WO2018133002A1

WO2018133002A1 - Rotation angle calibration device for c-arm system, and calibration method for c-arm system

Info

Publication number: WO2018133002A1
Application number: PCT/CN2017/071693
Authority: WO
Inventors: 陈垦; 王澄; 秦文健; 熊璟; 谢耀钦
Original assignee: 深圳先进技术研究院
Priority date: 2017-01-19
Filing date: 2017-01-19
Publication date: 2018-07-26

Abstract

A rotation angle calibration device for a C-arm system, and method of using the rotation angle calibration device for a C-arm system to calibrate a C-arm system. The method comprises a motion conversion component, a displacement sensor (8), a data transmitter (9), and a processor (10). The motion conversion component is configured to be connected to a C-arm (11), and converts rotary motion of the C-arm (11) into linear motion. The displacement sensor (8) is connected to the motion conversion component, and configured to acquire a displacement signal of the motion conversion component and transmit the displacement signal to the data transmitter (9) connected to the displacement sensor (8). The processor (10) is connected to the data transmitter (9), and configured to receive and analyze the displacement signal sent by the data transmitter (9).

Description

C-arm system rotation angle calibration device and C-arm system calibration method

Technical field

The present disclosure relates to the field of CT system parameter calibration techniques, for example, to a C-arm system rotation angle calibration device and a calibration method for a C-arm system.

Background technique

The medical diagnostic equipment based on X-ray radiation is called C-arm. The C-arm equipment is more and more widely used in the medical field. The C-arm can move around the guide to the part to be inspected or to be treated. For the purpose of comprehensive inspection of patients who are inconvenient to move or move. An X-ray device composed of an X-ray source at one end of a C-arm, an X-ray detector at the other end of the C-arm, or an image intensifier is used more and more widely as a diagnostic instrument.

In the X-ray three-dimensional image reconstruction, whether the X-ray source of the C-arm and the running track of the detector conform to the preset trajectory will affect the quality of the reconstructed image. The vibration of the mechanical structure during the operation of the C-arm system may cause the projection angle of the X-ray source to be different from the preset angle, which may cause artifacts in the reconstructed image and affect the image reconstruction quality. The lack of observation of the vibration of the mechanical structure makes it difficult to calibrate and correct the jitter of the mechanical structure.

In the related art, the method of calibrating the structural parameters of the CT system is usually to calibrate the difference between the system parameters and the design target in the static state, and cannot calibrate and correct the errors generated during the movement of the system. Calibration methods in the technology also require X-ray imaging, which creates additional radiation risks to the human body.

Summary of the invention

The present disclosure provides a C-arm system rotation angle calibration device and a method for calibrating a C-arm system using the C-arm system rotation angle calibration device, which can solve the rotation angle of the C-arm system that cannot be used in motion. The problem of calibration.

A C-arm system rotation angle calibration device includes a motion conversion component, a displacement sensor, a data transmitter, and a processor. The motion conversion assembly is configured to be coupled to the C-arm to convert rotational motion of the C-arm to linear motion. The displacement sensor is coupled to the motion conversion assembly and configured to acquire a displacement signal of the motion conversion assembly and transmit the displacement signal to the data transmitter coupled to the displacement sensor. The processor is coupled to the data transmitter and configured to receive and analyze a displacement signal transmitted by the data transmitter.

A method for calibrating a C-arm system by using the above-mentioned C-arm system rotation angle calibration device, comprising: the processor controls the displacement sensor to be set to zero, and the displacement sensor collects and collects during a one-degree rotation of the C-arm calibration Transmitting a displacement signal of the linear motion of the motion conversion component to the data transmitter; and according to the received displacement signal sent by the data transmitter, the processor calculates a rotation angle value corresponding to the C-arm at each moment Calibrating the value, and combining the rotation angle value of each moment with the corresponding calibration value to form a standard value pair; when the C-arm is freely rotating, when the controller controls the target angle value of the C-arm and all standard values When the values of the rotation angles of the pair do not match, the target angle value is interpolated and corrected by the standard value pair.

Optionally, the motion conversion assembly comprises: a base, a cam, a longitudinal rack, a transmission gear set and a transverse rack, the cam being fixed to the base by a fixed shaft, the fixed shaft being located at the geometry of the cam Centered on and perpendicular to the base, the geometric center of the cam is disposed in line with the center of rotation of the C-arm, one end of the longitudinal rack is in contact with the contour of the cam, and the other end is connected with an elastic member. The elastic member is disposed in vertical contact with the detector at one end of the C-arm; the lateral rack is drivingly connected to the longitudinal rack through the transmission gear set, and the displacement sensor is connected to one end of the lateral rack; The processor controls the displacement sensor to be set to zero. During the one-step rotation of the C-arm, the displacement sensor collects and transmits a displacement signal of the linear motion of the motion conversion component to the data transmitter, including: the processor controls the displacement The sensor is set to zero and keeps the cam fixed; during the rotation of the C-arm at a constant angular velocity ω, the displacement sensor collects and outputs the linear motion of the transverse rack Shift signal to the data transmission device, record displacement signal f (t) data collected by the transmitter, wherein t is time.

Optionally, the processor calculates a calibration value corresponding to the rotation angle value of the C-arm at each moment, and combines the rotation angle value of each moment with the corresponding calibration value to form a standard value pair, including:

When the contour of the cam satisfies: r=r(θ), where r is the polar diameter and θ is the rotation angle value of the C-arm during the calibration rotation, θ=ωt, θ∈[0,360], the transmission gear set When the magnification is α, the processor calculates a calibration value corresponding to the rotation angle value at each moment.

The rotation angle value θ at each time and the corresponding calibration value Θ are combined into a standard value pair (Θ, θ).

Optionally, during the free rotation of the C-arm, when the controller controls the C-arm target angle value to not match the rotation angle value of all the standard value pairs, the standard value pair is used. Interpolation corrections for the target angle values, including:

During the free rotation of the C-arm, when the controller of the C-arm determines that the target angle value does not match the rotation angle value of all the standard value pairs, the two closest to the target angle value are selected among the standard value pairs. The rotation angle values θ1 and θ2 respectively correspond to the calibration values Θ1 and Θ2, and the target angle values are interpolated and corrected by using the two selected calibration values Θ1 and Θ2 to obtain a difference result, and the difference result is the target angle value. Corresponding corrected angle.

Optionally, the interpolation method is a linear interpolation method.

A C-arm system includes a C-arm, a light source, a detector, and a controller, wherein the light source is disposed at one end of the C-arm and the detector is disposed at the other end of the C-arm. The C-arm is configured to drive the light source and the detector to rotate according to a control signal sent by the controller. The light source is configured to emit a scan signal to the object to be detected during free rotation of the C-arm. The detector is configured to collect projection data of the scan signal on the object to be detected. The controller is configured to be in communication with a processor of the C-arm system rotation angle calibration device and in communication with the detector.

Optionally, the controller is configured to receive and store a plurality of standard value pairs transmitted by a processor of the C-arm system rotation angle calibration device.

Optionally, the controller may be configured to compare the target angle value of the C-arm with all standard value pairs during the free rotation of the C-arm, and determine the target angle value of the C-arm and all standards. When the values of the rotation angles of the pair of values do not match, the target angle value is interpolated and corrected by the plurality of standard value pairs.

Optionally, the controller may be further configured to: when determining that the target angle value of the C-arm does not match the rotation angle value of all the standard value pairs, select the closest target angle value among the standard value pairs. The two rotation angle value angles θ1 and θ2 respectively correspond to the calibration values Θ1 and Θ2, and the target angle values are interpolated and corrected by using the two selected calibration values Θ1 and Θ2 to obtain a difference result, and the difference result is the The corrected angle corresponding to the target angle value.

The present disclosure provides a C-arm system rotation angle calibration device and a method for calibrating a C-arm system using the C-arm system rotation angle calibration device, the calibration device including a motion conversion component, a displacement sensor, and a data transmitter, motion The conversion assembly is configured to be coupled to the C-arm to convert the rotational motion of the C-arm into a linear motion. The displacement sensor is coupled to the motion conversion component and configured to acquire a displacement signal of the motion conversion component and transmit the displacement signal to the data transmitter connected to the displacement sensor. The device is simple in operation, stable and reliable in operation, and does not need to expose X-rays during use, which can reduce the radiation risk.

DRAWINGS

The one or more embodiments are exemplified by the accompanying drawings in the accompanying drawings, and FIG. The figures in the drawings do not constitute a scale limitation unless otherwise stated.

1 is a schematic structural view of a C-arm system rotation angle calibration device and a C-arm system according to the embodiment.

1-base; 2-cam; 3-fixed shaft; 4-longitudinal rack; 5-spring; 6-transmission gear set; 7-transverse rack; 8-displacement sensor; 9-data transmitter; 10-processor ; 11-C arm; 12-light source; 13-detector; 14-controller.

detailed description

In order to make the objects, the technical solutions and the advantages of the present disclosure more apparent, the technical solutions of the present disclosure will be clearly and completely described by the embodiments with reference to the accompanying drawings. The described embodiments are a part of the embodiments of the present disclosure, and not all of the embodiments. The features of the following embodiments and embodiments may be combined with each other without conflict.

Example 1

As shown in FIG. 1, the embodiment provides a C-arm system rotation angle calibration device, including a motion conversion component, a displacement sensor 8 and a data transmitter 9, and a processor 10.

The motion conversion assembly includes a base 1, a cam 2, a longitudinal rack 4, a spring 5, a transmission gear set 6, and a lateral rack 7. The cam 2 is fixed to the base 1 by a fixed shaft 3 which is located at the geometric center of the cam 2 and which is perpendicular to the base 1. The position of the cam 2 on the base 1 can be adjusted as needed. One end of the longitudinal rack 4 is in contact with the contour of the cam 2, which end is movable along the contour of the cam 2, and the other end of the longitudinal rack 4 is connected with a spring 5. The transverse rack 7 is drivingly connected to the longitudinal rack 4 via a transmission gear set 6. The displacement sensor 8 is connected to one end of the lateral rack 7 away from the longitudinal rack 4, and the data transmitter 9 is connected to the displacement sensor 8 and arranged to collect the reading of the displacement sensor 8. The processor 10 is arranged to be coupled to the data transmitter 9 to receive and analyze the data transmitted by the data transmitter 9.

Illustratively, the transmission gear set 6 may comprise two gears, the two gears being coaxially arranged, one of which meshes with the longitudinal rack 4 and the other of which meshes with the transverse rack 7 with the longitudinal rack 4 The diameter of the meshing gear is smaller than the diameter of the gear that meshes with the lateral rack 7. The number of gears of the transmission gear set 6 may also be more than two, and the plurality of gears may be coaxially arranged and different in diameter, one of the gears meshes with the longitudinal rack 4, and any one of the remaining gears and the lateral rack 7 In engagement, the diameter of the gear meshing with the longitudinal rack 4 is smaller than the diameter of the gear meshing with the transverse rack 7. Multiple gears for flexible adjustment of magnification.

This embodiment also provides a method of calibrating a C-arm system using a C-arm system rotation angle calibration device. Connecting the motion conversion assembly to the C-arm 11 and optionally, one end of the C-arm 11 The center of the light source 12 is center-aligned with the detector 13 at the other end of the C-arm 11. The fixed shaft 3 is passed through the geometric center of the cam 2 and fixed to the base 1, and the starting point of the contour of the cam 2 is aligned with the center of the detector 13, wherein the geometric center of the cam 2 is shared with the center of rotation of the C-arm 11 line. One end of the longitudinal rack 4 is brought into contact with the starting point of the contour of the cam 2, and the spring 5 connected at the other end is in contact with the detector 12. The transverse rack 7 is drivingly coupled to the longitudinal rack 4 via the transmission gear set 6 such that the displacement sensor 8 is coupled to one end of the lateral rack 7.

After the connection is completed, the C-arm is calibrated and corrected. The steps may include:

1) The processor 10 controls the displacement sensor 8 to be set to zero, the controller of the C-arm controls the rotation C-arm 11 to rotate in the counterclockwise direction, and the displacement sensor 8 collects and transmits the displacement signal of the linear motion of the motion conversion component to the data transmitter 9 The data transmitter 9 transmits the acquired displacement signal to the processor 10.

Alternatively, during the calibration rotation of the C-arm 11 , the holding cam 2 is fixed, and the controller 14 of the C-arm system controls the C-arm 11 to rotate counterclockwise at a constant angular velocity ω, and the rotational motion of the C-arm 11 Through the linear motion converted by the longitudinal rack 4 and the lateral rack 7, the displacement sensor 8 collects and outputs a displacement signal of the linear motion of the lateral rack 7 to the data transmitter 9, and the data transmitter 9 sends the obtained displacement signal to the processor. 10. The processor 10 records the displacement signal acquired by the data transmitter 9 as f(t), where t is time.

2) According to the displacement signal sent by the data transmitter 9, the processor 10 calculates a calibration value corresponding to the rotation angle value of the C-arm 11 at each moment, and combines the rotation angle value of each moment with the corresponding calibration value. Standard value pair.

Optionally, the contour line of the setting cam 2 satisfies: r=r(θ), where r is a polar diameter, θ is a polar angle, and θ represents a rotation angle value during a C-arm calibration rotation, θ=ωt, ∈∈[0,360]. The magnification of the transmission gear set 6 is set to α; the processor 10 calculates a calibration value corresponding to the rotation angle of each moment.

3) During the free rotation of the C-arm 11, when the controller of the C-arm determines that the target angle value does not match the rotation angle value of all the standard value pairs, the target value is used to calculate the target angle value. Interpolation correction.

Optionally, if the controller 14 of the C-arm system determines that the target angle value does not match the rotation angle value of all the standard value pairs, the two rotation angle values θ1 closest to the target angle value are selected among the standard value pairs. The calibration values Θ1 and Θ2 corresponding to θ2 respectively are interpolated and corrected by using the selected two calibration values Θ1 and Θ2 to obtain the difference result, and the difference result is used as the correction corresponding to the target angle value. After the angle.

In the above operation, in the operations in

steps

1 and 2, the C-arm system is calibrated using the C-arm system rotation angle calibration device. During the calibration of the C-arm system, the light source 12 of the C-arm system is turned off, thereby reducing the risk of radiation. After calibration, the processor 10 of the apparatus can calculate a calibration value corresponding to the rotation angle value of each time of the C-arm 11 and combine the rotation angle value of each moment with the corresponding calibration value to form a standard value pair.

In the above operation, in the operation of the step 3, the controller 14 of the C-arm system corrects the target angle value of the C-arm 11 during the free rotation by using the rotation angle value θ and the calibration value 上述 of the standard value pair. .

Optionally, the controller 14 of the C-arm system is communicatively coupled to the processor 10 of the C-arm system rotational angle calibration device, which transmits a plurality of standard value pairs to the controller 14. During the free rotation of the C-arm, when the controller 14 controls the target angle value of the C-arm rotation to not match the rotation angle value of all the standard value pairs, the rotation angle value and the calibration value pair in the standard value pair are utilized. The target angle value of the C-arm is interpolated.

In this embodiment, the interpolation method may be a linear interpolation method. In other embodiments, other suitable interpolation methods can also be employed.

The method is simple in operation, stable and reliable in operation, and does not need to expose X-rays during use, and can reduce the radiation risk.

This embodiment also provides a C-arm system. As shown in FIG. 1, the C-arm system may include a C-arm 11, a light source 12, a detector 13 and a controller 14, wherein the light source 12 is disposed at C. One end of the arm 11 and a detector 13 are disposed at the other end of the C-arm 11. The C-arm 11 is arranged to drive the light source 12 and the detector 13 to rotate according to a control signal sent by the controller 14. The light source 12 is arranged to emit a scan signal to the object being detected during free rotation of the C-arm. The detector 13 is arranged to acquire projection data of the scanning signal on the object to be detected. The controller 14 is arranged in communication with the processor 10 of the C-arm system rotation angle calibration device and is communicatively coupled to the detector 13.

Alternatively, the controller 14 may be arranged to receive and store a plurality of standard value pairs transmitted by the processor 10 of the C-arm system rotation angle calibration device.

Optionally, the controller 14 may be further configured to compare the target angle value of the C-arm with the plurality of standard value pairs during the C-arm free rotation, when determining the C-arm 11 When the target angle value does not match the rotation angle value in the plurality of standard value pairs, the standard value pair is used for the target The angle value is corrected by interpolation.

Optionally, the controller 14 may be further configured to: when determining that the target angle value of the C-arm does not match the rotation angle value of all the standard value pairs, select the closest target angle value among the standard value pairs. The two rotation angle value angles θ1 and θ2 respectively correspond to the calibration values Θ1 and Θ2, and the selected two calibration values Θ1 and Θ2 are used to interpolate the target angle value to obtain a difference result, and the difference result is The corrected angle corresponding to the target angle value.

Alternatively, the light source 12 can be an X-ray source.

Example 2

For the sake of brevity, only the differences between the second embodiment and the first embodiment will be described, the difference being that the motion conversion assembly can also be other mechanical structures that can convert the rotary motion into a linear motion, such as a crank slider mechanism. Or crank linkages, etc.

Industrial applicability

The present disclosure provides a C-arm system rotation angle calibration device and a method for calibrating a C-arm system using the C-arm system rotation angle calibration device. The device is simple in operation, stable and reliable in operation, and does not need to expose X-rays during use, which can reduce the radiation risk.

Claims

A C-arm system rotation angle calibration device, comprising a motion conversion component, a displacement sensor, a data transmitter and a processor;

The motion conversion assembly is configured to be coupled to the C-arm to convert the rotational motion of the C-arm into a linear motion;

The displacement sensor is coupled to the motion conversion assembly, configured to acquire a displacement signal of the motion conversion assembly, and transmit the displacement signal to the data transmitter coupled to the displacement sensor;

The processor is coupled to the data transmitter and configured to receive and analyze a displacement signal transmitted by the data transmitter.
The apparatus of claim 1 wherein said motion conversion assembly comprises: a base, a cam, a longitudinal rack, a drive gear set, and a transverse rack;

The cam is fixed to the base by a fixed shaft located at a geometric center of the cam and perpendicular to the base, the geometric center of the cam being disposed to be collinear with the center of rotation of the C-arm ;as well as

One end of the longitudinal rack is in contact with the contour of the cam, and the other end is connected with an elastic member, the elastic member is disposed in vertical contact with the detector at one end of the C-arm; the transverse rack passes through the transmission gear set The longitudinal rack is connected to the longitudinal rack, and the displacement sensor is connected to one end of the lateral rack.
The apparatus according to claim 2, wherein said transmission gear set includes two gears, said two gears being coaxially disposed, wherein one gear meshes with said longitudinal rack, and the other gear and said transverse gear The bars are engaged.
The apparatus of claim 3 wherein the diameter of the gear meshing with the longitudinal rack is smaller than the diameter of the gear meshing with the transverse rack.
The apparatus according to claim 2, wherein said transmission gear set has more than two gears, the plurality of gears are coaxially disposed, and the diameters are different from each other, wherein one of the gears meshes with said longitudinal rack, and the rest Any one of the gears meshes with the transverse rack.
The apparatus of claim 5 wherein the diameter of the gear meshing with the longitudinal rack is smaller than the diameter of the gear meshing with the transverse rack.
The device according to claim 2, wherein the elastic member is a spring.
A method for calibrating a C-arm system using the C-arm system rotation angle calibration device of claim 1 comprising:

The processor controls the displacement sensor to be set to zero;

The displacement sensor collects and transmits the motion conversion during one revolution of the C-arm calibration The displacement signal of the linear motion of the component to the data transmitter;

And the processor calculates a calibration value corresponding to the rotation angle value of the C-arm at each moment according to the received displacement signal sent by the data transmitter, and correspondingly the rotation angle value of each moment Calibration values form a standard value pair;

During the free rotation of the C-arm, when the controller controls the target angle value of the C-arm to not match the rotation angle value of all the standard value pairs, the target angle value is interpolated by the standard value pair Corrected.
The method of claim 8 wherein said motion conversion assembly comprises: a base, a cam, a longitudinal rack, a drive gear set and a transverse rack, said cam being secured to said base by a fixed shaft, said securing a shaft is located at a geometric center of the cam and perpendicular to the base, the geometric center of the cam being disposed collinear with a center of rotation of the C-arm, one end of the longitudinal rack being in contact with the contour of the cam, The other end is connected with an elastic member disposed in vertical contact with the detector at one end of the C-arm; the lateral rack is drivingly coupled to the longitudinal rack through the transmission gear set, one end of the transverse rack Connecting the displacement sensor;

The processor controls the displacement sensor to be set to zero. During the one-step rotation of the C-arm, the displacement sensor collects and transmits the displacement signal of the linear motion of the motion conversion component to the data transmitter, including:

The processor controls the displacement sensor to zero and keeps the cam stationary;

During the rotation of the C-arm at a constant angular velocity ω, the displacement sensor collects and outputs a displacement signal of the linear motion of the transverse rack to the data transmitter, and records the displacement signal f(t) collected by the data transmitter, where t is time.
The method according to claim 9, wherein said processor calculates a calibration value corresponding to a rotation angle value of the C-arm at each moment, and combines the rotation angle value of each moment with a corresponding calibration value. Value pairs, including:

When the contour of the cam satisfies: r=r(θ), where r is the polar diameter and θ is the rotation angle value of the C-arm during the calibration rotation, θ=ωt, θ∈[0,360], the transmission gear set When the magnification is α, the processor calculates a calibration value corresponding to the rotation angle value at each moment.
The rotation angle value θ at each time and the corresponding calibration value Θ are combined into a standard value pair (Θ, θ).
The method according to claim 10, wherein said utilizing said C-arm target angle value does not match a rotation angle value of all standard value pairs during free rotation of said C-arm The standard value pair is corrected for the target angle value row interpolation method, including:

During the free rotation of the C-arm, when the controller of the C-arm determines that the target angle value does not match the rotation angle value of all the standard value pairs, the two rotations closest to the target angle value are selected among the standard value pairs. The angle values θ1 and θ2 respectively correspond to the calibration values Θ1 and Θ2, and the target angle values are interpolated and corrected by the two calibration values Θ1 and Θ2 to obtain a difference result, wherein the difference result is corresponding to the target angle value. The corrected angle.
The method of claims 8-11, wherein the interpolation method is a linear interpolation method.
A C-arm system including a C-arm, a light source, a detector, and a controller, wherein

The light source is disposed at one end of the C-arm, and the detector is disposed at the other end of the C-arm;

The C-arm is configured to drive the light source and the detector to rotate according to a control signal sent by the controller;

The light source is configured to emit a scan signal to the object to be detected during the free rotation of the C-arm;

The detector is configured to collect projection data of the scan signal on the object to be detected;

The controller is configured to be in communication with a processor of the C-arm system rotation angle calibration device and in communication with the detector.
The system of claim 13 wherein said controller is configured to:

A plurality of standard value pairs transmitted by a processor of the C-arm system rotation angle calibration device are received and stored.
The system of claim 14 wherein said controller is configured to:

Comparing the target angle value of the C-arm with all of the standard value pairs during free rotation of the C-arm;

When it is determined that the target angle value of the C-arm does not match the rotation angle value of all the standard value pairs, the target angle value is interpolated and corrected by the plurality of standard value pairs.
The system of claim 15 wherein said controller is configured to:

When it is determined that the target angle value of the C-arm does not match the rotation angle value of all the standard value pairs, the two rotation angle values closest to the target angle value are selected from the standard value pairs, and the angles θ1 and θ2 respectively correspond to The calibration values Θ1 and Θ2 are interpolated to correct the target angle value by using two calibration values Θ1 and Θ2 to obtain a difference result, which is the corrected angle corresponding to the target angle value.