GB2634011A - Registration system - Google Patents

Abstract

A medical registration system comprising an on-tool imaging system 1301 configured to be mounted to a surgical tool 1303 using a mounting structure 100, and a calibration structure 700 comprising a shaft (701, fig. 7) configured for engagement at a first end (705, fig 7) in a chuck of the tool, the shaft having an axis of rotation (A, fig. 7). An arm (703, fig. 7) depending from the shaft is perpendicular to the axis of rotation, and comprises an optical reference portion (709, 711, fig. 7) spaced on the arm in relation to the axis of rotation. The system may receive data representing a position about an axis of rotation of an arm of the calibration structure corresponding to when an optical reference portion is aligned with a predetermined position. The data may be used to determine a measure for the angular rotation of the arm around the axis of rotation.

Description

REGISTRATION SYSTEM

Technical Field

The present disclosure relates, in general, to a registration system. Aspects relate to registration systems for use with surgical tools.

Background

Surgical procedures can be carried out using surgical tools that may require alignment in order to enable a user to operate on the correct part of a patient's body, thereby ensuring that the procedure is effective and efficient. Some procedures, such as free hand procedures, can use alignment jigs in order to ensure that any surgical tool is correctly positioned before use, and sometimes as the tool in question is in use. For example, a total knee replacement procedure requires a prosthesis to be accurately implanted to ensure that joint surfaces are properly aligned. Inaccurate alignment can lead to failure of the joint.

Jigs used to ensure alignment are complex devices and require a significant amount of time to install during a surgical procedure. Furthermore, as a procedure is carried out, misalignment can occur as a result of movement of any one or more of a surgical tool, the patient, and a jig. It can also be the case that a jig is used only at the start of a procedure in order to provide an initial alignment. Accordingly, subsequent removal of the jig during the procedure can lead to the introduction of alignment errors. Such errors and movement may be difficult to detect or rectify during a procedure, leading to mistakes or failures in a procedure.

In some cases, a computerised system can be used to guide a surgeon during a procedure.

However, the complexity and expense of such systems can be a barrier to their implementation, particularly in respect of some procedures where performance by free hand can be advantageous.

Furthermore, calibration of the surgical tool being used is required to ensure that a user has confidence that the surgical tool and/or an accessory connected thereto is being positioned where intended to ensure that any procedure being carried out is performed accurately.

Summary

An objective of the present disclosure is to provide a registration system for a surgical tool.

The foregoing and other objectives are achieved by the features of the independent claims.

Further implementation forms are apparent from the dependent claims, the description, and the Figures.

A first aspect of the present disclosure provides a medical registration system, comprising an on-tool imaging system, wherein the on-tool imaging system is configured to be mounted to a surgical tool using a mounting structure, and a calibration structure comprising a shaft configured for releasable engagement at a first end of the shaft with a chuck device of the surgical tool, wherein the shaft comprises an axis of rotation, and an arm, depending from the shaft, the arm provided perpendicular to the axis of rotation at a second end of the shaft, wherein the arm comprises an optical reference portion provided in spaced relation on the arm relative to the axis of rotation.

In an implementation of the first aspect, the medical registration can further comprise a probe comprising a tip, wherein the second end of the shaft comprises a probe registration structure provided in line with the axis of rotation of the shaft, wherein the probe registration structure is configured to receive the tip of the probe. In an example, the probe registration structure comprises a female portion or opening configured to receive the tip of the probe. The probe registration structure can comprise an opening in the second end of the shaft, wherein the opening converges in a direction towards the first end of the shaft to a point.

In an example, the point of the probe registration structure can comprise a profile and/or size selected to prevent lateral movement of the tip of a probe. The first end of the shaft can comprise a shank portion configured to releasably engage with a chuck of a tool, whereby to secure the calibration structure to the tool. The arm can comprise one or more additional optical reference portions provided in spaced relation on the arm relative to the axis of rotation. The optical reference portion can comprise a planar surface with a surface normal parallel to the axis of rotation. The optical reference portion can rotate about the axis of rotation.

In an example, the medical registration system can further comprise a processor, and a memory, the memory coupled to the processor, the memory comprising program code executable by the processor, the program code comprising one or more instructions, whereby to cause the medical registration system to generate data representing a position of the arm about the axis of rotation at which the optical reference portion is aligned with a predetermined reference position. The program code can comprise one or more instructions, whereby to cause the medical registration system to automatically generate the data representing the position of the arm about the axis of rotation at which the optical reference portion is aligned with the predetermined reference position in response to alignment of the optical reference portion with the predetermined reference position, wherein the alignment of the optical reference portion with the predetermined reference position is temporary or persists for a predetermined period of time. The probe can comprise a probe optical reference portion, and the program code can comprise one or more instructions, whereby to cause the medical registration system to generate data representing a position of the probe optical reference portion about the axis of rotation at which the probe optical reference portion is aligned with a predetermined probe reference position.

A second aspect of the present disclosure provides a machine-readable storage medium encoded with instructions for calibrating a medical registration system, the instructions executable by a processor, whereby to cause the processor to receive data representing a position about an axis of rotation of an arm, wherein the arm is for a calibration structure for a medical registration system, wherein the position corresponds to a position at which an optical reference portion of the ama is aligned with a predetermined reference position, and use the data representing the position of the arm, determine a measure for the angular rotation of the arm around the axis of rotation.

These and other aspects of the invention will be apparent from the embodiment(s) described below.

Brief Description of the Drawings

In order that the present disclosure may be more readily understood, embodiments will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic representation of a mounting structure according to an example; Figure 2 is a schematic representation of a first part of a mounting structure according to

an example;

Figure 3 is a schematic representation of a second part of a mounting structure according to an example; Figure 4 is a schematic representation of a second part of a mounting structure according to an example; Figure 5 is a schematic representation of a first part of a mounting structure according to

an example;

Figure 6 is a schematic representation of a mounting structure according to an example; Figure 7 is a schematic representation of a calibration structure for an on-tool imaging system according to an example; Figure 8 is a schematic representation of a calibration structure for an on-tool imaging system according to an example; Figure 9 depicts an exploded portion from a cross sectional view of the second end of the shaft of the calibration structure, according to an example; Figure 10 is a schematic representation of a probe, according to an example; Figure 11 is a schematic representation of a probe, according to an example; Figure 12 is a schematic representation of a probe, according to an example; Figure 13a is a schematic representation of a registration system according to an example; Figure 13b is a schematic representation of a registration system according to an example; Figure 14 is a flow chart of a calibration process according to an example; Figure 15 is a flow chart of a calibration process for a probe according to an example; and Figure 16 is a schematic representation of a machine according to an example.

Detailed Description

Example embodiments are described below in sufficient detail to enable those of ordinary skill in the art to embody and implement the systems and processes herein described. It is important to understand that embodiments can be provided in many alternate forms and should not be construed as limited to the examples set forth herein.

Accordingly, while embodiments can be modified in various ways and take on various alternative forms, specific embodiments thereof are shown in the drawings and described in detail below as examples. There is no intent to limit to the particular forms disclosed.

On the contrary, all modifications, equivalents, and alternatives falling within the scope of the appended claims should be included. Elements of the example embodiments are consistently denoted by the same reference numerals throughout the drawings and detailed description where appropriate.

The terminology used herein to describe embodiments is not intended to limit the scope.

The articles "a," "an," and "the" are singular in that they have a single referent, however the use of the singular form in the present document should not preclude the presence of more than one referent. In other words, elements referred to in the singular can number one or more, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes," and/or "including," when used herein, specify the presence of stated features, items, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, items, steps, operations, elements, components, and/or groups thereof The term "and/or" is only an association relationship for describing associated objects and represents that three relationships may exist such that A and/or B may indicate that A exists alone, A and B exist at the same time, or B exists alone. The character "I" generally represents that the associated objects are in an "or" relationship.

Unless otherwise defined, all terms (including technical and scientific terms) used herein are to be interpreted as is customary in the art. It will be further understood that terms in common usage should also be interpreted as is customary in the relevant art and not in an idealized or overly formal sense unless expressly so defined herein.

The following contains specific information related to implementations of the present disclosure. The drawings and their accompanying detailed disclosure are merely directed to implementations. However, the present disclosure is not limited to these implementations. Other variations and implementations of the present disclosure will be obvious to those skilled in the art.

The phrases "in one implementation," or "in some implementations," may each refer to one or more of the same or different implementations. The term "coupled" is defined as connected whether directly or indirectly through intervening components and is not necessarily limited to physical connections. The expression "at least one of A, B and C" or "at least one of the following: A, B and C" means "only A, or only B, or only C, or any combination of A, B and C." The terms "system" and "network" may be used interchangeably.

For the purposes of explanation and non-limitation, specific details such as functional entities, techniques, protocols, and standards are set forth for providing an understanding of the present disclosure. In other examples, detailed disclosure of well-known methods, technologies, systems, and architectures are omitted so as not to obscure the present disclosure with unnecessary details.

Persons skilled in the art will immediately recognize that any network function(s) or algorithm(s) disclosed may be implemented by hardware, software or a combination of software and hardware. Disclosed functions may correspond to modules which may be software, hardware, firmware, or any combination thereof A software implementation may include machine-and/or computer-readable and/or executable instructions stored on a machine-and/or computer-readable medium such as memory or other types of storage devices. One or more microprocessors or general-purpose computers with communication processing capability may be programmed with corresponding executable instructions and perform the disclosed network function(s) or algorithm(s).

The microprocessors or general-purpose computers may include Applications Specific Integrated Circuitry (ASIC), programmable logic arrays, and/or using one or more Digital Signal Processor (DSPs). Although some of the disclosed implementations are oriented to software installed and executing on computer hardware, alternative implementations implemented as firmware or as hardware or as a combination of hardware and software are well within the scope of the present disclosure. The computer readable medium includes but is not limited to Random Access Memory (RAM), Read Only Memory (ROM), Erasable Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM), flash memory, Compact Disc Read-Only Memory (CD-ROM), magnetic cassettes, magnetic tape, magnetic disk storage, or any other equivalent medium capable of storing computer-readable instructions.

According to an example, a registration system is provided. The registration system can be used to calibrate a surgical tool. In an implementation, a probe can be calibrated using the registration system. A calibrated probe can be used in concert with a calibrated surgical tool in order to ensure correct placement and alignment of the surgical tool and/or an accessory thereof during use.

In an implementation, a registration system comprises an on-tool imaging system that is configured to be mounted to a surgical tool using a mounting structure. The imaging system can be used with a calibration structure to calibrate the surgical tool. In an example, the calibration structure comprises a shaft configured for releasable engagement at a first end of the shaft with a chuck device of the surgical tool. The shaft comprises an axis of rotation. The calibration structure further comprises an arm depending from the shaft. The arm is provided perpendicular to the axis of rotation at a second end of the shaft. The arm comprises at least one optical reference portion provided in spaced relation on the arm relative to the axis of rotation.

Figure 1 is a schematic representation of a mounting structure according to an example. The mounting structure 100 in the example of figure 1, shown in perspective view, is provided for use with a surgical tool (not shown), and comprises a first part 101 and a second part 103. The first part 101 comprises an inner surface configured to engage the surgical tool. The inner surface of the first part 101 can comprise a first conforming shape to a first portion of an exterior surface of the surgical tool. That is, in an example, the inner surface of the first part 101 can be so profiled as to match the outer surface profile of a portion of a surgical tool.

The second part 103 comprises an inner surface configured to engage the surgical tool. The inner surface of the second part 103 comprises a second conforming shape to a second portion of an exterior surface of the surgical tool. That is, in an example, the inner surface of the second part 103 can be so profiled as to match the outer surface profile of a portion of a surgical tool.

A clamping structure that is configured to releasably secure the first part 101 and the second part 103 together is provided. In an example, the clamping structure comprises a first clamping arrangement 105 provided on the first part 101, and a second clamping arrangement 107 provided on the second part 103. The first clamping arrangement 105 comprises a locking wing structure configured to engage with a corresponding protrusion of the second clamping arrangement 107 provided on the second part 103.

The second part 103 comprises a locking structure 109 configured to releasably secure an on-tool imaging system to the mounting structure 100.

Figure 2 is a schematic representation of a first part of a mounting structure according to an example. The first part 101 of the mounting structure 100 is shown in perspective view in figure 2, and the view is arranged such that the underside of the first part 101 is visible. The inner surface, broadly depicted at 201, of the first part 101 defines a cavity within the first part 101 such that the first part 101 can be slid onto a first portion of the exterior surface of a surgical tool. For example, the first part 101 may be slid or positioned on a surgical tool in a direction A, as will be explained in more detail below.

In the example of figure 2, the first clamping arrangement 105 is depicted, and comprises a locking wing structure that comprises two wing portions, with one wing portion 203 on either side of a main body 205 (which defines the cavity as described above) of the first part 101. Each wing portion 203 comprises a toggle latch, which can be an articulating or hinged latch that is effectively in the form of a lever. Each wing portion 203 can be hooked over or otherwise engaged with a corresponding protrusion of the second clamping arrangement 107 provided on the second part 103, which protrusions form tensioning means, and the wing portion 203 is then tensioned towards the main body of the first part 101, thereby closing the toggle latch. This builds up tensile forces that correspond to a multiple of the actuating force. By closing the tensioning mechanism in the toggle latch, a so-called lever dead centre is overcome, which reliably and securely locks the wing portion 203 in a closed state, thereby releasably securing the first and second parts of the mounting structure together. Other suitable fastening mechanisms may be used to releasably secure the first and second parts of the mounting structure together, such as over-centre fasteners, spring claw latches, and draw latches etc. Figure 3 is a schematic representation of a second part of a mounting structure according to an example. The second part 103 of the mounting structure 100 is shown in perspective view in figure 3, and the view is arranged such that the underside of the second part 103 is visible.

The inner surface, broadly depicted at 301, of the second part 103 defines a cavity within the second part 103 such that the second part 103 can be slid onto a second portion of the exterior surface of a surgical tool. For example, the second part 103 may be slid or positioned on a surgical tool in a direction B, as will be explained in more detail below.

In an example, an aperture (just visible in the back portion 111 of the first part as shown in figure 3) may be provided. A surgical tool, such a drill may be canulated, i.e., their motor shaft is hollow. As such, they can be used as wire drivers. In this mode the drill can accept a wire (commonly called k-wire) with a sharp, self-tapping tip, but no flutes.

The wires are used to temporarily fixate fragments before a more permanent fixation with plates and/or screws. The usual approach is to drill the wire a short distance, slide the drill "backwards" along the body of the wire, and drill again. The aperture in the second part 103 can therefore be provided in order to enable a canulated tool to be used with, e.g., wire passing through the aperture into the tool.

Figure 4 is a schematic representation of a second part of a mounting structure according to an example. The second part 103 of the mounting structure 100 is shown in perspective view in figure 4, and the view is arranged such that the locking structure 109 is visible.

In an example, the locking structure 109 comprises a base portion 401 comprising a retaining structure 403 configured to receive a foot of an imaging system. The retaining structure 403 depends from the base portion 401. In the example of figure 4, the retaining structure 403 comprises multiple wall portions 405, eight of which are depicted in figure 4 forming an octagonal retaining structure 403. The top portions 407 of one or more of the wall portions 405 can be tapered or profiled. For example, tapering can be provided to enable a foot of an imaging system to be located in the retaining structure 403. That is, such tapering can be provided to guide a foot of an imaging system into the retaining structure 403 should it be misaligned. The foot can be held in the retaining structure 403 by way of interference fit.

One or more of the wall portions 405 can comprise an aperture 409. An aperture 409 can be configured to receive a protrusion of a foot of an imaging system, whereby to enable the foot to releasably lock into place within the retaining structure 403. In an example, a retaining structure 403 can comprise more or less wall portions 405 as described with reference to figure 4, and more or less apertures 409. Tapering may be provided on all, some, or no wall portions.

In an example, the base portion 401 comprises a lip 411 depending therefrom. The lip 411 is, in the example of figure 4, circular, and extends radially outwards to an overhang between the main body 413 of the second part 103 and the retaining structure 403. The lip 411 is so profiled such that, in use of the mounting structure, the lip 411 and the locking structure 109 can be passed through an opening in part of a sterile drape such that the sterile drape is held in place on the mounting structure. For example, the opening in part of the sterile drape can comprise an aperture that may be cinched underneath the lip 411 (i e, just above the main body 413 of the second part 103 and beneath the lip 411).

Figure 5 is a schematic representation of a first part of a mounting structure according to an example. The first part 101 of the mounting structure 100 is shown from underneath in figure 5 such that the underside of the first part 101 is visible. The first part 101 comprises a front portion 501; 503 configured to act as a stop for the first part 101 when the first part 101 is slid onto the first portion of the exterior surface of the surgical tool, whereby to limit axial movement of the first part 101. That is, in an example, as the first part 101 is slid onto a surgical tool, the front portion 501; 503 (see also figure 2) is configured to but against part of the surgical tool, such as a portion of a chuck in the case of a drill for example, to prevent the first part 101 from moving any farther along the tool (such as the barrel of a drill for example).

In an example, the locking wing structure can be aligned with a central long axis of the second part. The first part and/or the second part can be cuboidal in form, although it will be appreciated that any suitable shape may be used.

Figure 6 is a schematic representation of a mounting structure according to an example. In the example of figure 6, a surgical tool 601 is depicted. The surgical tool 601 is a drill in this particular example, although it will be appreciated that the mounting structure can be used with many different surgical tools. In an example, the first part 101 can be mounted onto a first portion of the exterior surface of the surgical tool 601. For example, the first part 101 can be slid over the front portion 603 of the surgical tool 601. As noted above, the inner surface of the first part 101 can comprise a first conforming shape to a first portion of an exterior surface of the surgical tool 601. That is, in an example of figure 6, the inner surface of the first part 101 can be so profiled as to match the outer surface profile of the front portion 603 of the surgical tool 603, and the front portion 501; 503 is configured to but against part of the surgical tool 601, such as a portion of a chuck 605 in the case of the surgical tool 601. The second part 103 can be mounted onto a second portion 607 of the exterior surface of the surgical tool 601, and the first and the part can be removably secured together using the clamping structure. With reference to figure 3, the second part 103 can comprise an end portion 111 that provides a stop to engage with the surgical tool 601. For example, when the second part 103 is slid onto the barrel of the surgical tool 601, the end portion 111 will but against the end 609 of the barrel 608 of the surgical tool 601, thereby preventing the second part 103 from moving any farther forwards on the barrel. In an example, the clamping structure can be adjustable in order to enable wing portions to engage with the protrusions 107 of the second part 103. In another example, the mounting structure and/or the clamping structure can be preconfigured for the surgical tool 601 so that the first and second parts can be fixed together. For example, the extent to which the first and/or the second parts extend along the barrel of the surgical tool 601 before reaching the portions 501; 503 and/or 111 engage with the surgical tool, thereby preventing further movement of the first and/or second parts, can be preconfigured.

Figure 7 is a schematic representation of a calibration structure for an on-tool imaging system according to an example. In the example of figure 7, shown in perspective view, the calibration structure 700 comprises a shaft 701, and an arm 703 depending from the shaft. The shaft 701 is configured to releasably engage, at a first end 705 thereof, with a chuck device of a tool. The shaft 701 comprises an axis of rotation, A. In an example, the axis of rotation, A, of the shaft 701 corresponds to an axis of rotation of a surgical tool to which the calibration structure is mounted. For example, in the case of a surgical tool in the form of a drill, with the shaft 701 engaged, at a first end 705 thereof, with a chuck device of such a drill, the axis of rotation of the shaft 701 will be in line with the axis of rotation of the drill surgical tool to which the calibration structure is mounted since, e.g., the drill chuck will be configured to enable mounting of a device to the drill such that the device can be rotated by the drill without any axial misalignment that might cause damage and so on.

The first end 705 of the shaft 701 comprises a shank portion 713 configured to releasably engage with a chuck of a tool, whereby to secure the calibration structure 700 to the tool.

In an example, the ann 703 is provided perpendicular to the axis of rotation, A, of the shaft 701 at a second end 707 of the shaft 701. The arm 703 comprises an optical reference portion 709 provided in spaced relation on the arm relative to the axis of rotation, A. In the example of figure 7, the arm comprises an additional optical reference portion 711 provided in spaced relation on the arm relative to the axis of rotation, A. The optical reference portion 709/711 comprises a planar surface with a surface normal 715 parallel to the axis of rotation, A. Figure 8 is a schematic representation of a calibration structure for an on-tool imaging system according to an example. In the example of figure 8, shown in perspective view, the second end 707 of the shaft 701 comprises a probe registration structure 801 provided in line with the axis of rotation of the shaft. In an example, the probe registration structure 801 is configured to receive the tip of a probe, which will be described in more detail below.

According to an example, the probe registration structure 801 comprises a female portion configured to receive the tip of a probe. For example, the probe registration structure 801 can comprise an opening in the second end 707 of the shaft 701. The opening can converge in a direction towards the first end 705 of the shaft to a point. The probe registration structure 801 comprises a profile and/or size selected to prevent lateral movement of the tip of a probe.

Figure 9 depicts an exploded portion from a cross sectional view of the second end of the shaft of the calibration structure, according to an example. In the example of figure 9, the probe registration structure 801 comprises an opening 901 in the second end 707 of the shaft 701. The opening 801 converges in a direction towards the first end 705 of the shaft to a point 903. The point 903 is aligned with the centre of the axis of rotation, A of the shaft 701. As such, the tip of a probe introduced into the mouth of the opening 901 and directed towards the first end 705 of the shaft 701 will be forced to follow a path that leads it to the terminus of the opening 901, i.e., the point 903, at which the tip of the probe cannot move any farther towards the first end 705 of the shaft 701 and will thus come to rest. Although the opening 901 as depicted in figure 9 comprises a cross-sectional profile that curves to the point 903 from the mouth of the opening, it will be appreciated that any suitable profile that defines the convergence of the opening to the point 903 can be used. For example, opening 901 may be triangular in cross-section (i.e., conical).

Figure 10 is a schematic representation of a probe, according to an example. In the example of figure 10, shown in perspective view, the probe 1000 comprises a probe tip 1003 and a probe optical reference portion 1001 (and/or probe optical reference portion 1002) provided in spaced relation from the probe tip 1003. Both probe optical reference portions comprise a planar surface with a surface normal 1005.

Figure 11 is a schematic representation of a probe, according to an example. In the example of figure 11, in which the probe 1000 is shown in side view, it can be seen that the probe tip 1003 comprises a hook-shaped portion that extends parallel to the surface normal 1003. In an example, the probe tip 1003 terminates at a plane 1007 that is parallel to and aligned with the planar surface of the probe optical reference portions. The probe tip 1003 points in a direction, B, that is generally perpendicular to the plane 1007 (i.e., parallel to the surface normal 1005).

Figure 12 is a schematic representation of a probe, according to an example. In the example of figure 12, in which the probe 1000 is shown from the front, it can be seen that the probe tip 1003 is directly in line with the centre of the probe optical reference portions.

According to an example, the calibration structure as described above can be used to calibrate a tool, which tool may be used for a surgical procedure. For example, the calibration structure 700 can be mounted to a tool. That is, shank portion 713 can be fixed into or otherwise engaged with a chuck of the tool, whereby to secure the calibration structure 700 to the tool. The calibration structure can be rotated in order to bring the optical reference portion 709 within a first preselected portion of a field of view of an imaging apparatus mounted on the tool, whereby to calibrate an axis of rotation of the tool.

The probe 1000 can be mounted on the calibration structure 700. Mounting the probe 1000 on the calibration structure 700 can comprise bringing the tip 1003 of the probe 1000 into contact with the probe registration structure 801; 901. For example, the tip 1003 can be provided in the opening 901 so that it engages or otherwise rests in or at point 903. The probe optical reference portion 1001 can be rotated in order to bring the probe optical reference portion 1001 within a second preselected portion of the field of view of the imaging apparatus mounted on the tool, whereby to register the position of the tip 1003 of the probe 1000 relative to a preselected reference point of the tool.

Figure 13a is a schematic representation of a registration system according to an example. in the example of figure 13a, shown in perspective view, an imaging apparatus 1301 is depicted mounted on a surgical tool 1303 (in this case a drill) using a mounting structure 100 as described above with reference to figures 1 to 6 for example. A calibration structure 700, as described above with reference to figures 7 to 9, is mounted to the surgical tool 1303. Four calibration sections 1305 are depicted. The calibration sections depicted in figure 13 comprise four preselected portions of the field of view of the imaging apparatus 1301 as mounted on the surgical tool 1303. According to an example, calibration of the surgical tool 1303 can be performed by determining the position (in the example of figure 13a, the rotational position) of an optical reference portion of the calibration structure as it moves though each calibration section.

In an implementation, a user of the tool can mount the calibration structure to the tool and move the calibration structure so that an optical reference portion moves though each calibration section. For example, in the case of a drill, with the calibration structure mounted in the chuck of the drill and the imaging apparatus mounted to the drill such that its field of view is directed towards the front of the drill (i.e., towards the direction of the calibration structure mounted in the chuck of the drill) the user can move the calibration structure (e.g., by rotating it around the axis, A). In doing so, an optical reference portion will pass through the calibration sections, which define regions within the field of view of the imaging apparatus within which data representing the position of an optical reference portion can be collected. For example, as an optical reference portion passes through a calibration section as the user rotates the arm of the calibration structure, multiple optical points can be generated per calibration section, each optical point representing the position of the optical reference portion within a calibration section. If the distance between optical points for a calibration section falls within a preselected threshold, the calibration section question can be considered calibrated. When all calibration sections are calibrated, the tool can be considered calibrated.

Figure 13b is a schematic representation of a registration system according to an example. In the example of figure 13b, shown in perspective view, an imaging apparatus 1301 is depicted mounted on a surgical tool 1303 (in this case a drill) using a mounting structure as described above with reference to figures 1 to 6 for example. A calibration structure 700, as described above with reference to figures 7 to 9, is mounted to the surgical tool 1303. Probe 1000 is mounted or otherwise held/positioned in the calibration structure 700. That is, the tip 1003 of the probe 1000 is provided in the opening 901. Probe 1000 may be moved around with tip 1003 provided in the opening 901. That is, the tip 1003 remains effectively stationary in the opening 901 as the rest of the probe structure is moved (e.g., by a user) in order to vary the position of the probe calibration portion 1001.

Five probe calibration sections 1390 are depicted in figure 13b. The probe calibration sections depicted in figure 13b comprise five preselected portions of the field of view of the imaging apparatus 1301 as mounted on the surgical tool 1303. According to an example, calibration of the probe can be performed by determining the position of a probe optical reference portion as it moves though each probe calibration section 1390.

In an implementation, a user of the tool can mount the calibration structure to the tool and move the probe so that a probe optical reference portion moves though each probe calibration section. For example, in the case of a drill, with the calibration structure mounted in the chuck of the drill and the imaging apparatus mounted to the drill such that its field of view is directed towards the front of the drill (i.e., towards the direction of the calibration structure mounted in the chuck of the drill) the user can move the probe with its tip in the opening of the calibration structure. In doing so, a probe optical reference portion will pass through the calibration sections 1309, which define regions within the field of view of the imaging apparatus within which data representing the position of an optical reference portion can be collected. For example, as a probe optical reference portion passes through a calibration section as the user moves the probe, multiple optical points can be generated per calibration section, each optical point representing the position of the probe optical reference portion within a calibration section. If the distance between optical points for a calibration section falls within a preselected threshold, the calibration section question can be considered calibrated. When all calibration sections are calibrated, the probe can be considered calibrated.

Figure 14 is a flow chart of a calibration process according to an example. In the example of figure 14, calibration of a surgical tool 1303 in the form of a drill is described with reference to the setup of figure 13. The calibration process described with reference to figure 14 may be performed or implemented by an apparatus as will be described in more detail below. Such an apparatus can be a standalone apparatus or may form part of the surgical tool in question for example.

A calibration process is started. For example, with reference to figure 13, an imaging apparatus 1301 is mounted on a surgical tool 1303 (in this case a drill) using a mounting structure 100 as described above with reference to figures 1 to 6. A calibration structure 700, as described above with reference to figures 7 to 11, is mounted to the surgical tool 1303. In block 1401 data representing the axis of rotation, A, of the surgical tool 1303 (nominal drill line), an angle limit of the surgical tool 1303 and a distance limit of the surgical tool 1303 is provided. The data representing a nominal drill line represents an axis of rotation of the drill 1303. This can be an uncalibrated axis of rotation that is determined with respect to the axis of rotation, A. That is, at inception of a calibration process, an axis of rotation of a surgical tool to be calibrated can be assumed to be the same as the axis of rotation, A, of the shaft of the calibration structure mounted thereto.

The angle limit and distance limit can comprise deviations of a calculated drill line (DrillLine) from the nominal drill line. For example, the angle limit and distance limit can comprise, respectively, a threshold for an angular deviation of a calculated drill line form the nominal drill line, and a threshold for a translation distance of a calculated drill line form the nominal drill line (i.e., how far away a calculated drill line can be from the nominal drill line). Deviations (angular, translational etc.) can comer about due to, e.g., manufacturing tolerances (of, for example, a drill, mounting structure, imaging structure and so on), errors in mounting, temperature variations and so on.

In block 1403, the imaging apparatus 1301, mounted on the surgical tool 1303, can be used to generate image data. According to an example, image data can be generated in relation to preselected portions of the field of view of the imaging apparatus 1301 as mounted on the surgical tool 1303. For example, image data can be generated when an optical reference portion of the calibration structure, for example, falls within a preselected portion of the field of view of the imaging apparatus 1301, each representing a calibration section 1305.

According to an example, calibration of the surgical tool 1303 can be performed by determining the position (in the example of figure 13, the rotational position) of an optical reference portion of the calibration structure as it moves into and/or within and/or through each calibration section. Accordingly, a calibration section 1305 can be in a calibrated or an uncalibrated state during the process of calibrating a surgical tool. In an example, an uncalibrated state comprises a state in which no optical reference portions of a calibration structure have been detected within a calibration section. A calibrated state comprises a state in which at least one optical reference portion of a calibration structure has been detected within a calibration section.

Accordingly, at block 1403 new optical data is generated from the imaging apparatus 1301. The optical data can comprise data representing an image of an optical reference portion in a calibration portion. In block 1405 it is determined whether the optical data comprises an image of an optical reference portion in an uncalibrated calibration portion. In an example, a list of optical points comprises data representing the position of an optical reference portion (e.g., the centre of an optical reference portion) and thus the position of a drill line (since the distance between the centre of an optical reference portion and the axis of the drill line is a known). Accordingly, each point, generated from optical data, can be used to determine a drill line for the calibration portion in question.

As such, if the optical data comprises an image of an optical reference portion in an uncalibrated calibration portion, the optical data representing the position of the optical reference portion in the uncalibrated calibration portion in question is added to the list of points in block 1409. Otherwise, the list of point is reset in block 1407 and the process of obtaining new optical data repeats in block 1403.

In block 1411 a check is performed to determine whether a list of at least 12 points have been determined for an uncalibrated calibration portion. If not, the process of obtaining new optical data repeats in block 1403. Otherwise, in block 1413, the first 12 points are retained and in block 1415 the angles between points (AnglesBP) and the nominal drill line and the distance between points (DistanceBP) and the nominal drill line are determined. For example, given a set of 12 points, the angle between a selected point and the nominal drill line can be determined. In an example, an average for all points can be calculated. A similar process can be followed for the distance between respective points and the nominal drill line. Again, in an example, an average for all points can be calculated for the distance, leading to values for AnglesBP and DistanceBP for the set of 12 points, thus representing, for a given calibration portion, an average of the deviation of a calculated drill line from the nominal drill line in terms of its angular deviation and distance or offset from the nominal drill line.

In block 1417 the values obtained in block 1415 for AnglesBP and DistanceBP for the set of 12 points (e.g., the overall angular and distance average values) are compared to threshold angle and distance values (angle limit and distance limit -block 1401), respectively. If the values obtained in block 1415 for AnglesBP and/or DistanceBP for the set of 12 points are greater than the threshold values, the process of obtaining new optical data repeats in block 1403. Otherwise, (i.e., the values obtained in block 1415 for AnglesBP and/or DistanceBP for the set of 12 points are less than the threshold values) in block 1419, data representing the number of calibrated calibration portions is incremented to indicate that the calibration portion in question has changed state from uncalibrated to calibrated. The data representing the number of calibrated calibration portions can comprise an identifier representing which calibration portions are considered to be calibrated. In an example, angle limit and distance limit can be predefined threshold values. For example, they may be provided by a user of the system or a manufacturer of the surgical tool.

In block 1423 it is determined whether the number of calibration portions that are calibrated is equal to, in this example, four (corresponding to the four portions 1305 depicted in figure 13, although it will be appreciated that more than or fewer than four such portions may be used). if not, the list of point is reset in block 1407 and the process of obtaining new optical data repeats in block 1403.

In block 1425 AnglesBP for each calibrated portion is used to calculate an average value AnglesSN, representing an average angular deviation from the nominal drill line for the calibrated portions. In block 1427, Angles BP is compared to the threshold angle limit. If it is greater than this threshold value, the drill calibration fails and is restarted in block 1431. Otherwise, in block 1428 the drill line determined from each of the calibrated portions is used to calculate a final output drill line (e g, by taking the average of the four drill lines from the calibrated portions), which can be output (block 1429).

Accordingly, a drill calibration process can be performed in two steps. Firstly, points for a calibration portion (Drill Section) are collected, and then a drill line for that portion is defined. When all portions have a drill line defined, then the second step it for those lines to be compared to the nominal (1425) and if they are within limits (1427) then, collectively are being used to calculate the DrillLine.

As described above, a nominal drill line comprises a drill line derived from the geometry of drill, such as that which runs through the centre of the shaft of drill from example, which can be calculated from the perspective of camera when mounted. The output drill line corresponds to a specific mounting case and takes into account errors in mounting, manufacturing tolerances etc. That is, it provides a corrected version that takes into account any errors versus the nominal drill line.

Figure 15 is a flow chart of a calibration process for a probe according to an example. In block 1501 data representing a nominal position for the tip of a probe, a drill line and coarse and fine limits for a probe position are provided and will be described in more detail below. In the example of figure 15, the tip of a probe 1003 is provided/held in the cavity 901.

With reference to figure 13b, in block 1503, the imaging apparatus 1301, mounted on the surgical tool 1303, can be used to generate image data. According to an example, image data can be generated in relation to preselected portions of the field of view of the imaging apparatus 1301 as mounted on the surgical tool 1303. For example, image data can be generated when a probe optical reference portion falls within a preselected portion of the field of view of the imaging apparatus 1301, each representing a probe calibration section 1390.

According to an example, calibration of the probe can be performed by determining the position of a probe optical reference portion as it moves into and/or within and/or through each probe calibration section 1390. Accordingly, a probe calibration section 1390 can be in a calibrated or an uncalibrated state during the process of calibrating a probe. In an example, an uncalibrated state comprises a state in which no probe optical reference portions have been detected within a probe calibration section. A calibrated state comprises a state in which at least one probe optical reference portion of a probe calibration structure has been detected within a probe calibration section.

Accordingly, at block 1503 new optical data is generated from the imaging apparatus 1301. The optical data can comprise data representing an image of a probe optical reference portion in a probe calibration portion. In block 1505 it is determined whether the optical data comprises an image of a probe optical reference portion in an uncalibrated probe calibration portion. In an example, a list of optical points comprises data representing the position of a probe optical reference portion (e.g., the centre of a probe optical reference portion) and thus the position of a probe tip (since the distance etc. between the centre of a probe optical reference portion and the probe tip are known). Accordingly, each point, generated from optical data, can be used to determine a probe tip position for the probe calibration portion in question.

As such, if the optical data comprises an image of a probe optical reference portion in an uncalibrated probe calibration portion, the optical data representing the position of the probe optical reference portion in the uncalibrated probe calibration portion in question is added to the list of points in block 1509. Otherwise, the list of points is reset in block 1507 and the process of obtaining new optical data repeats in block 1503.

In block 1511 a check is performed to determine whether a predetermined number of points (e.g., more than 2 for example) have been determined for an uncalibrated probe calibration portion. If not, the process of obtaining new optical data repeats in block 1503. Otherwise, in block 1515, for a given probe calibration portion, the distance (DistanceDL) between a point and determined drill line (e.g., as calculated above with reference to figure 14) is calculated as well as the distance (DistanceLP) between the points for the probe calibration portion.

In block 1517 the values obtained in block 1515 are compared to a predetermined threshold coarse limit value. If the values obtained in block 1515 are greater than the threshold value, the process of obtaining new optical data repeats in block 1503.

Otherwise, (i.e., the values obtained in block 1515 are less than the threshold value) in block 1519, data representing the number of calibrated probe calibration portions is incremented to indicate that the probe calibration portion in question has changed state from uncalibrated to calibrated. The data representing the number of probe calibrated calibration portions can comprise an identifier representing which probe calibration portions are considered to be calibrated.

In block 1523 it is determined whether the number of probe calibration portions that are calibrated is equal to, in this example, five (corresponding to the portions 1390 depicted in figure 13b, although it will be appreciated that more than or fewer than four such portions may be used). If not, the list of point is reset in block 1507 and the process of obtaining new optical data repeats in block 1503.

In block 1525 DistancesNPT, representing the distance of the nominal probe tip as obtained for each probe calibration portion are determined. In block 1527, the distances for each probe calibration portion are compared against the predefined fine limit. If all greater than this threshold value, the probe calibration fails and is restarted in block 1531.

Otherwise, in block 1528 the probe geometry determined from each of the probe calibration portions is used to calculate a final output probe geometry (e.g., by taking the average of the five drill lines from the probe calibrated portions), which can be output (block 1529).

Examples in the present disclosure can be provided as methods, systems or machine-readable instructions, such as any combination of software, hardware, firmware or the like. Such machine-readable instructions may be included on a computer readable storage medium (including but not limited to disc storage, CD-ROM, optical storage, etc.) having computer readable program codes therein or thereon.

The present disclosure is described with reference to flow charts and/or block diagrams of the method, devices and systems according to examples of the present disclosure.

Although the flow diagrams described above show a specific order of execution, the order of execution may differ from that which is depicted. Blocks described in relation to one flow chart may be combined with those of another flow chart. In some examples, some blocks of the flow diagrams may not be necessary and/or additional blocks may be added.

It shall be understood that each flow and/or block in the flow charts and/or block diagrams, as well as combinations of the flows and/or diagrams in the flow charts and/or block diagrams can be realized by machine readable instructions.

The machine-readable instructions may, for example, be executed by a machine such as a general-purpose computer, a platform comprising user equipment such as a smart device, e.g., a smart phone, a special purpose computer, an embedded processor or processors of other programmable data processing devices to realize the functions described in the description and diagrams. In particular, a processor or processing apparatus may execute the machine-readable instructions. Thus, modules of apparatus may be implemented by a processor executing machine readable instructions stored in a memory, or a processor operating in accordance with instructions embedded in logic circuitry. The term 'processor' is to be interpreted broadly to include a CPU, processing unit, ASIC, logic unit, or programmable gate set etc. The methods and modules may all be performed by a single processor or divided amongst several processors.

Such machine-readable instructions may also be stored in a computer readable storage that can guide the computer or other programmable data processing devices to operate in a specific mode. For example, the instructions may be provided on a non-transitory computer readable storage medium encoded with instructions, executable by a processor.

Figure 16 is a schematic representation of a machine according to an example. The machine 1600 can be, e.g., a system or apparatus, user equipment, a network apparatus, a medical registration system, a surgical tool or part thereof The machine 1600 comprises a processor 1603, and a memory 1605 to store instructions 1602, executable by the processor 1603. The machine comprises a storage 1609 that can be used to store data 101 representing points, nominal data values, threshold values and so on as described herein.

The instructions 1607, executable by the processor 1603, can cause the machine 1600 to receive data representing a position about an axis of rotation of an arm, wherein the arm is for a calibration structure for a medical registration system, wherein the position corresponds to a position at which an optical reference portion of the arm is aligned with a predetermined reference position, and use the data representing the position of the arm, determine a measure for the angular rotation of the arm around the axis of rotation.

Accordingly, the machine 1600 can implement a method for calibrating a medical registration system.

Such machine-readable instructions may also be loaded onto a computer or other programmable data processing devices, so that the computer or other programmable data processing devices perform a series of operations to produce computer-implemented processing, thus the instructions executed on the computer or other programmable devices provide an operation for realizing functions specified by flow(s) in the flow charts and/or block(s) in the block diagrams.

Further, the teachings herein may be implemented in the form of a computer or software product, such as a non-transitory machine-readable storage medium, the computer software or product being stored in a storage medium and comprising a plurality of instructions, e.g., machine readable instructions, for making a computer device implement the methods recited in the examples of the present disclosure.

In some examples, some methods can be performed in a cloud-computing or network-based environment. Cloud-computing environments may provide various services and applications via the Internet. These cloud-based services (e.g., software as a service, platform as a service, infrastructure as a service, etc.) may be accessible through a web browser or other remote interface of the user equipment for example. Various functions described herein may be provided through a remote desktop environment or any other cloud-based computing environment.

The preceding description has been provided to enable others skilled in the art to best utilize various aspects of the exemplary embodiments disclosed herein. This exemplary description is not intended to be exhaustive or to be limited to any precise form disclosed. Many modifications and variations are possible without departing from the spirit and scope of the instant disclosure. The embodiments disclosed herein should be considered in all respects illustrative and not restrictive. Reference should be made to the appended claims and their equivalents in determining the scope of the instant disclosure.

Claims (13)

1. Claims A medical registration system, comprising: an on-tool imaging system, wherein the on-tool imaging system is configured to be mounted to a surgical tool using a mounting structure; and a calibration structure comprising: a shaft configured for releasable engagement at a first end of the shaft with a chuck device of the surgical tool, wherein the shaft comprises an axis of rotation; and an arm, depending from the shaft, the arm provided perpendicular to the axis of rotation at a second end of the shaft, wherein the arm comprises an optical reference portion provided in spaced relation on the arm relative to the axis of rotation.
2. The medical registration system as claimed in claim 1, further comprising: a probe comprising a tip, wherein the second end of the shaft comprises a probe registration structure provided in line with the axis of rotation of the shaft, wherein the probe registration structure is configured to receive the tip of the probe.
3. 3. The medical registration system as claimed in claim 2, wherein the probe registration structure comprises a female portion configured to receive the tip of the probe.
4. 4. The medical registration system as claimed in claim 2 or 3, wherein the probe registration structure comprises an opening in the second end of the shaft, wherein the opening converges in a direction towards the first end of the shaft to a point.
5. 5. The medical registration system as claimed in claim 4, wherein the point of the probe registration structure comprises a profile and/or size selected to prevent lateral movement of the tip of a probe.
6. 6. The medical registration system as claimed in any preceding claim, wherein the first end of the shaft comprises a shank portion configured to releasably engage with a chuck of a tool, whereby to secure the calibration structure to the tool.
7. 7. The medical registration system as claimed in any preceding claim, wherein the arm comprises one or more additional optical reference portions provided in spaced relation on the arm relative to the axis of rotation.
8. 8. The medical registration system as claimed in any preceding claim, wherein the optical reference portion comprises a planar surface with a surface normal parallel to the axis of rotation.
9. 9. The medical registration system as claimed in any preceding claim, wherein the optical reference portion is configured to rotate about the axis of rotation.
10. 10. The medical registration system as claimed in any preceding claim, further comprising a processor, and a memory, the memory coupled to the processor, the memory comprising program code executable by the processor, the program code comprising one or more instructions, whereby to cause the medical registration system to: generate data representing a position of the arm about the axis of rotation at which the optical reference portion is aligned with a predetermined reference position.
11. 11. The medical registration system as claimed in claim 10, wherein the program code comprises one or more instructions, whereby to cause the medical registration system to: automatically generate the data representing the position of the an about the axis of rotation at which the optical reference portion is aligned with the predetermined reference position in response to alignment of the optical reference portion with the predetermined reference position, wherein the alignment of the optical reference portion with the predetermined reference position is temporary or persists for a predetermined period of time.
12. 12. The medical registration system as claimed in claim 10 or 11, wherein the probe comprises a probe optical reference portion, and wherein the program code comprises one or more instructions, whereby to cause the medical registration system to: generate data representing a position of the probe optical reference portion about the axis of rotation at which the probe optical reference portion is aligned with a predetermined probe reference position.
13. 13. A machine-readable storage medium encoded with instructions for calibrating a medical registration system, the instructions executable by a processor, whereby to cause the processor to: receive data representing a position about an axis of rotation of an arm, wherein the arm is for a calibration structure for a medical registration system, wherein the position corresponds to a position at which an optical reference portion of the arm is aligned with a predetermined reference position; and use the data representing the position of the arm, determine a measure for the angular rotation of the arm around the axis of rotation.