NAVIGATION METHOD FOR POSITIONING A MEDICAL ROBOT

Description

Scope of the invention

[0001] The present invention relates to the field of minimally invasive and non-invasive medical interventions assisted by a medical robot. The invention relates in particular to an optical navigation system for determining the position of a patient's anatomy of interest in order to optimally position a medical instrument attached to one end of an articulated arm of the medical robot. Specifically, the invention makes it possible to determine the position of the anatomy of interest even when an obstacle prevents obtaining a direct line of sight between an optical marker located at the level of the anatomy of interest and an optical sensor of the navigation system. The invention also relates to a method for determining the position of a patient's anatomy of interest. State of the art

[0002] Many medical procedures, such as minimally invasive or non-invasive procedures, require the precise positioning or movement of a medical instrument (e.g., a needle, catheter, electrode, ultrasound generator, drill bit, etc.) relative to a patient's anatomy of interest (e.g., a liver, lung, kidney, vertebra, etc.). The practitioner performing this type of procedure may be assisted by a medical robot. In this case, the medical robot positions, holds, and / or guides a medical instrument relative to the patient's anatomy of interest using a navigation system. The medical instrument is, for example, attached to one end of an articulated arm of the medical robot. The navigation system determines the position of the medical instrument and the position of the anatomy of interest.Information about the respective positions of the medical instrument and the anatomy of interest relative to each other then allows the medical robot to configure its articulated arm so that the medical instrument is optimally positioned relative to the anatomy of interest.

[0003] There are different types of navigation systems. Electromagnetic navigation systems have the disadvantage of being susceptible to interference and distortions of the electromagnetic field in the presence of metallic materials (such as the motors of a medical robot). Optical navigation systems, on the other hand, have the disadvantage of ceasing to function when the line of sight between a marker positioned on the anatomy of interest and an optical sensor of the navigation system is interrupted by an obstacle (this occurs, for example, when the practitioner is positioned between the marker and the optical sensor).

[0004] Determining the position of the anatomy of interest at a single opportune moment when a direct line of sight is available is generally insufficient, as the patient's anatomy of interest may be in motion, for example, due to the patient's breathing or the practitioner's movement of the anatomy. Therefore, it is essential to be able to track the position of the anatomy of interest over time using the navigation system, even during periods when the line of sight between a marker positioned at the level of the anatomy of interest and an optical sensor of the navigation system is interrupted by an obstacle.

[0005] Several prior art solutions involve optimizing the positioning of markers and optical sensors to reduce the risk of the line of sight being interrupted by an obstacle. These solutions are generally complex and do not always guarantee the operation of the optical navigation system when the line of sight is interrupted by an obstacle.

[0006] Patent application EP 3501443 A1 discloses, among other things, a system comprising a rotating component integrated into a surgical light to move a camera to a suitable position to aim at an anatomy of interest of a patient when an obstacle prevents obtaining a direct line of sight.

[0007] Some prior art solutions attempt to combine an optical navigation system with a complementary navigation system (for example, an electromagnetic navigation system) to ensure the system's continued operation when the line of sight is interrupted by an obstacle. However, these solutions result in complex and expensive systems whose accuracy can be affected by the presence of metallic objects. Description of the invention

[0008] The present invention aims to remedy all or part of the drawbacks of the prior art, in particular those set out above.

[0009] To this end, and according to a first aspect, the present invention proposes an optical navigation system for determining the position of a patient's anatomy of interest. The system includes, in particular, a patient reference frame intended to be positioned on the patient at the level of the anatomy of interest, a localization device, and a control unit. The localization device comprises at least two optical sensors. The patient reference frame comprises at least three optical markers. The respective positions of the optical markers of the patient reference frame relative to each other are known a priori by the control unit. The optical navigation system further comprises a reflective device whose position in a reference frame of the localization device is determinable by the control unit.When a direct line of sight between the patient reference and each optical sensor is available, the optical sensors are configured to measure, for each optical marker of the patient reference, a quantity representative of the position of said optical marker in the localization device's frame of reference, based on optical radiation originating from said optical marker and having, for each optical sensor, a direct path between said optical marker and said optical sensor. When a direct line of sight between the patient reference and an optical sensor is interrupted by an obstacle, the optical sensors are configured to measure, for each optical marker of the patient reference, a quantity representative of the position of said optical marker in the localization device's frame of reference, based on optical radiation originating from said optical marker and having a path reflected by the reflecting device back to each optical sensor.The control unit is configured to determine, from measurements taken by optical sensors, the position of the patient reference in the localization device's reference frame, and to deduce the position of the anatomy of interest in said reference frame.

[0010] In this application, "optical radiation" means electromagnetic radiation with a wavelength range from 100 nm (one hundred nanometers) to 1 mm (one millimeter). Thus, infrared radiation, visible light, and ultraviolet radiation are optical radiations. The term "optical ray" is sometimes used to define a specific path taken by optical radiation.

[0011] In this application, the term "position" represents the position and orientation in the three dimensions of a spatial reference frame (this corresponds to the term "pose" in the Anglo-Saxon literature).

[0012] The expression "the position of the reflective device is determinable by the control unit" means that the position of the reflective device is known a priori by the control unit (for example, the position of the reflective device is saved in a memory of the control unit), or that it can be determined by the control unit (for example, using optical markers placed on the reflective device).

[0013] With such provisions, the optical navigation system according to the invention is able to determine the position of the patient's anatomy of interest even when the line of sight is cut by an obstacle (for example by a practitioner who will have to perform a medical intervention on the anatomy of interest, or by the medical robot that assists said practitioner).

[0014] In particular embodiments, the invention may further comprise one or more of the following features, taken individually or in all technically possible combinations.

[0015] In particular embodiments, the reflective device comprises at least three optical markers. The respective positions of the optical markers of the reflective device relative to each other are known a priori by the control unit.

[0016] In particular embodiments, during a period when a direct line of sight between the patient reference and each optical sensor is available, the control unit is configured to estimate the movement of the patient reference within the localization device's frame of reference during one patient breathing cycle. Then, at a time when a direct line of sight between the patient reference and an optical sensor is no longer available, the control unit is configured to determine the patient reference's position based on, firstly, measurements taken by the optical sensors from the optical radiation emanating from the patient reference's optical markers and reflected by the reflecting device, and secondly, based on the estimated movement of the patient reference.

[0017] In particular embodiments, the patient reference also includes at least three radiopaque markers. The respective positions of the radiopaque markers relative to each other are known a priori by the control unit.

[0018] In particular embodiments, the position of the anatomy of interest in the localization device's reference frame is determined based on the position of the patient reference in said reference frame and based on a medical image of the patient's anatomy of interest on which the radio-opaque markers of the patient reference are visible.

[0019] In particular embodiments, the position of the anatomy of interest in the localization device's reference frame is further determined according to a biomechanical model of the anatomy of interest.

[0020] In particular embodiments, the optical navigation system comprises three reflective devices orthogonal in pairs.

[0021] In particular embodiments, the optical navigation system further comprises a robot reference frame intended to be positioned at the distal end of an articulated arm of a medical robot. The robot reference frame has at least three optical markers. The respective positions of the optical markers relative to each other are known a priori by the control unit. When a direct line of sight between the robot reference frame and each optical sensor is available, the optical sensors of the localization device are configured to measure, for each optical marker of the robot reference frame, a quantity representative of the position of said optical marker in the localization device's frame of reference, based on optical radiation originating from said optical marker and having, for each optical sensor, a direct path between said optical marker and said optical sensor.When a direct line of sight between the robot reference and an optical sensor is interrupted by an obstacle, the optical sensors are configured to measure, for each optical marker of the robot reference, a quantity representative of the position of said optical marker in the localization device's frame of reference. This measurement is taken from optical radiation originating from said optical marker and having a path reflected by the reflecting device back to each optical sensor. The control unit is configured to determine the position of the robot reference in the localization device's frame of reference based on the measurements thus obtained by the optical sensors.

[0022] In certain embodiments, the optical navigation system further comprises a medical robot with an articulated arm. The robot reference frame is positioned at a distal end of the articulated arm. The medical robot also includes articulated arm joint encoders that allow the robot reference frame's position to be determined at any given time within a reference frame of the medical robot. The medical robot is configured to transmit the robot reference frame's position in the robot's reference frame to the control unit. The control unit is configured to deduce from this the position of a medical instrument attached to the distal end of the articulated arm of the medical robot relative to the patient's anatomy of interest.

[0023] In particular embodiments, the optical markers of the patient reference and / or the robot reference are active markers and the optical radiation from an optical marker is infrared radiation generated by said optical marker.

[0024] In particular embodiments, the optical markers of the patient reference and / or the robot reference are passive markers and the optical radiation from an optical marker is infrared radiation generated by the localization device and reflected by said optical marker.

[0025] According to a second aspect, the present invention relates to a method for determining the position of a patient's anatomy of interest during a surgical procedure. The method is implemented by an optical navigation system comprising a patient reference frame intended to be positioned on the patient at the level of the anatomy of interest, and a localization device. The relative positions of the optical markers are known a priori. The localization device comprises at least two optical sensors. The patient reference frame comprises at least three optical markers. The optical navigation system further comprises a reflective device whose position in a reference frame of the localization device is known. The method comprises the following steps: When a direct line of sight between the patient reference and each optical sensor is available, a measurement, for each optical marker of the patient reference, of a quantity representative of the position of said optical marker in the reference frame of the localization device from optical radiation originating from said optical marker and having, for each optical sensor, a direct path between said optical marker and said optical sensor; when a direct line of sight between the patient reference and an optical sensor is interrupted by an obstacle, a measurement, for each optical marker of the patient reference, of a quantity representative of the position of said optical marker in the reference frame of the localization device from optical radiation originating from said optical marker and having a path reflected by the reflecting device towards each optical sensor; a determination,Based on the measurements thus taken by the optical sensors, of the patient reference position in the localization device's frame of reference, a determination, within said frame of reference of the localization device, of the position of the anatomy of interest relative to the patient reference position.

[0026] It should be noted that the positioning of the patient's anatomy of interest and the positioning of the medical instrument attached to one end of an articulated arm of the medical robot take place prior to the practitioner performing the medical procedure. Thus, the method according to the invention for determining the position of a patient's anatomy of interest does not involve any therapeutic or surgical treatment step.

[0027] In particular embodiments, the invention may further comprise one or more of the following features, taken individually or in all technically possible combinations.

[0028] In specific implementation methods, the process also includes the following steps: during a period when a direct line of sight between the patient reference and each optical sensor is available, an estimation of a movement followed by the patient reference in the localization device's frame of reference during a patient breathing cycle, at a time when a direct line of sight between the patient reference and an optical sensor is no longer available, a determination of the patient reference's position based on the measurements taken by the optical sensors from the optical radiation from the optical markers of the patient reference and reflected by the reflecting device, and based on the estimated movement of the patient reference.

[0029] In particular modes of implementation, the determination of the position of the anatomy of interest in the reference frame of the localization device is further carried out from a medical image of the patient's anatomy of interest on which radio-opaque markers of the patient reference are visible.

[0030] In particular modes of implementation, the determination of the position of the anatomy of interest in the reference frame of the localization device is also carried out from a biomechanical model of the anatomy of interest.

[0031] In specific implementations, the optical navigation system further includes a robot reference intended to be positioned at the distal end of an articulated arm of a medical robot. The robot reference comprises at least three optical markers, the relative positions of the optical markers being known a priori. The method further includes the following steps: When a direct line of sight between the robot reference and each optical sensor is available, a measurement, for each optical marker of the robot reference, of a quantity representative of the position of said optical marker in the reference frame of the localization device, from optical radiation originating from said optical marker and having, for each optical sensor, a direct path between said optical marker and said optical sensor; when a direct line of sight between the robot reference and an optical sensor is interrupted by an obstacle, a measurement, for each optical marker of the robot reference, of a quantity representative of the position of said optical marker in the reference frame of the localization device, from optical radiation originating from said optical marker and having a path reflected by the reflecting device towards each optical sensor.a determination of the robot reference position in the localization device's frame of reference based on measurements thus performed by the optical sensors.

[0032] In specific implementations, the optical navigation system also includes a medical robot. The medical robot has an articulated arm at one distal end of which the robot reference frame is positioned. The medical robot also includes articulation encoders for the articulated arm, enabling the position of the robot reference frame to be determined at any given time within a reference frame of the medical robot. The method then includes a step of determining the position of a medical instrument attached to the distal end of the articulated arm of the medical robot relative to the patient's anatomy of interest. Presentation of the figures

[0033] The invention will be better understood upon reading the following description, given by way of non-limiting example, and made with reference to the figures 1 to 10 which represent: [ Fig. 1 ] a schematic representation of an optical navigation system according to the invention when a direct line of sight is available, [ Fig. 2 ] a schematic representation of an optical navigation system according to the invention when the line of sight is interrupted by an obstacle, [ Fig. 3 ] a schematic representation of a patient reference comprising three optical markers and three radiopaque markers, [ Fig. 4 ] a schematic representation of a robot reference comprising three optical markers, [ Fig. 5 ] a schematic representation of a reflective device comprising four optical markers, [ Fig. 6] a schematic representation of the determination of the position of an optical marker of the patient reference, when the line of sight is interrupted by an obstacle, as a function of measurements taken by optical sensors on optical rays reflected by the reflecting device, [ Fig. 7 ] a schematic representation of the main steps in a procedure for determining the position of an anatomy of interest in a patient, [ Fig. 8 ] a schematic representation of an estimated movement of the patient reference during a patient breathing cycle, [ Fig. 9a ] a schematic representation of the determination of the position of an optical marker of the patient reference, when the line of sight is interrupted by an obstacle, based on measurements taken by optical sensors and based on the estimated movement of the patient reference, [ Fig. 9b a cross-sectional view of the figure 9a , [ Fig. 10] a schematic representation of the main steps of a particular method of implementing a process to determine the position of an anatomy of interest of a patient.

[0034] In these figures, identical references from one figure to another designate identical or analogous elements. For clarity, the elements shown are not necessarily to the same scale, unless otherwise stated. Detailed description of an embodiment of the invention

[0035] There figure 1 schematically represents an example of an optical navigation system 100 according to the invention.

[0036] In the example considered and illustrated in the figure 1 The optical navigation system 100 comprises the following main elements: a localization device 40, a control unit 43, a patient reference 21 intended to be positioned at a point of interest in a patient's anatomy 20, and a reflective device 30. In the example illustrated in the figure 1 Patient 20 is lying on a table 50 in an operating room.

[0037] The optical navigation system 100 aims to determine the position of the patient reference frame 21 in order to deduce the position of the anatomy of interest within a reference frame of the localization device 40. To this end, the control unit 43 is configured to implement all or part of the steps of a process for determining the position of the patient reference frame within the reference frame of the localization device 40. The control unit 43 includes, for example, one or more processors and a memory (magnetic hard drive, electronic memory, optical disc, etc.) in which a computer program product is stored, in the form of a set of program code instructions to be executed to implement the various steps of such a process. Alternatively or in addition, the control unit 43 includes one or more programmable logic circuits (FPGA, PLD, etc.).), and / or one or more specialized integrated circuits (ASICs), and / or a set of discrete electronic components, etc., adapted to implement all or part of the steps of the process.

[0038] As illustrated on the figure 1The optical navigation system 100 may also include a robot reference 11 intended to be positioned at a distal end of an articulated arm 13 of a medical robot 10, for example, on an instrument holder 14 attached to said end. The control unit 43 can then be configured to also determine the position of the robot reference in the frame of reference of the localization device 40. If the position of a medical instrument attached to the instrument holder 14 relative to the position of the robot reference 11 is known by the control unit 43, then the control unit 43 can determine the position of the medical instrument in the frame of reference of the localization device 40.The respective positions of the medical instrument and the anatomy of interest relative to each other can then allow the medical robot 10 to configure its articulated arm so that the medical instrument is optimally positioned relative to the anatomy of interest.

[0039] The control unit 43 can be integrated into the location device 40, as is the case in the example illustrated in the figure 1The control unit 43 can also be a separate entity from the localization device 40 or be integrated into the medical robot 10. If the control unit 43 is not integrated into the medical robot 10, it can be configured to transmit information to the medical robot 10 regarding the position of the anatomy of interest and / or the position of the medical instrument, so that the medical robot 10 can configure its articulated arm 13 to optimally position the medical instrument relative to the anatomy of interest. This information transmission can, for example, be carried out via wireless communication. If the control unit 43 is not integrated into the localization device 40, it is configured to receive information from the localization device 40 regarding the position of the patient reference 21 and / or the robot reference 11.Information transmission between the location device 40 and the control unit 43 can, for example, be carried out via wireless communication means.

[0040] There figure 3 schematically represents the patient reference 21. The patient reference 21 comprises at least three optical markers 26, such that the position of the patient reference 21 can be determined in the three spatial dimensions of the localization device's reference frame 40. The respective positions of the optical markers 26 of the patient reference 21 relative to each other are known a priori by the control unit 43. Advantageously, the geometric shape of each optical marker 26 can also be known a priori by the control unit 43. In the example illustrated in the figure 3 Patient reference 21 includes three spherical optical markers 26. The spherical shape optimizes the reflection of optical radiation.

[0041] The optical markers 26 can be passive or active. Passive optical markers reflect optical radiation emitted by another element, such as the positioning device 40. Passive optical markers can be, for example, reflective spheres detectable by an infrared stereoscopic camera (this is what is used, for example, in the Polaris® navigation systems manufactured by Northern Digital Inc.), or black and white patterns visible by a stereoscopic camera (this is what is used, for example, in the MicronTracker® navigation system from ClaroNav). Active optical markers themselves emit optical radiation, for example, infrared radiation, detectable by the positioning device 40.

[0042] There figure 4schematically represents the robot reference 11. The robot reference 11 comprises at least three optical markers 16, such that the position of the robot reference 11 can be determined in the three spatial dimensions of the reference frame of the localization device 40. The respective positions of the optical markers 16 of the robot reference 11 relative to each other are known a priori by the control unit 43. Advantageously, the geometric shape of each optical marker 16 can also be known a priori by the control unit 43. In the example illustrated in the figure 4 The robot reference 11 has three spherical optical markers 16. What was previously mentioned regarding the active or passive type of the optical markers 26 in the patient reference 21 also applies to the optical markers 16 in the robot reference 11.

[0043] The relative positions of the optical markers 16 of the robot reference 11 differ from the relative positions of the optical markers 26 of the patient reference 21. Such arrangements allow the localization device 40 to distinguish between the patient reference 21 and the robot reference 11.

[0044] As illustrated on the figure 1The localization device 40 comprises at least two optical sensors 41, corresponding, for example, to two sensors of a stereoscopic camera operating in the infrared radiation range or in the visible light range. In the following description, it is considered, by way of non-limiting example, that the optical sensors 41 of the localization device 40 and the various optical markers 16, 21 of the optical navigation system 100 are designed to operate with infrared optical radiation, that is to say, electromagnetic radiation with a wavelength ranging from 780 nm to 1 mm.It should be noted, however, that the optical navigation system 100 according to the invention could also be designed to operate in the visible light range (electromagnetic radiation with a wavelength between 380 nm and 780 nm) or in the ultraviolet range (electromagnetic radiation with a wavelength between 10 nm and 380 nm).

[0045] In a conventional manner, and as illustrated on the figure 1, when a direct line of sight is available between the patient reference 21 and the optical sensors 41 of the localization device 40 (i.e. when there is no obstacle between the patient reference 21 and the optical sensors 41 of the localization device 40, or in other words when the infrared radiation can follow a direct path 22 in a straight line between each optical marker 26 of the patient reference 21 and each optical sensor 41 of the localization device 40), the position of each optical marker 26 can be determined as a function of the travel time of an infrared ray corresponding to said direct path 22 between said optical marker 26 and an optical sensor 41 (the speed of the infrared radiation being known since it is equal to the speed of light), and / or as a function of an angle of arrival of said infrared ray at the level of said optical sensor 41.

[0046] For example, when the optical markers 26 used in the optical navigation system 100 are passive markers, the optical sensors 41 can be configured to emit infrared radiation. This infrared radiation is then reflected by the various optical markers 26 back to the optical sensors 41. The optical sensors 41 are configured to receive this reflected infrared radiation. The distance between an optical marker 26 and an optical sensor 41 is then equal to half the time taken by an infrared ray to travel to and from said optical sensor 41 and said optical marker 26, multiplied by the speed of light.By knowing the distance between each optical marker 26 and each optical sensor 41, and by knowing a priori the arrangement of the optical markers 26 in relation to each other on the patient reference 21, it is possible to determine the position of the patient reference 21 in the reference frame of the localization device 40.

[0047] According to another example, when the optical markers 26 used in the optical navigation system 100 are active markers, each optical sensor 41 is configured to determine an angle of arrival at said optical sensor 41 of the infrared radiation which is directly generated by an optical marker 26. By knowing for each optical marker 26 the angle of arrival at each optical sensor 41, and by knowing a priori the arrangement of the optical markers 26 relative to each other on the patient reference 21, it is possible to determine the position of the patient reference 21 in the reference frame of the localization device 40.

[0048] Similarly, the localization device 40 can determine the position of the robot reference 11 in the localization device reference frame 40 when a direct line of sight is available between the robot reference 11 and the optical sensors 41 of the localization device 40.

[0049] It is necessary to be able to determine the position of the patient's anatomy of interest from the position of the patient reference 21. To this end, and as illustrated on the figure 3The patient reference 21 may include radiopaque markers 27. The respective positions of the radiopaque markers 27 relative to each other are known a priori by the control unit 43. Advantageously, the geometric shape of the radiopaque markers 27 may also be known a priori by the control unit 43. Preferably, the patient reference 21 includes at least three radiopaque markers 27. The position of the anatomy of interest in the localization device's reference frame 40 can then be determined based on the position of the patient reference 21 in said reference frame and based on a medical image of the patient's anatomy of interest on which the radiopaque markers 27 of the patient reference 21 are visible. The medical image provides information on the position of the anatomy of interest relative to the position of the patient reference 21.By knowing the position of the patient reference 21 in the reference frame of the localization device 40, we can then deduce the position of the anatomy of interest in this reference frame.

[0050] Radiopaque markers 27 can be, for example, ceramic or metallic beads visible in a medical image (e.g., computed tomography, three-dimensional rotational angiography, magnetic resonance imaging, ultrasound, etc.). A medical image of patient 20 is acquired with patient reference 21. This medical image can be registered with another image of the same patient acquired previously and containing intervention planning data, or it can be used directly to plan the intervention. The planned intervention can be ablation (e.g., by radiofrequency, microwave, electroporation, laser, cryotherapy, ultrasound) of a tumor in an anatomy of interest (e.g., the liver, lung, or kidney).The planned intervention may also involve the insertion of a medical instrument into the brain, the spine (for example, for vertebroplasty and cementoplasty), or another bony structure (for example, the knee). Planning includes determining the trajectory that a medical instrument (for example, a needle) must follow between an entry point in the patient's skin and a target point (within the tumor) in the anatomy of interest. Once the position of the patient's anatomy of interest is determined within the localization device's reference frame, the position that the medical instrument must assume within this frame can be deduced from this planning data.

[0051] As illustrated on the figure 2A problem arises in determining the position of patient reference 21 when an obstacle 60 cuts the line of sight between patient reference 21 and the sensors 41 of the localization device 40 (even if this is not illustrated on the figure 2 , a similar problem arises for determining the position of the robot reference 11 when an obstacle cuts the line of sight between the robot reference 11 and the sensors 41 of the localization device 40).

[0052] To overcome this problem, the present invention proposes to use a reflective device 30 whose position in the reference frame of the localization device 40 is known by the control unit 43.

[0053] The position of the reflective device 30 is, for example, known a priori and stored in the memory of the control unit 43. In a variant, and as illustrated in the figure 5The reflective device 30 comprises at least three optical markers 36. The respective positions of the optical markers 36 relative to each other are known a priori by the control unit 43. Advantageously, the geometric shape of each optical marker 36 can also be known a priori by the control unit 43. The position of the reflective device 30 can then be determined by the control unit 43 using the optical sensors 41 of the localization device 40. As illustrated in the Figures 1 And 2 , the reflective device 30 is for example fixed to the intervention table 50, and the position of the reflective device 30 is not changed during the period of time in which the anatomy of interest of the patient is to be determined.

[0054] The reflective device 30 corresponds, for example, to a glass plate onto which a thin sheet of metal (e.g., aluminum or silver) is bonded, itself coated with a layer of copper or lead. Alternatively, the glass plate can be coated with a thin sheet of gold. The reflective device 30 can be a flat mirror or a concave mirror designed to concentrate infrared rays. In the example considered, the reflective device 30 is a rectangular flat mirror. As illustrated in the figure 5 , an optical marker 36 can be positioned at each corner of the rectangle formed by the reflective device 30.

[0055] As illustrated on the figure 2 and on the figure 6When a direct line of sight between the patient reference 21 and an optical sensor 41 is interrupted by an obstacle 60, the optical sensors 41 are configured to measure, for each optical marker 26 of the patient reference 21, a quantity representative of the position of said optical marker 26 in the reference frame of the localization device 40, based on an infrared beam originating from said optical marker 26 and following a path reflected 23 by the reflecting device 30 to each optical sensor 41 (and not based on an infrared beam corresponding to a direct path 22 between said optical marker 26 and said optical sensor 41). By "a quantity representative of the marker's position," we mean, for example, the travel time of the infrared beam between the optical sensor and the optical marker, or the angle of arrival of the infrared beam at the optical sensor 41.

[0056] For example, and as illustrated on the figure 6If, for each optical sensor 41, the angle of arrival of an infrared ray 23 reflected by the reflecting device 30 and originating from an optical marker 26 of the patient reference 21 is known, and if the position of the reflecting device 30 is known, then it is possible to determine the position of said optical marker 26. It should be noted that the infrared ray 23 is reflected in the reflecting device 30 at a point of reflection 28, forming a reflection angle θ with respect to a line δ perpendicular to the reflecting device 30 and passing through the point of reflection 28. This reflection angle θ is identical for the incident ray and for the reflected ray. On the figure 6The angle of arrival of the infrared ray 23 at the optical sensor 41 in a plane containing the infrared ray 23 and the line δ corresponds to the angle Φ. If the angle of arrival Φ at the optical sensor 41 and the position of the reflecting device 30 are known, it is possible to determine the value of the angle of reflection θ. A reflection angle can thus be determined for the infrared ray associated with each of the two optical sensors 41. The position of the optical marker 26 corresponds to the intersection of the two infrared rays.

[0057] It should be noted that the position of the optical marker 26 could also be determined from an optical sensor 41 as a function of the angle of arrival of the infrared ray 23 and as a function of the travel time of the infrared ray 23 between the optical marker 26 and the optical sensor 41 (assuming that this travel time can be determined).

[0058] There figure 7 schematically represents the main steps of a process implemented by control unit 43 to determine the position of the patient's anatomy of interest.

[0059] The process 200 includes a first step in which it is detected whether an obstacle cuts a direct line of sight between the patient reference 21 and the optical sensors 41 of the localization device 40.

[0060] If a direct line of sight is available (no obstacle), the process 200 includes a step 201 in which measurements are taken by the optical sensors 41 from infrared rays following direct paths 22 between the optical markers 26 of the patient reference 21 and the optical sensors 41.

[0061] If the line of sight is cut (presence of an obstacle), then the process 200 includes a step 202 in which measurements are taken by the optical sensors 41 from infrared rays 23 following indirect paths involving a reflection on the reflective device 30, between the optical markers 26 of the patient reference 21 and the optical sensors 41.

[0062] At step 203, the position of the patient reference 21 is determined from the positions of the optical markers 26 determined from the measurements made by the optical sensors 41.

[0063] At step 204, the position of the anatomy of interest 204 is determined from the position of the patient reference 21.

[0064] The optical sensors 41 are configured, for example, to work by default with infrared beams 23 coming directly from a workspace in which the patient reference 21 and / or the robot reference 11 are assumed to be located. If such infrared beams are not detected, then the control unit 43 configures the optical sensors 41 to work with infrared beams 23 reflected by the reflecting device 30.

[0065] Thus, it is possible to determine the position of the patient's anatomy of interest at any time, even when a direct line of sight is not available.

[0066] What has just been explained above for determining the position of the patient reference 21 also applies to determining the robot reference 11 when an obstacle cuts the line of sight between the robot reference 11 and the sensors 41 of the localization device 40.

[0067] In particular embodiments, the medical robot 10 further includes joint encoders on its articulated arm 13, enabling the position of the robot reference 11 to be determined at any given time within a reference frame of the medical robot 10. The medical robot 10 is configured to transmit the position of the robot reference 11 within the reference frame of the medical robot 10 to the control unit 43. The control unit 43 is configured to deduce from this the position of a medical instrument fixed to the distal end of the articulated arm 13 of the medical robot 10 relative to the anatomy of interest of the patient 20.

[0068] For this purpose, it is conceivable, for example, during a preliminary setup step, that the articulated arm 13 of the medical robot 10 performs a predefined movement to make the robot reference 11 assume different calibration positions distributed within the common workspace of the medical robot 10 and the optical navigation system 100. For each calibration position taken by the robot reference 11, the control unit 43 receives position information from the articulation encoders and from the optical markers 16 of the robot reference 11. The reference frame of the medical robot 10 and the reference frame of the localization device 40 can be realigned (aligned) by matching the different calibration positions and calculating rigid realignment point by point.

[0069] When the patient breathes, the patient's anatomy of interest (and more specifically a target area within the anatomy of interest) follows the respiratory movements. It is necessary to be able to track the position of the anatomy of interest over time using the optical navigation system, even during periods when the line of sight between a marker positioned at the level of the anatomy of interest and an optical sensor of the navigation system is interrupted by an obstacle.

[0070] There figure 8 This schematically represents the movement of reference patient 21 over a period of time encompassing several respiratory cycles of the patient. The movement is represented in a two-coordinate system with x and y coordinates. Each x or y axis thus corresponds to a component of the movement of reference patient 21.

[0071] For example, during the time period considered, a direct line of sight is always available between the patient reference 21 and the optical sensors 41 of the localization device 40. The position of each optical marker 26 of the patient reference 21 is determined at several times during the time period. It is then possible to determine, for the time period considered, an estimated movement 24 corresponding, for example, to the average movement of the patient reference 21, along the two chosen components, during one respiratory cycle of the patient. In the following description, for the sake of simplicity, the estimated movement 24 of the patient reference 21 is considered to be substantially identical to the movement followed by each optical marker 26 of the patient reference 21.In reality, each optical marker 26 of the patient reference 21 could have a particular movement, and the movement of the patient reference would then correspond to a resultant of the movements of the different optical sensors (it would then be possible to consider an estimated movement for each optical marker 26 of the patient reference 21).

[0072] THE figures 9a and 9b schematically represent how the position of an optical marker 26 of the patient reference 21 can be determined based on the estimated movement 24 of said optical marker 26 when the line of sight is interrupted by an obstacle. figure 9b is a two-dimensional representation of the figure 9a in the plane containing the infrared ray 23 coming from the optical marker 26 and reflected by the reflecting device 30 as well as the line δ perpendicular to the reflecting device 30 passing through the point of reflection 28.

[0073] As illustrated on the figures 9a and 9b When the line of sight is no longer available between the patient reference 21 and an optical sensor 41, it is possible to determine the position of an optical marker 26 based, on the one hand, on measurements taken by an optical sensor 41 from the optical beam 23 originating from said optical marker 26 of the patient reference 21 and reflected by the reflecting device 30, and on the other hand, on the estimated movement 24 of the optical marker 26. As illustrated in the figure 9bThe estimated motion 24 of the optical marker 26 is decomposed into two orthogonal components x and y belonging to the plane containing the infrared ray 23 and the line δ. The infrared ray 23 is reflected in the reflecting device 30 at the point of reflection 28, forming a reflection angle θ with respect to the line δ. This reflection angle θ is identical for the incident and reflected ray. The infrared ray 23 forms an arrival angle Φ at the optical sensor 41.

[0074] If the angle of arrival Φ at the optical sensor 41 and the position of the reflecting device 30 are known, it is possible to determine the value of the angle of reflection θ. It is then possible to determine the position of the optical marker 26 because it corresponds to the intersection of the infrared ray 23 with the trajectory followed by the estimated movement 24 of the optical marker 26.

[0075] According to another example, if the travel time of the infrared ray 23 between the optical marker 26 and the optical sensor 41 is known, in other words if the distance traveled by said infrared ray is known, it is also possible to determine the position of the optical marker 26 because there is only one point on the path followed by the estimated movement 24 of the optical marker 26 from which an infrared ray 23 reflecting off the reflective device 30 would reach the optical sensor 41 by traveling said distance.

[0076] Once the position of each optical marker 26 is determined, the position of the patient reference 21 can also be determined. It is then possible to deduce the position of the anatomy of interest, particularly if the position of the anatomy of interest can be defined relative to the position of the patient reference on a medical image.

[0077] Furthermore, a biomechanical model of the anatomy of interest can be used to optimize the determination of its position based on the position of reference patient 21 and the estimated movement 24 followed by reference patient 21. Indeed, it is possible to model the deformations of the various anatomical structures (muscles, tendons, bone structures, organs, vascular network, etc.) and the mechanical interactions between these structures using a biomechanical model. The biomechanical model can then be used to better define the movement followed by the anatomy of interest based on the movement followed by reference patient 21.

[0078] There Figure 10 schematically represents a particular method of implementing process 200 described with reference to the figure 7Specifically, step 201, direct line-of-sight measurement of the position of the optical markers 26 of the patient reference, is repeated at several different times during a period of time comprising at least one patient breathing cycle. As previously described with reference to the figures 8 This allows, in step 205, the estimation of a movement of the patient reference 21 during a patient breathing cycle. This estimated movement 24 is then used in step 203 to determine the position of the patient reference 21 when the line of sight is no longer available (as described previously with reference to figures 9a and 9b ). The position of the patient's anatomy of interest can then be determined, in step 204, from the position of the patient reference 21.

[0079] The invention thus makes it possible to determine the position of an anatomy of interest of a patient using an optical navigation system 100 even when a direct line of sight is not available between the patient reference 21 and the optical sensors 41 of a localization device 40 of the optical navigation system 100.

[0080] In particular embodiments, and as illustrated in the Figures 1 And 2The localization device 40 may further include a camera 42 that provides images to the control unit 43 to determine the insertion depth of the medical instrument during the procedure. Images of the procedure are continuously captured by the camera 42. When the medical robot 10 is positioned relative to the patient according to the procedure plan, the practitioner inserts the medical instrument (e.g., a needle) into the patient's anatomy of interest to reach a target area (e.g., a tumor). The images from the camera 42 are analyzed by the control unit 43, which is configured to detect the medical instrument. Based on knowledge of the total length of the medical instrument and the position of the target area, the control unit 43 can determine the insertion depth of the medical instrument and when the instrument has reached the target area.When the target area is reached, a message for the practitioner is displayed, for example on a control screen. The message may be accompanied by an audible signal.

[0081] In particular embodiments, the images provided by the camera 42 of the localization device 40 are analyzed by the control unit 43 to recognize gestures made by a hand (gloved or ungloved) of the practitioner, said gestures being associated with specific commands intended for the medical robot 10 (for example, to configure the articulated arm of the medical robot in a predetermined position, to move the base of the medical robot to a predetermined position, to urgently interrupt all movement of the medical robot, etc.). The gestures made by the practitioner may obstruct the line of sight between the patient reference 21 and the optical sensors 41; however, the reflective device 30 allows the optical navigation system 100 according to the invention to determine the position of the patient reference 21.

[0082] It should be noted that several reflective devices 30 can be used to increase the number of different paths followed by optical radiation from an optical marker. In particular embodiments, the optical navigation system 100 advantageously comprises three different reflective devices arranged orthogonally in pairs. When a direct line of sight is not available, the position of the patient reference 21 can then be determined from optical rays reflected by one or more of the reflective devices.

Claims

1. Optical navigation system (100) for determining the position of a patient's anatomy of interest (20), comprising : - a locating device (40) with at least two optical sensors (41), - a control unit (43), - a patient reference (21) comprising at least three optical markers (26), the respective positions of the optical markers (26) relative to one another being known a priori by the control unit (43), said patient reference being intended to be positioned on the patient (20) at the anatomy of interest, said optical navigation system (100) being characterized in that : - the optical navigation system (100) further comprises a reflective device (30) whose position in a reference frame of the locating device (40) can be determined by the control unit (43), - when a direct line of sight between the patient reference (21) and each optical sensor (41) is available, the optical sensors (41) are configured to measure, for each optical marker (26) of the patient reference (21), a quantity representative of the position of said optical marker (26) in the reference frame of the locating device (40) from optical radiation originating from said optical marker (26) and having for each optical sensor (41) a direct path (22) between said optical marker (26) and said optical sensor (41), - when a direct line of sight between the patient reference (21) and an optical sensor (41) is intersected by an obstacle (60), the optical sensors (41) are configured to measure, for each optical marker (26) of the patient reference (21), a quantity representative of the position of said optical marker (26) in the reference frame of the locating device (40) from optical radiation originating from said optical marker (26) and having a path reflected (23) by the reflective device (30) to each optical sensor (41), - the control unit (43) is configured to determine, from the measurements made by the optical sensors (41), the position of the patient reference (21) in the frame of reference of the locating device (40), and to deduce therefrom the position of the anatomy of interest in said frame of reference.

2. The optical navigation system (100) according to claim 1, wherein the reflective device (30) comprises at least three optical markers (36), the respective positions of the optical markers (36) relative to one another being known a priori by the control unit (43).

3. The optical navigation system (100) according to one of claims 1 to 2, wherein the control unit (43) is configured for: - estimating a movement (24) followed by the patient reference (21) in the reference frame of the locating device (40) during a patient's breathing cycle (20), during a period when a direct line of sight between the patient reference (21) and each optical sensor (41) is available, - at a time when a direct line of sight between the patient reference (21) and an optical sensor (41) is no longer available, determining the position of the patient reference (21) as a function on the one hand of the measurements made by the optical sensors (41) from the optical radiation originating from the optical markers (26) of the patient reference (21) and reflected by the reflective device (30), and on the other hand as a function of the estimated movement (24) of the patient reference (21).

4. The optical navigation system (100) according to one of claims 1 to 3, wherein the patient reference (21) further comprises at least three radio-opaque markers (27), the respective positions of the radio-opaque markers (27) relative to one another being known a priori by the control unit (43).

5. The optical navigation system (100) according to claim 4, wherein the position of the anatomy of interest in the reference frame of the locating device (40) is determined as a function of the position of the patient reference (21) in said reference frame and as a function of a medical image of the patient's anatomy of interest on which the radio-opaque markers (27) of the patient reference (21) are visible.

6. The optical navigation system (100) according to claim 5, wherein the position of the anatomy of interest in the frame of reference of the locating device (40) is further determined as a function of a biomechanical model of the anatomy of interest.

7. The optical navigation system (100) according to one of claims 1 to 6, comprising three reflective devices (30) orthogonal in pairs.

8. The optical navigation system (100) according to one of claims 1 to 7, further comprising a robot reference (11) intended to be positioned at a distal end of an articulated arm (13) of a medical robot (10), said robot reference (11) comprising at least three optical markers (16), the respective positions of the optical markers (16) relative to one another being known a priori by the control unit (43), and wherein - when a direct line of sight between the robot reference (11) and each optical sensor (41) is available, the optical sensors (41) are configured to measure, for each optical marker (16) of the robot reference (11), a quantity representative of the position of said optical marker (16) in the reference frame of the locating device (40), from optical radiation originating from said optical marker (16) and having for each optical sensor a direct path between said optical marker and said optical sensor (41), - when a direct line of sight between the robot reference (11) and an optical sensor (41) is intersected by an obstacle, the optical sensors (41) are configured to measure, for each optical marker (16) of the robot reference (11), a quantity representative of the position of said optical marker (16) in the reference frame of the locating device (40) from optical radiation originating from said optical marker (16) and having a path reflected by the reflective device (30) towards each optical sensor (41), - the control unit (43) is configured to determine the position of the robot reference (11) in the reference frame of the locating device (40) from the measurements thus made by the optical sensors (41).

9. The optical navigation system (100) according to claim 8, further comprising a medical robot (10) comprising an articulated arm (13), the robot reference (11) being positioned at a distal end of the articulated arm (13), said medical robot (10) further comprising articulation encoders of the articulated arm (13) enabling the position of the robot reference (11) in a reference frame of the medical robot (10) to be determined at any time, the medical robot (10) being configured to transmit to the control unit (43) the position of the robot reference (11) in the frame of reference of the medical robot (10), and the control unit (43) is configured to deduce therefrom the position of a medical instrument attached to the distal end of the articulated arm (13) of the medical robot (10) relative to the anatomy of interest of the patient (20).

10. The optical navigation system (100) according to one of claims 8 to 9, wherein the optical markers (26, 16) of the patient reference (21) and / or robot reference (11) are active markers and the optical radiation from an optical marker (26, 16) is infrared radiation generated by said optical marker (26, 16).

11. The optical navigation system (100) according to one of claims 8 to 9, wherein the optical markers (26, 16) of the patient reference (21) and / or robot reference (11) are passive markers and the optical radiation from an optical marker (26, 16) is infrared radiation generated by the locating device (40) and reflected by said optical marker (26, 16).

12. A method (200) for determining the position of an anatomy of interest of a patient (20), said method (200) being implemented by an optical navigation system (100) comprising: - a locating device (40) with at least two optical sensors (41), - a patient reference (21) comprising at least three optical markers (26), the respective positions of the optical markers (26) relative to one another being known a priori, said patient reference (21) being intended to be positioned on the patient (20) at the anatomy of interest, said method being characterized in that the optical navigation system (100) further comprises a reflective device (30) whose position in a reference frame of the locating device (40) is known, and the method (200) comprises the following steps: - when a direct line of sight between the patient reference (21) and each optical sensor (41) is available, measuring (201), for each optical marker (26) of the patient reference (21), of a quantity representative of the position of said optical marker (26) in the reference frame of the locating device (40) from optical radiation originating from said optical marker (26) and having for each optical sensor (41) a direct path (22) between said optical marker (26) and said optical sensor (41), - when a direct line of sight between the patient reference (21) and an optical sensor (41) is intersected by an obstacle (60), measuring (202), for each optical marker (26) of the patient reference (20), of a quantity representative of the position of said optical marker (26) in the reference frame of the locating device (40) from optical radiation originating from said optical marker (26) and having a path reflected (23) by the reflective device (30) to each optical sensor (41), - determining (203) the position of the patient reference (21) in the reference frame of the locating device (40), based on the measurements made by the optical sensors (41), - determining (204), in said reference frame of the locating device (40), the position of the anatomy of interest from the position of the patient reference (21).

13. The method (200) according to claim 12, further comprising the following steps: - during a period when a direct line of sight between the patient reference (21) and each optical sensor (41) is available, estimating (205) a movement (24) followed by the patient reference (21) in the reference frame of the locating device (40) during a breathing cycle of the patient (20), - at a time when a direct line of sight between the patient reference (21) and an optical sensor (41) is no longer available, determining (203) the position of the patient reference (21) as a function on the one hand of the measurements made by the optical sensors (41) from the optical radiation originating from the optical markers (26) of the patient reference (21) and reflected by the reflective device (30), and as a function on the other hand of the estimated movement (24) of the patient reference (21).

14. The method (200) according to claim 13, wherein the determination (204) of the position of the anatomy of interest in the reference frame of the locating device (40) is further carried out on the basis of a medical image of the patient's anatomy of interest (20) on which radio-opaque markers (27) of the patient reference (21) are visible.

15. The method (200) according to claim 14, wherein the determination (204) of the position of the anatomy of interest in the reference frame of the locating device (40) is additionally carried out from a biomechanical model of the anatomy of interest.

16. The method (200) according to one of claims 12 to 15, wherein the optical navigation system (100) further comprises a robot reference (11) intended to be positioned at a distal end of an articulated arm (13) of a medical robot (10), said robot reference (11) comprising at least three optical markers (16), the respective positions of the optical markers (16) relative to one another being known a priori, said method (200) further comprising the following steps: - when a direct line of sight between the robot reference (11) and each optical sensor (41) is available, measuring, for each optical marker (16) of the robot reference (11), a quantity representative of the position of said optical marker (16) in the reference frame of the locating device (40), from optical radiation originating from said optical marker (16) and having for each optical sensor (41) a direct path between said optical marker (16) and said optical sensor (41), - when a direct line of sight between the robot reference (11) and an optical sensor (41) is intersected by an obstacle, measuring, for each optical marker (16) of the robot reference (11), a quantity representative of the position of said optical marker (16) in the reference frame of the locating device (40) from optical radiation originating from said optical marker (16) and having a path reflected by the reflective device (30) towards each optical sensor (41), - determining the position of the robot reference (11) in the reference frame of the locating device (40) from the measurements thus made by the optical sensors (41).

17. The method (200) according to claim 16, wherein the optical navigation system (100) further comprises a medical robot (10) comprising an articulated arm (13), the robot reference (11) being positioned at a distal end of the articulated arm (13), said medical robot (10) further comprising articulation encoders of the articulated arm (13) making it possible to determine at any time the position of the robot reference (11) in a reference frame of the medical robot (10), said method (200) further comprising a step of determining the position of a medical instrument attached to the distal end of the articulated arm (13) of the medical robot (10) with respect to the anatomy of interest of the patient (20).