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WO2018133090A1 - Procédé, dispositif et système d'étalonnage de paramètre pour machine à rayons x - Google Patents

Procédé, dispositif et système d'étalonnage de paramètre pour machine à rayons x Download PDF

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Publication number
WO2018133090A1
WO2018133090A1 PCT/CN2017/072177 CN2017072177W WO2018133090A1 WO 2018133090 A1 WO2018133090 A1 WO 2018133090A1 CN 2017072177 W CN2017072177 W CN 2017072177W WO 2018133090 A1 WO2018133090 A1 WO 2018133090A1
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Prior art keywords
rotating arm
projection
rotation
standard phantom
target
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English (en)
Chinese (zh)
Inventor
陈垦
王澄
秦文健
熊璟
谢耀钦
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Shenzhen Institute of Advanced Technology of CAS
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Shenzhen Institute of Advanced Technology of CAS
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Priority to PCT/CN2017/072177 priority Critical patent/WO2018133090A1/fr
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
    • G01N23/04—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material

Definitions

  • the present disclosure relates to signal processing techniques, such as a method, apparatus, and system for parameter calibration of an X-ray machine.
  • parameter calibration for the difference between system parameters and design goals in static state can be used.
  • the present disclosure provides a method, device and system for parameter calibration of an X-ray machine, which can calibrate errors generated in the movement of the X-ray machine.
  • a parameter calibration method for an X-ray machine may include:
  • the error parameter is calibrated according to the projection result of the standard phantom to obtain a calibration result of the error parameter
  • a dynamic correction matrix for correcting the actual projection result of the X-ray machine is generated based on the mechanical structural motion state of the rotating arm at each set rotational position and the calibration result of the error parameter.
  • a parameter calibration device for an X-ray machine which can be used to perform parameter calibration of the X-ray machine described in this embodiment
  • the device can include:
  • the projection result acquisition module is configured to control the X-ray machine rotating arm to perform a rotation scan around the standard phantom, and collect the projection results of the standard phantom at a plurality of set rotation positions;
  • a motion state recording module configured to record a mechanical structural motion state of the rotating arm at each set rotational position
  • the error parameter calibration module is configured to, at each set rotation position, calibrate the error parameter according to a projection result of the standard phantom to obtain a calibration result of the error parameter;
  • a dynamic correction matrix generating module configured to generate a correction for correcting an actual projection result of the X-ray machine according to a mechanical structural motion state of the rotating arm at each set rotational position and a calibration result of the error parameter Dynamic correction matrix.
  • a parameter calibration system for an X-ray machine may include:
  • a rotating arm an X-ray source disposed opposite the rotating arm, and a detector, a processor, an image acquisition device, a motion state acquisition component, and a standard phantom;
  • the rotating arm is configured to drive the X-ray light source and the detector to rotate a plurality of set rotation angles around the standard phantom according to a control signal sent by the processor;
  • the X-ray source is configured to send an X-ray scan signal to the standard phantom
  • the detector is configured to collect projection data of the X-ray scan signal on the standard phantom
  • the image acquisition device is configured to generate a projection result of a standard phantom according to the projection data collected by the detector;
  • the motion state collecting component is configured to acquire a mechanical structural motion state of the rotating arm
  • the processor is configured to control the rotating arm to perform a rotational scan around the standard phantom to obtain a projection result at a plurality of set rotational positions; at each set rotational position, record the mechanical structural motion of the rotating arm a state; at each set rotational position, the error parameter is calibrated according to a projection result of the standard phantom to obtain a calibration result of the error parameter; according to the mechanism of the rotating arm at each set rotational position
  • the structural motion state and the calibration result of the error parameter generate a dynamic correction matrix for correcting the actual projection result of the X-ray machine.
  • the parameter calibration method, device and system for the X-ray machine provided by the embodiment are controlled by rotating the rotating arm of the X-ray machine around the standard phantom, and the projection result of the standard phantom at a plurality of rotational positions can be realized.
  • the error parameters of the different mechanical structures of the rotating arm are calibrated, so that the method of calibrating the structural parameters of the system is usually calibrated according to the difference between the system parameters and the design target in the static state, and cannot be applied to the system.
  • the problem of calibration and correction of the error caused by motion can be used to calibrate the error parameters generated during the movement of the X-ray machine.
  • the number calibration provides a new idea. By using the error parameter calibration result to correct the actual projection result, the quality of the image after 3D reconstruction can be improved.
  • FIG. 1 is a flow chart of a parameter calibration method of an X-ray machine according to Embodiment 1.
  • 2a is a flow chart of a method for parameter calibration of an X-ray machine according to the second embodiment.
  • FIG. 2b is a schematic diagram of a plurality of parameters for calculating a tangential displacement error according to the second embodiment.
  • 2c is a schematic diagram of a plurality of parameters for calculating a radial displacement error provided by the second embodiment.
  • FIG. 3a is a flowchart of a parameter calibration method of an X-ray machine according to Embodiment 3.
  • Figure 3b is a top plan view of a standard phantom provided in the third embodiment.
  • Figure 3c is a left side view of a standard phantom provided in the third embodiment.
  • Figure 3d is a front elevational view of a standard phantom provided in the third embodiment.
  • FIG. 3e is a schematic diagram of calculating a plurality of parameters of an acquisition angle in a projected image of a standard phantom according to the third embodiment.
  • FIG. 4 is a flow chart of a method for parameter calibration of an X-ray machine according to Embodiment 4.
  • FIG. 5 is a flowchart of a parameter calibration method of an X-ray machine according to Embodiment 5.
  • FIG. 6 is a structural diagram of a parameter calibration apparatus for an X-ray machine according to Embodiment 6.
  • FIG. 7 is a structural diagram of a parameter calibration system of an X-ray machine according to Embodiment 7.
  • FIG. 8 is a flowchart of a calibration method corresponding to a parameter calibration system of an X-ray machine in an application scenario provided in the seventh embodiment.
  • FIG. 9 is a structural diagram of a parameter calibration system of an X-ray machine in an application scenario provided in the seventh embodiment.
  • This embodiment can be applied to calibrate parameters of an X-ray machine.
  • X-ray machines can be used as an instrument for capturing images of human bodies.
  • Parameter calibration is a method to reduce the system error. It can be that the pointer calibrates the error of the structural parameters of the system, and then a reasonable compensation amount can be set based on the error amount of the calibration to reduce the measurement error of the system. purpose.
  • a standard human body model (hereinafter referred to as a standard phantom) is constructed, and the rotating arm of the X-ray machine is controlled to rotate around the standard phantom, and the projection result and ideal according to the standard phantom at a plurality of rotational positions are performed.
  • the difference between the projection results can be used to calibrate the error parameters of the different mechanical structures of the rotating arm, so that the error caused by the X-ray machine motion can be calibrated.
  • Embodiment 1 is a flow chart of a parameter calibration method of an X-ray machine according to Embodiment 1.
  • the method of this embodiment can be applied to the case of calibrating an error generated during the rotation of the X-ray machine rotating arm.
  • the method can be performed by a parameter calibration device of an X-ray machine, which can be implemented by software and/or hardware, and can generally be integrated into an X-ray machine.
  • the method of this embodiment may include S110-S140.
  • the X-ray machine rotating arm is controlled to perform a rotational scan around the standard phantom, and the projection results of the standard phantoms at the plurality of set rotational positions are acquired.
  • the standard phantom may refer to a pre-configured, alternative to the actual scanning object whose shape conforms to the set rule, to calibrate the amount of error generated during the actual movement of the X-ray machine. Wherein, considering that the projection diameter of the spherical shape is the same in all directions, the standard phantom may be selected as a spherical phantom.
  • the rotating arm of the X-ray machine may be a C-arm or an O-arm.
  • the rotating arm can reach different rotation positions by controlling the rotation angle of the X-ray machine rotating arm.
  • the rotation angle can be set to ⁇ /3, 5 ⁇ /6, 4 ⁇ /3, and 11 ⁇ /6, respectively. Wait.
  • the projection result may refer to a projection image of the standard phantom obtained by the X-ray source rotating the X-ray machine rotating to the set rotation position and emitting X-rays by the X-ray source.
  • the projection position of the X-ray source of the X-ray machine in the detector may be adjusted before the rotation of the X-ray machine rotating arm is controlled around the standard phantom. Overlaps the center of the detector and adjusts the geometric center of the standard phantom to overlap the design center of rotation of the X-ray machine's rotating arm.
  • the detector can be a flat panel detector.
  • the mechanical structure motion state may refer to a motion distance, a motion direction, or a motion speed corresponding to the one or more mechanical structures at a rotational position.
  • the mechanical structure motion state can be represented by a vector.
  • the mechanical structure motion state at one rotational position i can be represented by a vector s i
  • the mechanical structural motion states corresponding to all the set rotational positions constitute a matrix S.
  • the error parameter is calibrated according to the projection result of the standard phantom, and a calibration result of the error parameter is obtained.
  • the projection result of the standard phantom should have a desired expected value.
  • the error parameter in the rotation process may be determined by comparing the actual projection result of the standard phantom obtained during the actual rotation scanning process with the ideal expected value, wherein the error parameter may be actual.
  • the difference between the projection result and the ideal expected value for example, the theoretical expected value of the center of rotation of the X-ray machine's rotating arm is F at a set rotation angle, and the actual projection center calculated by the actual projection result is H, Then (FH) can be used as an error parameter; the error parameter can also be a deviation value corresponding to the ideal expected value, for example, setting the ideal rotation angle of the X-ray machine rotating arm to 30°, determined by the actual projection result. If the actual rotation angle of the rotating arm is 31°, 31° can be used as an error parameter.
  • the error parameters of the rotating arm in different mechanical structure motion states can be calibrated according to the difference between the actual projection result and the ideal expected value. Further, after the actual scanning object is placed on the X-ray machine, the projected image of the scanned object is corrected according to the mechanical structure motion state of the X-ray machine and the pre-calibrated error parameter.
  • a dynamic correction matrix for correcting the actual projection result of the X-ray machine is generated based on the mechanical structure motion state of the rotating arm at each set rotational position and the calibration result of the error parameter.
  • the set rotation angle of the rotating arm is limited. Therefore, it is impossible to calculate the corresponding error parameters in different mechanical structure states by exhausting the mechanical motion state of all the rotating arms.
  • the rotating arm of the X-ray machine may be rotated to any angle, and the error parameter of the mechanical structure motion state corresponding to the angle may not be pre-calibrated. At this time, the X-ray machine's rotating arm cannot be corrected based on the pre-calibration result.
  • an optimal estimation matrix can be constructed based on the error parameters of the motion state of the plurality of mechanical structures that have been calibrated, that is, the dynamic correction matrix is used to realize the error of the motion state of any one of the mechanical structures through the finite number of calibrated mechanical structure motion states.
  • the parameters are estimated.
  • the parameter calibration method of the X-ray machine provided by the embodiment is controlled by rotating the rotating arm of the X-ray machine around the standard phantom, and the movement state of the different mechanical structures of the rotating arm according to the projection result of the standard phantom at the plurality of rotating positions
  • the calibration of the error parameters can solve the traditional calibration of the system structural parameters.
  • the calibration method is usually based on the difference between the system parameters and the design objectives in the static state.
  • the errors generated in the system motion cannot be calibrated and
  • the revised problem can calibrate the error parameters generated in the X-ray machine motion, and provide a new idea for the parameter calibration of the X-ray machine.
  • the error parameter calibration result By using the error parameter calibration result to calibrate the actual projection result, the three-dimensional can also be improved. The quality of the image after reconstruction.
  • 2a is a flowchart of a method for calibrating a parameter of an X-ray machine according to the second embodiment.
  • the standard body is selected as a spherical phantom, and the standard phantom is diametrically oriented.
  • Two orthogonal alignment through holes may be included, and correspondingly, before the rotation of the rotating arm of the X-ray machine is controlled around the standard phantom to obtain a projection result of the standard phantom at a plurality of set rotation positions, Determining that a projection position of the X-ray source of the X-ray machine in the detector overlaps with a center of the detector, and a center of the standard phantom overlaps with a designed rotation center of the X-ray machine rotating arm;
  • the error parameter may include: a tangential displacement error of the rotation center in the rotation plane and a radial displacement error, and based on the type of the error parameter, a calculation process of the error parameter is given.
  • the method of this embodiment may include the following steps.
  • the standard phantom is a spherical phantom, and the center of the standard phantom is adjusted such that the center of the standard phantom overlaps with the designed rotation center of the X-ray machine rotating arm, the standard The phantom may include two orthogonally aligned through holes in the diametrical direction.
  • the standard phantom is placed in the C-arm imaging range, and the position of the standard phantom along a diameter direction is adjusted.
  • the laser light emitted by the X-ray source passes through a through hole in the diameter direction of the standard phantom.
  • the rotating arm is rotated by ⁇ /2 to adjust the position of the standard phantom along the other diameter direction, and the laser passes through the standard body.
  • Another through hole in the diameter direction of the mold wherein the two through holes in the diameter direction are orthogonally aligned through holes. At this time, it can be determined that the center of the standard phantom is located at the design rotation center of the rotating arm.
  • the X-ray machine rotating arm is controlled to perform a rotational scan around the standard phantom, and a plurality of projection results of the standard phantom at the set rotational position are acquired.
  • a rotating scan period of the rotating arm can be set to 2 ⁇ .
  • the set rotation angle can be multiple, so that the comprehensiveness of the set rotation angle can be ensured, and a relatively rich target projection result can be obtained.
  • the standard phantom is a spherical phantom, so after the rotation of the rotating arm of the X-ray machine, the diameter of the standard phantom corresponds to the projected diameter.
  • the projection center of the standard phantom has a position difference with the image center of the target projection result.
  • the target tangential displacement error of the rotation center in the tangential direction of the rotation plane is calculated according to the projection diameter of the standard phantom, the actual diameter of the standard phantom, and the source plate distance of the rotating arm.
  • Figure 2b is a schematic diagram of various parameters for calculating the target tangential displacement error, wherein the standard phantom has a projection diameter d 1 , the standard phantom has an actual diameter d 2 , and the rotating arm X-ray center A to the flat panel detector
  • the distance between the distances (hereinafter referred to as the source plate distance of the rotating arm) is L.
  • the target tangential displacement error of the projection point D of the rotating center C of the rotating arm in the tangential direction of the rotating plane is y i .
  • point A is the center of the X-ray source
  • B is the center of the standard phantom
  • C is the center of rotation of the rotating arm
  • D is the projection point of the center of rotation in the tangential direction of the plane of rotation
  • point E is the DC connection and An intersection of the projection ray of the X-ray source
  • F is the projection center of the standard phantom on the flat panel detector
  • G is the intersection of the outermost ray tangential to the standard phantom and the flat panel detector of the rotating arm. Since the distance from the center of rotation C of the rotating arm to the center B of the standard phantom is small, that is, the value of y i is small, the length of DE is approximately d 2 /2.
  • the center B of the standard phantom is placed on the rotating center C of the rotating arm.
  • the distance from the center B of the standard phantom to the center A of the X source, that is, the length of AB, and the distance L from the source plate of the rotating arm is k, and the length of AD is kL+y i . According to the similarity principle of triangles, ⁇ AFG ⁇ ADE can be obtained. which is therefore
  • FIG. 2c is a schematic diagram of a plurality of parameters for calculating a target radial displacement error, wherein the standard phantom has a projection diameter of d 1 , the standard phantom has an actual diameter of d 2 , and the rotating arm has a source plate distance of L, the target machine In the motion state, the target radial displacement error of the center of rotation in the tangential direction of the plane of rotation is x i .
  • point A is the center of the X-ray source
  • B is the center of the standard phantom
  • C is the center of rotation.
  • D1 is the projection point of the center of rotation in the radial direction of the plane of rotation
  • D is the projection point of the center of rotation in the tangential direction of the plane of rotation
  • point H is the intersection of the extension line of the AC line and the flat panel detector of the rotating arm, ie At the center of the target projection result
  • F is the projection center of the standard phantom
  • G is the intersection of the outermost ray tangential to the standard phantom and the flat panel detector.
  • the length of the FH is the position difference X between the standard phantom projection center and the target projection result center. According to the similarity principle of the triangle, ⁇ AFH ⁇ ADC can be obtained. which is Combine therefore
  • the technical solution of the embodiment obtains a dynamic correction matrix for correcting the rotation center of the actual projection result of the X-ray machine by calibrating the tangential displacement error and the radial displacement error of the rotation center of the rotating arm under different mechanical structural motion states,
  • the dynamic correction matrix By applying the dynamic correction matrix, the tangential displacement error and the radial displacement error of the actual rotation center of the projection result can be corrected, and the image quality after three-dimensional imaging can be improved.
  • FIG. 3a is a flowchart of a method for calibrating a parameter of an X-ray machine according to Embodiment 3.
  • This embodiment is based on the above embodiment, and two standard intersecting with any one of the aligned through holes are disposed on the standard phantom.
  • the marking through holes are symmetrical with respect to the center of the standard phantom and perpendicular to the plane defined by the two aligned through holes.
  • the parameter calibration method of the X-ray machine may further include: In each setting At a fixed rotational position, the rotational angle of the rotating arm is recorded; the error parameter may be an acquisition angle included in a different mechanical structural motion state of the rotating arm, and the error parameter is calculated based on the type of the error parameter. process.
  • the method of this embodiment may include the following steps.
  • the standard phantom is a spherical phantom
  • the standard phantom includes two orthogonally aligned through holes in a diameter direction, optionally, and is disposed on the standard phantom
  • Two mark through holes intersecting the through holes are aligned, the two mark through holes being symmetric with respect to the center of the standard phantom and perpendicular to the plane defined by the two aligned through holes, respectively.
  • the distance from the center of the sphere can be set to be 1/2 radius from the center of the sphere.
  • Figure 3b shows a top view of a standard phantom
  • Figure 3c shows a left side view of a standard phantom
  • Figure 3d shows a front view of a standard phantom with alignment through holes 31 and markings Through hole 32.
  • the X-ray machine rotating arm is controlled to perform a rotational scan around the standard phantom to obtain a projection result of a plurality of standard phantoms at the set rotational position.
  • the rotation angle of the rotating arm may be a set rotation angle input to a central processing unit of the X-ray machine, and based on the set rotation angle, the X-ray machine can control the rotating arm to perform corresponding mechanical motion. In order to adjust the rotating arm to the set rotation angle, and then after the rotation of the rotating arm is finished, the corresponding mechanical structure motion parameters are recorded.
  • a target acquisition angle in a moving state of the target mechanical structure is calculated according to a projection distance between the two marked through holes of the standard phantom, the target rotation angle, and a projection diameter of the standard phantom.
  • 3e is a schematic diagram of calculating a plurality of parameters of a target acquisition angle in a projection image of a standard phantom, wherein a projection distance between two standard through-holes 32 of the standard phantom is a, an acquisition angle value is ⁇ , a standard phantom
  • the projection diameter is d 1 .
  • the rotation angle values corresponding to the four quadrants are ⁇ , ⁇ + ⁇ /2, ⁇ , respectively. + ⁇ , ⁇ + 3 ⁇ /2, the set of four angles as the acquisition angle.
  • the acquisition angle ⁇ corresponding to the rotation angle ⁇ in one rotation scan period is:
  • ⁇ ⁇ cos -1 (2a/d 1 ), (cos -1 (2a/d 1 ))+ ⁇ /2), (cos -1 (2a/d 1 ))+ ⁇ ), (cos -1 ( (2a/d 1 )) +3 ⁇ /2 ⁇ .
  • the acquisition angle that minimizes the difference between the acquisition angle set and the target rotation angle is used as the calibration result of the target acquisition angle.
  • the target rotation angle is When the target acquisition angle is corrected, That is, the calibration result of the target acquisition angle is the acquisition angle value with the smallest difference from the target rotation angle, thereby ensuring that the obtained acquisition angle value is closest to the target rotation angle, that is, the target acquisition angle is consistent with the actual rotation angle.
  • a dynamic correction matrix for correcting the actual projection result of the X-ray machine is generated according to the calibration result of the target acquisition angle and the mechanical structure motion state of the rotating arm.
  • the calibration result ⁇ i according to the target acquisition angle constitutes an error matrix P, which is a matrix composed of ⁇ i .
  • the mechanical structure motion state s i at all set rotational positions is made up of a mechanical structure matrix S.
  • Perform singular value decomposition on the error matrix to obtain P EW, W is the weight matrix, and E is the eigenvalue matrix.
  • the technical solution of the embodiment calculates the target acquisition angle under the motion state of the target mechanical structure by the projection distance between the two calibrated through holes of the standard phantom, the target rotation angle and the projection diameter of the standard phantom, and the calibration according to the target acquisition angle.
  • a dynamic correction matrix for correcting the actual projection result of the X-ray machine is generated, and the actual correction result can be corrected by using the dynamic correction matrix when the corresponding error parameter is used for the acquisition angle.
  • the quality of the image is a dynamic correction matrix for correcting the actual projection result of the X-ray machine is generated, and the actual correction result can be corrected by using the dynamic correction matrix when the corresponding error parameter is used for the acquisition angle.
  • the dynamic correction matrix for correcting the actual projection result of the X-ray machine may further comprise: forming a mechanical structure motion state at a plurality of set rotation positions into a mechanical structure matrix S; and moving the plurality of mechanical structures in a state of motion Error parameters constitute an error matrix P;
  • the method in this embodiment may include:
  • the X-ray machine rotating arm is controlled to perform a rotational scan around the standard phantom to obtain projection results of a plurality of standard phantoms at the set rotational position.
  • the error parameter is calibrated according to the projection result of the standard phantom, and a calibration result of the error parameter is obtained.
  • error parameters may be a radial displacement error x i, y i tangential displacement error calibration results and the acquisition angle ⁇ i
  • the configuration E(WS T (SS T ) -1 ) is constructed as a dynamic correction matrix for correcting the actual projection result of the X-ray machine.
  • S is a matrix of motion states s i of all mechanical structures.
  • the technical solution of the embodiment constructs a dynamic correction matrix by using error parameters, which can correct the actual projection result and improve the quality of the image after three-dimensional imaging.
  • FIG. 5 is a flowchart of a parameter calibration method for an X-ray machine according to Embodiment 5, on the basis of the foregoing embodiment, the parameter calibration method of the X-ray machine can further increase a dynamic repair matrix generated according to the calibration, and the actual The process of correcting the projection result.
  • the method of this embodiment may include the following steps.
  • the X-ray machine rotating arm is controlled to perform a rotational scan around the standard phantom, and a plurality of projection results of the standard phantom at the set rotational position are acquired.
  • the error parameter is calibrated according to the projection result of the standard phantom, and a calibration result of the error parameter is obtained.
  • the X-ray machine rotating arm is controlled to perform a rotation scan around the object to be measured, and the projection result to be corrected at the actual rotation position is obtained.
  • an actual error parameter corresponding to the motion state of the measured mechanical structure is generated according to the measured mechanical structure motion state and the dynamic correction matrix.
  • the actual error parameter may include: a measured target tangential displacement error y j of the rotation center on the rotation plane and a measured target radial displacement error x j under the measured mechanical structure motion state s j of the rotating arm;
  • the actual error parameter, and performing image correction on the projection result to be corrected may include the following steps.
  • the target correction target projection result is subjected to a scaling process of a set ratio.
  • the measured target tangential displacement error wherein, the projection diameter d 1 of the standard phantom, the actual diameter d 2 of the standard phantom, and the source plate distance L, k of the rotating arm are the distance from the center of the sphere of the standard phantom to the light source, that is, the length of the AB, and the distance from the source plate.
  • the ratio of L, the ratio of the actual image of the standard phantom to the projected image make Among them, ideally Therefore, the projection result of the target to be corrected can be multiplied as The scaling operation to eliminate scaling errors.
  • k 1/2
  • the target radial displacement error Where X is the position difference between the standard phantom projection center and the target projection result center, the projection diameter d 1 of the standard phantom, and the actual diameter d 2 of the standard phantom, the difference between the standard phantom projection center and the target projection result center Therefore, by performing the projection result of the target to be corrected Pan, you can eliminate the translation error.
  • the actual error parameter may include an actual acquisition angle in a state of motion of the measured mechanical structure of the rotating arm.
  • performing image correction on the to-be-corrected projection result according to the actual error parameter may include: performing three-dimensional reconstruction on each to-be-corrected projection result according to the actual acquisition angle in different measured mechanical structure motion states.
  • the three-dimensional reconstruction is performed according to the corrected image and the corresponding angle ⁇ j to improve the image quality after the three-dimensional reconstruction.
  • the target tangential displacement error is used to perform a scaling process on the target to be corrected projection result; according to the target radial displacement error, the target distance to be corrected is subjected to a set distance translation, according to different actual measurements.
  • the actual acquisition angle of the mechanical structure in motion state, three-dimensional reconstruction of each projection result to be corrected, can achieve image correction, and achieve the effect of improving the image quality after three-dimensional reconstruction.
  • FIG. 6 is a structural diagram of a parameter calibration apparatus for an X-ray machine according to Embodiment 6.
  • the parameter calibration device of the X-ray machine provided by the embodiment of the present disclosure can be applied to the parameter calibration system of the X-ray machine described in the embodiment of the present disclosure.
  • the apparatus includes a projection result acquisition module 610, a motion state recording module 620, an error parameter calibration module 630, and a dynamic correction matrix generation module 640.
  • the projection result obtaining module 610 is configured to control the X-ray machine rotating arm to perform a rotation scan around the standard phantom, and collect the projection results at the plurality of set rotation positions.
  • the motion state recording module 620 is configured to record the mechanical structural motion state of the rotating arm at each of the set rotational positions.
  • the error parameter calibration module 630 is configured to calibrate the error parameter according to the projection result of the standard phantom at each set rotation position to obtain a calibration result of the error parameter.
  • the dynamic correction matrix generating module 640 is configured to generate a correction for the actual projection result of the X-ray machine according to the mechanical structure motion state of the rotating arm at each set rotational position and the calibration result of the error parameter Dynamic correction matrix.
  • the parameter calibration device of the X-ray machine provided by the embodiment is controlled to rotate around the standard phantom by controlling the rotating arm of the X-ray machine, and the mechanical structure of the rotating arm is moved according to the projection result of the standard phantom at a plurality of rotating positions.
  • the calibration of the error parameters can solve the problem that the calibration of the system structural parameters is usually based on the difference between the system parameters and the design objectives in the static state, and the error caused by the system motion cannot be calibrated and corrected. It can realize the calibration of the error parameters generated in the X-ray machine motion, and provide a new idea for the parameter calibration of the X-ray machine. By using the error parameter calibration result to correct the actual projection result, the image quality after 3D reconstruction is improved.
  • the standard phantom is a spherical phantom, and the standard phantom includes two orthogonally aligned through holes in the diametrical direction.
  • the parameter calibration device of the X-ray machine may further include: a projection position determining module configured to perform a rotational scan around the standard phantom of the rotating arm of the X-ray machine to obtain a standard phantom at a plurality of set rotational positions; Before the projection result, determining that the projection position of the X-ray source of the X-ray machine in the detector overlaps with the center of the detector, the spherical center of the standard phantom and the design rotation of the X-ray machine rotating arm The center overlaps.
  • the error parameter may include a tangential displacement error of the center of rotation on the plane of rotation and a radial displacement error in each mechanical structural motion state of the rotating arm.
  • the error parameter calibration module 630 can be configured to: acquire a target projection result corresponding to the set rotation position i and a target mechanical structure motion state, i ⁇ [1, N], N is a rotation scan of the rotating arm a total number of set rotation angles through which the cycle passes; in the target projection result, a projection diameter of the standard phantom, and a position difference between a projection center of the standard phantom and an image center of the target projection result; a projection diameter of the standard phantom, an actual diameter of the standard phantom, and a source plate distance of the rotating arm, and calculating a target tangential displacement error of the rotation center in a tangential direction of the rotation plane; projection according to the standard phantom The diameter, the actual diameter of the standard phantom, and the position difference between the projection center of the standard phantom and the image center of the target projection result, and the target radial displacement error of the rotation center in the radial direction of the rotation plane is calculated.
  • two standard through holes intersecting any one of the aligned through holes are disposed on the standard phantom, the two labeled through holes being symmetric with respect to a center of the standard phantom and perpendicular to the two alignments respectively The plane defined by the through hole.
  • the motion state recording module 620 can also be configured to record the rotation angle of the rotating arm at each set rotation position.
  • the error parameter may include an acquisition angle in a different mechanical structural motion state of the rotating arm.
  • the error parameter calibration module 630 can be configured to: acquire a target projection result corresponding to the set rotation position i, a target mechanical structure motion state, and a target rotation angle of the rotating arm, 1 ⁇ [1, N], N is a total number of set rotation angles of a rotation scan period of the rotating arm; in the target projection result, a projection diameter of the standard phantom is acquired, and between the two mark through holes of the standard phantom Projection distance; calculating a target acquisition angle in a moving state of the target mechanical structure according to a projection distance between the two marked through holes of the standard phantom, the target rotation angle, and a projection diameter of the standard phantom.
  • the dynamic correction matrix generating module 640 may be configured to: compose a mechanical structure motion state at a plurality of set rotation positions into a mechanical structure matrix S; and combine error parameters in a plurality of mechanical structure motion states into an error matrix P
  • the parameter calibration device of the X-ray machine may further include: a projection result obtaining module to be corrected, configured to be calibrated according to a mechanical mechanism motion state of the rotating arm at each set position and the error parameter
  • a projection result obtaining module to be corrected configured to be calibrated according to a mechanical mechanism motion state of the rotating arm at each set position and the error parameter
  • the measured mechanical structure motion state recording module is configured to generate an actual projection result for the X-ray machine based on a calibration result of a mechanical mechanism motion state of the rotating arm at each set position and the error parameter After the modified dynamic correction matrix, the measured mechanical motion state of the rotating arm is recorded at the actual rotational position.
  • the actual error parameter production module is configured to generate an actual error parameter corresponding to the motion state of the measured mechanical structure according to the measured mechanical structure motion state and the dynamic correction matrix.
  • the projection result correction module to be corrected is configured to perform image correction on the projection result to be corrected according to the actual error parameter.
  • the actual error parameter may include: an actual tangential displacement error of the center of rotation of the rotating arm in the plane of rotation and an actual radial displacement error at the actual rotational position;
  • the actual error parameter production module may be configured to: acquire a target to be corrected projection result corresponding to the actual rotation position j, the actual mechanical structure motion state of the nuclear target, j ⁇ [1, M], M is a rotation scan period of the rotating arm The total number of actual rotation angles passed; according to the dynamic correction matrix, acquiring a target tangential displacement error and a target radial displacement error corresponding to the moving state of the target measured mechanical structure; and waiting for the target according to the target tangential displacement error Correcting the projection result to perform scaling processing of the set ratio; And shifting the set distance to the target to be corrected projection result according to the target radial displacement error.
  • the actual error parameter may include an actual acquisition angle in a state of motion of the measured mechanical structure of the rotating arm.
  • the actual error parameter production module may be further configured to perform three-dimensional reconstruction on each of the projections to be corrected according to the actual acquisition angles in different motion states of the mechanical structure.
  • the parameter calibration device of the X-ray machine provided in this embodiment can be used to perform the parameter calibration method of the X-ray machine provided by any of the above embodiments, and has a corresponding function module.
  • FIG. 7 is a structural diagram of a parameter calibration system for an X-ray machine according to Embodiment 7. As shown in FIG. 7, the system may include: a rotating arm 710, an X-ray source 720 disposed opposite the rotating arm, and a detector 730, a processor 740, an image capturing device 750, a motion state collecting component 760, and Standard phantom 770.
  • the rotating arm 710 is configured to drive the X-ray source and the flat panel detector to rotate a plurality of set rotation angles around the standard phantom according to a control signal sent by the processor.
  • the X-ray source 720 is configured to transmit an X-ray scan signal to the standard phantom.
  • the detector 730 is configured to collect projection data of the X-ray scan signal on the standard phantom.
  • the image acquisition device 750 is configured to generate a projection result of the standard phantom according to the projection data collected by the detector.
  • the motion state collecting component 760 is configured to acquire a mechanical structural motion state of the rotating arm.
  • the processor 740 is configured to control the rotating arm to perform a rotational scan around the standard phantom to acquire a projection result of setting a standard phantom at a plurality of rotational positions; at each set rotational position, the rotating arm is recorded The mechanical structure motion state; at each set rotation position, the error parameter is proofed according to the projection result of the standard phantom, and the proofreading result of the error parameter is obtained; according to each set rotation position A mechanical correction state of the rotating arm and a calibration result of the error parameter generate a dynamic correction matrix for correcting the actual projection result of the X-ray machine.
  • the standard phantom 770 is a spherical phantom, and the standard phantom 770 includes two orthogonally aligned through holes in a diameter direction.
  • the processor 740 may be further configured to: determine an X-ray source of the X-ray machine before controlling a rotation scan of the X-ray machine around the standard phantom 770 to obtain a projection result of the standard phantom at different rotational positions
  • the projected position of 720 in detector 730 overlaps the center of detector 730
  • the center of the standard phantom 770 overlaps the designed center of rotation of the X-ray machine's rotating arm.
  • two standard through holes intersecting any one of the aligned through holes are disposed on the standard phantom 770, and the two labeled through holes are symmetric with respect to a center of a standard phantom, and are perpendicular to the two pairs respectively.
  • the plane defined by the through hole is disposed on the standard phantom 770, and the two labeled through holes are symmetric with respect to a center of a standard phantom, and are perpendicular to the two pairs respectively. The plane defined by the through hole.
  • the processor 740 may be further configured to record a rotation angle of the rotating arm at each set rotational position.
  • FIG. 8 is a flow chart of a calibration method corresponding to a parameter calibration system of an X-ray machine, which may include:
  • Initial alignment may refer to aligning the center of the standard phantom and X-ray source with the center of the flat panel detector.
  • Exposure imaging can refer to a rotational scan of a standard phantom.
  • the actual projection result of the measured object is corrected to obtain a more realistic high quality image.
  • FIG. 9 is a structural diagram of a parameter calibration system of an X-ray machine.
  • the parameter calibration system of the X-ray machine may include: an initial alignment module 910, which is set as an initial alignment of a standard phantom; and an image acquisition module 920. And set to collect the actual projection result of the object to be corrected; the system calibration module 930 is configured as an error parameter of the calibration system; and the image correction module 940 is configured to correct the actual projection result of the object to be corrected according to the error parameter;
  • the human-computer interaction module 950 is set to human-computer interaction.
  • the parameter calibration system of the X-ray machine provided by the embodiment is controlled by rotating the rotating arm of the X-ray machine around the standard phantom, and the different mechanical parts of the rotating arm according to the projection result of the standard phantom at the plurality of rotating positions Calibration of the error parameters in the structural motion state can be solved.
  • the method of calibrating the system structural parameters is usually calibrated according to the difference between the system parameters and the design target in the static state, and the error caused by the system motion cannot be calibrated.
  • the correction problem can calibrate the error parameters generated in the X-ray machine motion, and provide a new idea for the parameter calibration of the X-ray machine.
  • the present disclosure provides a parameter calibration method, device and system for an X-ray machine, which can realize X-ray
  • the error parameters generated during the motion of the machine are calibrated.
  • the quality of the image after three-dimensional reconstruction can be improved.

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Abstract

L'invention concerne également un procédé, un dispositif et un système d'étalonnage de paramètres pour une machine à rayons X. Le procédé comprend : la commande à un bras rotatif d'une machine à rayons X de tourner autour et de balayer un fantôme étalon, et l'acquisition des résultats de projection du fantôme étalon à de multiples positions de rotation prédéfinies (S110) ; l'enregistrement, à chacune des positions de rotation prédéfinies, d'un état de mouvement de structure mécanique du bras rotatif (S120) ; l'étalonnage, à chacune des positions de rotation prédéfinies et selon les résultats de projection du fantôme étalon, d'un paramètre d'erreur pour obtenir un résultat d'étalonnage du paramètre d'erreur (S130) ; et la génération, en fonction de l'état de mouvement de structure mécanique du bras rotatif à chacune des positions de rotation prédéfinies et du résultat d'étalonnage du paramètre d'erreur, d'une matrice de correction dynamique pour corriger un résultat de projet réel de la machine à rayons X (S140).
PCT/CN2017/072177 2017-01-23 2017-01-23 Procédé, dispositif et système d'étalonnage de paramètre pour machine à rayons x Ceased WO2018133090A1 (fr)

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CN102652674A (zh) * 2011-03-04 2012-09-05 首都师范大学 一种消除ct图像中的几何伪影的方法和系统
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