Patent Description:
Magnetic position tracking systems are used in a wide range of medical applications, such as in minimally invasive procedures. Examples of prior art techniques are provided below.

<CIT> describes a location pad of a magnetic position tracking system. The location pad includes multiple field-generators and a frame. The field-generators are configured to generate respective magnetic fields in a region-of-interest of a patient body, for measuring a position of a medical instrument in the region-of-interest. The frame is configured to fix the multiple field-generators at respective positions surrounding the region-of-interest. The frame is open on at least one side of the region-of-interest.

<CIT> describes a system for navigating a medical device including a magnetic field generator assembly that generates a magnetic field. Position sensors on the medical device, on an imaging system and on the body generate signals indicative of the positions within the magnetic field. The generator assembly and reference sensors are arranged such that a correlation exists between them and the positions of the body and of a radiation emitter and a radiation detector of the imaging system. An electronic control unit (ECU) determines, responsive to signals generated by the sensors, a position of the medical device, a position of one of the radiation emitter and detector and a distance between the emitter and detector.

Patent application publication <CIT> describes a system and method for embedding tracking technology in a medical table. According to the document, a plurality of table sensors is attached to a medical table to form an array. An instrument sensor is attached to an instrument. At least one of the table sensors and the instrument sensor generates at least one magnetic dipole field. The instrument sensor is moved relative to the array while at least one of the table sensors and the instrument sensor measures at least one vector component of the field. The measured vector component(s) are communicated to tracker electronics that determine at least one of a position and orientation of the instrument sensor relative to the array.

An embodiment of the present invention that is described herein provides a location pad defined by appended claim <NUM>, including multiple field-generators and a frame. The multiple field-generators are configured to generate respective magnetic fields in a region-of-interest of a patient organ, so as to measure a position of a medical instrument in the region-of-interest. The frame is transparent to an X-ray radiation, and is configured to fix the multiple field-generators at respective positions surrounding the region-of-interest.

In some embodiments, the field-generators include at least first and second field-generators, and the location pad includes at least a first electrical cable connected to the first field-generator, and a second electrical cable connected to the second field-generator, and the first and second electrical cables are positioned out of the region-of-interest. In other embodiments, the frame includes a substance selected from a list of substances consisting of carbon and organic polymer. In yet other embodiments, the patient is positioned on a table, and the location pad is configured to be positioned between the patient and the table.

In an embodiment, at least one of the field-generators includes multiple non-concentric coils. In another embodiment, at least one of the field-generators includes multiple concentric coils.

There is additionally provided, in accordance with an embodiment of the present invention, a method for producing a location pad.

There is further provided, in accordance with an embodiment not defined by the appended claims, a method including positioning a location pad relative to a region-of-interest of a patient, the location pad includes a frame that fixes multiple field-generators at respective positions surrounding the region-of-interest, and the frame is transparent to an X-ray radiation at least at the region-of-interest. A medical instrument is inserted into the region of interest. A position of the medical instrument is tracked using the field-generators. Simultaneously with the position tracking, the region-of-interest is irradiated with a fluoroscopic imaging system, so as to produce an image of the region-of-interest.

The present disclosure will be more fully understood from the following detailed description of the embodiments thereof, taken together with the drawings, in which:.

Medical instruments and guidewires are used in various therapeutic and diagnostic medical procedures, such as in neurosurgery.

Described hereinbelow are methods and apparatus for improving anatomical imaging and simultaneously tracking medical instruments during neurosurgical procedures.

In neurosurgical procedures carried out using a neurosurgical system, a surgeon may insert a guidewire into the patient head and may navigate the guidewire to the target region in the patient brain for performing the neurosurgical procedure.

In some embodiments, the neurosurgical system may comprise a magnetic position tracking subsystem, which is configured to track the position of the guidewire in the patient head. In some embodiments, the magnetic position tracking subsystem comprises multiple field-generators that are typically fixed on a location pad, and are configured to apply respective magnetic fields to a region-of-interest (ROI) at the patient head. In some embodiments, the magnetic position tracking subsystem comprises a position sensor, typically installed at the distal end of the guidewire. The position sensor is configured to produce, in response to the magnetic fields, a position signal indicative of the position and orientation of the distal end within the patient head.

In some embodiments, the position tracking subsystem comprises a processor, which is configured to display, based on the position signal, a position of the distal end overlaid on an anatomical image of the patient head.

In some scenarios, it is desirable to apply a fluoroscopic system simultaneously with the magnetic position tracking system. For example, in order to acquire an X-ray image, also referred to herein as a fluoroscopic image, of the ROI of the patient head or of any other organ in question. In a neurosurgical procedure, parts of the location pad may fall within the irradiated volume of the fluoroscopic system, and may block or obstruct portions of the fluoroscopic image of the patient brain.

In some embodiments, the location pad comprises a frame that is transparent to the X-ray radiation, also referred to herein as "fluoro-transparent," at least at the ROI. The fluoro-transparent frame is configured to fix the field-generators thereon, at respective positions surrounding the ROI. The transparency of the frame to the X-ray radiation causes little or no obstruction to the fluoroscopic imaging, at least in fluoroscopic projections that are commonly used in neurosurgical procedures.

In some embodiments, the location pad may comprise field-generators having non-concentric coils arranged so as to enable a low profile location pad. Such a location pad can be easily placed between a moving table, on which the patient is positioned, and the patient head, as opposed to conventional location pads that are thicker and have to be placed below the table. In other embodiments, at least one of (and typically all) the field-generators may comprise concentric coils. This configuration may be used in case the low profile location pad is not necessary, or for enhancing the functionality of the location pad.

The disclosed techniques improve the quality of neurosurgical procedures by enabling simultaneous imaging and treatment of the brain during surgical or any other invasive procedures. Moreover, the disclosed techniques may be applied, mutatis mutandis, to medical procedures carried out on other organs of the patient body.

<FIG> is a schematic pictorial illustration of a neurosurgical system <NUM>, in accordance with an embodiment of the present invention. In some embodiment, neurosurgical system <NUM> comprises a fluoroscopic imaging subsystem <NUM>, which is configured to irradiate X-rays to an organ in question, and a magnetic position tracking subsystem <NUM> described in detail below.

Reference is now made to an inset <NUM>. In some embodiments, during a neurosurgical procedure, a surgeon <NUM> navigates any suitable type of a guidewire <NUM>, into a brain <NUM> of a patient <NUM>. In some embodiments, a position sensor <NUM> is coupled to a distal end <NUM> of guidewire <NUM>.

In some embodiments, surgeon <NUM> navigates distal end <NUM> to a target location within a region-of-interest (ROI) <NUM> of brain <NUM>, and subsequently, applies a medical device (not shown) typically guided along guidewire <NUM> to distal end <NUM>, so as to carry out a medical procedure in ROI <NUM>, e.g., tumor removal.

Reference is now made to an inset <NUM>. In some embodiments, neurosurgical system <NUM> comprises a low-profile location pad <NUM> placed below the head of patient <NUM>. Location pad <NUM> comprises field-generating coils, referred to herein as field-generators 36A-36D that are mounted on a frame <NUM> around ROI <NUM>.

In some embodiments, frame <NUM> is transparent to X-rays, such that X-rays irradiated by an X-ray source <NUM> of subsystem <NUM>, pass through pad <NUM> and brain <NUM>, and sensed by an X-ray detector <NUM>. Note that frame <NUM> has a low-profile (e.g., thickness of about <NUM>) and X-ray detector <NUM> is configured to output electrical signal indicative of the sensed X-rays for producing an anatomical image <NUM> of at least a section of ROI <NUM>, as will described below.

In some embodiments, location pad <NUM> further comprises electrical cables <NUM> and <NUM> configured to electrically couple between field-generators 36A-36D and a driver circuit <NUM> of magnetic position tracking subsystem <NUM>. Location pad <NUM> is described in more detail in <FIG> below.

In the context of the present disclosure, the terms "about" or "approximately" for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein.

In some embodiments, neurosurgical system <NUM> comprises an operating console, referred to herein as a console <NUM> for brevity. Console <NUM> comprises a processor <NUM>, driver circuit <NUM>, interface circuitry <NUM> to fluoroscopic imaging subsystem <NUM>, input devices <NUM>, and a display <NUM>. In the exemplary configuration of <FIG>, pad <NUM> comprises four field-generators 36A-36D, in other embodiments, pad <NUM> may comprise any other suitable number of field-generating coils.

In some embodiments, position sensor <NUM> is configured to sense magnetic fields generated by field-generators 36A-36D and to transmit, to processor <NUM>, electrical signals indicative of the position and orientation of distal end <NUM> in ROI <NUM>.

Magnetic position tracking subsystem <NUM> may be implemented, for example, in the CARTO™ system, produced by Biosense Webster Inc. (Irvine, Calif. ) and is described in detail, for example, in <CIT>, <CIT>, <CIT>,<CIT>, <CIT>and <CIT>, in <CIT>, and in <CIT>, <CIT>and <CIT>.

Reference is now made to an inset <NUM>. In some embodiments, location pad is positioned on top of a table <NUM> and under the patient head, such that generators 36A-36D are located at fixed, known positions external to patient <NUM>. Driver circuit <NUM> is configured to drive field-generators 36A-36D with suitable signals so as to generate the aforementioned magnetic fields in a predefined volume around ROI <NUM> of brain <NUM>.

In some embodiments, at least one of field-generators 36A-36D may comprise three non-concentric coils arranged and packaged in a low profile field-generator. Each coil is thus configured to generate a magnetic field component in one direction out of three mutually-orthogonal directions. In this configuration two of the coils are positioned side-by-side in a given plane, and the third coil is wound around the two coils in the given plane so as to obtain the low profile field-generator. This configuration is described in detail in <CIT>.

In other embodiments, at least one of field-generators 36A-36D may comprise three concentric coils. Such configuration, however, typically results in a thicker field-generator. Note that typically all field-generators 36A-36D have the same configuration, and the arrangement of the coils is determined based on various parameters, such as but not limited to the specified thickness of the location pad. In the example of neurosurgery the thickness may not be critical, and therefore both configurations may be applicable. Note that location pad <NUM> may comprise any suitable number of field-generators, other than four.

In some embodiments, an operator of neurosurgical system <NUM> may produce anatomical image <NUM> by operating subsystem <NUM> using input devices <NUM> and a suitable graphical user interface (GUI), and processor <NUM> is configured to display anatomical image <NUM> on display <NUM>. In some embodiments, processor <NUM> is further configured to receive, from position sensor <NUM>, a position signal indicative of the position of distal end <NUM> in brain <NUM>. Based on the position signal, processor <NUM> is configured to display (a) the position of distal end overlaid on anatomical image <NUM>, and (b) a frame, indicative of the position of ROI <NUM>, so that an operator of subsystem <NUM> may adjust the direction of the irradiated X-rays on the head of patient <NUM>.

This particular configuration of neurosurgical system <NUM> is shown by way of example, in order to illustrate certain problems that are addressed by embodiments of the present invention and to demonstrate the application of these embodiments in enhancing the performance of such a system. Embodiments of the present invention, however, are by no means limited to this specific sort of example system, and the principles described herein may similarly be applied to other sorts of surgical systems, and particularly, to other sorts of position tracking systems applied in conjunction with imaging systems or subsystems, such as but not limited to, fluoroscopic-based, or computerized tomography (CT)-based systems or subsystems.

<FIG> is a schematic top-view of location pad <NUM>, in accordance with an embodiment of the present invention. In some embodiments, frame <NUM> comprises a rigid substance that is transparent to X-rays, such as but not limited to carbon film, carbon fiber and various types of organic polymers (e.g., plastic).

In some embodiments, field-generators 36A and 36D are fixed at one side of frame <NUM> using a fixing device <NUM>, and are electrically connected to driver circuit <NUM> via electrical cable <NUM>. Similarly, field-generators 36B and 36C are fixed at the opposite side of frame <NUM> using a fixing device <NUM>, and are electrically connected to driver circuit <NUM> via electrical cable <NUM>. In such embodiments, field-generators 36A-36D, fixing devices <NUM> and <NUM>, and electrical cables <NUM> and <NUM>, are all fixed on frame <NUM> outside ROI <NUM>, as shown in <FIG>.

In accordance with the invention, fixing devices are movable to other locations on the surface of frame <NUM>, so as to set the size and shape of ROI <NUM>.

In other embodiments, frame <NUM> is configured to fix field-generators 36A-36D at respective positions surrounding ROI <NUM>. In such embodiments, field-generators 36A-<NUM> may be attached on frame <NUM> using any suitable technique, such as but not limited to gluing, welding, soldering, or screwing. Note that in this configuration, fixing devices <NUM> and <NUM> may be removed from location pad <NUM>.

In some embodiments, field-generators 36A-36D are configured to generate respective magnetic fields in ROI <NUM> of patient brain <NUM> so as to measure the position of distal end <NUM> in ROI <NUM>. In such embodiments, when surgeon <NUM> is positioning distal end <NUM> at a position <NUM> within brain <NUM>, processor <NUM> is receiving from position sensor <NUM> a position signal indicative of position <NUM>, and overlays position <NUM> on anatomical image <NUM>.

In some embodiments, surgeon <NUM> may use guidewire <NUM> for positioning any suitable medical instrument for performing the medical procedure. Additionally or alternatively,.

In other embodiments, surgeon <NUM> may use the same techniques for positioning, at a target position within brain <NUM>, any other neurosurgical-related medical device having position sensor <NUM> coupled to its distal end. In such embodiments, guidewire <NUM> may be removed from the configuration of neurosurgical system <NUM>.

<FIG> is a flow chart that schematically illustrates a method for simultaneous imaging and position tracking during a neurosurgical procedure.

The method begins at a patient positioning step <NUM>, with positioning patient <NUM> on table <NUM>, relative to location pad <NUM>, such that location pad <NUM> is positioned between table <NUM> and the patient head. At a guidewire insertion step <NUM>, surgeon <NUM> inserts guidewire <NUM> into the head of patient <NUM>.

At a tracking step <NUM>, which is carried out during the neurosurgical procedure, surgeon <NUM> may apply magnetic position tracking subsystem <NUM> for tracking distal end <NUM>. In such embodiments, surgeon <NUM> may use console <NUM> for controlling driver circuit <NUM> to apply the aforementioned magnetic fields to ROI <NUM>, and further controls position sensor <NUM> and processor <NUM> for tracking the position of distal end <NUM> in brain <NUM> and for displaying the position overlaid on anatomical image <NUM>. At an irradiation step <NUM>, which is carried out in parallel to tracking step <NUM>, surgeon <NUM> may apply subsystem <NUM> for irradiating ROI <NUM> of brain <NUM>. Note that the structure of location pad <NUM> enables simultaneous imaging of ROI <NUM> and position tracking of distal end <NUM> within ROI <NUM>.

At a medical procedure conducting step <NUM>, surgeon <NUM> conducts the neurosurgical procedure based the displayed position of distal end <NUM> overlaid on anatomical image <NUM>. Note that step <NUM> typically terminates the method of <FIG>, however, surgeon may apply steps <NUM> and <NUM> simultaneously to carry out additional activities related to the procedure, such as but not limited to retracting distal end <NUM> out of the head of patient <NUM>.

Although the embodiments described herein mainly address neurosurgical procedures, the methods and systems described herein can also be used in other applications.

Claim 1:
A location pad (<NUM>), comprising:
multiple field-generators (36A-36D), which are configured to generate respective magnetic fields in a region-of-interest (<NUM>) of a patient organ, for measuring a position of a medical instrument in the region-of-interest; and
a frame (<NUM>), which is configured to fix the multiple field-generators at respective positions surrounding the region-of-interest,
characterised in that the frame is transparent to an X-ray radiation, and by the frame comprising at least one moveable fixing device (<NUM>, <NUM>) wherein each fixing device is configured to fix at least one of the multiple field-generators to the frame, wherein the at least one fixing device is movable on the surface of the frame so as to set the size and shape of the region-of-interest.