Method and device for rapidly recalibrating non-contact ultrasonic probeTechnical Field
The invention relates to the technical field of ultrasonic probe positioning, in particular to a non-contact type ultrasonic probe rapid recalibration method and device.
Background
Because the medical ultrasonic imaging technology has the advantages of small equipment volume, low cost, no radiation, good real-time performance and the like, the medical ultrasonic imaging technology is widely applied to medical examination and surgical operation. In particular in minimally invasive percutaneous interventions, ultrasound images can provide real-time surgical navigation for the surgeon with respect to anatomical structures that are not visible to the surgical object. However, the ultrasonic imaging technology does not have a space positioning function, and in order to accurately position the focus or other characteristic points on the ultrasonic image, the ultrasonic probe needs to be calibrated. The main current ultrasonic probe calibrating method is to install a positioner (such as an optical tracker and a magnetic positioning device) on an ultrasonic probe and a specific calibrating device, and scan the calibrating device by using the ultrasonic probe. The result of the ultrasonic probe calibration is to obtain the conversion relation between the coordinate system established by the optical tracker or the magnetic positioning device on the ultrasonic probe and the ultrasonic image coordinate system.
Because the locator on the ultrasonic probe can be influenced by external force in the clinical use process, the position of the locator is changed, and in order to ensure the calibration precision of the ultrasonic probe, the ultrasonic probe needs to be calibrated again through the calibration device before operation or after the locator fixing device is changed. The cumbersome calibration device and cumbersome calibration procedure greatly increase preoperative preparation time and require a certain skill in the operation of performing the calibration by the user. The surgeon needs to know the calibration method and operation more skillfully to ensure that frequent calibration work can achieve better accuracy each time.
Disclosure of Invention
The invention aims to provide a non-contact type ultrasonic probe rapid recalibration method, which aims to overcome the defects of the prior art.
Other features and advantages of the present disclosure will be apparent from the following detailed description, or may be learned in part by the practice of the disclosure.
According to one aspect of the invention, a method for rapidly recalibrating a non-contact ultrasonic probe is disclosed, comprising the following steps:
Step 1, fixing an optical positioning system and a binocular stereoscopic vision camera, and fixing an optical tracker and marking points on a probe, wherein the number of the marking points is a positive integer greater than or equal to 4;
Step 2, rotating the tip of the probe as a rotation center in a common visual field range of the optical positioning system and the binocular stereo vision camera, and recording the position and the gesture of the optical tracker acquired by the optical positioning system and the position and the gesture of the mark point acquired by the binocular stereo vision camera at N different moments, wherein N is a positive integer greater than or equal to 4;
Step 3, calculating the positions and the postures of the probe tips under the optical positioning system coordinate system and the binocular stereoscopic vision camera coordinate system respectively at n moments through a rotation calibration principle according to the positions and the postures of the optical tracker acquired by the optical positioning system and the positions and the postures of the mark points acquired by the binocular stereoscopic vision camera, and obtaining the conversion relation between the optical positioning system coordinate system and the binocular stereoscopic vision camera coordinate system through establishing an equation and solving by adopting a least square method;
Step 4, fixing the optical tracker and the mark point on an ultrasonic probe, and placing the optical tracker and the mark point in a common visual field range of the optical positioning system and the binocular stereo vision camera;
step 5, completing ultrasonic probe calibration through a calibration phantom based on the optical positioning system, and obtaining a conversion relation between the optical tracker coordinate system and an ultrasonic image coordinate system;
Step 6, calculating the conversion relation between the coordinate system of the mark point and the ultrasonic image coordinate system;
and 7, reading out the positions and the postures of the optical tracker and the mark point on the ultrasonic probe in the optical positioning system and the binocular stereoscopic vision camera respectively when the optical tracker is changed and needs to be re-calibrated, and calculating to obtain a calibration result of the ultrasonic probe.
Preferably, the marking points of the probe and the ultrasonic probe are planar patterns, which are directly attached to or drawn on the surface of the ultrasonic probe or the probe.
Preferably, in the step 3, the calculating the conversion relation between the coordinate system of the optical positioning system and the coordinate system of the binocular stereo camera specifically includes setting the coordinate system of the optical positioning system as O, the coordinate system of the binocular stereo camera as V, and the coordinate system of the Tip of the probe as Tip, then obtaining the coordinate relation of O, V, tip at n different moments:
calculating the coordinate relation between the needle tip of the probe and the coordinate system of the binocular stereoscopic vision camera and the optical positioning system at n different moments based on a matrix inversion function, wherein inv is the matrix inversion function, so as to obtain E and F:
further, the conversion relation between the origin coordinate system of the optical positioning system and the origin coordinate system of the binocular stereo vision camera is calculated as follows
Wherein, will beRepresenting a homogeneous transformation matrix from the coordinate system B to the coordinate system A;
wherein, R represents the rotation quantity of the matrixes A to B, P represents the translation quantity of the matrixes A to B, and the homogeneous conversion matrixes simultaneously comprise the relative position and the gesture information between the coordinate systems.
Preferably, in the step 6, the conversion relation between the coordinate system of the mark point of the binocular stereoscopic camera and the coordinate system of the ultrasonic image is calculated, specifically including setting the coordinate system of the optical tracker to be M1, the coordinate system of the ultrasonic image to be U, and the coordinate system of the mark point to be M2, to obtain the formula:
wherein,And the conversion relation between the binocular stereoscopic vision camera mark point coordinate system and the ultrasonic image coordinate system is obtained.
Preferably, in the step 7, the calculating to obtain the calibration result of the ultrasonic probe includes:
wherein,And the conversion relation between the optical tracker and the ultrasonic image coordinate system is obtained.
Preferably, the calibration phantom contains a material that is developable in ultrasound scanning, and is filled with a human tissue-like material.
According to a second aspect of the present disclosure, there is provided a quick recalibration device of a non-contact type ultrasonic probe, including an optical positioning system, a binocular stereoscopic vision camera, a computing device, a calibration phantom, an ultrasonic probe and a probe, the probe and the ultrasonic probe are respectively provided with an optical tracker and a marker in sequence, the positions of the optical positioning system and the binocular stereoscopic vision camera are relatively fixed, wherein the computing device is used for:
when the tip of the probe is used as a rotation center to rotate in a common visual field range of the optical positioning system and the binocular stereo vision camera, recording the position and the gesture of the optical tracker acquired by the optical positioning system and the position and the gesture of the mark point acquired by the binocular stereo vision camera at N different moments, wherein N is a positive integer greater than or equal to 4;
According to the position and the gesture of the optical tracker acquired by the optical positioning system and the position and the gesture of the mark point acquired by the binocular stereo vision camera, the position and the gesture of the probe tip under the coordinate system of the optical positioning system and the coordinate system of the binocular stereo vision camera at n moments are calculated through a rotation calibration principle, and the conversion relation between the coordinate system of the optical positioning system and the coordinate system of the binocular stereo vision camera is obtained through establishing an equation and solving by adopting a least square method;
the calibration of the ultrasonic probe is completed based on the optical positioning system and the calibration phantom, and the conversion relation between the optical tracker coordinate system and the ultrasonic image coordinate system is obtained;
Calculating the conversion relation between the coordinate system of the mark point and the ultrasonic image coordinate system;
and when the optical tracker is changed and needs to be re-calibrated, reading the positions and the postures of the optical tracker and the mark point on the ultrasonic probe in the optical positioning system and the binocular stereoscopic vision camera respectively, and calculating to obtain a calibration result of the ultrasonic probe.
Preferably, the calibration phantom contains a material that is developable in ultrasound scanning, and is filled with a human tissue-like material.
Preferably, the material capable of being developed in ultrasonic scanning is nylon rope, and the human tissue-imitating material is agar.
The technical scheme of the present disclosure has the following beneficial effects:
After the positioner fixing device of the ultrasonic probe is changed before operation or after the positioner fixing device of the ultrasonic probe is changed, medical staff does not need to use a heavy calibration device to recalibrate, and a new ultrasonic probe calibration result can be obtained by combining a binocular stereo camera with an optical positioning system to read probe parameters again. The operation difficulty of repeated calibration of the ultrasonic probe is remarkably reduced, the preoperative preparation time is shortened, the calibration efficiency is improved, and the problem of precision reduction after repeated calibration is avoided. The surgeon can easily complete repeated calibration of the ultrasonic probe without being familiar with a calibration method and a calibration device, so that the ultrasonic probe calibration accuracy is conveniently and regularly checked and the emergency situation (such as displacement caused by incorrect operation of a positioner fixing device in the operation) is treated.
Drawings
FIG. 1 is a diagram of the positional relationship of various parts in a rapid recalibration device of a non-contact ultrasound probe in an embodiment of the present disclosure;
FIG. 2 (a) is a schematic structural diagram of an ultrasonic probe with an optical tracker and marker point fixed in an embodiment of the present disclosure;
FIG. 2 (b) is a schematic diagram of a probe with an optical tracker and a marker immobilized thereon according to an embodiment of the present disclosure;
FIG. 3 is a schematic structural view of a calibration phantom in an embodiment of the present disclosure;
fig. 4 is a flowchart of a method for quick recalibration of a non-contact ultrasonic probe according to an embodiment of the present disclosure.
Detailed Description
The following description of the embodiments of the present invention will be made apparent and fully in view of the accompanying drawings, in which some, but not all embodiments of the invention are shown. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1, the embodiment provides a rapid recalibration device of a non-contact type ultrasonic probe, which comprises an optical positioning system 1, a binocular stereo vision camera 2, a computing device 3, an ultrasonic device 4, a calibration phantom 5, an ultrasonic probe 6 and a probe 7, wherein the positions of the optical positioning system 1 and the binocular stereo vision camera 2 are relatively fixed.
Referring to fig. 2 (a), the ultrasonic probe 6 is fixed with a first optical tracker 8 and first marker points 9 which can be recognized by a binocular stereo camera, the number of the first marker points being greater than or equal to 4.
Referring to fig. 2 (b), the probe 7 is fixed with a second optical tracker 10 and second marking points 11, and the number of the second marking points 11 is greater than or equal to 4.
The first optical tracker 8 and the second optical tracker 10 may be the same, that is, the first optical tracker 8 is fixed on the probe and then is fixed on the ultrasonic probe 6 after being acquired, or may be two of the same shape and function. Similarly, the first marker 9 and the second marker 11 may be the same or may be two of the same shape and function.
Referring to fig. 3, the calibration phantom 5 corresponding to the ultrasound probe 6 contains a nylon wire 51 or other material that can be easily developed in the ultrasound device 4 in a fixed position, and the rest is filled with agar to simulate human tissue.
The computing device 3 may collect an ultrasonic image scanned by the ultrasonic probe 6 controlled by the ultrasonic device 4, and calculate the real-time positions and attitudes of the first optical tracker 8 and the second optical tracker 10 collected by the optical positioning system 1 and the real-time positions and attitudes of the first marker point 9 and the second marker point 11 collected by the binocular stereo vision camera 2, which are specifically as follows:
When the needle tip of the probe 7 is used as a rotation center to rotate in the common visual field of the optical positioning system 1 and the binocular stereo camera 2, the conversion relation between the coordinate system of the optical tracker and the coordinate system of the ultrasonic image is obtained by recording the position and the posture of the optical tracker collected by the optical positioning system 1 and the position and the posture of the marker point collected by the binocular stereo camera 2 at N different moments, N is a positive integer greater than or equal to 4, according to the position and the posture of the optical tracker collected by the optical positioning system 1 and the position and the posture of the marker point collected by the binocular stereo camera 2, the conversion relation between the coordinate system of the marker point and the coordinate system of the ultrasonic image is calculated, the conversion relation between the coordinate system of the probe 7 and the coordinate system of the ultrasonic image is calculated, the coordinate system of the ultrasonic probe 6 is calculated by the rotation calibration principle, the conversion relation between the coordinate system of the probe 7 and the coordinate system of the binocular stereo camera 2 is obtained by establishing an equation and solving the conversion relation between the coordinate system of the optical positioning system 1 and the coordinate system of the binocular stereo camera 2 by adopting a least square method, the conversion relation between the coordinate system of the coordinate system 1 and the coordinate system of the binocular stereo camera 2 is obtained based on the optical positioning system 1 and the calibration body model 5, the conversion relation between the coordinate system of the ultrasonic probe 6 is obtained, the coordinate system of the ultrasonic image is calculated, the coordinate system of the marker point is calculated, the conversion relation between the coordinate system of the marker point is needed to be read out of the coordinate system and the probe 6, and the coordinate system of the probe is calculated, and the coordinate system is read out of the coordinate system, and the coordinate system is obtained, and the coordinate system is calculated, and the coordinate system is obtained by the coordinate system is calculated
From the above embodiments, it is known that the actual disclosure does not require the use of a cumbersome calibration device to recalibrate after preoperative or positioner fixation device changes. And the parameters of the ultrasonic probe 6 are read again through the binocular stereo camera 2 combined with the optical positioning system 1, so that a new calibration result of the ultrasonic probe 6 can be obtained. The operation difficulty of repeated calibration of the ultrasonic probe 6 is remarkably reduced, the preoperative preparation time is shortened, the calibration efficiency is improved, and the problem of precision reduction after repeated calibration is avoided. The surgeon can easily complete repeated calibration of the ultrasonic probe 6 without being familiar with the calibration method and the calibration device, thereby facilitating periodic inspection of the calibration accuracy of the ultrasonic probe 6 and handling of intraoperative emergencies (e.g., displacement of the fixture due to improper operation during surgery).
Based on the above-mentioned device, the embodiment of the present disclosure further provides a method for rapidly recalibrating a non-contact ultrasonic probe, referring to fig. 4, including steps S401 to S407:
In step S401, fixing the optical positioning system and the binocular stereo vision camera, and fixing an optical tracker and marking points on the probe, wherein the number of the marking points is a positive integer greater than or equal to 4;
In step S402, rotating the tip of the probe as a rotation center within a common field of view of the optical positioning system and the binocular stereo vision camera, and recording the position and posture of the optical tracker collected by the optical positioning system and the position and posture of the mark point collected by the binocular stereo vision camera at N different moments, where N is a positive integer greater than or equal to 4;
In step S403, according to the position and posture of the optical tracker collected by the optical positioning system and the position and posture of the mark point collected by the binocular stereo vision camera, the position and posture of the probe tip under the coordinate system of the optical positioning system and the coordinate system of the binocular stereo vision camera at n times are calculated by a rotation calibration principle, and the conversion relation between the coordinate system of the optical positioning system and the coordinate system of the binocular stereo vision camera is obtained by establishing an equation and solving by a least square method;
in step S404, an optical tracker and a marker point are fixed on the ultrasonic probe and placed in a common field of view of the optical positioning system and the binocular stereo camera;
In step S405, calibration of the ultrasonic probe is completed through a calibration phantom based on the optical positioning system, so as to obtain a conversion relationship between the optical tracker coordinate system and the ultrasonic image coordinate system;
In step S406, a conversion relationship between the coordinate system of the marker point and the coordinate system of the ultrasound image is calculated;
in step S407, when the optical tracker is changed and needs to be re-calibrated, the positions and postures of the optical tracker and the mark point on the ultrasonic probe in the optical positioning system and the binocular stereo vision camera are read out, and the calibration result of the ultrasonic probe is obtained through calculation.
In one embodiment, the probe and the marking point of the ultrasonic probe are planar patterns, which are directly attached to or drawn on the surface of the ultrasonic probe or probe.
Additionally, in step S403, the conversion relation between the coordinate system of the optical positioning system and the coordinate system of the binocular stereo camera is calculated, specifically including that the coordinate system of the optical positioning system is O, the coordinate system of the binocular stereo camera is V, and the coordinate system of the Tip of the probe is Tip, then the coordinate relation of O, V, tip at n different moments is obtained:
Calculating the coordinate relation between the needle points of the probes at n different moments and the coordinate systems of the binocular stereoscopic vision camera and the optical positioning system based on matrix inversion function, wherein inv is the matrix inversion function, and E and F are obtained:
further, the conversion relation between the origin coordinate system of the optical positioning system and the origin coordinate system of the binocular stereo camera is calculated as follows
Wherein, will beRepresenting a homogeneous transformation matrix from the coordinate system B to the coordinate system A;
Wherein R represents the rotation amount of the matrixes A and B, P represents the translation amount of the matrixes A and B, and the homogeneous conversion matrix simultaneously comprises the relative position and posture information between the coordinate systems.
In addition, in step S406, the conversion relation between the coordinate system of the mark point of the binocular stereoscopic vision camera and the coordinate system of the ultrasonic image is calculated, specifically comprising the steps of setting the coordinate system of the optical tracker as M1, the coordinate system of the ultrasonic image as U, and the coordinate system of the mark point as M2, thereby obtaining the formula:
wherein,The method is a conversion relation between a binocular stereoscopic vision camera mark point coordinate system and an ultrasonic image coordinate system.
Additionally, in step S407, the calibration result of the ultrasonic probe is calculated, including:
wherein,Is the conversion relation between the optical tracker and the ultrasonic image coordinate system.
It should be noted that the above embodiments are merely for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that the technical solution described in the above embodiments may be modified or some or all of the technical features may be equivalently replaced, and these modifications or substitutions do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the present invention. Furthermore, those skilled in the art will appreciate that while some embodiments described herein include some features but not others included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the claims below, any of the claimed embodiments may be used in any combination. The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.