Monitoring equipment for medical intervention using navigation

Abstract

The present invention relates to an optical monitoring device (10) for monitoring the movement of a region of interest of a patient (50) during minimally invasive medical intervention. The optical monitoring device (10) includes a base layer (11) that serves as a sterile drape and includes an intervention region (12) and a marking region (13) that at least partially surrounds the intervention region (12). The marking region (13) includes, on the inner surface, an adhesive substance for attaching the monitoring device (10) to the skin of the patient (50), and on the outer surface (11b), at least three optical markers (14), or at least three mounting supports each intended to house an optical marker (14). The marking region (14) also includes an optical fiber sensor (15), which is firmly attached to the base layer (11) and has measurement points associated with each of the optical markers (14) or the mounting supports for attachment.

Description

Technical Field

[0001] Field of the Invention The devices and methods disclosed herein belong to the field of optical navigation for tracking the movement of a patient's target site of interest during minimally invasive medical interventions. More specifically, an optical monitoring device based on a patient's skin and an optical navigation method using such an optical monitoring device are also proposed.

Background Art

[0002] Prior Art In minimally invasive medical interventions, precise positioning or movement of a medical instrument (e.g., a needle, catheter, electrode, ultrasonic generator, drill, etc.) with respect to a patient's target site of interest (e.g., the liver, lung, kidney, bone, etc.) is required. A physician performing this type of intervention can receive assistance from a medical robot. In this case, the medical robot utilizes a navigation system to position, hold, and / or guide the medical instrument with respect to the target site of interest. The instrument is fixed, for example, to one end of a multi-joint arm of the robot. The navigation system enables the identification of the position of the instrument and the position of the target site of interest. Based on the information regarding the respective positions of the instrument and the target site of interest relative to each other, the robot can configure its multi-joint arm so that the instrument is optimally positioned with respect to the target site of interest.

[0003] In the case of an optical navigation system, the optical monitoring device is generally installed on the patient's skin near the target site of interest. This monitoring device generally includes at least three optical markers, enabling the navigation system to accurately identify the position of the monitoring device. The position of the target site of interest can thus be determined based on the position of the monitoring device and with the assistance of a medical image in which both the target site of interest and the monitoring device (or at least a part of the monitoring device) can be seen therein.

[0004] During the intervention, the site of interest can move, for example, due to the patient's respiratory movement. Therefore, with the assistance of a navigation system, it is necessary to be able to monitor the position of the site of interest over a period of time. However, the line of sight between the optical markers of the monitoring device and the optical sensors of the navigation system can be blocked by obstacles (e.g., by a physician, an instrument, or a multi-joint arm of a robot), which may interfere with the identification of the position of the monitoring device.

[0005] Various optical markers are sometimes individually attached to the patient's skin. Apart from this being a relatively time-consuming and complex process, the adhesion of the optical markers to the patient's skin is sometimes insufficient and may be peeled off by the physician's inadvertence during the intervention. In some cases, all of the optical markers are fixed to the same adhesive tape that is intended to be attached to the patient's skin so as to surround the intervention zone. In any case, the optical markers must not be covered by a sterile drape applied to the patient. Therefore, it is necessary to make one large opening or multiple openings at different locations in the sterile drape, which is undesirable because it is necessary to sterilize the patient's skin at the level of these opening zones.

[0006] U.S. Patent Application Publication No. 2020 / 0008897A1 describes a monitoring device including a base layer that serves as a sterile drape, a plurality of optical markers fixed to the outer surface of the base layer, and an adhesive substance on the inner surface for attaching the base layer to the patient's skin. During the intervention, an incision is made in the patient through the base layer of the monitoring device (in other words, since the entire surface of the base layer has adhesiveness, the base layer and the patient's skin must be incised simultaneously). However, this type of device is not suitable for percutaneous interventions. In fact, in the case of percutaneous interventions, it is a principle to reduce the patient's contamination risk by directly inserting a needle into the patient's skin without making an incision beforehand. This also often applies to this type of intervention for treating multiple lesions or treating a lesion using multiple needles via different paths. Therefore, simultaneous incision of the monitoring device and the patient cannot be performed with respect to this minimally invasive method.

Summary of the Invention

Problems to be Solved by the Invention

[0007] Description of the Invention The solution proposed in the present application aims to improve the drawbacks in the prior art, particularly some or all of those already disclosed.

Means for Solving the Problems

[0008] Therefore, and according to a first aspect, an optical monitoring device is proposed for monitoring the movement of a region of interest of a patient during minimally invasive medical intervention. The optical monitoring device includes a base layer that serves as a sterile drape and has an inner surface intended to face the patient's skin and an outer surface opposite the inner surface. The base layer includes an intervention region corresponding to a region intended to be cut out to expose the patient's skin in the opening or the zone where the intervention is to be performed. The base layer also includes a marking region that at least partially surrounds the intervention region. The marking region includes an adhesive substance on the inner surface for fixing the optical monitoring device to the patient's skin. The marking region includes at least three optical markers on the outer surface, or at least three fixed supports each intended to receive one optical marker. The marking region also includes an optical fiber sensor, and the optical fiber sensor is fixed to the base layer and includes at least one measurement point associated with each of the optical markers or the fixed supports.

[0009] The optical monitoring device is particularly easy to attach to the patient because all of the optical markers or all of the fixed supports for the optical markers are collectively fixed. To attach the optical monitoring device, an adhesive substance may be applied to the patient's skin.

[0010] The optical monitoring device hardly interferes with the intervention zone. By locally dispersing the optical markers to expand the configuration of the monitoring device, in fact, the doctor can access the intervention zone without any obstacles.

[0011] The configuration of the monitoring device can optimize its adhesion to the patient's skin, thereby limiting the risk that the optical markers will move unintentionally during the intervention. The adhesion area of the adhesive substance can actually be optimized because the position of the optical markers on the monitoring device is known empirically.

[0012] The monitoring device can also reduce the area of the patient's skin to be sterilized. In fact, the monitoring device incorporates both a sterile drape and an optical marker (or a fixed support for the optical marker), and the area to be sterilized corresponds only to the opening corresponding to the intervention area of the sterile drape.

[0013] The optical fiber sensor can acquire information regarding the in-space position of the optical markers relative to each other. Therefore, even if some of the optical markers are not visible to the positioning device (for example, when the line of sight between the positioning device and the optical markers is blocked by an obstacle), the position of the non-visible optical markers can still be estimated based on the position of at least one visible optical marker and the relative positions of the optical markers. The optical fiber sensor can in particular include an optical fiber provided with a Bragg diffraction grating.

[0014] In certain embodiments, the optical monitoring device may further have one or more of the following features, either individually or in any technically possible combination.

[0015] In certain embodiments, the base layer is a polyethylene film lined with a cellulose absorbent film.

[0016] In certain embodiments, the intervention area is pre-cut within the base layer.

[0017] In certain embodiments, the base layer includes a visual display defining a marking area.

[0018] In certain embodiments, the adhesive material takes the form of an adhesive tape that interconnects various points where the optical markers or the fixed supports are disposed. The adhesive tape enables a semi-rigid connection between the optical markers, thereby facilitating their attachment and optimizing their stability.

[0019] In certain embodiments, the adhesive tape is a polyethylene film coated with an acrylic adhesive or a rayon fabric covered with an acrylic adhesive.

[0020] In certain embodiments, the monitoring device further includes at least three radiation-opaque markers, each rigidly connected to a respective optical marker or a respective fixed support. The radiation-opaque markers serve to identify the position of the optical monitoring device in a medical image.

[0021] In certain embodiments, the optical markers are active, and each active optical marker is configured to emit infrared signals of different modulations.

[0022] In certain embodiments, the optical markers are passive, and the monitoring device includes at least four optical markers.

[0023] According to a second aspect, - any of the above-described embodiments of an optical monitoring device, wherein the optical monitoring device comprises optical markers, and - a measuring device configured to cooperate with an optical fiber sensor to determine the relative position of each of the optical markers within the reference frame of the measuring device, and - a positioning device configured to cooperate with the optical markers to determine the position of each of the optical markers within the reference frame of the positioning device, and an optical navigation system is proposed that includes the above.

[0024] In the present application, an optical marker is considered "active" when it is configured to directly emit an optical signal and the signal is not generated by any other element. On the other hand, an optical marker is considered "passive" when it is configured to reflect an optical signal generated by another element.

[0025] According to a third aspect, a navigation method using an optical navigation system as described above is proposed. The method includes - identifying, with the assistance of a positioning device, the position of at least one optical marker visible to the positioning device; - identifying the at least one visible optical marker from among all of the optical markers; - identifying, with the assistance of a measuring device, the relative positions of all of the optical markers with respect to each other; - identifying the position of at least one optical marker not visible to the positioning device based on the positions of the visible optical markers and the relative positions of the optical markers with respect to each other; - estimating the position of the optical monitoring device from the positions of at least three optical markers; and includes.

[0026] In a particular embodiment, the optical markers are active, each optical marker is configured to emit infrared signals with different modulations, and the at least one visible optical marker is identified by identifying the modulation of the infrared signals emitted by the optical markers.

[0027] In a particular embodiment, the optical markers are passive, the optical monitoring device includes at least four passive optical markers, the distances between any two of the optical markers taken two at a time all differ by at least one predetermined margin value, and the method includes - identifying, with the assistance of a positioning device, the positions of at least three optical markers visible to the positioning device; - identifying, from among all of the optical markers, the three optical markers based on the distances between two optical markers identified for at least two different pairs of optical markers formed from among the at least three visible optical markers; further comprising.

[0028] In a particular embodiment, the navigation method includes a preliminary step of generating, with the assistance of a positioning device and a measuring device, for each optical marker, a model representing a substantially periodic movement of the optical marker. The identification of the at least one visible optical marker is then performed by identifying the model corresponding to the movement of the visible optical marker.

[0029] Description of the Drawings The present invention will be better understood from the following description, which is given by way of non-limiting example, with reference to the following Figures 1 to 4.

Brief Description of the Drawings

[0030]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0031] In these figures, the same reference numerals between the drawings refer to the same or similar elements. For clarity, the elements shown are not necessarily to scale, unless otherwise specified.

[0032] Detailed Description of One Embodiment of the Invention Figures 1 and 2 schematically show an optical monitoring device 10 according to one exemplary embodiment of the present invention.

[0033] The optical monitoring device 10 is intended to be attached near a site of interest of a patient where a minimally invasive medical intervention must be performed on the patient's skin.

[0034] The site of interest corresponds to, for example, the liver, lungs, kidneys, bones, etc. The minimally invasive medical intervention is, for example, for performing a biopsy or resection of a lesion (e.g., cyst, tumor, etc.) in the site of interest. The lesion can be resected by various methods (high frequency, microwave, cryotherapy, laser, electroporation, focused ultrasound, etc.). Then, it is necessary to position or move a medical device (e.g., a needle, catheter, electrode, ultrasonic generator, drill, etc.) with high precision with respect to the site of interest of the patient. As will be described in detail later, the positioning device can be used to estimate the position of the optical monitoring device 10 in real time. The preoperative medical image representing both the site of interest of the patient and the optical monitoring device 10 can enable the position of the site of interest with respect to the optical monitoring device 10 to be specified. Then, by grasping the position of the optical monitoring device 10 in real time, it is possible to specify the position of the site of interest of the patient in real time. Then, the medical instrument can be guided in real time according to the estimated position of the site of interest of the patient. It should be noted that the position of the site of interest and the position of the monitoring device 10 change with time, particularly due to the patient's respiratory movement.

[0035] In the present application, the expression "position of the monitoring device 10" should be understood in a broad sense, that is, including both the position and orientation of the monitoring device 10 (the term "posture" may be used in the literature to represent a combination of the position and orientation of an object). The same applies to the expression "position of the medical instrument" which should be understood as the position and orientation of the medical instrument and the expression "position of the site of interest" which should be understood as the position and orientation of the site of interest.

[0036] As shown in FIGS. 1 and 2, the optical monitoring device 10 includes a base layer 11 that serves as a sterile drape. The base layer 11 has an inner surface 11a and an outer surface 11b. The inner surface 11a is shown in FIG. 2. The inner surface 11a will face the patient's skin. The outer surface 11b is shown in FIG. 1. The outer surface 11b is opposite to the inner surface 11a.

[0037] The base layer 11 corresponds to a sterile drape. The base layer 11 includes, for example, a polyethylene sheet lined with a cellulose absorbent film. Then, the inner surface 11a of the base layer 11 is formed of the cellulose absorbent film. In order to reduce the risk of infection and cross - contamination, the polyethylene film forming the outer surface 11b of the base layer is preferably impermeable to bacteria and liquids.

[0038] The base layer 11 includes an intervention area 12 corresponding to an area of the patient's skin that is intended to be exposed to the opening or the zone where the intervention is to be performed. In FIGS. 1 and 2, the intervention area 12 corresponds to the area within the smaller dashed - line rectangle.

[0039] In a particular embodiment, the intervention area 12 corresponds to a pre - cut zone in the base layer 11. Among the sterile drape, the portion forming the intervention area 12 can then be easily removed by a doctor after the optical monitoring device 10 is attached to the patient. Alternatively, the intervention area 12 can be cut by the doctor and may not be pre - cut. The size and shape of the intervention area 12 are adjusted to suit the planned medical intervention. The intervention area 12 can be positioned at the center of the base layer 11 or at other locations on the base layer 11.

[0040] The base layer 11 also includes a marking area 13 that surrounds at least a portion of the intervention area 12. In FIGS. 1 and 2, the marking area 13 corresponds to the area between two dashed rectangles. For example, as shown in FIGS. 1 and 2, the marking area 13 can take the form of a substantially rectangular strip around the intervention area. Nevertheless, the marking area 13 can also take any other form, such as a substantially circular strip, or an arcuate strip, or a C-shaped, U-shaped, or V-shaped strip that partially surrounds the intervention area 12.

[0041] As shown in FIG. 2, the marking area 13 includes, on the inner surface 11a, an adhesive substance 16 for fixing the optical monitoring device 10 to the patient's skin.

[0042] As shown in FIG. 1, the marking area 13 includes, on the outer surface 11b, at least three optical markers 14, or at least three fixing supports each intended to receive one optical marker 14.

[0043] The optical marker 14 corresponds to, for example, a reflective sphere visible to an infrared stereo camera (such as those in the Polaris® navigation solution sold by Northern Digital), or a black-and-white pattern visible to a stereo camera (such as those in the MicronTracker® navigation solution sold by ClaroNav). In these examples, the optical marker is a passive marker.

[0044] Alternatively, the optical marker can be an active marker configured to emit an infrared signal detectable by an infrared camera. The optical marker can include a retroreflective lens (such as the Radix® lens developed by Northern Digital).

[0045] When the optical markers 14 are active, it is advantageous for each optical marker 14 to be configured to emit infrared signals with different modulations. Therefore, it is possible to identify each optical marker 14 from among all of the optical markers 14 based on the infrared signals emitted by the optical marker 14.

[0046] It is advantageous to use small optical markers to limit the overall size of the optical monitoring device 10 and make it easier to access the intervention zone.

[0047] The optical markers 14 are either incorporated directly into the base layer 11 (these can be adhered to the base layer 11 with a thermal adhesive, for example), or are attached by the operator to the fixed support of the optical monitoring device 10.

[0048] The position of the optical monitoring device 10 is determined based on the positions of at least three optical markers 14. The optical monitoring device 10 may advantageously include four or more optical markers 14 (or four or more fixed supports for the optical markers 14). This can increase the chance that at least three optical markers 14 are visible at some point, even if some of the optical markers are hidden by obstacles.

[0049] The marking region 13 also includes an optical fiber sensor 15 fixed to the base layer 11. As will be described in more detail later, the optical fiber sensor 15 is intended to be connected to a measuring device to determine the spatial position of the optical markers 14 relative to each other. For this purpose, the optical fiber sensor 15 is characterized by at least one measurement point associated with each of the optical markers 14 or each of the fixed supports. The optical fiber sensor can be formed by a fiber incorporating a Bragg diffraction grating, such as a solution proposed by Sensuron® or The Shape Sensing Company®. The optical fiber sensor 15 can be positioned on either the inner surface 11a or the outer surface 11b of the base layer 11.

[0050] The Bragg diffraction grating is a resonant microstructure on the core of the optical fiber. This resonant structure functions as a selective mirror (a narrow-band filter around the wavelength specific to the Bragg diffraction grating) according to the wavelength. When light travels through the optical fiber, only a narrow portion centered on the wavelength of the Bragg diffraction grating in the spectrum of the light is reflected. The remaining portion of the light spectrum continues to travel along the optical fiber to the next Bragg diffraction grating. The wavelength of the Bragg diffraction grating is basically determined by the period of the microstructure and the refractive index of the core of the fiber. The fiber can include different Bragg diffraction gratings in series, and each Bragg diffraction grating is associated with a specific wavelength. The optoelectronic measuring device can measure the wavelength reflected by each Bragg diffraction grating. Each Bragg diffraction grating corresponds to a measurement point. When the optical fiber is deformed, the period of the microstructure changes, and as a result, the wavelength of the Bragg diffraction grating also changes. Therefore, by measuring the difference between the reference wavelength of the Bragg diffraction grating (the wavelength of the non-deformed Bragg diffraction grating) and the measured wavelength of the Bragg diffraction grating (the wavelength of the deformed Bragg diffraction grating), it is possible to identify the deformation applied to the optical fiber at the level of each Bragg diffraction grating. By measuring the various deformations applied at the levels of the respective different Bragg diffraction gratings, it becomes possible to identify their relative spatial positions.

[0051] Different technical elements are incorporated into the marking area 13. This is a technical zone that must not be degraded. In certain embodiments, the base layer 11 includes a visual display that defines the extent of the marking area 13. This can indicate to the physician the zone of the sterile drape that must not be cut.

[0052] The optical monitoring device 10 can be adhered to the patient's skin by the adhesive substance 16. This adhesive substance may or may not be dispersed substantially uniformly and continuously in the portion of the inner surface 11a corresponding to the marking area 13.

[0053] Considered here, in the example shown in FIG. 2, the adhesive material 16 takes the form of an adhesive tape that collectively connects various points where the optical markers 14 or the fixed support are disposed.

[0054] The adhesive tape is a polyethylene film coated with an acrylic adhesive or a rayon fabric covered with an acrylic adhesive. By using a rayon fabric, the absorbency of the base layer 11 in contact with the patient can be preserved.

[0055] The adhesive tape can be attached or adhered to the base layer 11. The adhesive tape can semi-rigidly connect the optical markers to each other, which facilitates the attachment and optimizes their stability. The tape form also makes it possible to reduce the overall size of the marking area 13.

[0056] As described above, the pre-operative medical image displays both the region of interest of the patient and the optical monitoring device 10, thereby enabling the position of the region of interest with respect to the optical monitoring device 10 to be specified.

[0057] This image can be, for example, a medical image obtained by sectional densitometry (or computed tomography (CT-scan)), by angiography, or by magnetic resonance imaging (MRI).

[0058] In certain embodiments, the optical monitoring device 10 includes at least three radiopaque markers, each rigidly fixed to a respective optical marker 14 or to a respective fixed support to assist in specifying the position of the optical monitoring device 10 in the medical image. These radiopaque markers can be, for example, ceramic beads or an adhesive containing radiopaque ink.

[0059] However, it should be noted that these radiopaque markers are not necessarily indispensable since, due to the nature of the materials used in the manufacture of some elements of the optical monitoring device 10 (in particular, the optical markers 14), these elements can sometimes be made visible in the medical image.

[0060] FIG. 3 illustrates a schematic diagram of one embodiment of an optical navigation system 20 according to the present invention.

[0061] The optical navigation system 20 includes an optical monitoring device 10 conforming to any of the previously described embodiments. The optical monitoring device 10 comprises an optical marker 14. In the example shown in Figure 3, the optical monitoring device 10 corresponds to that described with respect to Figures 1 and 2.

[0062] The optical navigation system 20 also includes a positioning device 40 configured to cooperate with the optical marker 14 to determine the location of the optical marker 14 within a reference frame of the positioning device 40 .

[0063] The positioning device 40 includes, for example, a stereoscopic video camera working in the infrared range or the visible light range. The stereoscopic video camera includes two optical sensors 41 configured to receive optical signals from the optical markers 14 and infer therefrom the position of the optical markers 14 (based on the time of arrival and / or the angle of each optical signal). These can be optical signals directly transmitted by the optical markers 14, if the optical markers 14 are active, or optical signals reflected by the optical markers 14, if the optical markers 14 are passive. If the optical markers 14 are active, a ToF (time of flight) or RGB-D (red-green-blue-depth) video camera can be used. As a non-limiting example, a stereoscopic infrared video camera is used in the Polaris® navigation solution proposed by Northern Digital.

[0064] The positioning device 40 may further comprise an auxiliary video camera 42 for continuously acquiring images of the intervention. The video camera 42 may in particular be integrated with a stereoscopic video camera system having the same viewing axis. The video camera 42 may be used, for example, to monitor the insertion of the medical instrument and to estimate the insertion depth of the medical instrument at a given point in time.

[0065] As considered here, in the example shown in FIG. 3, the patient 50 is positioned on the operating table 70 to receive minimally invasive medical intervention to the site of interest. The optical monitoring device 10 is positioned near the site of interest on the skin of the patient 50. The medical robot 60 is used to assist the physician during the intervention. The medical robot includes, for example, an articulated arm, and a medical instrument is fixed to its end.

[0066] The purpose of the positioning device 40 is to finally identify the position of the site of interest by identifying the position of the optical marker 14 in real time and inferring the position of the optical monitoring device 10 therefrom. Equivalently, the positioning device 40 may be configured to identify the position of the medical instrument with the assistance of another optical monitoring device directly positioned on the medical robot 60 or on the medical instrument. The position of the medical instrument can also be identified with the assistance of the video camera 42. Once the respective positions of the medical instrument and the site of interest relative to each other are known (e.g., in the reference frame of the positioning device 40), the articulated arm of the medical robot 60 can be configured to optimally position the medical instrument with respect to the site of interest.

[0067] The positioning device 40 includes, for example, a control unit, which includes one or more processors configured to identify the respective positions of the site of interest and the medical instrument relative to each other, and a communication module configured to transmit that information to the medical robot 60.

[0068] The optical navigation system 20 also includes a measuring device 30 configured to identify the relative position of each of the optical markers 14 within the reference frame of the measuring device 30 in cooperation with the optical fiber sensor 15. The optical fiber sensor 15 is connected to the measuring device 30, for example, when the optical monitoring device 10 is positioned on the patient 50.

[0069] The measuring device 30 and the optical fiber sensor 15 form devices that are redundant with respect to the positioning device 40 for identifying the position of the optical marker 14. This is particularly beneficial when one or more of the optical markers 14 are not visible to the positioning device 40. This is the case, for example, when the line of sight between the optical sensor 41 and the optical marker 14 is blocked by an obstacle (e.g., a doctor, an operator, a multi-joint arm of a medical robot 60, a medical instrument, etc.). If an optical marker 14 is not visible, the positioning device 40 cannot identify its position. However, if at least one optical marker 14 is visible and can be identified from among all of the optical markers, and the relative positions of each of the optical markers 14 are known, then it is possible to infer the positions of all of the optical markers 14 therefrom.

[0070] Therefore, the information supplied by the measuring device 30 can be added to the information obtained by the positioning device 40. As a result, all of the optical markers 14 can be used permanently, and the accuracy of the positioning device 40 can be optimized.

[0071] FIG. 4 schematically shows the main steps of an optical navigation method 100 using the navigation system 20 described above with respect to FIG. 3.

[0072] The method 100 includes a step 101 of identifying the position of at least one optical marker 14 visible to the positioning device 40 (which means that the line of sight between the optical marker 14 and the positioning device 40 is not blocked by an obstacle) with the assistance of the positioning device 40.

[0073] The method 100 then includes a step 102 of identifying the visible optical marker 14 from among all of the optical markers 14. As will be described in detail later, there are various methods for identifying an optical marker 14 from among all of the optical markers 14.

[0074] The method 100 includes a step 103 of identifying the relative positions of all of the optical markers 14 with the assistance of the measuring device 30.

[0075] Method 100 includes step 104 of identifying the position of at least one optical marker 14 that is not visible to the positioning device 40 from the positions of the visible optical markers 14 relative to each other and the positions of the optical markers 14.

[0076] Finally, method 100 includes step 105 of estimating the position of the optical monitoring device 10 from the positions of at least three optical markers 14.

[0077] There can be various ways to identify a certain optical marker 14 among all of the optical markers 14.

[0078] In a first example, when the optical marker 14 is active, each optical marker 14 can be configured to emit infrared signals with different modulations. The identification 102 of the visible optical marker 14 can then be performed by identifying the modulation of the infrared signals emitted by the optical marker 14.

[0079] In a second example, in the case of passive optical markers 14, it can be assumed that at least four optical markers 14 are placed on the optical monitoring device 10, particularly in such a way that a clear identification of the optical markers becomes possible as soon as at least three optical markers are visible. The optical markers 14 can be positioned, for example, such that the distances separating two optical markers 14 when taken out two by two are all different by at least a predetermined margin value (e.g., for any of the optical markers under consideration, the distance between two optical markers must differ by at least 5 mm from the distance between any other two optical markers). When at least three visible optical markers 14 are identified by the positioning device 40, it is possible to clearly identify, from among all of the optical markers 14, the three optical markers 14 based on the distances between the two optical markers identified for at least two different pairs of optical markers 14 formed from among the at least three visible optical markers 14.

[0080] In a third example, method 100 may include a preliminary step of generating, with the aid of positioning device 40 and measuring device 30, a model representing a substantially periodic motion of the optical marker 14. In this case, the visible optical marker 14 can be identified by identifying a model corresponding to the observed motion of the visible optical marker 14.

[0081] In other words, in this third example, the identification 102 of the visible optical marker 14 is performed by using together the motion information supplied by the measuring device and that supplied by the optical positioning device 40. The identification 102 of the visible optical marker 14 is specified by analyzing each motion characteristic of the optical marker 14, matching the information supplied by the measuring device 30 and that supplied by the optical positioning device 40, and by using these motion characteristics for the clear identification of the visible optical marker. Assuming a substantially periodic motion, as in the case of the motion generated by the breathing of patient 50, this matching method makes it possible to reconstruct the complete position information of the optical monitoring device 10 even if only one of the optical markers 14 is visible. The motion characteristics of the optical marker 14 may correspond, for example, to the amplitude of the motion of the optical marker 14 and / or the frequency of the motion of the optical marker 14 in the main direction followed by the optical marker 14. These characteristics form a model representing the motion of the optical marker 14 during one period.

[0082] The optical navigation method 100 uses together the accurate information regarding the absolute spatial position supplied by the positioning device 40 on the one hand and the relative position information supplied by the measuring device 30 on the other hand, thereby greatly limiting the problem of loss of line of sight while at the same time enabling the maintenance of high accuracy.

[0083] In the example shown in FIG. 3, the optical navigation system 20 can be used as follows.

[0084] Patient 50 is either stopped from breathing or the physician tells patient 50 to hold their breath, and the position of the optical marker 14 is recorded (when the patient is stopped from breathing, the position of the optical marker 14 is fixed).

[0085] The pre-operative medical image of patient 50 is acquired when patient 50 is not breathing. The pre-operative medical image enables viewing both the region of interest of patient 50 and the optical monitoring device 10. This makes it possible to identify the position of the region of interest with respect to the optical monitoring device 10 at the moment during the breathing cycle when the patient is not breathing. Knowing the position of the optical monitoring device 10 at this moment makes it possible to identify in real time the position of the region of interest of the patient at that moment. Next, the patient resumes normal breathing.

[0086] The pre-operative medical image is used to plan a surgical intervention. For example, it is possible to identify the trajectory that a medical instrument must follow during its insertion. This trajectory is defined, for example, based on the entry point at the level of the patient's skin and the target point at the level of the lesion to be treated.

[0087] In order to insert a medical needle into the patient, the patient is again stopped from breathing at the moment when the position of the optical monitoring device 10 is substantially the same as the position during the acquisition of the pre-operative medical image (i.e., is substantially within the same phase of the breathing cycle). This ensures that the region of interest is in substantially the same position as that shown in the pre-operative medical image used to plan the intervention.

[0088] During these operations, the physician may block the target line of one or more of the optical markers 14 of the optical monitoring device 10. As soon as at least one distinguishable optical marker 14 out of all of the optical markers 14 is visible to the positioning device 40, the redundancy introduced by the optical fiber sensor 15 and the measuring device 30 makes it possible to identify the position of the optical monitoring device 10 with high precision. According to the optical navigation system 20, it is also possible to detect unexpected movements of the patient.

[0089] In some cases, it is necessary to insert multiple medical instruments (or insert the same medical instrument multiple times) to reach different target points at the lesion level. Due to the configuration of the monitoring device 10, this is possible without any special restrictions regarding the entry position.

[0090] The above description clearly shows that the various devices and methods described achieve the goals for which they are set by their various features and advantages. In particular, the optical monitoring device 10 is easy to attach, hardly enters the intervention zone, can optimize the adhesion to the skin of the patient 50, can limit the area to be sterilized on the skin of the patient 50, and can ensure very precise navigation even if some of the optical markers 14 are not visible to the positioning device 40.

[0091] It should be noted that the embodiments considered so far are described by non-limiting examples, and thus other variations can be envisaged.

[0092] In particular, the selection of the specific dimensions, shape, or composition of the base layer 11 of the monitoring device 10 is merely one form of the present invention. The same applies to the selection of the specific shape of the marking area 13 or the position of the marking area 13 on the base layer 11. This also applies to the selection of the specific dimensions, shape, or position of the intervention area 12 on the base layer 11.

[0093] As described above, the optical marker 14 of the monitoring device 10 may be an active marker or a passive marker.

[0094] Regarding the optical navigation method 100, various processes for identifying at least one visible optical marker 14 from all of the optical markers 14 of the monitoring device 10 have been presented. However, other processes can also be used in the said method 100, and the selection of a specific process is merely one variation of the present invention.

Claims

1. An optical monitoring device (10) for monitoring the movement of a region of interest of a patient (50) during minimally invasive medical intervention, comprising a base layer (11) serving as a sterile drape and having an inner surface (11a) intended to face the skin of the patient (50) and an outer surface (11b) opposite the inner surface, the base layer (11) comprising an intervention region (12) corresponding to a region of the skin of the patient (50) that is intended to be cut out to expose the opening or the zone where the intervention is to be performed, and a marking region (13) at least partially surrounding the intervention region (12), the marking region (13) being - on the inner surface (11a), an adhesive substance (16) for fixing the optical monitoring device (10) to the skin of the patient (50), and - on the outer surface (11b), at least three optical markers (14), or at least three fixing supports each intended to receive one optical marker (14), and - an optical fiber sensor (15) fixed to the base layer (11) and including at least one measurement point associated with each of the optical markers (14) or the fixing supports, the optical fiber sensor (15) including an optical fiber incorporating a Bragg diffraction grating, An optical monitoring device (10) comprising.

2. The optical monitoring device (10) according to claim 1, wherein the base layer (11) is a polyethylene film lined with a cellulose absorbent film.

3. The optical monitoring device (10) according to any one of claims 1 or 2, wherein the intervention region (12) is pre-cut within the base layer.

4. The optical monitoring device (10) according to any one of claims 1 to 3, wherein the base layer (11) includes a visual display defining the marking region (13).

5. The optical monitoring device (10) according to any one of claims 1 to 4, wherein the adhesive substance (16) is in the form of an adhesive tape connecting the various points where the optical markers (14) or the fixing supports are arranged to each other.

6. The optical monitoring device (10) according to claim 5, wherein the adhesive tape is a polyethylene film coated with an acrylic adhesive or a rayon fabric covered with an acrylic adhesive.

7. The optical monitoring device (10) according to any one of claims 1 to 6, comprising at least three radiation-opaque markers each rigidly connected to a respective optical marker (14) or to a respective fixed support.

8. The optical marker (14) is active, and each active optical marker (14) is configured to emit infrared signals of different modulations, the optical monitoring device (10) according to any one of claims 1 to 7.

9. The optical marker (14) is passive, and there are at least four optical markers (14), the optical monitoring device (10) according to any one of claims 1 to 7.

10. - An optical monitoring device (10) according to any one of claims 1 to 7, comprising an optical marker (14), the optical monitoring device (10); - A measuring device (30) configured to cooperate with the optical fiber sensor (15) to identify the relative position of each of the optical markers (14) within the reference frame of the measuring device (30), the measuring device (30); - A positioning device (40) configured to cooperate with the optical marker (14) to identify the position of each of the optical markers (14) within the reference frame of the positioning device (40), the positioning device (40); An optical navigation system (20) comprising.

11. A navigation method (100) using the optical navigation system (20) according to claim 10, comprising: - Identifying (101) the position of at least one optical marker (14) visible to the positioning device (40) with the assistance of the positioning device (40); - Identifying (102) the at least one visible optical marker (14) from among all of the optical markers (14); - Identifying (103) the relative positions of all of the optical markers (14) with the assistance of the measuring device (30); - Identifying (104) the position of at least one optical marker (14) not visible to the positioning device (40) based on the position of the visible optical marker (14) and the relative positions of the optical markers (14); - Estimating (105) the position of the optical monitoring device (10) from the positions of at least three optical markers (14); An optical navigation method (100) comprising.

12. The optical marker (14) is active, each optical marker (14) is configured to emit infrared signals with different modulations, and the at least one visible optical marker (14) is identified (102) by identifying the modulation of the infrared signal emitted by the optical marker (14). The optical navigation method (100) according to claim 11.

13. The optical navigation method (100) according to claim 11, wherein the optical marker (14) is passive, the optical monitoring device (10) includes at least four passive optical markers (14), and the distances between two optical markers (14) when taken out two by two are all different by at least one predetermined margin value. The method includes: - Identifying (101) the positions of at least three optical markers (14) visible to the positioning device (40) with the assistance of the positioning device (40); - Identifying (102) the three optical markers (14) from all of the optical markers (14) based on the distances between two optical markers (14) identified for at least two different pairs of optical markers (14) formed from the at least three visible optical markers (14); An optical navigation method (100) including the above.

14. Including a preliminary step of generating, with the assistance of the positioning device (40) and the measuring device (30), for each optical marker (14), a model representing a substantially periodic motion of the optical marker (14), and the identifying (102) of the at least one visible optical marker (14) is performed by identifying the model corresponding to the motion of the visible optical marker (14). The optical navigation method (100) according to claim 11.

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