CN116669649A - System and method for improved electromagnetic tracking - Google Patents

Abstract

Tracking the pose of a portion of the anatomical structure using the reverse electromagnetic navigation system may include generating a signal comprising a plurality of frequencies. The signal including the plurality of frequencies may be received at a transmitter coil array. The transmitter coil array includes a plurality of transmit microcoils. Each transmit microcoil of the plurality of transmit microcoils is coupled to a portion of the anatomy of a patient. In response to receiving the signal including the plurality of frequencies, an electromagnetic field may be generated at each of the plurality of transmit microcoils based on the received signal. Each of the generated electromagnetic fields may be detected at a receiver coil array including at least one receiver coil. The pose of at least one transmit microcoil of the plurality of transmit microcoils may then be determined.

Description

System and method for improved electromagnetic tracking

RELATED APPLICATIONS

The present application claims priority from U.S. provisional application No. 63/126,061, filed on 12/16 in 2020, and entitled "reverse spread spectrum signaling electromagnetic navigation (reverted-DIRECTION, SPREAD-SPECTRUM SIGNALING ELECTROMAGNETIC NAVIGATION)", and U.S. utility application No. 17/455,163, filed on 11/16 in 2021, and entitled "system and method for improved electromagnetic tracking (SYSTEMS AND METHODS FOR IMPROVED ELECTROMAGNETIC TRACKING)", both of which are hereby incorporated by reference in their entirety.

Technical Field

The present disclosure relates generally to devices and systems for tracking the pose of one or more portions of a structure. More particularly, the present disclosure relates to Electromagnetic (EM) tracking systems for tracking vertebral pose during spinal corrective surgery.

Drawings

For ease of identifying a discussion of any particular element or act, one or more of the most significant digits in a reference number refer to the figure number in which that element is first introduced.

FIG. 1 illustrates an electromagnetic navigation system according to one embodiment.

FIG. 2A illustrates a reverse electromagnetic navigation system according to one embodiment.

FIG. 2B illustrates a reverse electromagnetic navigation system according to one embodiment.

FIG. 3 illustrates a flow chart of a method associated with a reverse electromagnetic navigation system, according to one embodiment.

FIG. 4 illustrates an exemplary computer architecture that facilitates operation of the principles described herein.

Detailed Description

In some cases, corrective surgery may be performed on a patient to treat or correct an acute injury, chronic injury, or chronic disease (e.g., scoliosis) of the patient's anatomy (e.g., spine). For example, corrective spinal procedures may be performed to align the displaced or misaligned vertebrae when the retention implant or hardware is secured to the vertebrae. In such cases, an Electromagnetic (EM) navigation (or tracking) system may be used to track the pose of the vertebrae relative to adjacent vertebrae to facilitate adequate displacement and alignment of the spine. As used herein, pose is understood to include at least some tracked or navigated position coordinates (e.g., x, y, z) and/or orientation coordinates (e.g., roll, pitch, yaw). The EM navigation system may track the position and/or orientation of the tracked structure, including six degrees of freedom of movement (e.g., three-dimensional position and multiple (e.g., pitch, roll, and yaw) orientations). Thus, the pose or position and/or orientation of the tracked structure may be determined over time.

EM navigation systems typically use a large coil transmitter and a small coil or micro-coil receiver as part of standard direction signaling. Notably, the magnetic field sensor may also be used as a receiver (i.e., in addition to or instead of a coil receiver). Such magnetic field sensors may include, but are not limited to, fluxgates, hall sensors, magnetoresistive sensors, optical sensors, and atomic sensors.

A large transmitter of standard directional signaling (i.e., a large coil transmitter) transmits a magnetic field and induces a voltage over a large volume to navigate over a large range. Thus, the received signal must be balanced with both magnetic field distortion and conduction distortion. These distortions can be removed or reduced by various methods. Specifically, the conduction distortion can be removed by the disclosed method discussed in the following: U.S. patent application No. 15/963,444 (titled "position determination system and METHOD (POSITION DETERMINATION SYSTEM AND METHOD)" and filed on 2018, 4, 26); U.S. patent application 16/855,487 (titled "system and method for navigation (SYSTEM AND METHOD FOR NAVIGATION)" and filed on 22 th 4/2020); U.S. patent application No. 16/855,521 (titled "system and method for navigation (SYSTEM AND METHOD FOR NAVIGATION)" and filed on 22 th 4/2020); and U.S. patent application 16/855,573 (titled "system and method for navigation (SYSTEM AND METHOD FOR NAVIGATION)" and filed on 22 months 2020), each of which is incorporated herein by reference in its entirety. Similarly, magnetic field distortion can be removed by methods disclosed in U.S. patent application Ser. No. 16/855,487, U.S. patent application Ser. No. 16/855,521, and U.S. patent application Ser. No. 16/855,573. In addition, as further described herein, magnetic field distortion may be reduced at very low field strengths achievable with reverse EM navigation systems (i.e., systems using microcoil transmitters and large coil receivers) and/or spread spectrum signaling.

It should be noted that the magnetization and permeability of ferromagnetic materials change with the applied magnetic field strength. In addition, with regard to EM navigation systems having a large set of coils or sensors, a micro-set of coils or sensors, tracking over the same range and/or meeting relevant temperature constraints, the following also applies: a. magnetic field strengths used with systems that transmit magnetic fields with large coils and receive magnetic fields with micro-coils or sensors in many cases by pulsed Direct Current (DC) or sinusoidal Very Low Frequency (VLF) signals can create magnetic field distortions by affecting the magnetization and permeability of ferromagnetic materials in the magnetic field (e.g., forcing large magnetizations of ferromagnetic materials and sampling high magnetic permeability); magnetic field strengths used with inverse systems (i.e., systems that transmit with microcoils and receive with large coils) that may include pulsed DC or sinusoidal LF signaling can create magnetic field distortions by affecting the magnetization and permeability of ferromagnetic materials in the magnetic field (e.g., forcing a medium magnetization of ferromagnetic materials and sampling high permeability).

It should also be noted that the reverse sinusoidal signaling system can reduce the transmitted magnetic field strength to 1/10 by increasing the frequency by a factor of 10. In addition, back pulse DC signaling systems typically have a reduced range due to limited dynamic range or temperature constraints, or both. However, the strength of the emitted magnetic field used with the inverse spread spectrum signaling system has limited impact on the ferromagnetic material. These systems further reduce the emitted magnetic field strength, force very small magnetizations of ferromagnetic materials, sample low permeability, and significantly reduce magnetic field distortion. Furthermore, the reverse spread spectrum signaling system significantly reduces the field strength to 1/100 by increasing the frequency by a factor of 10 and increasing the frequency bandwidth by a factor of 10 or more.

Thus, the reverse signaling system (i.e., the micro-coil transmitter and the large-coil receiver) can significantly reduce distortion compared to standard directional signaling systems (i.e., the large-coil transmitter and the small/micro-coil receiver) while still maintaining clinically relevant navigation volumes and ranges. In addition, as further described herein, spread spectrum signaling may be utilized in a reverse system to transmit signals, correct for conduction distortion, and further reduce magnetic field distortion while expanding the reverse navigation volume and range. Spread spectrum signaling may also reduce the computational burden associated with correcting distorted data received from the transmit coil. Spread spectrum systems, such as frequency hopping, may include modulation and demodulation of selected signals, as well as selected signal transformations for confirming or eliminating distortion or distorted signals within the system. Thus, the navigation system may incorporate a spread spectrum system to acknowledge or determine the signal.

Thus, in some embodiments, an EM navigation system may include a transmit coil array including a plurality of transmit microcoils, each attached to a separate vertebra of the spine. The transmitting micro-coil may receive signals from a signal generator of the coil array controller. In some embodiments, the signal may be a low power spread spectrum signal. Each of these transmit microcoils may be configured to form a different EM field as part of the navigation region. A receiver coil array including receiver coils may be disposed opposite the transmit coil array. The receiver coil may detect a field component of each of the EM fields. Data may be transmitted from the receiver coil to the receiver coil array interface and then to the processor of the control unit. The processor may process the data to determine a pose of each of the transmit microcoils in the form of multiple degrees of freedom (e.g., three positional degrees of freedom and three orientational degrees of freedom) relative to adjacent transmit microcoils.

In some embodiments, aberrations may also be introduced into the navigation area. For example, the aberrations may include surgical instruments used during corrective surgery. Such aberrations may cause aberrations in at least one of the EM fields. As discussed further herein, distortion of the EM field may be reduced through the use of a reverse signaling system and spread spectrum signaling. The EM fields and corresponding data detected by the receiver coils may also be transmitted to the receiver coil array interface and processor. The processor is configured to process the data and add additional corrections to any distorted fields to help determine the undistorted pose of each of the transmit microcoils.

Embodiments may be understood by reference to the drawings, in which like parts are indicated by like numerals throughout. Those of ordinary skill in the art having the benefit of the present disclosure will readily appreciate that the components of the embodiments as generally described and illustrated in the figures herein could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the various embodiments, as represented in the figures, is not intended to limit the scope of the disclosure, but is merely representative of the various embodiments. While various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

It should be appreciated that various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure. Many of these features may be used alone and/or in combination with one another.

The phrases "coupled to" and "in communication with" … … refer to any form of interaction between two or more entities, including mechanical, electrical, magnetic, electromagnetic, fluid, and thermal interactions. The two components may be coupled to or in communication with each other even though they are not in direct contact with each other. For example, two components may be coupled to each other or in communication with each other through an intermediate component.

Fig. 1-2B illustrate different views of an EM navigation system and related components. In some views, each device may be coupled to or shown with additional components not included in each view. Furthermore, in some views, only selected components are shown to provide details regarding the relationship of the components. Some components may be shown in multiple views, but are not discussed in connection with each view. The disclosure provided in connection with any drawing is relevant and applicable to the disclosure provided in connection with any other drawing or embodiment.

Fig. 1 illustrates a reverse EM navigation system 100 for tracking one or more poses of a portion of an anatomical structure (e.g., a spine or head of an individual) during a corrective surgical procedure (e.g., a spinal corrective surgical procedure). Fig. 1 depicts a spine 104 of a patient 102 in a prone position. As shown, the EM navigation system 100 may include a transmitter coil array 106, a receiver coil array 112, a coil array controller 114, a receiver coil array interface 116, and a display device 128.

The transmitter coil array 106 includes a series of transmit coils coupled to the spine 104 of the patient 102, as further described with respect to fig. 2A. Each of these transmit coils of the transmitter coil array 106 (and/or the receiver coils of the receiver coil array 112) may include a conductive material formed or placed in coils surrounding a magnetically permeable core. The coil array controller 114 may be coupled to the transmitter coil array 106. More specifically, the coil array controller 114 may be configured to signal the transmitter coil array 106 to cause the transmitter coil array 106 (and each of the coils therein) to generate or form an electromagnetic field by driving a current through the coils of the transmitter coil array 106, as further shown in fig. 2B. When current is driven through the coil, the generated electromagnetic field will extend away from the coil and form a navigational domain or volume, such as one that encompasses all or a portion of the head, spine, or other suitable portion.

Thus, each of the transmit coils (i.e., the transmit microcoils 208a-208 d) of the transmitter coil array 106 is configured to generate an EM field that is sensed by the receiver coil array 112, which may be positioned on the chest or abdomen of the patient opposite the transmitter coil array 106 in some embodiments. In other embodiments, the receiver coil array 112 may be positioned at any location adjacent to the patient 102 that is within the range of detecting the different generated EM fields of the transmit microcoils of the transmitter coil array 106, as further shown and discussed with respect to fig. 2B. For example, the receiver coil array 112 may be included within a surgical tool (or tracking device) used during an applicable surgical procedure. Notably, the receiver coil array 112 may also include a series of one or more coils comprising a conductive material and arranged to receive a plurality of EM field components having a particular geometry.

The receiver coil array interface 116 may be coupled to the receiver coil array 112 and configured to assist the receiver coil array 112 in determining the pose of the transmit microcoils (e.g., 208 in fig. 2) and/or the anatomy (e.g., vertebrae) to which the transmit microcoils are attached during a corrective surgical procedure. The display device 128 may include a display system configured to present an image of an object of the procedure (e.g., spine, head, etc.). Additionally, in some embodiments, the display device 128 may analyze and display imaging information (and/or models derived from imaging information) from any type of applicable imaging system, including, but not limited to, magnetic Resonance Imaging (MRI) systems, fluoroscopic imaging systems, computed tomography systems, and the like. Accordingly, the display device 128 may include a Graphical User Interface (GUI) capable of presenting the target anatomy in real-time. Additionally, the display device 128 may be capable of overlaying multiple rendered images at a single time based on imaging information from multiple corresponding imaging systems. Each of the coil array controller 114, the receiver coil array interface 116, and the display device 128 may also be embodied, for example, by a computing system 400, as further described with respect to fig. 4.

Notably, more general details associated with EM navigation systems including generating EM fields using transmit coils and tracking such fields through receive coils are further summarized and discussed in U.S. application No. 15/963,444 entitled "position determination system and METHOD (POSITION DETERMINATION SYSTEM AND METHOD)" filed on month 4 of 2018, which is incorporated herein by reference in its entirety.

Fig. 2A and 2B illustrate more specific views of a reverse EM navigation system 200 (e.g., EM navigation system 100 of fig. 1). As shown in fig. 2A, EM navigation system 200 includes patient 102, spine 104, transmitter coil array 106, transmit microcoils 208 (i.e., transmit microcoils 208 a-208 d), vertebrae 210, receiver coil array 112, coil array controller 114, receiver coil array interface 116, leads 218, processor 220, and signal generator 222. It is noted that the configuration of EM navigation system 200 (and EM navigation system 100) is for example purposes only and may include more or fewer entities than are included (e.g., coil array controller 114, receiver coil array interface 116, etc.).

As shown, the transmitter coil array 106 may be attached to the spine 104 of the patient 102. Notably, while the transmitter coil array 106 is shown for use with the spine, the transmitter coil array 106 and principles described herein are not limited to such examples and may be practiced with respect to any applicable anatomy (e.g., skull, knee, shoulder, other joints, ventricles, lungs) or non-anatomy outside of the medical field.

As briefly described with respect to fig. 1, the transmitter coil array 106 may include a plurality of transmit microcoils 208 (e.g., transmit microcoils 208 a-208 d) that are each configured to generate a different electromagnetic field into a navigation region or patient space of the patient 102 (as further described with respect to fig. 2B). Each transmit microcoil 208 is coupled to and disposed on a separate vertebra (e.g., vertebra 210) of the spine 104. Although four transmit microcoils 208 are shown in fig. 2A and 2B (i.e., transmit microcoils 208a through 208 d), any number of transmit microcoils may be utilized in a transmitter coil array (e.g., transmitter coil array 106). In one example, the transmitter coil array may include up to 24 transmit microcoils. In another example, the transmitter coil array may include as few as one transmit microcoil.

In some embodiments, each transmit microcoil 208 may include a conductive material formed or placed in a coil having a length of about 2 millimeters (mm) and an Outer Diameter (OD) of about 0.2 mm. In other embodiments, each transmit microcoil 208 may include a coil of about 6mm OD and about 0.5mm length. In still other embodiments, each transmit microcoil 208 may include a coil having a maximum dimension between about 1mm and 10 mm. In addition, each of the transmit microcoils 208 may be coupled to any posterior side of a corresponding individual vertebra (e.g., vertebra 210). For example, each transmit microcoil 208 may be coupled to a transverse process or spinous process of a given vertebra (e.g., vertebra 210). Such coupling of the transmit microcoil 208 to the individual vertebrae 210 (or another applicable anatomy) may utilize any suitable technique, such as gluing, insertion into a borehole, and the like.

In the embodiment shown in fig. 2A, each of the leads 218 is attached at a first end to a corresponding one of the transmit microcoils 208 and is operatively coupled at a second end to the coil array controller 114. The leads 218 are configured to transmit signals generated at the coil array controller 114 to the transmit microcoil 208. Notably, the coil array controller may provide the generated signals to the plurality of transmit microcoils in a direct or indirect manner. For example, the controller may provide signals directly to the micro-coil via leads 218 or indirectly from the controller via wireless communication to electronics connected locally to the micro-coil 208, thereby eliminating the need for leads.

The coil array controller 114 (and signal generator 222) may be configured to control and/or drive the transmitter coil array 106 (and each of the transmit microcoils 208). Additionally, as shown, the coil array controller 114 may include a signal generator 222 configured to generate and transmit signals to the transmit microcoil 208. The coil array controller 114 (and signal generator 222) may signal each transmit micro-coil 208 in the transmitter coil array 106 in a time division multiplexed, frequency division multiplexed, or code division multiplexed manner. In this regard, each transmit microcoil 208 may be driven separately at different times, or all transmit microcoils 208 may be driven simultaneously, with each transmit microcoil driven by a different frequency, frequencies, or spread spectrum with orthogonal or near-orthogonal codes.

The use of a spread spectrum system such as frequency hopping (with the reverse EM navigation system 200) may include modulation and demodulation of selected signals, as well as selected signal transformations for further confirming or eliminating distortion or distorted signals within the system. Thus, the EM navigation system 200 may incorporate a spread spectrum system to confirm distortion or eliminate/reduce distortion from the signal. In particular, the conduction distortion depends on frequency and includes a phase offset. Thus, utilizing spread spectrum signaling (or even multiple different frequencies) allows for determining distorted phase offsets or impulse responses for many different frequencies used. For example, four different frequencies may allow four different offsets to be determined. In this way, distortion can be identified and removed.

In addition, spread spectrum signaling may improve the range of transmit microcoils of a reverse EM navigation system that operate at relatively low power (1 mW transmit coil heat). In particular, the range of the coil is proportional to the signal-to-noise ratio and the noise is equal to the variance of the received signal. Spread spectrum signaling may improve the signal-to-noise ratio, and thus the range of the transmitting microcoil, as described in U.S. patent application No. 16/855,487, U.S. patent application No. 16/855,521, and U.S. patent application No. 16/855,573.

Such spread spectrum emissions span or spread over a large or broad spectrum, which may also be divided over time. For example, the spread spectrum signal may emit a signal that spans a frequency spectrum of about 1 kilohertz (kHz) to about 400kHz. In another example, the spread spectrum signal may transmit the signal across a spectrum of about 1Hz to 30 megahertz (MHz), including about 10Hz to about 400kHz transmitted at a sample rate equal to or about 375 kHz. In yet another example, when multiple frequencies are used, the transmitted signal may include any suitable frequency range of about 200kHz (e.g., a range including 190kHz, 195kHz, 200kHz, 205kHz, etc.). In some embodiments, the frequency range of such multiple frequencies includes any frequency within 100kHz higher or lower than 200kHz (i.e., a range between 100kHz and 300 kHz). In some embodiments, the frequency range of such multiple frequencies may span 10kHz to 400kHz. Notably, the use of spread spectrum signaling is also discussed in greater detail in U.S. patent application Ser. No. 16/855,487, U.S. patent application Ser. No. 15/963,444, and U.S. patent Ser. No. 16/855,521.

The coil array controller 114 may also include a processor 220. The processor 220 may be configured to receive and process data received at the receiver coil array 112/receiver coil array interface 116 to determine a pose associated with each of the transmit microcoils 208. In particular, the processor 220 may be configured to intelligently analyze (e.g., using machine learning or artificial intelligence) the data received at the receiver coil array 112/receiver coil array interface to correct or reduce distortion of the EM field generated by the transmit microcoil 208. Notably, the processor 220 may also be embodied by a processor 402 as further described with respect to fig. 4.

As shown in fig. 2B, when signaling the transmit microcoils 208 of the transmitter coil array 106 with the coil array controller 114, a different EM field 230 is generated by each transmit microcoil 208 in the region where the medical procedure is being performed (note that only one magnetic field generated by the transmit microcoil 208c is shown here). The generated EM field 230 may induce voltages and currents in the coils of the receiver coil array 112. Notably, the receiver coil array includes at least one receiver coil, which may include conductive material formed or placed in the coil between about 10mm to 60mm OD. In other embodiments, the receive coils of the receiver coil array may include coils of about 54mm OD and about 7mm length. The inductive signals from the receiver coil array 112 are delivered to the receiver coil array interface 116 and then forwarded to the processor 220 of the coil array controller 114. The receiver coil array interface 116 may include amplifiers, filters, and buffers for interfacing directly with the receiver coils of the receiver coil array 112. Alternatively, the receiver coil array 112 may employ a wireless communication channel rather than being directly coupled to the receiver coil array interface 116.

Thus, the reverse EM navigation system 200 (and EM navigation system 100) is configured to determine the pose of an anatomical structure (e.g., a given vertebra) by placing the transmitter coil array 106 within/near the site of a medical procedure (e.g., on multiple vertebrae during a spinal corrective procedure) to generate a low energy EM field associated with each transmit micro-coil 208 of the transmitter coil array 106. A unique set of field components associated with each transmit micro-coil 208 may then be detected/tracked by the receiver coil array 112 and the receiver coil array interface 116 to ultimately determine the pose of each of the transmit micro-coils 208 (and the anatomy in which each coil is placed) by measuring the field components at the receiver coils of the receiver coil array 112.

When in use, for example during corrective spinal surgery, EM navigation system 200 (and EM navigation system 100) may track the pose of each of vertebrae 103 in patient's vertebrae 102 repositioned by a clinician to treat a disease of patient 102, such as scoliosis. By tracking the pose of each vertebra 210, the clinician can properly position each vertebra relative to the adjacent vertebrae while implanting the spinal implant. EM navigation system 200 (and EM navigation system 100) may track the pose of each vertebra 210 in the form of multiple degrees of freedom including translation, angle, pitch, yaw, and rotation. The pose of each vertebra 210 may also be displayed on the display device 128 in real time.

Typically, when using an EM navigation system, a distorter element may be introduced into the EM navigation system. For example, the distorter member may include a surgical tool/device for use during a surgical procedure utilizing an EM navigation system. In the illustrated embodiment, the surgical instrument acting as a distorter member may comprise a ferrous material. In other embodiments, the distorter element may be any object comprising a ferrous material.

When inserted into an EM navigation system environment, the distorter element may cause distortion of at least one of the EM fields. In particular, both magnetic field distortion (or forced distortion) and conduction distortion (or induced distortion) may occur within the environment of the EM navigation system. Such distortion can be particularly problematic in standard direction signaling EM navigation systems by causing distortion tracking of the generated EM field at the receiver coil array. However, a reverse EM navigation system (such as EM navigation system 200 described herein) may greatly reduce such distortion. In addition, spread spectrum signaling (or even multiple frequencies) may be utilized in such reverse EM navigation systems to reduce and/or correct for distortion (e.g., by allowing phase shifts or impulse responses to be identified). In addition, spread spectrum signaling may be utilized in such reverse EM navigation systems to increase transmit coil range by increasing signal-to-noise ratio, as described in U.S. patent application No. 16/855,487, U.S. patent application No. 16/855,521, and U.S. patent application No. 16/855,573.

Fig. 3 illustrates a flow chart of a method 300 for tracking a pose of a portion of an anatomical structure (e.g., vertebrae of the spinal column) using a reverse electromagnetic navigation system. In block 302, the method 300 generates a signal comprising a plurality of frequencies. For example, the signal generator 222 of the coil array controller 114 may generate a signal including spread spectrum signaling. In block 304, the method 300 receives a signal including a plurality of frequencies at a transmitter coil array. For example, spread spectrum signaling may be received at the transmit microcoil 208. In addition, the transmitter coil array may include a plurality of transmit microcoils, and each of the plurality of transmit microcoils may be coupled to a portion of the anatomy of the patient (e.g., vertebrae of the spinal column).

In block 306, the method 300 generates an electromagnetic field at each of a plurality of transmit microcoils based on the received signals in response to receiving a signal comprising a plurality of frequencies. For example, each of these transmit coils in the ongoing example may generate an electromagnetic field based on the received spread spectrum signaling. In block 308, the method 300 detects each of the generated electromagnetic field components at a receiver coil array that includes at least one receive coil, and more generally a plurality of receive coils. For example, the receiver coil array 112 may detect each of the generated electromagnetic field components and provide information associated with this detection to the receiver coil array interface 116. In block 310, the method 300 determines a pose of at least one transmit microcoil of a plurality of transmit microcoils. For example, the receiver coil array interface 116 and/or the processor 220 may utilize such information received from the receiver coil array 112 to determine the pose of the at least one vertebra 210/transmit microcoil 208.

In this way, the reverse EM navigation system (i.e., micro-transmit coils and large receive coils) may significantly reduce distortion while providing clinically relevant useful navigation volumes and ranges. In addition, spread spectrum signaling (or the use of multiple frequencies) within the reverse EM may allow correction of conduction distortion and further reduce magnetic field distortion while expanding the reverse navigation volume and range.

It is noted that while the novel tracking aspects described herein are generally described with respect to the medical arts, these principles may be applied to a variety of other arts as well. In particular, these principles may be practiced in any field or aspect that may benefit from high-precision identification of the position and/or orientation of a structure being tracked. For example, shipping logistics (e.g., tracking crates), automated "pick and place" type operations (e.g.,warehouse), augmented Reality (AR) applications (e.g., AR headphones that track a surgeon), robotic applications, etc.

Some general discussion of computing systems will now be described with respect to FIG. 4. Computing systems are now increasingly taking a wide variety of forms. The computing system may be, for example, a handheld device, an appliance, a laptop computer, a desktop computer, a mainframe, a distributed computing system, a data center, or even a device not conventionally considered a computing system, such as a wearable device (e.g., glasses, a smart watch, etc.). In this specification and in the claims, the term "computing system" is broadly defined to encompass any device or system (or combination thereof) that includes at least one physical and tangible processor, as well as physical and tangible memory capable of having thereon computer-executable instructions that can be executed by the processor. The memory may take any form and may depend on the nature and form of the computing system. The computing system may be distributed in a network environment and may include a plurality of constituent computing systems.

As shown in FIG. 4, in its most basic configuration, computing system 400 typically includes at least one hardware processing unit 102 (or processor 402) and memory 404. Memory 404 may be physical system memory, which may be volatile, nonvolatile, or some combination of the two. The term "memory" may also be used herein to refer to non-volatile mass storage devices, such as physical storage media. If the computing system is distributed, the processing, memory, and/or storage capabilities may also be distributed.

Computing system 400 also has multiple structures thereon, commonly referred to as "executable components". For example, the memory 404 of the computing system 400 is shown as including executable components 406. The term "executable component" is a name for a structure that is well understood by those of ordinary skill in the computing arts to be a structure that may be software, hardware, or a combination thereof. For example, when implemented in software, those of ordinary skill in the art will understand that the structure of an executable component may include software objects, routines, methods, etc. that may be executed on a computing system, whether such an executable component is present in a heap of the computing system or on a computer readable storage medium.

In this case, those of ordinary skill in the art will recognize that the structure of the executable components resides on a computer readable medium such that when interpreted by one or more processors of the computing system (e.g., by a processor thread) cause the computing system to perform functions. Such structures may be directly computer readable by a processor (as if the executable components were binary). Alternatively, the structure may be configured to be interpretable and/or compiled (whether in a single stage or in multiple stages) in order to generate such binary that may be directly interpreted by the processor. When the term "executable component" is used, such an understanding of the exemplary structure of the executable component is well within the understanding of one of ordinary skill in the computing arts.

The term "executable component" is also well understood by those of ordinary skill to include structures that are exclusively or near exclusively implemented in hardware, such as within a Field Programmable Gate Array (FPGA), an Application Specific Integrated Circuit (ASIC), a Central Processing Unit (CPU), a Graphics Processing Unit (GPU), or any other special purpose circuit. Thus, the term "executable component" is a structural term well understood by those of ordinary skill in the computing arts, whether implemented in software, hardware, or a combination. In this specification, the terms "component," "service," "engine," "module," "control," and the like may also be used. As used in this specification and in this context, these terms (whether expressed with or without modifying clauses) are also intended to be synonymous with the term "executable component" and thus also have a structure well understood by one of ordinary skill in the computing arts.

In the following description, embodiments are described with reference to acts performed by one or more computing systems. If such actions are implemented in software, the one or more processors (of the associated computing system that performs the actions) direct the operation of the computing system in response to having executed the computer-executable instructions that make up the executable components. For example, such computer-executable instructions may be embodied on one or more computer-readable media forming a computer program product. Examples of such operations involve manipulation of data.

Computer-executable instructions (and manipulated data) may be stored in the memory 404 of the computing system 400. Computing system 400 may also contain communication channels 408 that allow computing system 400 to communicate with other computing systems over, for example, network 410.

While not all computing systems require a user interface, in some embodiments, computing system 400 includes a user interface 412 for interfacing with a user. The user interface 412 may include an output 414 (or output mechanism 114) and an input 416 (or input mechanism 116). The principles described herein are not limited to a precise type of output 414 or a precise type of input 416, as this will depend on the nature of the device. However, the output 414 may include, for example, speakers, displays, haptic outputs, holograms, and the like. Examples of input 416 may include, for example, a microphone, a touch screen, a hologram, a camera, a keyboard, a mouse for other pointer inputs, any type of sensor, and so forth.

Embodiments described herein may include or utilize a special purpose or general-purpose computing system including computer hardware, such as one or more processors and system memory, as discussed in greater detail below. Embodiments described herein also include physical media and other computer-readable media for carrying or storing computer-executable instructions and/or data structures. Such computer-readable media can be any available media that can be accessed by a general purpose or special purpose computing system. The computer-readable medium storing the computer-executable instructions is a physical storage medium. The computer-readable medium carrying computer-executable instructions is a transmission medium. Thus, by way of example, and not limitation, embodiments of the invention may include at least two distinctly different types of computer-readable media: storage medium and transmission medium.

Computer-readable storage media includes RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other physical and tangible storage medium that can be used to store desired program code means in the form of computer-executable instructions or data structures and that can be accessed by a general purpose or special purpose computing system.

A "network" (e.g., network 410) is defined as one or more data links that enable transmission of electronic data between computing systems and/or modules and/or other electronic devices. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a computing system, the computing system properly views the connection as a transmission medium. The transmission media can include networks and/or data links, which can be used to carry desired program code means in the form of computer-executable instructions or data structures, and which can be accessed by a general purpose or special purpose computing system. Combinations of the above should also be included within the scope of computer-readable media.

Further, upon reaching the various computing system components, program code means in the form of computer-executable instructions or data structures can be automatically transferred from transmission media to storage media (or vice versa). For example, computer-executable instructions or data structures received over a network or data link may be buffered in RAM within a network interface module (e.g., a "NIC") and then ultimately transferred to computing system RAM and/or less volatile storage media at the computing system. Accordingly, it should be appreciated that the storage medium may be included in computing system components that also (or even primarily) utilize the transmission medium.

Computer-executable instructions comprise, for example, instructions and data which, when executed at a processor, cause a general purpose computing system, special purpose computing system, or special purpose processing device to perform a certain function or group of functions. Alternatively or in addition, the computer-executable instructions may configure the computing system to perform a particular function or group of functions. The computer-executable instructions may be, for example, instructions that are binary or even undergo some translation (such as compilation) prior to being directly executed by the processor, such as intermediate format instructions, such as assembly language, or even source code.

Those skilled in the art will appreciate that the invention may be practiced in network computing environments with many types of computing system configurations, including personal computers, desktop computers, laptop computers, message processors, hand-held devices, multiprocessor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, mobile telephones, PDAs, pagers, routers, switches, data centers, wearable devices (such as glasses), and the like. The invention may also be practiced in distributed system environments where local and remote computing systems, which are linked (either by hardwired data links, wireless data links, or by a combination of hardwired and wireless data links) through a network, both perform tasks. In a distributed system environment, program modules may be located in both local and remote memory storage devices.

Those skilled in the art will also appreciate that the present invention may be practiced in a cloud computing environment. The cloud computing environment may be distributed, but this is not required. In a distributed case, the cloud computing environment may be distributed globally within an organization and/or have components owned across multiple organizations. In this specification and in the following claims, "cloud computing" is defined as a model for enabling on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services). The definition of "cloud computing" is not limited to any other numerous advantages that may be obtained from such a model when properly deployed.

Such as by using the term "substantially" to refer to approximations throughout the specification. For each such mention, it is to be understood that in some implementations, a value, feature, or characteristic may be specified without approximation. For example, where qualifiers such as "about" and "substantially" are used, these terms include within their scope qualifiers lacking the qualifiers thereof. For example, where the term "substantially vertical" is recited with respect to a feature, it should be understood that in other embodiments the feature may have a precisely vertical configuration.

Similarly, in the description of embodiments above, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure. However, this method of the disclosure should not be construed to reflect the following intent: any claim requires more features than those explicitly recited in that claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of any single foregoing disclosed embodiment.

The claims following this written disclosure are hereby expressly incorporated into this written disclosure, with each claim standing on its own as a separate embodiment. The present disclosure includes all permutations of the independent claims and their dependent claims. Furthermore, additional embodiments that can be derived from the following independent and dependent claims are also expressly incorporated into this written description.

Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The claims and embodiments disclosed herein are to be construed as merely illustrative and exemplary and not limitative of the scope of the present disclosure in any way whatsoever. It will be apparent to those having ordinary skill in the art having had the benefit of the present disclosure that the details of the foregoing embodiments may be changed without departing from the basic principles of the disclosure herein. In other words, various modifications and improvements of the embodiments specifically disclosed in the above description are within the scope of the appended claims. Moreover, the order of the steps or actions of the methods disclosed herein may be altered by persons skilled in the art without departing from the scope of the disclosure. In other words, unless a particular sequence of steps or actions is required for proper operation of the embodiment, the sequence or use of particular steps or actions may be modified. Accordingly, the scope of the invention is defined by the following claims and their equivalents.

Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the described features or acts described above or the order of acts described above. Rather, the described features and acts are disclosed as example forms of implementing the claims.

The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims (18)

1. An electromagnetic navigation system, the electromagnetic navigation system comprising:

a transmitter coil array comprising a plurality of transmit microcoils, each transmit microcoil of the plurality of transmit microcoils configured to be coupled to a structure to be tracked;

a coil array controller configured to be coupled to each of the plurality of transmit microcoils and configured to generate a signal comprising a plurality of frequencies and to provide the generated signal to each of the plurality of transmit microcoils, wherein the generated signal is configured to cause each of the plurality of transmit microcoils to generate a corresponding electromagnetic field based on the generated signal; and

A receiver coil array including at least one receiving coil, the receiver coil array configured to detect the generated corresponding electromagnetic field of each of the plurality of transmitting microcoils, thereby determining a pose of at least one of the plurality of transmitting microcoils.

2. The electromagnetic navigation system of claim 1, wherein the plurality of frequencies comprises a spread spectrum, wherein the electromagnetic field generated by each of the plurality of transmitting microcoils comprises a spread spectrum electromagnetic field.

3. The electromagnetic navigation system of claim 2, wherein the spread spectrum is in a range of approximately 1 kilohertz (kHz) to 400 kHz.

4. The electromagnetic navigation system of claim 1, wherein each of the plurality of frequencies includes a frequency between approximately 10kHz and 400 kHz.

5. The electromagnetic navigation system of claim 1, wherein a largest dimension of the plurality of transmitting microcoils is between about 1 millimeter (mm) and 10 mm.

6. The electromagnetic navigation system of claim 1, wherein a maximum dimension of the at least one receive coil is between approximately 10mm and 60 mm.

7. A method of tracking a pose of a tracked structure using a reverse electromagnetic navigation system, the method comprising:

generating a signal comprising a plurality of frequencies;

receiving the signal comprising the plurality of frequencies at a transmitter coil array, the transmitter coil array comprising a plurality of transmit microcoils, each transmit microcoil of the plurality of transmit microcoils coupled to a structure being tracked;

generating an electromagnetic field at each of the plurality of transmit microcoils based on the received signals in response to receiving the signals comprising the plurality of frequencies;

detecting each of the generated electromagnetic fields at a receiver coil array comprising at least one receiving coil; and

a pose of at least one transmit microcoil of the plurality of transmit microcoils is determined.

8. The method of claim 7, wherein the plurality of frequencies comprise a spread spectrum, wherein the electromagnetic field generated at each of the plurality of transmit microcoils comprises a spread spectrum electromagnetic field.

9. The method of claim 8, wherein the spread spectrum is in a range of about 1 kilohertz (kHz) to 400 kHz.

10. The method of claim 7, wherein each of the plurality of frequencies comprises a frequency between approximately 10kHz and 400 kHz.

11. The method of claim 7, wherein a largest dimension of the plurality of transmit microcoils is between about 1 millimeter (mm) and 10 mm.

12. The method of claim 7, wherein the maximum dimension of the at least one receive coil is between about 10mm and 60 mm.

13. A computer program product comprising one or more computer-readable media having stored thereon computer-executable instructions executable by one or more processors of a computing system to cause the computing system to track a pose of a tracked structure using a reverse electromagnetic navigation system, the computer-executable instructions comprising instructions executable to cause the computing system to perform at least the following:

generating a signal comprising a plurality of frequencies;

transmitting the signal comprising the plurality of frequencies to a transmitter coil array comprising a plurality of transmit microcoils, each transmit microcoil of the plurality of transmit microcoils coupled to a structure being tracked, wherein the transmitter coil array generates an electromagnetic field at each transmit microcoil of the plurality of transmit microcoils based on the received signal;

Detecting each of the generated electromagnetic fields via a receiver coil array comprising at least one receiving coil; and

a pose of at least one transmit microcoil of the plurality of transmit microcoils is determined.

14. The computer program product of claim 13, wherein the plurality of frequencies comprise a spread spectrum, wherein the electromagnetic field generated at each of the plurality of transmit microcoils comprises a spread spectrum electromagnetic field.

15. The computer program product of claim 14, wherein the spread spectrum is in a range of approximately 1 kilohertz (kHz) to 400 kHz.

16. The computer program product of claim 13, wherein each frequency of the plurality of frequencies comprises a frequency between approximately 10kHz and 400 kHz.

17. The computer program product of claim 13, wherein a largest dimension of the plurality of transmit microcoils is between about 1 millimeter (mm) and 10 mm.

18. The computer program product of claim 13, wherein a maximum dimension of the at least one receive coil is between about 10mm and 60 mm.