FA'R-A'BA'L) Wherein A isFALIs represented by AFAnd ALOf a'FA'RRepresents A'FAnd A'ROf a'BA′LRepresents A'BAnd A'LA distance between A and AFARIs represented by AFAnd ARThe distance between them.
Further, an XOY plane of the three-dimensional coordinate system is a plane where the flat panel detector is located, a Z axis is perpendicular to the XOY plane, and a forward direction of the Z axis is a direction of the flat panel detector facing the light source; the "generating the three-dimensional coordinates of the light source based on the relative distances between the circle centers corresponding to the four calibration objects and the three-dimensional coordinates of the center points corresponding to the four first projection areas" specifically includes: the four circle centers are respectively AF、AB、ALAnd ARCenter of a circle AFCorresponding elliptical line is EFOval line EFIs A 'from the center point of'F(ii) a Circle center ABCorresponding elliptical line is EBOval line EBIs A 'from the center point of'B(ii) a Circle center ALCorresponding elliptical line is ELOval line ELIs A 'from the center point of'L(ii) a Circle center ARCorresponding elliptical line is EROval line ERIs A 'from the center point of'R(ii) a Wherein A isFAnd ABAre two opposite outer side surfaces which respectively correspond to circle centers ALAnd ARThe two opposite outer side surfaces are respectively corresponding to circle centers; the "controlling the light source to emit light" specifically includes: controlling the light source to emit light, wherein the light source is positioned at the circle center AROutside the outer side surface and at the circle center AFAnd the center of a circle ABBetween the corresponding planes of the two outer side surfaces;
the three-dimensional coordinate of the light source is (X)0,Y0,Z0) Wherein:wherein, XlIs an elliptical line ELCenter point A 'of'LX coordinate value of (2), RlIs an elliptical line ELIs the square root of the ratio of the major axis to the minor axis, XrIs an elliptical line ERCenter point A 'of'RX coordinate value of (2), RrIs an elliptical line ERThe square root of the ratio of the major axis to the minor axis of (a);wherein, YfIs an elliptical line EFCenter point A 'of'FX coordinate value of (2), RfIs an elliptical line EFSquare root of the ratio of major axis to minor axis of (a), YbIs an elliptical line EBCenter point A 'of'BX coordinate value of (2), RbIs an elliptical line EbThe square root of the ratio of the major axis to the minor axis of (a); z0＝AFAL·A'FA'R·A'BA'L/AFAR/(A'FA'R-A'BA'L) Wherein A isFALIs represented by AFAnd ALOf a'FA'RRepresents A'FAnd A'ROf a'BA′LRepresents A'BAnd A'LA distance between A and AFARIs represented by AFAnd ARThe distance between them.
Further, the "acquiring three-dimensional coordinates of a plurality of second projection regions corresponding to each calibration object based on the projection picture" specifically includes: improving the contrast of the projection picture by using a dynamic range compression algorithm, extracting the edge of the projection picture, and performing expansion processing on the edge; obtaining a plurality of outlines corresponding to each calibration object from the projection picture; the "acquiring three-dimensional coordinates of the center points of the elliptical lines corresponding to the plurality of second projection areas" specifically includes: and fitting the plurality of profiles by using a least square method to obtain an elliptic line, and acquiring the three-dimensional coordinates of the central point of the elliptic line.
An embodiment of the present invention provides an apparatus for generating a light source position for a tomosynthesis system, where the tomosynthesis system includes: the light source is positioned above the flat panel detector and can move relative to the flat panel detector, a plurality of calibration objects are arranged between the light source and the flat panel detector, the positions of different calibration objects are different, and the position of each calibration object relative to the flat panel detector is fixed; the system comprises the following modules: the light emitting module is used for controlling the light source to emit light, the light emitted by the light source can irradiate the plurality of calibration objects, and a plurality of first projection areas which correspond to the plurality of calibration objects one to one can be formed on the flat panel detector; the parameter acquisition module is used for controlling the flat panel detector to acquire three-dimensional coordinates of a plurality of first projection areas; and the control module is used for generating the three-dimensional coordinates of the light source based on the relative distances among the calibration objects and the three-dimensional coordinates of the first projection areas, wherein the three-dimensional coordinates of the first projection areas and the three-dimensional coordinates of the light source are based on the same three-dimensional coordinate system.
Furthermore, the number of the calibration objects is 4, the 4 calibration objects are respectively positioned on four outer side surfaces of a square body, the four outer side surfaces are perpendicular to the flat panel detector, and each calibration object comprises a plurality of spheres arranged along a circular ring; the light emitting module is further configured to: controlling the light source to emit light, wherein the emitted light can irradiate all spheres in each calibration object, and each sphere can form a second projection area on the flat panel detector; the plurality of second projection areas corresponding to each calibration object are arranged along an elliptic line or a line segment; the parameter acquisition module is further configured to: controlling the flat panel detector to obtain a projection picture, obtaining three-dimensional coordinates of a plurality of second projection areas corresponding to each calibration object based on the projection picture, and obtaining central points of elliptic lines or line segments corresponding to the plurality of second projection areas, wherein the three-dimensional coordinates of the first projection area are the three-dimensional coordinates of the central points; the control module is further configured to: and generating the three-dimensional coordinates of the light source based on the relative distances of the circle centers of the diameters of the rings corresponding to the four calibration objects and the three-dimensional coordinates of the central points corresponding to the four first projection areas.
Further, an XOY plane of the three-dimensional coordinate system is a plane where the flat panel detector is located, a Z axis is perpendicular to the XOY plane, and a forward direction of the Z axis is a direction of the flat panel detector facing the light source; the light emitting module is further configured to: controlling the light source to emit light, wherein the light source is positioned in a space enclosed by the four outer side faces;
the parameter acquisition module is further configured to: the four circle centers are respectively AF、AB、ALAnd ARCenter of a circle AFCorresponding elliptical line is EFOval line EFIs A 'from the center point of'F(ii) a Circle center ABCorresponding elliptical line is EBOval line EBIs A 'from the center point of'B(ii) a Circle center ALCorresponding elliptical line is ELOval line ELIs A 'from the center point of'L(ii) a Circle center ARCorresponding elliptical line is EROval line ERIs A 'from the center point of'R(ii) a Wherein A isFAnd ABAre two opposite outer side surfaces which respectively correspond to circle centers ALAnd ARThe two opposite outer side surfaces respectively correspond to circle centers, and the three-dimensional coordinates of the light source are as follows;wherein, XlIs an elliptical line ELCenter point A 'of'LX coordinate value of (2), RlIs an elliptical line ELIs the square root of the ratio of the major axis to the minor axis, XrIs an elliptical line ERCenter point A 'of'RX coordinate value of (2), RrIs an elliptical line ERThe square root of the ratio of the major axis to the minor axis of (a);wherein, YfIs an elliptical line EFCenter point A 'of'FX coordinate value of (2), RfIs an elliptical line EFSquare root of the ratio of major axis to minor axis of (a), YbIs an elliptical line EBCenter point A 'of'BX coordinate value of (2), RbIs an elliptical line EbThe square root of the ratio of the major axis to the minor axis of (a); z0＝AFAL·A'FA'R·A'BA'L/AFAR/(A'FA'R-A'BA'L) Wherein A isFALIs represented by AFAnd ALOf a'FA′RRepresents A'FAnd A'ROf a'BA′LRepresents A'BAnd A'LA distance between A and AFARIs represented by AFAnd ARThe distance between them.
Further, an XOY plane of the three-dimensional coordinate system is a plane where the flat panel detector is located, a Z axis is perpendicular to the XOY plane, and a forward direction of the Z axis is a direction of the flat panel detector facing the light source;
the control module is further configured to: the four circle centers are respectively AF、AB、ALAnd ARCenter of a circle AFCorresponding elliptical line is EFOval line EFIs A 'from the center point of'F(ii) a Circle center ABCorresponding elliptical line is EBOval line EBIs A 'from the center point of'B(ii) a Circle center ALCorresponding elliptical line is ELOval line ELIs A 'from the center point of'L(ii) a Circle center ARCorresponding elliptical line is EROval line ERIs A 'from the center point of'R(ii) a Wherein A isFAnd ABAre two opposite outer side surfaces which respectively correspond to circle centers ALAnd ARThe two opposite outer side surfaces are respectively corresponding to circle centers; the "controlling the light source to emit light" specifically includes: controlling the light source to emit light, wherein the light source is positioned at the circle center AROutside the outer side surface and at the circle center AFAnd the center of a circle ABBetween the corresponding planes of the two outer side surfaces;
the three-dimensional coordinate of the light source is (X)0,Y0,Z0) Wherein:wherein, XlIs an elliptical line ELCenter point A 'of'LX coordinate value of (2), RlIs an elliptical line ELIs the square root of the ratio of the major axis to the minor axis, XrIs an elliptical line ERCenter point A 'of'RX coordinate value of (2), RrIs an elliptical line ERThe square root of the ratio of the major axis to the minor axis of (a);wherein, YfIs an elliptical line EFCenter point A 'of'FX coordinate value of (2), RfIs an elliptical line EFSquare root of the ratio of major axis to minor axis of (a), YbIs an elliptical line EBCenter point A 'of'BX coordinate value of (2), RbIs an elliptical line EbThe square root of the ratio of the major axis to the minor axis of (a); z0＝AFAL·A'FA'R·A'BA'L/AFAR/(A'FA'R-A'BA'L) Wherein A isFALIs represented by AFAnd ALOf a'FA'RRepresents A'FAnd A'ROf a'BA′LRepresents A'BAnd A'LA distance between A and AFARIs represented by AFAnd ARThe distance between them.
Further, the parameter obtaining module is further configured to: improving the contrast of the projection picture by using a dynamic range compression algorithm, extracting the edge of the projection picture, and performing expansion processing on the edge; obtaining a plurality of outlines corresponding to each calibration object from the projection picture; the parameter acquisition module is further configured to: and fitting the plurality of profiles by using a least square method to obtain an elliptic line, and acquiring the three-dimensional coordinates of the central point of the elliptic line.
The embodiment of the invention provides a method and a device for generating a light source position, wherein the method comprises the following steps: the embodiment of the invention discloses a method and a device for generating a light source position, wherein the method comprises the following steps: controlling the light source to emit light, wherein the light emitted by the light source can irradiate the plurality of calibration objects and can form a plurality of first projection areas corresponding to the plurality of calibration objects one to one on the flat panel detector; controlling the flat panel detector to acquire three-dimensional coordinates of a plurality of first projection areas; and generating the three-dimensional coordinates of the light source based on the relative distances among the calibration objects and the three-dimensional coordinates of the first projection areas, wherein the three-dimensional coordinates of the first projection areas and the three-dimensional coordinates of the light source are based on the same three-dimensional coordinate system. The method is capable of generating coordinates of the light source.
Drawings
FIG. 1 is a schematic diagram of a tomosynthesis system in accordance with the present invention;
FIG. 2 is a schematic flow chart of a method of generating a light source position in the present invention;
FIGS. 3, 4A and 4B are schematic diagrams of a method of generating a location of a light source in accordance with the present invention;
FIG. 5 is a graph showing the results of the experiment according to the present invention.
Detailed Description
The present invention will be described in further detail with reference to examples.
An embodiment of the present invention provides a method for generating a light source position for a tomosynthesis system, where the tomosynthesis system includes: the device comprises a light source 1 and a flat panel detector 2, wherein the light source 1 is positioned above the flat panel detector 2 and can move relative to the flat panel detector 2, a plurality of calibration objects 3 are arranged between the light source 1 and the flat panel detector 2, the positions of different calibration objects 3 are different, and the position of each calibration object 3 relative to the flat panel detector 2 is fixed; here, the positional relationship of the calibration object 3 with respect to the flat panel detector 2 is uncertain; in addition, the material of the calibration object 3 may be steel. Here, the calibration object 3 may be located directly above the flat panel detector 2, and it is understood that when the light source 1 irradiates the calibration object 3, if the irradiation angle is not appropriate, the projection formed by the calibration object 3 is likely not to be located on the flat panel detector 2, and the projection formed by the calibration object 3 is located directly above the flat panel detector 2, and the projection formed by the calibration object 3 is likely to be located on the flat panel detector 2 with a high probability. In practical use, a human body is usually located on the upper surface of the flat panel detector 2, and therefore, in order not to affect the normal use of the tomosynthesis system, the calibration object 3 may be located on the outer side of the flat panel detector 2, for example, the flat panel detector 2 is usually a square plate-shaped object, and then a plurality of calibration objects 3 may be provided on one side of the plate-shaped object, or a plurality of calibration objects 3 may be provided on two sides, three sides or four sides, and furthermore, the calibration objects 3 may be provided only on two opposite sides.
The method comprises the following steps:
step 201: controlling the light source 1 to emit light, wherein the light emitted by the light source 1 can be irradiated to the plurality of calibration objects 3, and a plurality of first projection areas 21 corresponding to the plurality of calibration objects 3 one to one can be formed on the flat panel detector 2; here, in actual use, several preset positions of the light source 1 are preset, but due to the influence of various factors, the actual position of the light source 1 is likely to be inconsistent with the preset positions, and in this case, the method for generating the light source position needs to be performed to obtain the actual position of the light source 1. Optionally, the light source 1 emits X-rays.
Step 202: controlling the flat panel detector 2 to acquire three-dimensional coordinates of a plurality of first projection areas 21;
step 203: based on the relative distances between the plurality of calibration objects 3 and the three-dimensional coordinates of the plurality of first projection areas 21, the three-dimensional coordinates of the light source 1 are generated, wherein the three-dimensional coordinates of the first projection areas 21 and the three-dimensional coordinates of the light source 1 are based on the same three-dimensional coordinate system.
Here, as shown in fig. 3, for one calibration object 3, the light source 1, the calibration object 3, and the corresponding first projection area 21 are all located on the same straight line, and it can be understood that the three-dimensional coordinates of the light source 1 can be acquired by the relative distances between the plurality of calibration objects 3 and the three-dimensional coordinates of the plurality of first projection areas 21.
Here, for the convenience of calculation, it is necessary to first establish a three-dimensional coordinate system, so that the three-dimensional coordinate of the plane where the flat panel detector 2 is located is determined, the three-dimensional coordinate of each point in the flat panel detector 2 is determined, and further, the three-dimensional coordinate of each pixel point in the image acquired by the flat panel detector 2 is also determined, and further, the three-dimensional coordinate of each first projection area 21 is obtained.
In this embodiment, the number of the calibrators 3 is 4, the 4 calibrators 3 are respectively located on four outer side surfaces of a square, the four outer side surfaces are perpendicular to the flat panel detector 2, and each calibrator 3 includes a plurality of spheres 32 arranged along a circular ring; here, the square body may be an imaginary object or a square object, for example, in the example shown in fig. 4A and 4B, the square body is a square housing 31, the material of the housing 31 may be organic glass, the square housing 31 includes six housing plates, that is, an upper housing plate, a lower housing plate, a front housing plate, a rear housing plate, a left housing plate and a right housing plate, a plurality of spheres 32 are disposed in the front housing plate, the rear housing plate, the left housing plate and the right housing plate, the plurality of spheres 32 are arranged along a circular ring, and for convenience of description, the plurality of spheres 32 in the same housing plate may be referred to as a group; the light source 1 may be located above the upper casing 31, or just on the upper casing 31, and the flat panel detector 2 is tightly attached to the lower surface of the lower casing, and the front casing, the rear casing, the left casing and the right casing are all perpendicular to the flat panel detector 2.
Optionally, in the four shell plates, the number of the spheres 32 is 12, and the spheres are uniformly distributed along the circular ring, the radii of the four circular rings are all equal, and the heights of the centers of the circular rings are the same relative to the flat panel detector 2.
Optionally, the material of the square body may be organic glass, and the material of the sphere 32 may be steel, it can be understood that, because the density difference between the organic glass and the sphere 32 is large, the first projection area 21 corresponding to the sphere 32 is convenient to identify on the projection picture.
The "controlling the light source 1 to emit light, the light emitted by the light source 1 being capable of irradiating the plurality of calibration objects 3 and being capable of forming a plurality of first projection regions 21 corresponding to the plurality of calibration objects 3 one to one on the flat panel detector 2" specifically includes: controlling the light source 1 to emit light, wherein the emitted light can irradiate all the spheres 32 in each calibration object 3, and each sphere 32 can form a second projection area 22 on the flat panel detector 2; the plurality of second projection areas 22 corresponding to each calibration object 3 are arranged along an elliptical line or a line segment; here, it is understood that, if the light source 1 is located directly above one outer side face, the plurality of second projection regions 22 corresponding to the plurality of spheres 32 on the outer side face are arranged along one line segment, and the plurality of second projection regions 22 corresponding to the plurality of spheres 32 on the remaining outer side face are arranged along one elliptical line; if the light source 1 is not located directly above one of the outer side faces, the second projection areas 22 corresponding to the plurality of spheres 32 on each of the outer side faces are arranged along one elliptical line.
The step of controlling the flat panel detector 2 to acquire the three-dimensional coordinates of the plurality of first projection regions 21 specifically includes: controlling the flat panel detector 2 to obtain a projection picture, obtaining three-dimensional coordinates of a plurality of second projection areas 22 corresponding to each calibration object 3 based on the projection picture, and obtaining center points of ellipses or line segments corresponding to the plurality of second projection areas 22, wherein the three-dimensional coordinates of the first projection area 21 are the three-dimensional coordinates of the center points;
the "generating three-dimensional coordinates of the light source 1 based on the relative distances between the plurality of calibration objects 3 and the three-dimensional coordinates of the plurality of first projection regions 21" specifically includes: and generating the three-dimensional coordinates of the light source 1 based on the relative distances between the centers of circles corresponding to the four calibration objects 3 and the three-dimensional coordinates of the central points corresponding to the four first projection areas 21.
Here, in use, the actual three-dimensional coordinate of the light source 1 is (X)0,Y0,Z0) At this time, the light source 1 emits light rays towards the front, the back, the left and the right shell plates, the spheres 32 on the four shell plates can form an elliptical or circular projection area on the flat panel detector 2, and for the same group of spheres 32, a plurality of spheres 32 are arranged along a circular ring (assuming that the center of the circular ring is a), but on the flat panel detector 2, each sphere 32 can emit light rays towards the front, the back, the left and the right shell platesAn ellipse or circular projection area is corresponding to the projection area (the three-dimensional coordinates of the projection area can be calculated), the plurality of ellipse projections are arranged or arranged into a line segment along an ellipse line, the relevant geometric parameters of the ellipse line or the line segment can be calculated, and then a projection point A' (which is the central point of the ellipse line and is the intersection point of the major axis and the minor axis or the central point of the line segment) corresponding to the circle center A on the flat panel detector 2 is obtained; in summary, based on the relative distances between the four circle centers and the three-dimensional coordinates of the center points (i.e., the center points of the elliptical lines) corresponding to the four first projection areas 21, the actual three-dimensional coordinates of the light source 1 can be obtained.
In this embodiment, an XOY plane of the three-dimensional coordinate system is a plane where the flat panel detector 2 is located, a Z axis is perpendicular to the XOY plane, and a forward direction of the Z axis is a direction in which the flat panel detector 2 faces the light source 1;
the "controlling the light source 1 to emit light" specifically includes: controlling the light source 1 to emit light, wherein the light source 1 is positioned in a space enclosed by four outer side faces;
the "generating the three-dimensional coordinates of the light source 1 based on the relative distances between the centers of circles corresponding to the four calibration objects 3 and the three-dimensional coordinates of the center points corresponding to the four first projection areas 21" specifically includes:
the four circle centers are respectively AF、AB、ALAnd ARCenter of a circle AFCorresponding elliptical line is EFOval line EFIs A 'from the center point of'F(ii) a Circle center ABCorresponding elliptical line is EBOval line EBIs A 'from the center point of'B(ii) a Circle center ALCorresponding elliptical line is ELOval line ELIs A 'from the center point of'L(ii) a Circle center ARCorresponding elliptical line is EROval line ERIs A 'from the center point of'R(ii) a Wherein A isFAnd ABAre two opposite outer side surfaces which respectively correspond to circle centers ALAnd ARThe two opposite outer side surfaces respectively correspond to circle centers, and the three-dimensional coordinate of the light source 1 is;
wherein, XlIs an elliptical line ELCenter point A 'of'LX coordinate value of (2), RlIs an elliptical line ELIs the square root of the ratio of the major axis to the minor axis, XrIs an elliptical line ERCenter point A 'of'RX coordinate value of (2), RrIs an elliptical line ERThe square root of the ratio of the major axis to the minor axis of (a);
wherein, YfIs an elliptical line EFCenter point A 'of'FX coordinate value of (2), RfIs an elliptical line EFSquare root of the ratio of major axis to minor axis of (a), YbIs an elliptical line EBCenter point A 'of'BX coordinate value of (2), RbIs an elliptical line EbThe square root of the ratio of the major axis to the minor axis of (a);
Z0＝AFAL·A'FA'R·A'BA'L/AFAR/(A'FA'R-A'BA'L) Wherein A isFALIs represented by AFAnd ALOf a'FA′RRepresents A'FAnd A'ROf a'BA′LRepresents A'BAnd A'LA distance between A and AFARIs represented by AFAnd ARThe distance between them.
In this embodiment, an XOY plane of the three-dimensional coordinate system is a plane where the flat panel detector 2 is located, a Z axis is perpendicular to the XOY plane, and a forward direction of the Z axis is a direction in which the flat panel detector 2 faces the light source 1;
the "generating the three-dimensional coordinates of the light source 1 based on the relative distances between the centers of circles corresponding to the four calibration objects 3 and the three-dimensional coordinates of the center points corresponding to the four first projection areas 21" specifically includes:
the four circle centers are respectively AF、AB、ALAnd ARCenter of a circle AFCorresponding elliptical line is EFOval line EFIs A 'from the center point of'F(ii) a Circle center ABCorresponding elliptical line is EBOval line EBIs A 'from the center point of'B(ii) a Circle center ALCorresponding elliptical line is ELOval line ELIs A 'from the center point of'L(ii) a Circle center ARCorresponding elliptical line is EROval line ERIs A 'from the center point of'R(ii) a Wherein A isFAnd ABAre two opposite outer side surfaces which respectively correspond to circle centers ALAnd ARThe two opposite outer side surfaces are respectively corresponding to circle centers;
the "controlling the light source 1 to emit light" specifically includes: controlling the light source 1 to emit light, wherein the light source 1 is positioned at the circle center AROutside the outer side surface and at the circle center AFAnd the center of a circle ABBetween the corresponding planes of the two outer side surfaces;
the three-dimensional coordinate of the light source 1 is (X)0,Y0,Z0) Wherein:
wherein, XlIs an elliptical line ELCenter point A 'of'LX coordinate value of (2), RlIs an elliptical line ELIs the square root of the ratio of the major axis to the minor axis, XrIs an elliptical line ERCenter point A 'of'RX coordinate value of (2), RrIs an elliptical line ERThe square root of the ratio of the major axis to the minor axis of (a);
wherein, YfIs an elliptical line EFCenter point A 'of'FX coordinate value of (2), RfIs an elliptical line EFSquare root of the ratio of major axis to minor axis of (a), YbIs an elliptical line EBCenter point A 'of'BX coordinate value of (2), RbIs an elliptical line EbThe square root of the ratio of the major axis to the minor axis of (a);
Z0＝AFAL·A'FA'R·A'BA'L/AFAR/(A'FA'R-A'BA'L) Wherein A isFALIs represented by AFAnd ALOf a'FA′RRepresents A'FAnd A'ROf a'BA′LRepresents A'BAnd A'LA distance between A and AFARIs represented by AFAnd ARThe distance between them.
In this embodiment, the "obtaining three-dimensional coordinates of the plurality of second projection regions 22 corresponding to each calibration object 3 based on the projection picture" specifically includes:
improving the contrast of the projection picture by using a dynamic range compression algorithm, extracting the edge of the projection picture, and performing expansion processing on the edge; obtaining a plurality of outlines corresponding to each calibration object 3 from the projection picture;
the "acquiring the three-dimensional coordinates of the central points of the elliptical lines corresponding to the plurality of second projection regions 22" specifically includes: and fitting the plurality of profiles by using a least square method to obtain an elliptic line, and acquiring the three-dimensional coordinates of the central point of the elliptic line.
Here, in practice, since the projection image acquired by the flat panel detector 2 includes the projection of air, so that the projection images corresponding to the sphere 32 and the shell plate portion are relatively dark and not beneficial to the subsequent processing, a dynamic range compression algorithm may be used to improve the contrast of the projection image, then the edge of the projection image is extracted, then the edge is expanded, and then the elliptical contour of the elliptical projection is found, it can be understood that the elliptical contour or the circular contour corresponding to each sphere 32 in each shell plate may be obtained by the above method, and further, for each group of spheres 32, the least square method is used to perform the fitting processing on a plurality of contours, so that the relevant geometric parameters of the elliptical line, such as the central point, the major axis, the minor axis, and the like of the elliptical line, may be obtained.
Optionally, the ray algorithm, the piecewise function mapping algorithm, the adaptive logarithm mapping algorithm, and the high dynamic range compression algorithm may include: linear shift algorithms, logarithmic mapping range image visualization algorithms, and the like.
An embodiment of the present invention provides an apparatus for generating a light source position for a tomosynthesis system, where the tomosynthesis system includes: the device comprises a light source 1 and a flat panel detector 2, wherein the light source 1 is positioned above the flat panel detector 2 and can move relative to the flat panel detector 2, a plurality of calibration objects 3 are arranged between the light source 1 and the flat panel detector 2, the positions of different calibration objects 3 are different, and the position of each calibration object 3 relative to the flat panel detector 2 is fixed; the system comprises the following modules:
the light emitting module is used for controlling the light source 1 to emit light, the light emitted by the light source 1 can be irradiated to the plurality of calibration objects 3, and a plurality of first projection areas 21 corresponding to the plurality of calibration objects 3 one to one can be formed on the flat panel detector 2;
a parameter obtaining module, configured to control the flat panel detector 2 to obtain three-dimensional coordinates of the plurality of first projection regions 21;
and the control module is used for generating the three-dimensional coordinates of the light source 1 based on the relative distances among the calibration objects 3 and the three-dimensional coordinates of the first projection areas 21, wherein the three-dimensional coordinates of the first projection areas 21 and the three-dimensional coordinates of the light source 1 are based on the same three-dimensional coordinate system.
In this embodiment, the number of the calibrators 3 is 4, the 4 calibrators 3 are respectively located on four outer side surfaces of a square, the four outer side surfaces are perpendicular to the flat panel detector 2, and each calibrator 3 includes a plurality of spheres 32 arranged along a circular ring;
the light emitting module is further configured to: controlling the light source 1 to emit light, wherein the emitted light can irradiate all the spheres 32 in each calibration object 3, and each sphere 32 can form a second projection area 22 on the flat panel detector 2; the plurality of second projection areas 22 corresponding to each calibration object 3 are arranged along an elliptical line or a line segment;
the parameter acquisition module is further configured to: controlling the flat panel detector 2 to obtain a projection picture, obtaining three-dimensional coordinates of a plurality of second projection areas 22 corresponding to each calibration object 3 based on the projection picture, and obtaining center points of ellipses or line segments corresponding to the plurality of second projection areas 22, wherein the three-dimensional coordinates of the first projection area 21 are the three-dimensional coordinates of the center points;
the control module is further configured to: and generating the three-dimensional coordinates of the light source 1 based on the relative distances between the circle centers of the diameters of the circular rings corresponding to the four calibration objects and the three-dimensional coordinates of the central points corresponding to the four first projection areas 21.
In this embodiment, an XOY plane of the three-dimensional coordinate system is a plane where the flat panel detector 2 is located, a Z axis is perpendicular to the XOY plane, and a forward direction of the Z axis is a direction in which the flat panel detector 2 faces the light source 1;
the light emitting module is further configured to: controlling the light source 1 to emit light, wherein the light source 1 is positioned in a space enclosed by four outer side faces;
the parameter acquisition module is further configured to:
the four circle centers are respectively AF、AB、ALAnd ARCenter of a circle AFCorresponding elliptical line is EFOval line EFIs A 'from the center point of'F(ii) a Circle center ABCorresponding elliptical line is EBOval line EBIs A 'from the center point of'B(ii) a Circle center ALCorresponding elliptical line is ELOval line ELIs A 'from the center point of'L(ii) a Circle center ARCorresponding elliptical line is EROval line ERIs A 'from the center point of'R(ii) a Wherein A isFAnd ABAre two opposite outer side surfaces which respectively correspond to circle centers ALAnd ARThe two opposite outer side surfaces respectively correspond to circle centers, and the three-dimensional coordinate of the light source 1 is;
wherein, XlIs an elliptical line ELCenter point A 'of'LX coordinate ofValue RlIs an elliptical line ELIs the square root of the ratio of the major axis to the minor axis, XrIs an elliptical line ERCenter point A 'of'RX coordinate value of (2), RrIs an elliptical line ERThe square root of the ratio of the major axis to the minor axis of (a);
wherein, YfIs an elliptical line EFCenter point A 'of'FX coordinate value of (2), RfIs an elliptical line EFSquare root of the ratio of major axis to minor axis of (a), YbIs an elliptical line EBCenter point A 'of'BX coordinate value of (2), RbIs an elliptical line EbThe square root of the ratio of the major axis to the minor axis of (a);
Z0＝AFAL·A'FA'R·A'BA'L/AFAR/(A'FA'R-A'BA'L) Wherein A isFALIs represented by AFAnd ALOf a'FA′RRepresents A'FAnd A'ROf a'BA′LRepresents A'BAnd A'LA distance between A and AFARIs represented by AFAnd ARThe distance between them.
In this embodiment, an XOY plane of the three-dimensional coordinate system is a plane where the flat panel detector 2 is located, a Z axis is perpendicular to the XOY plane, and a forward direction of the Z axis is a direction in which the flat panel detector 2 faces the light source 1;
the control module is further configured to:
the four circle centers are respectively AF、AB、ALAnd ARCenter of a circle AFCorresponding elliptical line is EFOval line EFIs A 'from the center point of'F(ii) a Circle center ABCorresponding elliptical line is EBOval line EBIs A 'from the center point of'B(ii) a Circle center ALCorresponding elliptical line is ELOval line ELIs A 'from the center point of'L(ii) a Circle center ARCorresponding elliptical line is EROval line ERIs A 'from the center point of'R(ii) a Wherein A isFAnd ABAre two opposite outer side surfaces which respectively correspond to circle centers ALAnd ARThe two opposite outer side surfaces are respectively corresponding to circle centers;
the "controlling the light source 1 to emit light" specifically includes: controlling the light source 1 to emit light, wherein the light source 1 is positioned at the circle center AROutside the outer side surface and at the circle center AFAnd the center of a circle ABBetween the corresponding planes of the two outer side surfaces;
the three-dimensional coordinate of the light source 1 is (X)0,Y0,Z0) Wherein:
wherein, XlIs an elliptical line ELCenter point A 'of'LX coordinate value of (2), RlIs an elliptical line ELIs the square root of the ratio of the major axis to the minor axis, XrIs an elliptical line ERCenter point A 'of'RX coordinate value of (2), RrIs an elliptical line ERThe square root of the ratio of the major axis to the minor axis of (a);
wherein, YfIs an elliptical line EFCenter point A 'of'FX coordinate value of (2), RfIs an elliptical line EFSquare root of the ratio of major axis to minor axis of (a), YbIs an elliptical line EBCenter point A 'of'BX coordinate value of (2), RbIs an elliptical line EbThe square root of the ratio of the major axis to the minor axis of (a);
Z0＝AFAL·A'FA'R·A'BA'L/AFAR/(A'FA'R-A'BA'L) Wherein A isFALIs represented by AFAnd ALOf a'FA′RRepresents A'FAnd A'ROf a'BA′LRepresents A'BAnd A'LA distance between A and AFARIs represented by AFAnd ARThe distance between them.
In this embodiment, the parameter obtaining module is further configured to:
improving the contrast of the projection picture by using a dynamic range compression algorithm, extracting the edge of the projection picture, and performing expansion processing on the edge; obtaining a plurality of outlines corresponding to each calibration object 3 from the projection picture;
the parameter acquisition module is further configured to: and fitting the plurality of profiles by using a least square method to obtain an elliptic line, and acquiring the three-dimensional coordinates of the central point of the elliptic line.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.