An electromagnetic position tracking system for medical navigation

Abstract

The application relates to an electromagnetic positioning tracking system for medical navigation, comprising a magnetic field generator, a reference calibrator, a tracking sensor and a tracking processing terminal; the magnetic field generator is used for generating a magnetic field which simultaneously covers the reference calibrator and the tracking sensor; the reference calibrator is placed outside a patient's body and is used for sensing a magnetic field signal; the tracking sensor is used for following the movement of a medical device placed in the patient's body and sensing a magnetic field signal; the tracking processing terminal determines the position and posture information of the reference calibrator and the tracking sensor in the coordinate system of the magnetic field generator according to the magnetic field signals sensed by the reference calibrator and the tracking sensor; the position and posture information of the tracking sensor in the reference coordinate system relative to the reference calibrator is calculated again; and real-time positioning tracking of the tracking locator is carried out according to the position and posture information of the tracking sensor in the reference coordinate system. The application realizes the tracking positioning of the medical device placed in the patient's body, has high accuracy, no radiation hazard and is easy to implement and popularize.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic positioning and medical device technology, specifically relating to an electromagnetic positioning and tracking system for medical navigation. Background Technology

[0002] With the rapid development of medical technology, digital medical navigation systems have become an important auxiliary device for minimally invasive interventional surgeries such as spinal, cranial, and neurosurgical procedures. By providing intelligent real-time tracking and navigation for minimally invasive interventional surgeries, they enable uninterrupted two-way information exchange between medical devices and medical professionals, making high-risk surgeries safer, more precise, and more reliable.

[0003] In minimally invasive interventional therapy, medical devices (such as electrophysiological catheters, specialized catheters, guidewires, and puncture tools) can reach the lesion site for diagnosis and treatment through the patient's vascular system. Doctors need to know the exact location of the medical device within the patient's body, which is usually not obtainable through direct methods. Currently, commonly used methods in clinical practice include X-ray imaging, nuclear medicine imaging, and real-time ultrasound. These methods typically involve radiation exposure, cannot be used for continuous monitoring for several hours, and require large, expensive equipment, limiting the examination to specific locations and impacting the patient's normal work and life.

[0004] Therefore, there is a demand for tracking and positioning systems that are highly accurate, radiation-free, easy to implement and promote, and suitable for implanting medical devices within patients. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to disclose an electromagnetic positioning and tracking system for medical navigation, which solves the problem of tracking and positioning medical devices implanted in the patient's body.

[0006] This invention discloses an electromagnetic positioning and tracking system for medical navigation, comprising: a magnetic field generator, a reference calibrator, a tracking sensor, and a tracking processing terminal;

[0007] The magnetic field generator is used to generate a magnetic field that simultaneously covers the reference calibrator and the tracking sensor;

[0008] The reference calibrator is placed outside the patient's body and is communicatively connected to the tracking processing terminal. It is used to sense magnetic field signals and output them to the tracking processing terminal.

[0009] The tracking sensor follows the movement of the medical device placed inside the patient's body and is communicatively connected to the tracking processing terminal to sense magnetic field signals and output them to the tracking processing terminal.

[0010] The tracking processing terminal determines the position and attitude information of the reference calibrator and the tracking sensor in the coordinate system of the magnetic field generator based on the magnetic field signals sensed by the reference calibrator and the tracking sensor; then calculates the position and attitude information of the tracking sensor in the reference coordinate system relative to the reference calibrator; and performs real-time positioning and tracking of the tracking locator based on the position and attitude information of the tracking sensor in the reference coordinate system.

[0011] Furthermore, the magnetic field generator includes eight single-axis magnetic field transmitting antennas;

[0012] The single-axis magnetic field transmitting antenna is arranged in three rows in a "3-2-3" pattern, forming the antenna arrangement area;

[0013] In a rectangular coordinate system established with the center of the antenna arrangement area as the origin and the row direction of the three rows as the x-axis, the pose data of the eight single-axis magnetic field transmitting antennas, composed of the x and y axis coordinates, azimuth rotation angle, and elevation rotation angle in the rectangular coordinate system, are as follows:

[0014] First transmitting antenna (-58.7mm, -58.4mm, 142°, -73°);

[0015] Second transmitting antenna (-1.6mm, -57.3mm, 64°, 15°);

[0016] Third transmitting antenna (62.6mm, -61.3mm, 92°, -33°);

[0017] Fourth transmitting antenna (-38.5mm, 0.9mm, 163°, 17°);

[0018] Fifth transmitting antenna (39.4mm, 1.3mm, 154°, 29°);

[0019] The sixth transmitting antenna (-61.4mm, 64.1mm, 39.3°, 63°);

[0020] The seventh transmitting antenna (-5.4mm, 64.3mm, 80°, 9°);

[0021] Eighth transmitting antenna (58.8mm, 59.9mm, 93°, 87°);

[0022] In the rectangular coordinate system, the error range for the x and y directions is ±3mm, and the error range for the azimuth and pitch rotation angles is ±5°.

[0023] Furthermore, the reference calibrator includes a magnetic sensor S1, a magnetic sensor S2, a printed circuit board, and a housing;

[0024] The magnetic sensors S1 and S2 are mounted on the printed circuit board with a fixed heading angle θ.

[0025] The outer casing is shaped like a Reilly triangle; a cable hole is provided in the middle of one side of the casing, through which the external cable of the reference calibrator is led out.

[0026] Furthermore, the tracking sensor, magnetic sensor S1, and magnetic sensor S2 are all single-axis magnetic induction coils.

[0027] Furthermore, the tracking processing terminal includes a first pose determination module, a second pose determination module, and a tracking module;

[0028] The first pose determination module is used to determine the position and pose information of the reference calibrator center point and the tracking sensor in the magnetic field generator coordinate system;

[0029] The second pose determination module is used to calculate the position difference between the center point of the tracking sensor and the reference calibrator and the transformation matrix from the reference coordinate system to the tracking sensor coordinate system; based on the position difference and the transformation matrix, the position and attitude information of the tracking sensor in the reference coordinate system is calculated.

[0030] The tracking module is used to perform real-time positioning and tracking of the tracking sensor based on the position and attitude information of the tracking sensor in the reference coordinate system.

[0031] Furthermore, in the first attitude determination module, the position and attitude information of the reference calibrator center point is determined using an electromagnetic positioning method; the positioning process includes:

[0032] 1) Based on electromagnetic positioning, obtain the five-axis position and attitude information of magnetic sensors S1 and S2 in the coordinate system of the magnetic field generator; wherein, the five-axis position and attitude information includes three-axis position information and heading attitude angle and pitch attitude angle;

[0033] 2) Pitch attitude angle P obtained through magnetic sensor S1 TS1 And magnetic sensor S2 pitch attitude angle P TS2 The roll attitude angle of magnetic sensor S1 was determined. Rolling attitude angle of magnetic sensor S2

[0034] 3) Based on the six-axis position and attitude information of magnetic sensor S1 and magnetic sensor S2, determine the six-axis position and attitude information of the reference calibrator center point in the coordinate system of the magnetic field generator.

[0035] Furthermore, based on the position and attitude data of the magnetic sensor S1, the position coordinates of the reference calibrator center point in the magnetic field generator coordinate system are determined as follows:

[0036]

[0037] Among them, XTS1 Y TS1 Z TS1 This provides the position information of the magnetic sensor S1 in the coordinate system of the magnetic field generator. X is the inverse of the transformation matrix from the coordinate system of the magnetic field generator to the coordinate system of the magnetic sensor S1; RS1 Y RS1 Z RS1 This provides the position information of the magnetic sensor S1 in the reference coordinate system;

[0038] Based on the position and attitude data of magnetic sensor S2, the position coordinates of the center point of the reference calibrator in the coordinate system of the magnetic field generator are determined as follows:

[0039]

[0040] X TS2 Y TS2 Z TS2 This provides the position information of the magnetic sensor S2 in the coordinate system of the magnetic field generator.

[0041] L is the inverse of the transformation matrix from the magnetic field generator coordinate system to the magnetic sensor S2 coordinate system; S1->S2 (-θ;0;0) is the transformation matrix from the S1 coordinate system of the magnetic sensor to the S2 coordinate system of the magnetic sensor; X RS2 Y RS2 Z RS2 This is the position information of the magnetic sensor S2 in the reference coordinate system.

[0042] Furthermore, the calculation process in the second pose determination module includes:

[0043] 1) Calculate the position difference between the center point of the tracking sensor and the center point of the reference calibrator based on the position information of the center point of the tracking sensor and the reference calibrator;

[0044] 2) Perform coordinate transformation based on the attitude information of the center points of the tracking sensor and the reference calibrator to obtain the transformation matrix from the reference coordinate system to the tracking sensor coordinate system:

[0045] 3) Based on the position difference and transformation matrix, calculate the position and attitude information of the tracking sensor in the reference coordinate system;

[0046] 4) Based on the transformation matrix, calculate the attitude information of the tracking sensor in the reference coordinate system.

[0047] Furthermore, based on the aforementioned position difference, the calculated position information of the tracking sensor in the reference coordinate system is as follows:

[0048]

[0049] X TS3 Y TS3 Z TS3 To track the sensor's position information in the magnetic field generator coordinate system; X TRC Y TRC Z TRC This is to provide the position information of the center point of the reference calibrator in the coordinate system of the magnetic field generator;

[0050] L T->R C(C TRC ;P TRC ;R TRC C is the transformation matrix from the magnetic field generator coordinate system to the reference coordinate system; TRC P TRC R TRC The reference calibrator center point is used in the coordinate system of the magnetic field generator to determine the heading attitude angle, pitch attitude angle, and roll attitude angle.

[0051] Furthermore, based on the transformation matrix, the attitude information of the tracking sensor in the reference coordinate system is calculated as follows:

[0052] Tracking sensor heading attitude angle

[0053] P pitch attitude angle of the tracking sensor RS3 =atan(sin PRS3 )*180 / pi.

[0054] This invention can achieve at least one of the following beneficial effects:

[0055] This invention provides an electromagnetic positioning and tracking system for medical navigation that uses magnetic field signals to track and locate medical devices implanted in the patient's body. Furthermore, the method employs electromagnetic technology, eliminating reliance on radiographic methods for location detection. This makes it easier for medical personnel, medically trained family members, and friends of patients to use, allowing these technologies to be applied in medical institutions or home care wards. It features high accuracy, no radiation hazards, and ease of implementation and promotion. Attached Figure Description

[0056] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0057] Figure 1 This is a block diagram of the electromagnetic positioning and tracking system in an embodiment of the present invention;

[0058] Figure 2 This is a top view of the antenna assembly and circuit board of the magnetic field generator inside the housing after the housing is opened, according to an embodiment of the present invention.

[0059] Figure 3 This is a coordinate diagram of the eight single-axis magnetic field transmitting antennas in a rectangular coordinate system according to an embodiment of the present invention;

[0060] Figure 4 This is a schematic block diagram showing the components and connections of the signal generator in an embodiment of the present invention;

[0061] Figure 5 This is an external view of the reference calibrator in an embodiment of the present invention;

[0062] Figure 6 This is an exploded view of the reference scaler in an embodiment of the present invention;

[0063] Figure 7 This is a schematic block diagram showing the components and connections of the tracking processing terminal in an embodiment of the present invention. Detailed Implementation

[0064] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and, together with the embodiments of the present invention, serve to illustrate the principles of the present invention.

[0065] An electromagnetic positioning and tracking system for medical navigation according to the present invention, such as Figure 1 As shown, it includes: a magnetic field generator, a reference calibrator, a tracking sensor, and a tracking processing terminal;

[0066] The magnetic field generator is used to generate a magnetic field that simultaneously covers the reference calibrator and the tracking sensor;

[0067] The reference calibrator is placed outside the patient's body and is communicatively connected to the tracking processing terminal. It is used to sense magnetic field signals and output them to the tracking processing terminal.

[0068] The tracking sensor follows the movement of the medical device placed inside the patient's body and is communicatively connected to the tracking processing terminal to sense magnetic field signals and output them to the tracking processing terminal.

[0069] The tracking processing terminal determines the position and attitude information of the reference calibrator and the tracking sensor in the coordinate system of the magnetic field generator based on the magnetic field signals sensed by the reference calibrator and the tracking sensor; then calculates the position and attitude information of the tracking sensor in the reference coordinate system relative to the reference calibrator; and performs real-time positioning and tracking of the tracking locator based on the position and attitude information of the tracking sensor in the reference coordinate system.

[0070] Specifically, the magnetic field generator is a time-division multiplexing local alternating magnetic field generator used to generate a local alternating magnetic field that simultaneously covers the reference calibrator and the tracking sensor; it includes an antenna assembly, a signal generator, a circuit board, cables, connectors, and a housing;

[0071] like Figure 2 As shown, a top view of the antenna assembly and circuit board inside the housing is given after the housing is opened.

[0072] The antenna assembly includes eight single-axis magnetic field transmitting antennas; each single-axis magnetic field transmitting antenna is electrically connected to a signal generator; the signal generator generates a magnetic field excitation signal and outputs it to each single-axis magnetic field transmitting antenna in a time-division switching manner, so that the excited single-axis magnetic field transmitting antenna radiates a magnetic field signal outward, and the eight single-axis magnetic field transmitting antennas radiate magnetic field signals outward in a time-division switching manner to form an alternating spatial magnetic field.

[0073] The circuit board carries and fixes the excitation signal generator and antenna assembly, so that the eight single-axis magnetic field transmitting antennas are arranged in three rows of "3-2-3" on the circuit board, forming a planar antenna arrangement area;

[0074] The housing encloses the circuit board, signal generator, and antenna assembly within a sealed space; the housing is provided with horizontal mounting holes to position the eight single-axis magnetic field transmitting antennas on a horizontal plane; and with vertical mounting holes to position the eight single-axis magnetic field transmitting antennas on a vertical plane.

[0075] To address the issue of low magnetic field signal strength and spatial magnetic field inhomogeneity in certain regions of space when arranging eight single-axis magnetic field transmitting antennas in simple orthogonal or other configurations, this embodiment employs simulation testing of the eight single-axis magnetic field transmitting antennas to determine the position and orientation of each antenna.

[0076] Specifically, the pose data of the eight single-axis magnetic field transmitting antennas are as follows:

[0077] like Figure 3 As shown, a rectangular coordinate system is established with the center of the antenna arrangement area as the origin and the row direction of the three rows as the x-axis;

[0078] The pose data of the eight single-axis magnetic field transmitting antennas, consisting of the x and y axis coordinates and azimuth and elevation rotation angles in a rectangular coordinate system, are as follows:

[0079] First transmitting antenna (-58.7mm, -58.4mm, 142°, -73°);

[0080] Second transmitting antenna (-1.6mm, -57.3mm, 64°, 15°);

[0081] Third transmitting antenna (62.6mm, -61.3mm, 92°, -33°);

[0082] Fourth transmitting antenna (-38.5mm, 0.9mm, 163°, 17°);

[0083] Fifth transmitting antenna (39.4mm, 1.3mm, 154°, 29°);

[0084] The sixth transmitting antenna (-61.4mm, 64.1mm, 39.3°, 63°);

[0085] The seventh transmitting antenna (-5.4mm, 64.3mm, 80°, 9°);

[0086] Eighth transmitting antenna (58.8mm, 59.9mm, 93°, 87°);

[0087] In the rectangular coordinate system, the error range for the x and y directions is ±3mm, and the error range for the azimuth and pitch rotation angles is ±5°.

[0088] Specifically, the single-axis magnetic field transmitting antenna includes a transmitting coil, a coil frame, and a series resonant capacitor network; the transmitting coil is wound on the outer surface of the coil frame, and the transmitting coil and the series resonant capacitor network are connected in series to form a series resonant circuit.

[0089] The series resonant capacitor network consists of several COG-grade ceramic capacitors with capacitance values ​​ranging from pF to nF and a withstand voltage of over 600V connected in parallel to form a series resonant circuit with the transmitting coil.

[0090] The outer shell is made of a high-temperature resistant non-metallic material, which is a composite material based on polyetheretherketone (PEEK), and the high-temperature resistance of the non-metallic material is not less than 300°C.

[0091] Specifically, such as Figure 4 As shown, the signal generator includes a magnetic field drive generator, a transmitting antenna switcher, and an interface circuit;

[0092] The interface circuit is electrically connected to the magnetic field drive generator and the transmitting antenna switcher, respectively; the magnetic field drive generator is electrically connected to the transmitting antenna switcher, and the transmitting antenna switcher is electrically connected to each single-axis magnetic field transmitting antenna, respectively.

[0093] The magnetic field drive generator receives external input commands through the interface circuit and outputs a magnetic field excitation signal to the transmitting antenna switcher.

[0094] The transmitting antenna switcher receives external input commands through the interface circuit and switches the magnetic field excitation signal to the corresponding single-axis magnetic field transmitting antenna, which then radiates the magnetic field signal outward.

[0095] More specifically, the magnetic field drive generator includes a DDS (direct digital frequency synthesizer), a filter, a gain amplifier, and a power amplifier.

[0096] The DDS is an AD9951 with a 32-bit frequency adjustment word; under the control of receiving externally input frequency control word instructions from the interface circuit, it outputs a 5kHz excitation signal to the filter.

[0097] The filter is a high-order low-pass filter used to filter out high-order harmonics in the excitation signal generated by the DDS excitation signal generation module and output a smoothed excitation signal. The filter is a fourth-order active low-pass filter composed of two multi-feedback filters built with low-noise amplifiers OPA2189 connected in series, with its cutoff frequency set to 26kHz.

[0098] The gain amplifier is a programmable gain amplifier. The gain amplifier amplifies the smoothed excitation signal output from the filter.

[0099] The programmable gain amplifier can achieve gain adjustment under the control of externally input gain control word commands received in the interface circuit. The programmable gain amplifier is a non-inverting proportional amplifier circuit composed of a low-noise amplifier OPA189 and a digitally controlled potentiometer AD5293. The digitally controlled potentiometer is connected in series in the feedback loop of the amplifier circuit. Under the control of the gain control word commands, the 1024 ranges of the digitally controlled potentiometer can be adjusted to achieve continuous gain amplification and adjustment of the smoothed excitation signal.

[0100] The power amplifier amplifies the output signal of the gain amplifier and outputs a drive excitation signal to the antenna assembly.

[0101] The transmit antenna switcher includes a drive signal switcher and a freewheeling protector, each connected to a single-axis magnetic field transmit antenna. Under the control of an externally input switching command, the drive signal switcher uses an optocoupler relay to rapidly switch the excitation drive signal to the series resonant circuit containing the transmit coil of the connected single-axis magnetic field transmit antenna. The freewheeling protector uses an optocoupler relay to release the inductive load backlash signal generated by the excitation drive signal on the series resonant circuit containing the transmit coil, thereby protecting the circuit.

[0102] The optocoupler relay is a miniature high-speed optocoupler relay TLP3475S.

[0103] It also includes a current detection circuit connected between the magnetic field drive generator and the transmitting antenna switcher. The current detection circuit is connected to the interface circuit, detects the magnetic field excitation signal of the magnetic field drive generator, and outputs the detection signal through the interface circuit.

[0104] The current detection circuit conditions and samples the drive current when switching to the single-axis magnetic field transmitting antenna to obtain a detection signal, which is then output through the interface circuit.

[0105] The current detection circuit includes a high-precision current sampling circuit, a sampling conditioning circuit, and a high-precision analog-to-digital converter (ADC);

[0106] The high-precision current sampling circuit samples the excitation current in the transmitting antenna coil and outputs a sampled voltage signal with a gain of 1mV / 1mA.

[0107] The high-precision current sampling circuit features an extremely high-precision surface-mount current sensing chip resistor, VCS1625ZP, with a resistance value of 1Ω, a resistance tolerance of ±1‰, and a temperature coefficient of ±0.05ppm / ℃.

[0108] The sampling conditioning circuit amplifies the sampled voltage signal and outputs the amplified sampled signal.

[0109] The sampling conditioning circuit includes a proportional amplifier circuit composed of an amplifier circuit consisting of a differential amplifier LT6376 and an amplifier circuit consisting of a low-noise amplifier OPA189 connected in series. The gain of the amplifier circuit consisting of the differential amplifier LT6376 is 10, and the gain of the amplifier circuit consisting of the low-noise amplifier OPA189 is 1.5.

[0110] The high-precision analog-to-digital converter performs analog-to-digital conversion on the amplified sampled signal and outputs the digital conversion result; the high-precision analog-to-digital converter is the AD7768-4, a 24-bit ADC with a bandwidth of 110.8KHz.

[0111] The interface circuit can be an existing interface circuit such as RS232 or RS422, or it can be extended to other types of existing interface circuits. The interface circuit is connected to an external cable, and the external cable is led out from the housing through a cable outlet hole provided on the housing.

[0112] Preferably, the interface circuit is connected to the tracking processing terminal via a cable and connector. The tracking processing terminal integrates a control module for the magnetic field generator.

[0113] The control module of the magnetic field generator generates frequency control commands, power control commands, and switching control commands based on the stored program parameters and the feedback signal from the current detection circuit output by the magnetic field generator. These commands are then output to the magnetic field generator to control the frequency and power of the driving voltage and the antenna switching, thereby controlling the time-division multiplexed local alternating magnetic field generated by the magnetic field generator.

[0114] Specifically, the reference calibrator includes a housing, a printed circuit board, a magnetic sensor S1, a magnetic sensor S2, a cable, and a connector;

[0115] The outer casing is in the shape of a Reno triangle; the printed circuit board is placed inside the outer casing; the magnetic sensors S1 and S2 are mounted on the printed circuit board with a fixed heading angle θ and are electrically connected to the tracking and processing terminal via cables and connectors.

[0116] The outer shell of the Leylow triangle has a cable hole in the middle of one side; the cable extends from this cable hole, giving the reference calibrator a clear directionality.

[0117] Figure 5 This is a diagram of the reference calibrator. Figure 6 This is an exploded view of the reference calibrator; the magnetic sensors S1 and S2 mounted on the printed circuit board, as well as the cables and connectors that connect to the printed circuit board via the cables, are omitted from the view.

[0118] The outer casing includes an upper cover and a base; the printed circuit board is fixed on the base, and the center point of the structural dimensions coincides with the center point of the structural dimensions of the base.

[0119] The printed circuit board and the housing adopt the same Rell's triangle structure, and the size is scaled down according to the size ratio of the calibrator housing, with a scaling ratio not exceeding 0.8.

[0120] Specifically, both magnetic sensor S1 and magnetic sensor S2 are uniaxial magnetic induction coils.

[0121] The uniaxial magnetic induction coil includes a coil frame and an induction coil; the coil frame is made of glass-encased amorphous wire; the induction coil is tightly wound on the outer surface of the coil frame.

[0122] The induction coil is fixed by a close-wound method, which improves the measurement sensitivity of the single-axis magnetic field induction coil and enhances the accuracy of single-point magnetic field measurement in space under the requirement of fixed position of the single-axis magnetic field induction coil.

[0123] More specifically, the length of the amorphous wire skeleton is 5mm to 6.5mm; preferably 6mm; the induction coil uses self-adhesive enameled wire with a diameter of no more than 0.02mm, and the length of the wound induction coil does not exceed 5mm.

[0124] Specifically, the tracking sensor uses the same single-axis magnetic induction coil as magnetic sensors S1 and S2, and is connected to the tracking processing terminal via leads.

[0125] The magnetic sensors S1 and S2, as well as the tracking sensor, all employ single-axis magnetic induction coils placed within an alternating spatial magnetic field generated by a magnetic field generator. They sense changes in the magnetic field and output induced information. The position and attitude information of the magnetic sensors S1, S2, and the tracking sensor are determined based on electromagnetic positioning. The use of the same single-axis magnetic induction coil and the same electromagnetic positioning method for determining position and attitude information simplifies implementation.

[0126] The calibrator housing adopts a Reilly triangle structure, approximating the xiphoid process of the human ribcage. This allows the reference calibrator to be quickly, accurately, and stably placed on the patient's xiphoid process. Furthermore, with the cable attached, the reference calibrator has clear directionality, meeting ergonomic design requirements and facilitating clinical application. In certain specific usage scenarios, clinical staff can securely position the reference calibrator on the patient's xiphoid process, with the calibrator cable extending downwards along the patient's torso and towards the lower limbs.

[0127] The tracking processing terminal is connected to the magnetic field generator and controls the time-division multiplexed local alternating magnetic field generated by the magnetic field generator. The reference calibrator placed outside the patient and the tracking sensor placed inside the patient sense the local alternating magnetic field and output the sensed magnetic field signal to the tracking processing terminal.

[0128] The tracking processing terminal determines the position and attitude information of the reference calibrator and the tracking sensor in the coordinate system of the magnetic field generator based on the magnetic field signals sensed by the reference calibrator and the tracking sensor; then it calculates the position and attitude information of the tracking sensor in the reference coordinate system relative to the reference calibrator; and performs real-time positioning and tracking of the tracking locator based on the position and attitude information of the tracking sensor in the reference coordinate system.

[0129] Specifically, such as Figure 7 As shown, the tracking processing terminal includes a first pose determination module, a second pose determination module, and a tracking module;

[0130] The first pose determination module is used to determine the position and attitude information of the reference calibrator center point and the position and attitude information of the tracking sensor in the magnetic field generator coordinate system. The magnetic field generator coordinate system takes the center of the antenna arrangement area of ​​the magnetic field generator as the origin and the front-right-down direction of the antenna arrangement area as the three axes. The "front" of the magnetic field generator can be the direction in which the eight single-axis magnetic field transmitting antennas are located on the circuit board.

[0131] The second pose determination module is used to calculate the position difference between the center point of the tracking sensor and the center point of the reference calibrator; perform coordinate transformation based on the pose information of the center points of the tracking sensor and the reference calibrator to obtain a transformation matrix from the reference coordinate system to the tracking sensor coordinate system; and calculate the position and pose information of the tracking sensor in the reference coordinate system based on the position difference and the transformation matrix. The reference coordinate system has the center point of the reference calibrator as its origin and the front-right-down direction of the reference calibrator as its three axes. The "front" of the reference calibrator can refer to the direction facing the patient when the reference calibrator is placed on the patient's body. The tracking sensor coordinate system has the center point of the sensor axis as its three axes, with the right-front-down direction as its three axes. The "front" of the tracking sensor can refer to the direction pointed to by the sensor axis.

[0132] Based on the coordinate system of the magnetic field generator, the coordinate system of the tracking sensor, and the reference coordinate system, the attitude axes of the corresponding coordinate systems can be determined according to the right-hand screw rule.

[0133] The tracking module is used to perform real-time positioning and tracking of the tracking sensor based on the position and attitude information of the tracking sensor in the reference coordinate system.

[0134] It also includes a display module for showing real-time location tracking information for observation by doctors or other assistive medical personnel.

[0135] Specifically, in the first pose determination module, the position and attitude information of the reference calibrator center point are determined using an electromagnetic positioning method. The positioning process includes:

[0136] 1) Based on electromagnetic positioning, obtain the five-axis position and attitude information of magnetic sensors S1 and S2 in the coordinate system of the magnetic field generator; the five-axis position and attitude information includes three-axis position information and heading and pitch attitude angles; that is, the five-axis position and attitude information of magnetic sensor S1 (X TS1 ;Y TS1 Z TS1 C TS1 ;P TS1 ), magnetic sensor S2 five-axis position and attitude information (X TS2 ;Y TS2 Z TS2 C TS2 ;P TS2 );

[0137] In this embodiment, the five-axis spatial position measurement of a single-axis magnetic induction coil in an alternating spatial magnetic field can be achieved using existing techniques in the art. Any method capable of measuring the five-axis spatial position of a single-axis magnetic induction coil can be applied to this embodiment without affecting the scope of protection of this invention. For example, the method described in the article "Research Progress of Electromagnetic Tracking Methods" summarized by Ge Xin et al. can be used.

[0138] 2) Determine the roll attitude angles of magnetic sensors S1 and S2 using the pitch attitude angles of magnetic sensors S1 and S2;

[0139] Rolling attitude angle of magnetic sensor S1

[0140] Rolling attitude angle of magnetic sensor S2

[0141] 3) Based on the six-axis position and attitude information of magnetic sensor S1 and magnetic sensor S2, determine the six-axis position and attitude information of the reference calibrator center point in the coordinate system of the magnetic field generator.

[0142] Obtain the six-axis position and attitude information (X) of the magnetic sensor S1 TS1 ;Y TS1 Z TS1 C TS1 ;P TS1 ;R TS1 ), magnetic sensor S2 six-axis position and attitude information (X TS2 ;Y TS2 Z TS2 C TS2 ;P TS2 ;R TS2 );

[0143] Based on this, the position coordinates of the reference calibrator center point in the magnetic field generator coordinate system can be determined according to the position and attitude data of the magnetic sensor S1:

[0144]

[0145] Among them, X TS1 Y TS1 Z TS1 This provides the position information of the magnetic sensor S1 in the coordinate system of the magnetic field generator. X is the inverse of the transformation matrix from the coordinate system of the magnetic field generator to the coordinate system of the magnetic sensor S1; RS1 Y RS1 Z RS1 This represents the position information of the magnetic sensor S1 in the reference coordinate system.

[0146] Since there is a fixed heading angle θ between magnetic sensors S1 and S2, the position coordinates of the reference calibrator center point in the magnetic field generator coordinate system can also be determined based on the position and attitude data of magnetic sensor S2:

[0147]

[0148] X TS2 Y TS2 Z TS2This provides the position information of the magnetic sensor S2 in the coordinate system of the magnetic field generator.

[0149] L is the inverse of the transformation matrix from the magnetic field generator coordinate system to the magnetic sensor S2 coordinate system; s1->S2 (-θ;0;0) is the transformation matrix from the S1 coordinate system of the magnetic sensor to the S2 coordinate system of the magnetic sensor; X RS2 Y RS2 Z RS2 This is the position information of the magnetic sensor S2 in the reference coordinate system.

[0150] The coordinate transformation matrix from the magnetic field generator coordinate system to the magnetic sensor S1 or S2 coordinate system is as follows:

[0151]

[0152] in,

[0153] L TSi 11 = cosC TSi *cos P TSi

[0154] L TSi 12 = cos P TSi *sin C TSi

[0155] L TSi 13 = -sin P TSi

[0156] L TSi 21=-cosR TSi *sin C TSi +cos C TSi *sinR TSi

[0157] L TSi 22 = sin P TSi *cosR TSi *cos C TSi +sinR TSi *sin C TSi *sin P TSi

[0158] L TSi 23 = cos P TSi *sinR TSi

[0159] L TSi 31=sinR TSi *sin C TSi +cosR TSi*cos C TSi *sin P TSi

[0160] L TSi 32 = -cos C TSi *sinR TSi +cosR TSi *sin C TSi *sin P TSi

[0161] L TSi 33 = cosR TSi *cos P TSi ;

[0162] Transformation matrix from magnetic sensor S1 coordinate system to magnetic sensor S2 coordinate system:

[0163]

[0164] Specifically, the attitude data of the reference calibrator center point in the magnetic field generator coordinate system can be determined based on the attitude data of the magnetic sensor S1.

[0165] The reference coordinate system's attitude axes are set parallel to the three axes of the tracking sensor S1, according to the right-hand screw rule. The reference calibrator's heading attitude angle C is then obtained. TRC =C TS1 Pitch attitude angle P TRC =P TS1 The roll attitude angle is the same as the pitch attitude angle R. TRC =R TS1 .

[0166] This determines the six-axis position and attitude information of the reference calibrator center point in the magnetic field generator coordinate system.

[0167] Using the same method as magnetic sensors S1 and S2, the five-axis position and attitude information (X) of the tracking sensor in the magnetic field generator coordinate system is obtained. TS3 ;Y TS3 Z TS3 C TS3 ;P TS3 ;R TS3 ).

[0168] Specifically, the calculation process in the second pose determination module includes:

[0169] 1) Calculate the position difference between the center point of the tracking sensor and the center point of the reference calibrator based on the position information of the center point of the tracking sensor and the reference calibrator;

[0170] XTS3 Y TS3 Z TS3 To track the sensor's position information in the magnetic field generator coordinate system; X TRC Y TRC Z TRC This is to provide the position information of the center point of the reference calibrator in the coordinate system of the magnetic field generator.

[0171] 2) Perform coordinate transformation based on the attitude information of the center points of the tracking sensor and the reference calibrator to obtain the transformation matrix from the reference coordinate system to the tracking sensor coordinate system:

[0172]

[0173] Where C RS3 P RS3 R RS3 The heading, pitch, and roll attitude angles of the tracking sensor are shown in the reference coordinate system.

[0174] L RC->S3 (C RS3 ;P RS3 ;R RS3 () represents the transformation matrix from the reference coordinate system to the tracking sensor coordinate system;

[0175] C TS3 P TS3 R TS3 To track the sensor's heading, pitch, and roll attitude angles in the magnetic field generator coordinate system;

[0176] L T->S3 (C TS3 ;P TS3 ;R TS3 () represents the coordinate transformation matrix from the magnetic field generator coordinate system to the tracking sensor coordinate system;

[0177] The inverse of the transformation matrix from the magnetic field generator coordinate system to the reference coordinate system.

[0178] Because the five-axis position and attitude information of the tracking sensor in the coordinate system of the magnetic field generator was obtained, the roll attitude angle R was not obtained. TS3 Information. The attitude information C from the tracking sensor has been obtained. TS3 ;P TS3 ;R TS3 And calculate to obtain the RC attitude information C of the origin of the reference coordinate system. TRC ;P TRC ;R TRC In this case, solve C TS3 ;P TS3 Time and R TS3The value is independent. Therefore, the rolling attitude angle R of the tracking sensor in the magnetic field generator coordinate system is... TS3 Set to 0°; then, the transformation matrix from the reference coordinate system to the tracking sensor coordinate system is:

[0179]

[0180] in,

[0181] L RCS3 11 = cosC RS3 *cosP RS3

[0182] L RCS3 12 = cosP RS3 *sinC RS3

[0183] L RCS3 13 = -sinP RS3

[0184] L RCS3 21=-cosR RS3 *sinC RS3 +cosC RS3 *sinR RS3

[0185] L RCS3 22=sinP RS3 *cosR RS3 *cosC RS3 +sinR RS3 *sinC RS3 *sinP RS3

[0186] L RcS3 23 = cosP RS3 *sinR RS3

[0187] L RCS3 31=sinR RS3 *sinC RS3 +cosR RS3 *cosC RS3 *sinP RS3

[0188] L RCS3 32=-cosC RS3 *sinR RS3 +cosR RS3 *sinC RS3 *sinP RS3

[0189] L RCS333 = cosR RS3 *cosP RS3 .

[0190] 3) Based on the position difference and transformation matrix, calculate the position and attitude information of the tracking sensor in the reference coordinate system;

[0191] Based on the position difference, the calculated position information of the tracking sensor in the reference coordinate system is as follows:

[0192]

[0193] L T->RC (C TRC ;P TRC ;R TRC C is the transformation matrix from the magnetic field generator coordinate system to the reference coordinate system; TRC P TRC R TRC The reference calibrator center point is used in the coordinate system of the magnetic field generator to determine the heading attitude angle, pitch attitude angle, and roll attitude angle.

[0194] Specifically, the aforementioned

[0195] L TRC 11 = cosC TRC *cosP TRC

[0196] L TRC 12 = cosP TRC *sinC TRC

[0197] L TRC 13 = -sinP TRC

[0198] L TRC 21=-cosR TRC *sinC TRC +cosC TRC *sinR TRC

[0199] L TRC 22=sinP TRC *cosR TRC *cosC TRC +sinR TRC *sinC TRC *sinP TRC

[0200] L TRC 23 = cosP TRC *sinR TRC

[0201] L TRC 31=sinR TRC *sinC TRC +cosR TRC *cosC TRC *sinP TRC

[0202] L TRC 32=-cosC TRC *sinR TRC +cosR TRC *sinC TRC *sinP TRC

[0203] L TRC 33 = cosR TRC *cosP TRC .

[0204] 4) Based on the transformation matrix, the attitude information of the tracking sensor in the reference coordinate system is calculated as follows:

[0205] Tracking sensor heading attitude angle

[0206]

[0207] Tracking sensor pitch attitude angle

[0208] P RS3 =atan(-L RCS3 13)*180 / pi=atan(sinP RS3 )*180 / pi.

[0209] Since the tracking sensor follows the movement of the medical device in this embodiment, and the roll attitude angle of the tracking sensor is not a concern, there is no need to measure the roll attitude angle.

[0210] That is, the five-axis position and attitude information of the tracking sensor in the reference coordinate system is measured; (X RS3 ;Y RS3 Z RS3 C RS3 ;P RS3 ;R RS3 ).

[0211] Specifically, in the tracking module, the five-axis position and attitude information (X, Y, F, Z) of the tracking sensor in the continuously calculated reference coordinate system is used as the basis for tracking. RS3 ;Y RS3 Z RS3 C RS3 ;P RS3 ;R RS3), to perform real-time positioning and tracking of the tracking sensor.

[0212] In summary, this embodiment utilizes electromagnetic technology, which does not rely on radiographic methods for location detection. This makes it easier for medical personnel, medically trained family members, and friends of patients to use, and thus these technologies can be used in medical institutions or home care wards. It features high accuracy, no radiation hazards, and ease of implementation and promotion.

[0213] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. An electromagnetic positioning and tracking system for medical navigation, characterized in that, include: Magnetic field generator, reference calibrator, tracking sensor, and tracking processing terminal; The magnetic field generator is used to generate a magnetic field that simultaneously covers the reference calibrator and the tracking sensor; The reference calibrator is placed outside the patient's body and is communicatively connected to the tracking processing terminal. It is used to sense magnetic field signals and output them to the tracking processing terminal. The tracking sensor follows the movement of the medical device placed inside the patient's body and is communicatively connected to the tracking processing terminal to sense magnetic field signals and output them to the tracking processing terminal. The tracking processing terminal determines the position and attitude information of the reference calibrator and the tracking sensor in the magnetic field generator coordinate system based on the magnetic field signals sensed by the reference calibrator and the tracking sensor. Next, calculate the position and attitude information of the tracking sensor relative to the reference calibrator in the reference coordinate system; then, perform real-time positioning and tracking of the tracking locator based on the position and attitude information of the tracking sensor in the reference coordinate system. The reference calibrator includes a magnetic sensor S1, a magnetic sensor S2, a printed circuit board, and a housing; The magnetic sensors S1 and S2 rotate at a fixed heading angle. Mounted on the printed circuit board; The outer casing is shaped like a Reilly triangle; a cable hole is provided in the middle of one side of the outer casing, from which the external cable of the reference calibrator is led out; During navigation, the reference calibrator is fixed to the patient's xiphoid process, and the reference calibrator cable extends down the patient's torso and toward the lower limbs; The tracking sensor, magnetic sensor S1 and magnetic sensor S2 are all single-axis magnetic induction coils; The tracking processing terminal includes a first pose determination module, a second pose determination module, and a tracking module; The first pose determination module is used to determine the position and pose information of the reference calibrator center point and the tracking sensor in the magnetic field generator coordinate system; The second pose determination module is used to calculate the position difference between the center point of the tracking sensor and the reference calibrator and the transformation matrix from the reference coordinate system to the tracking sensor coordinate system; Based on the position difference and transformation matrix, the position and attitude information of the tracking sensor in the reference coordinate system is calculated; the reference coordinate system takes the center point of the reference calibrator as the origin and the front-right-down direction of the reference calibrator as the three axes. The tracking module is used to perform real-time positioning and tracking of the tracking sensor based on the position and attitude information of the tracking sensor in the reference coordinate system. Based on the position and attitude data of magnetic sensor S1, the position coordinates of the center point of the reference calibrator in the coordinate system of the magnetic field generator are determined as follows: ； in, , , This provides the position information of the magnetic sensor S1 in the coordinate system of the magnetic field generator. This is the inverse of the transformation matrix from the coordinate system of the magnetic field generator to the coordinate system of the magnetic sensor S1; , , This provides the position information of the magnetic sensor S1 in the reference coordinate system. , , The heading attitude angle, pitch attitude angle, and roll attitude angle of the magnetic sensor S1; The magnetic sensor S1 provides five-axis position and attitude information, including three-axis position information, heading attitude angle, and pitch attitude angle, obtained based on electromagnetic positioning, and roll attitude angle. Pitch attitude angle via magnetic sensor S1 And magnetic sensor S2 pitch attitude angle Sure; .

2. The electromagnetic positioning and tracking system according to claim 1, characterized in that, The magnetic field generator includes eight single-axis magnetic field transmitting antennas; The single-axis magnetic field transmitting antenna is arranged in three rows in a "3-2-3" pattern, forming the antenna arrangement area; In a rectangular coordinate system established with the center of the antenna arrangement area as the origin and the row direction of the three rows as the x-axis, the pose data of the eight single-axis magnetic field transmitting antennas, composed of the x and y axis coordinates, azimuth rotation angle, and elevation rotation angle in the rectangular coordinate system, are as follows: First transmitting antenna (-58.7mm, -58.4mm, 142°, -73°); Second transmitting antenna (-1.6mm, -57.3mm, 64°, 15°). Third transmitting antenna (62.6mm, -61.3mm, 92°, -33°). Fourth transmitting antenna (-38.5mm, 0.9mm, 163°, 17°); Fifth transmitting antenna (39.4mm, 1.3mm, 154°, 29°). The sixth transmitting antenna (-61.4mm, 64.1mm, 39.3°, 63°). Seventh transmitting antenna (-5.4mm, 64.3mm, 80°, 9°); Eighth transmitting antenna (58.8mm, 59.9mm, 93°, 87°); In the rectangular coordinate system, the error range for the x and y directions is ±3mm, and the error range for the azimuth and pitch rotation angles is ±5°.

3. The electromagnetic positioning and tracking system according to claim 1, characterized in that, In the first pose determination module, the position and attitude information of the reference calibrator center point is determined using an electromagnetic positioning method; the positioning process includes: 1) Based on electromagnetic positioning, obtain the five-axis position and attitude information of magnetic sensors S1 and S2 in the coordinate system of the magnetic field generator; among which, the five-axis position and attitude information includes three-axis position information, heading attitude angle and pitch attitude angle; 2) Pitch attitude angle via magnetic sensor S1 And magnetic sensor S2 pitch attitude angle The roll attitude angles of magnetic sensor S1 and magnetic sensor S2 were determined. ; 3) Based on the obtained six-axis position and attitude information of magnetic sensor S1 and magnetic sensor S2, determine the six-axis position and attitude information of the reference calibrator center point in the coordinate system of the magnetic field generator.

4. The electromagnetic positioning and tracking system according to claim 3, characterized in that, Based on the position and attitude data of magnetic sensor S2, the position coordinates of the center point of the reference calibrator in the coordinate system of the magnetic field generator are determined as follows: ； , , This provides the position information of the magnetic sensor S2 in the coordinate system of the magnetic field generator. This is the inverse of the transformation matrix from the magnetic field generator coordinate system to the magnetic sensor S2 coordinate system; This is the transformation matrix from the S1 coordinate system of the magnetic sensor to the S2 coordinate system of the magnetic sensor; , , This is the position information of the magnetic sensor S2 in the reference coordinate system.

5. The electromagnetic positioning and tracking system according to claim 1, characterized in that, The calculation process in the second pose determination module includes: 1) Calculate the position difference between the center point of the tracking sensor and the center point of the reference calibrator based on the position information of the center point of the tracking sensor and the reference calibrator; 2) Perform coordinate transformation based on the attitude information of the center points of the tracking sensor and the reference calibrator to obtain the transformation matrix from the reference coordinate system to the tracking sensor coordinate system; 3) Based on the position difference and transformation matrix, calculate the position and attitude information of the tracking sensor in the reference coordinate system; 4) Based on the transformation matrix, calculate the attitude information of the tracking sensor in the reference coordinate system.

6. The electromagnetic positioning and tracking system according to claim 5, characterized in that, Based on the aforementioned position difference, the calculated position information of the tracking sensor in the reference coordinate system is as follows: ； ; , , To track the sensor's position information in the coordinate system of the magnetic field generator; , , This is to provide the position information of the center point of the reference calibrator in the coordinate system of the magnetic field generator; This is the transformation matrix from the magnetic field generator coordinate system to the reference coordinate system; The reference calibrator center point is used in the coordinate system of the magnetic field generator to determine the heading attitude angle, pitch attitude angle, and roll attitude angle.

7. The electromagnetic positioning and tracking system according to claim 5, characterized in that, Transformation matrix from reference coordinate system to tracking sensor coordinate system: ； in, This is the inverse of the transformation matrix from the magnetic field generator coordinate system to the reference coordinate system; This is the transformation matrix from the magnetic field generator coordinate system to the tracking sensor coordinate system; , To track the sensor's heading and pitch attitude angles in the magnetic field generator coordinate system; Based on the transformation matrix from the reference coordinate system to the tracking sensor coordinate system, the attitude information of the tracking sensor in the reference coordinate system is calculated as follows: Tracking sensor heading attitude angle ; Tracking sensor pitch attitude angle .

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