Monitoring device for navigating and guiding medical intervention

Abstract

The present application relates to an optical monitoring device (10) for monitoring movement of a target anatomical portion of a patient (50) during a minimally invasive medical intervention. The optical monitoring device (10) comprises a base layer (11), which serves as a sterile drape and comprises an intervening region (12) and a marking region (13) at least partially surrounding the intervening region (12). The marking region (13) comprises, on an inner surface, an adhesive material for attaching the monitoring device (10) to the skin of a patient (50), and, on an outer surface (11b), at least three optical markers (14) or at least three fixing brackets, each for accommodating one optical marker (14). The marking area (13) further comprises a fiber optic sensor (15) firmly fixed to the base layer (11) and having a measurement point associated with each optical marking (14) or attachment bracket.

Description

Technical Field

[0001] The device and method disclosed in the present application belong to the field of optical navigation, and are used to track the movement of a patient's target anatomical structure during minimally invasive medical intervention. More specifically, an optical monitoring device based on the patient's skin and an optical navigation method using the optical monitoring device are proposed. Background Art

[0002] Minimally invasive medical interventions require very precise positioning or movement of a medical device (e.g., needle, catheter, electrode, ultrasound generator, drill, etc.) relative to a patient's target anatomical structure (e.g., liver, lung, kidney, bone, etc.). The physician performing such an intervention may be assisted by a medical robot. In this case, the medical robot positions, fixes and / or guides the medical device relative to the target anatomical structure by means of a navigation system. For example, the device is fixed at one end of an articulated arm of the robot. The navigation system is able to determine the position of the device and the position of the target anatomical structure. Information about the respective positions of the device and the target anatomical structure relative to each other enables the robot to configure its articulated arm so that the device is in the optimal position relative to the target anatomical structure.

[0003] In the case of an optical navigation system, an optical monitoring device is typically placed on the patient's skin near the target anatomical structure. The monitoring device typically includes at least three optical markers to enable the navigation system to accurately determine the location of the monitoring device. The location of the target anatomical structure can then be determined based on the location of the monitoring device and with the aid of a medical image in which both the target anatomical structure and the monitoring device (or at least a portion of the monitoring device) are visible.

[0004] During an intervention, the target anatomical structure may move, for example due to respiratory movements of the patient. Therefore, it is necessary to be able to monitor the position of the target anatomical structure over time with the help of a navigation system. However, the line of sight between the optical markers of the monitoring device and the optical sensors of the navigation system may be interrupted by obstacles (e.g. by the physician, the instrument or the articulated arm of the robot), which may hinder the determination of the position of the monitoring device.

[0005] Various optical markers are sometimes adhered individually to the patient's skin. Besides being a relatively lengthy and complex process, the adhesion of the optical markers to the patient's skin is sometimes insufficient and can fall off due to the physician's negligence during the intervention. In some cases, the optical markers are all fixed to the same tape, which is intended to be adhered to the patient's skin to surround the intervention area. In all cases, the optical markers must not be obscured by the sterile drape covering the patient. Therefore, it is necessary to cut a large opening or multiple openings in different locations of the sterile drape, which is not ideal because the patient's skin needs to be sterilized in the area of ​​these openings.

[0006] Patent application US2020 / 0008897 A1 describes a monitoring device comprising a base layer used as a sterile drape, a plurality of optical markers fixed to the outer surface of the base layer, and an adhesive material located on the inner surface of the base layer for adhering the base layer to the patient's skin. During the intervention, an incision is made on the patient through the base layer of the monitoring device (in other words, the base layer and the patient's skin must be incised at the same time, because all surfaces of the base layer are adhesive). However, this type of device is not suitable for percutaneous intervention. In fact, for percutaneous intervention, the principle is to insert the needle directly into the patient's skin without prior incision to reduce the risk of infection to the patient. In this type of intervention, it is also often necessary to treat multiple lesions, or to treat one lesion through different paths with the help of multiple needles. Therefore, in the context of this minimally invasive practice, it is not possible to make an incision on the monitoring device and the patient at the same time. Summary of the invention

[0007] The solution proposed in this application aims to remedy some or all of the disadvantages of the prior art, in particular those disclosed above.

[0008] To this end, according to a first aspect, an optical monitoring device is proposed for monitoring the movement of a target anatomical structure of a patient during a minimally invasive medical intervention. The optical monitoring device includes a base layer used as a sterile cover cloth, the base layer having an inner surface facing the patient's skin and an outer surface opposite to the inner surface. The base layer includes an intervention area corresponding to an opening or intended to be cut to expose an area on the patient's skin where intervention is to be performed. The base layer also includes a marking area that at least partially surrounds the intervention area. The marking area includes an adhesive material on the inner surface for fixing the optical monitoring device to the patient's skin. The marking area includes at least three optical markers or at least three fixing brackets on the outer surface, each fixing bracket is used to accommodate an optical marker. The marking area also includes a fiber optic sensor fixed to the base layer, which includes at least one measurement point associated with each optical marker or fixing bracket.

[0009] The optical monitoring device is particularly easy to mount on the patient, since all optical markers or all fixing supports for the optical markers are fixed together. It is sufficient to apply an adhesive material to the patient's skin to mount the optical monitoring device.

[0010] The optical monitoring device is minimally invasive to the interventional area. The extended configuration of the monitoring device and the local distribution of optical markers allow the physician virtually unhindered access to the interventional area.

[0011] The configuration of the monitoring device allows it to be optimally adhered to the patient's skin, thus limiting the risk of involuntary movement of the optical markers during the interventional procedure. In fact, by knowing in advance the position of the optical markers on the monitoring device, the bonding area of ​​the adhesive material can be optimized.

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

[0013] The fiber optic sensor is able to obtain information about the positions of the optical markers relative to each other in space. Thus, even if some of the optical markers are not visible to the positioning device (for example, if the line of sight between the positioning device and the optical markers is interrupted by an obstacle), the positions of the invisible optical markers can still be estimated based on the position of at least one visible optical marker and the positions of the optical markers relative to each other. The fiber optic sensor may in particular possibly include an optical fiber incorporating a Bragg grating.

[0014] In a specific embodiment, the optical monitoring device may also have one or more of the following features, alone or in all technically possible combinations.

[0015] In a specific embodiment, the substrate layer is a polyethylene film lined with a cellulosic absorbent film.

[0016] In specific embodiments, the intervening region is pre-cut in the base layer.

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

[0018] In a specific embodiment, the adhesive material is in the form of a tape that connects together the various points where the optical markers or the fixing brackets are located. The tape enables a semi-rigid connection between the optical markers, which facilitates their mounting and optimizes their stability.

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

[0020] In a specific embodiment, the monitoring device further comprises at least three radiopaque markers, each of which is rigidly connected to a corresponding optical marker or a corresponding fixed support. The radiopaque markers are intended to identify the position of the optical monitoring device in the medical image.

[0021] In a specific embodiment, the optical markers are active, and each active optical marker is configured to emit a differently modulated infrared signal.

[0022] In a specific embodiment, the optical markers are passive and the monitoring device comprises at least four optical markers.

[0023] According to a second aspect, an optical navigation system is provided, comprising:

[0024] - any one of the above embodiments of the optical monitoring device, wherein the optical monitoring device is provided with an optical marker,

[0025] - a measuring device configured to cooperate with the fiber optic sensor to determine the relative position of each optical marker in a reference frame of the measuring device,

[0026] - a positioning device configured to cooperate with the optical markers to determine the position of each optical marker in a reference frame of the positioning device.

[0027] In this application, an optical marker is considered "active" when it is configured to directly emit a light signal that is not generated by another element. On the other hand, an optical marker is considered "passive" when it is configured to reflect a light signal generated by another element.

[0028] According to a third aspect, a navigation method using the optical navigation system as described above is proposed. The method comprises the following steps:

[0029] - determining with the aid of a locating device the position of at least one optical marking visible to the locating device,

[0030] - identifying said at least one visible optical marking from among all optical markings,

[0031] - determining the positions of all optical markings relative to one another by means of a measuring device,

[0032] - determining the position of at least one optical marker which is not visible to the positioning device based on the positions of the visible optical markers and the positions of the optical markers relative to each other,

[0033] - estimating the position of the optical monitoring device based on the positions of at least three optical markers.

[0034] In a specific embodiment, the optical markers are active, each optical marker is configured to emit a differently modulated infrared signal, and the at least one visible optical marker is identified by identifying the modulation of the infrared signal emitted by the optical marker.

[0035] In a specific embodiment, the optical marker is passive, the optical marker device comprises at least four passive optical markers, the distance between two optical markers differs by at least one predetermined margin value, and the method further comprises the following steps:

[0036] - determining the positions of at least three optical markings visible to the positioning device by means of the positioning device,

[0037] - identifying said three optical markings from all optical markings based on the distances between two optical markings determined for at least two different pairs of optical markings formed from said at least three visible optical markings.

[0038] In a specific embodiment, the navigation method comprises a preliminary step of generating a model for each optical marker by means of a positioning device and a measuring device, the model representing the substantially periodic movement of the optical marker. Then, the at least one visible optical marker is identified by identifying the model corresponding to the movement of the visible optical marker. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] After reading the following description given by way of non-limiting example and referring to Figures 1 to 4 After that, you will better understand this application. Figures 1 to 4 express:

[0040] [ Figure 1 ] A schematic diagram of the outer surface of an exemplary embodiment of an optical monitoring device according to the present application,

[0041] [ Figure 2 ] Figure 1 A schematic diagram of the inner surface of the optical monitoring device shown,

[0042] [ Figure 3 ]use Figure 1 and Figure 2 A schematic diagram of an exemplary embodiment of an optical navigation system of a monitoring device shown in,

[0043] [ Figure 4 ]use Figure 3 Schematic diagram of the main steps of the optical navigation method of the navigation system shown.

[0044] In these figures, the same reference numerals from one figure to another represent the same or similar elements. For clarity, unless otherwise specified, the elements represented do not necessarily have the same scale. DETAILED DESCRIPTION

[0045] Figure 1 and Figure 2 An exemplary embodiment of an optical monitoring device 10 according to the present application is schematically represented.

[0046] The optical monitoring device 10 is intended to be mounted on the skin of a patient proximate to a target anatomical structure of the patient where minimally invasive medical intervention is necessary.

[0047] The target anatomical structure corresponds to, for example, the liver, lungs, kidneys, bones, etc. Minimally invasive medical interventions are intended to, for example, biopsy or ablate lesions (e.g., cysts, tumors, etc.) in the target anatomical structure. Lesions can be ablated by various methods (radiofrequency, microwave, cryotherapy, laser, electroporation, focused ultrasound, etc.). It is then necessary to very accurately position or move a medical device (e.g., a needle, catheter, electrode, ultrasonic generator, drill, etc.) relative to the patient's target anatomical structure. As described in detail below, a positioning device can be used to estimate the position of the optical monitoring device 10 in real time. A pre-interventional medical image representing the patient's target anatomical structure and the optical monitoring device 10 can determine the position of the target anatomical structure relative to the optical monitoring device 10. Real-time information of the position of the optical monitoring device 10 can then determine the position of the patient's target anatomical structure in real time. The medical device can then be guided in real time based on the estimated position of the patient's target anatomical structure. It should be noted that the position of the target anatomical structure and the position of the monitoring device 10 can change over time, particularly due to the patient's respiratory movements.

[0048] In this application, the expression "position of the monitoring device 10" must be understood in a broad sense, that is, it includes both the position of the monitoring device 10 and its orientation (the term "posture" is sometimes used in the literature to refer to the combination of the position and orientation of an object). The same applies to the expression "position of the medical device", which must be understood as "position and orientation of the medical device", and the expression "position of the target anatomical structure", which must be understood as "position and orientation of the target anatomical structure".

[0049] like Figure 1 and Figure 2 As shown, the optical monitoring device 10 includes a base layer 11 used as a sterile cover. The base layer 11 has an inner surface 11a and an outer surface 11b. The inner surface 11a is as shown in FIG. Figure 2 The inner surface 11a is intended to face the patient's skin. The outer surface 11b is as shown. Figure 1 The outer surface 11b is opposite to the inner surface 11a.

[0050] The base layer 11 corresponds to a sterile drape. The base layer 11 comprises, for example, a polyethylene sheet lined with a cellulose absorbent film. Then, the inner surface 11a of the base layer 11 is formed by 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.

[0051] The base layer 11 comprises an intervention area 12, which corresponds to an opening or a predetermined cutting area so as to expose the area on the patient's skin where the intervention is to be performed. Figure 1 and Figure 2 In FIG. 1 , the intervening region 12 corresponds to the region within the smaller dashed rectangle.

[0052] In a specific embodiment, the interventional region 12 corresponds to a pre-cut area in the base layer 11. After the optical monitoring device 10 is installed on the patient, the physician can easily remove the portion of the sterile drape that forms the interventional region 12. Alternatively, the interventional region 12 can be cut by the physician, rather than pre-cut. The size and shape of the interventional region 12 are suitable to accommodate the envisioned medical intervention. The interventional region 12 can be located in the center of the base layer 11 or elsewhere on the base layer 11.

[0053] The base layer 11 further comprises a marking area 13 at least partially surrounding the intervention area 12. Figure 1 and Figure 2 In FIG. 1 , the marked area 13 corresponds to the area between the two dashed rectangles. Figure 1 and Figure 2 As shown, the marking area 13 can take the form of a generally rectangular strip around the intervention area. However, the marking area 13 can also take other forms, such as a generally circular strip, an arc strip, or a C-shaped, U-shaped or V-shaped strip partially around the intervention area 12.

[0054] like Figure 2 As shown, the marking area 13 includes an adhesive material 16 on the inner surface 11a for securing the optical monitoring device 10 to the patient's skin.

[0055] like Figure 1 As shown, the marking area 13 includes at least three optical markings 14 or at least three fixing brackets on the outer surface 11 b , each of which is used to accommodate the optical marking 14 .

[0056] The optical marker 14 corresponds, for example, to a reflective sphere visible to an infrared stereo camera (e.g., in the case of Northern Digital GmbH). navigation solutions) or black and white patterns visible to stereo cameras (e.g., in ClaroNav’s navigation solutions). In these examples, the optical markers are passive markers.

[0057] Alternatively, the optical marker may be an active marker configured to emit an infrared signal detectable by an infrared camera. The optical marker may include a retroreflective lens (such as the one developed by Northern Digital, Inc. lens).

[0058] When the optical markers 14 are active, it is advantageous that each optical marker 14 is configured to emit a differently modulated infrared signal. Thus, each optical marker 14 can be identified from all optical markers 14 based on the infrared signal emitted by the optical marker 14.

[0059] Advantageously, the use of small optical markers helps limit the overall size of the optical monitoring device 10 and facilitates access to the interventional area.

[0060] The optical markers 14 are either directly integrated into the substrate layer 11 (for example, they may be hot-glued to the substrate layer 11 ) or mounted on a fixed support of the optical monitoring device 10 by an operator.

[0061] 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 more than three optical markers 14 (or more than three fixing brackets for optical markers 14). This increases the chance that at least three optical markers 14 are visible at a given time, even if some optical markers are obscured by obstacles.

[0062] The marking area 13 also comprises an optical fiber sensor 15 fixed to the substrate layer 11. As described in detail below, 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. To this end, the optical fiber sensor 15 has at least one measuring point associated with each optical marker 14 or each fixed support. The optical fiber sensor can be formed by an optical fiber incorporating a Bragg grating, such as the one from Sensuron. or The Shape Sensing Proposed Solution The optical fiber sensor 15 can be placed equally well on the inner surface 11a or the outer surface 11b of the substrate layer 11 .

[0063] A Bragg grating is a resonant microstructure on the core of an optical fiber. This resonant structure acts as a wavelength-selective mirror (a narrowband filter around the specific wavelength of the Bragg grating): when light passes through the fiber, only a narrow part of the spectrum centered around the Bragg grating wavelength is reflected. The rest of the spectrum of light continues along the fiber to the next Bragg grating. The wavelength of the Bragg grating is essentially defined by the period of the microstructure and the refractive index of the fiber core. The fiber can contain different Bragg gratings in series, each associated with a specific wavelength. An optoelectronic measurement device is able to measure the wavelength reflected by each Bragg grating. Each Bragg grating corresponds to a measurement point. A deformation of the fiber leads to a change in the period of the microstructure and thus also to a change in the wavelength of the Bragg grating. Therefore, by measuring the difference between the reference wavelength of the Bragg grating (the wavelength of the Bragg grating when it is not deformed) and the measured wavelength of the Bragg grating (the wavelength of the Bragg grating after deformation), the fiber deformation applied at each Bragg grating can be determined. The measurement of the various deformations applied at the level of the individual Bragg gratings allows their positions relative to each other in space to be determined.

[0064] The marking area 13 integrates different technical elements. This is a technical area that cannot be degraded. In a specific embodiment, the base layer 11 includes a visual indication that defines the marking area 13. This makes it possible to indicate to the doctor the area on the sterile drape that must not be cut.

[0065] The adhesive material 16 enables the optical monitoring device 10 to be adhered to the patient's skin. The adhesive material may be more or less uniformly continuous or not distributed at all over the portion of the inner surface 11a corresponding to the marking area 13.

[0066] In the example considered here, if Figure 2 As shown, the adhesive material 16 is in the form of a tape that connects together the various points where the optical marker 14 or the fixing bracket is located.

[0067] The tape is, for example, a polyethylene film coated with an acrylic adhesive or a rayon fabric covered with an acrylic adhesive. The use of rayon fabric enables the absorption properties of the substrate 11 in contact with the patient to be maintained.

[0068] The tape can be sewn or glued to the base layer 11. The tape enables a semi-rigid connection between the optical markers, which facilitates their installation and optimizes their stability. The tape form can also minimize the overall size of the marking area 13.

[0069] As described above, the pre-interventional medical image may simultaneously represent the target anatomical structure of the patient and the optical monitoring device 10 to determine the position of the target anatomical structure relative to the optical monitoring device.

[0070] The image may be a medical image obtained, for example, by tomographic densitometry (or computed tomography (CT scan)), angiography or magnetic resonance imaging (MRI).

[0071] In a specific embodiment, the optical monitoring device 10 includes at least three radiopaque markers, each of which is rigidly fixed to a corresponding optical marker 14 or a corresponding fixed support to help determine the position of the optical monitoring device 10 in the medical image. These radiopaque markers can be, for example, ceramic beads or adhesives including radiopaque inks.

[0072] However, it should be noted that these radiopaque markers are not necessarily essential, as the nature of the materials used to make some elements of the optical monitoring device 10 (particularly the optical markers 14) is such that these elements may sometimes be visible in medical images.

[0073] Figure 3 One embodiment of an optical navigation system 20 according to the present application is schematically represented.

[0074] The optical navigation system 20 comprises an optical monitoring device 10 according to any of the above embodiments. The optical monitoring device 10 is equipped with an optical marker 14. Figure 3 In the example shown, the optical monitoring device 10 corresponds to the above reference Figure 1 and Figure 2 The optical monitoring device.

[0075] The optical navigation system 20 further includes a positioning device 40 configured to cooperate with the optical marker 14 to determine a position of the optical marker 14 in a reference frame of the positioning device 40 .

[0076] The positioning device 40 comprises a stereo camera operating, for example, in the infrared range or in the visible light range. The stereo camera comprises two optical sensors 41, which are configured to receive light signals from the optical marker 14 and to infer therefrom the position of the optical marker 14 (based on the arrival time and / or angle of each light signal). These can be light signals directly transmitted by the optical marker 14 when the optical marker 14 is active, or light signals reflected by it when the optical marker 14 is passive. When the optical marker 14 is active, a ToF (time of flight) or RGB-D (red, green, blue, depth) camera can be used. As a non-limiting example, the method proposed by Northern Digital Co., Ltd. The navigation solution uses a stereo infrared camera.

[0077] The positioning device 40 may also include an auxiliary camera 42 for continuously acquiring images of the intervention. The camera 42 may be particularly integrated into a stereo camera system to have the same visual axis field. The camera 42 may be used to monitor the insertion of the medical device and estimate the insertion depth of the medical device at a given time.

[0078] In the example considered here, if Figure 3 As shown, a patient 50 is placed on an intervention table 70 for minimally invasive medical intervention on a target anatomical structure. An optical monitoring device 10 is placed on the skin of the patient 50 near the target anatomical structure. A medical robot 60 is used to assist a physician during the intervention. The medical robot includes, for example, an articulated arm with a medical instrument fixed at its end.

[0079] The purpose of the positioning device 40 is to determine in real time the position of the optical marker 14, thereby inferring the position of the optical monitoring device 10, so as to ultimately determine the position of the target anatomical structure. The positioning device 40 can also be configured to determine the position of the medical device with the aid of another optical monitoring device located on the medical robot 60 or directly on the medical device. The position of the medical device can also be determined with the aid of the camera 42. When the respective positions of the medical device and the target anatomical structure 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 device relative to the target anatomy.

[0080] The positioning device 40 comprises, for example, a control unit including one or more processors configured to determine the respective positions of the target anatomical structure and the medical instrument relative to each other and a communication module configured to transmit this information to the medical robot 60 .

[0081] The optical navigation system 20 also includes a measuring device 30 configured to cooperate with the fiber optic sensor 15 to determine the relative position of each optical marker 14 in the reference frame of the measuring device 30. For example, once the optical monitoring device 10 is placed on the patient 50, the fiber optic sensor 15 is connected to the measuring device 30.

[0082] The measuring device 30 and the fiber optic sensor 15 form a redundant device with respect to the positioning device 40 for determining the position of the optical marker 14. This is particularly useful when one or more 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 interrupted by an obstacle (e.g. a doctor, an operator, an articulated arm of the medical robot 60, a medical instrument, etc.). When an optical marker 14 is not visible, the positioning device 40 cannot determine its position. However, if at least one optical marker 14 is visible and can be identified from all optical markers, and if the position of each optical marker 14 relative to each other is known, the position of all optical markers 14 can be inferred therefrom.

[0083] The information provided by the measuring device 30 can thus be added to the information obtained by the positioning device 40. This allows the accuracy of the positioning device 40 to be optimized, since all optical markings 14 can be used permanently.

[0084] Figure 4 Schematically depicts the use of Figure 3 The navigation system 20 performs the main steps of the optical navigation method 100 .

[0085] The method 100 comprises a step 101 of determining, by means of the locating device 40 , a position of at least one optical marking 14 which is visible to the locating device 40 (this means that the line of sight between the optical marking 14 and the locating device 40 is not interrupted by obstacles).

[0086] The method 100 then includes a step 102 of identifying the visible optical marker 14 from among all optical markers 14. As described in detail below, there are various methods for identifying the optical marker 14 from among all optical markers 14.

[0087] The method 100 comprises a step 103 of determining the positions of all optical markings 14 relative to one another by means of the measuring device 30 .

[0088] The method 100 comprises a step 104 of determining the position of at least one optical marker 14 that is not visible to the positioning device 40 based on the positions of the visible optical markers 14 and the positions of the optical markers 14 relative to each other.

[0089] Finally, the method 100 comprises a step 105 of estimating the position of the optical monitoring device 10 based on the positions of at least three optical markings 14 .

[0090] There are various methods for identifying one optical marker 14 from among all the optical markers 14 .

[0091] In a first example, if the optical markers 14 are active, each optical marker 14 can be configured to emit differently modulated infrared signals. Then, by identifying the modulation of the infrared signals emitted by the optical markers 14, identification 102 of the visible optical markers 14 can be achieved.

[0092] In a second example, for passive optical markers 14, it is conceivable to place at least four optical markers 14 on the optical monitoring device 10 in a specific manner, so that these optical markers can be clearly identified once at least three optical markers are visible. The optical markers 14 can be positioned, for example, so that the distance between two optical markers 14 differs by at least a predetermined margin value (for example, no matter what the optical marker in question is, the distance between two optical markers must differ by at least 5 mm relative to the distance between two other optical markers). When the positioning device 40 has determined the positions of at least three visible optical markers 14, the three optical markers 14 can be clearly identified based on the distances between at least two pairs of different optical markers 14 of the at least three visible optical markers 14.

[0093] In a third example, the method 100 may include a preliminary step of generating, for each optical marker 14, a model representing the substantially periodic motion of the optical marker 14 by means of the positioning device 40 and the measuring device 30. In this case, the visible optical marker 14 may be identified by identifying a model corresponding to the observed motion of the visible optical marker 14.

[0094] In other words, in this third example, the identification 102 of the visible optical markers 14 is achieved by jointly using the motion information provided by the measuring device and the optical positioning device 40. The identification 102 of the visible optical markers 14 is determined by analyzing the motion characteristics of each optical marker 14, matching the information provided by the measuring device 30 and the optical positioning device 40, and using these motion characteristics to unambiguously identify the visible optical marker. Assuming a substantially periodic motion, like the motion produced by the breathing of the patient 50, this matching method can reconstruct the complete position information of the optical monitoring device 10 even if only one optical marker 14 is visible. The motion characteristics of the optical marker 14 can 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 its main direction of motion. These features form a model representing the motion of the optical marker 14 in one cycle.

[0095] The optical navigation method 100 is able to significantly limit the problems of loss of sight while maintaining high precision, thanks to the combined use of precise information on the absolute position in space provided by the positioning device 40 on the one hand and the relative position information provided by the measuring device 30 on the other hand.

[0096] exist Figure 3 In the example shown, the optical navigation system 20 may be used in the following manner.

[0097] The patient 50 stops breathing, or the doctor asks the patient 50 to hold his breath, and the position of the optical marker 14 is recorded (when the patient stops breathing, the position of the optical marker 14 is fixed).

[0098] A pre-interventional medical image of the patient 50 is acquired while the patient 50 is not breathing. The pre-interventional medical image enables observation of the target anatomical structure of the patient 50 and the optical monitoring device 10. This enables determination of the position of the target anatomical structure relative to the optical monitoring device 10 at a moment in the respiratory cycle when the patient is not breathing. Knowing the position of the optical monitoring device 10 at this time allows determination of the position of the target anatomical structure of the patient in real time. The patient then begins to breathe normally again.

[0099] Pre-interventional medical images are used to plan surgical interventions. For example, it is possible to determine the trajectory that a medical device must follow during insertion. For example, the trajectory is defined based on an entry point at the level of the patient's skin and a target point at the level of the lesion to be treated.

[0100] For inserting the medical needle, the patient is again stopped breathing at a time when the optical monitoring device 10 is in substantially the same position as when the pre-interventional medical image was acquired (i.e., substantially at the same phase of the respiratory cycle). This ensures that the target anatomical structure is in substantially the same position as represented in the pre-interventional medical image used for the planned intervention.

[0101] During these operations, the physician may obstruct the target line of one or more optical markers 14 of the optical monitoring device 10. Due to the redundancy introduced by the fiber optic sensor 15 and the measuring device 30, once the positioning device 40 can see at least one identifiable optical marker 14 among all the optical markers 14, the position of the optical monitoring device 10 can be determined with good accuracy. The optical navigation system 20 can also detect unexpected movement of the patient.

[0102] In some cases, it is necessary to insert multiple medical devices (or insert the same medical device multiple times) to reach different target points at the lesion level. The configuration of the monitoring device 10 makes this possible without any particular restrictions on the entry point.

[0103] The above description clearly shows that, thanks to their various features and advantages, the various devices and methods described achieve the objectives set for them. In particular, the optical monitoring device 10 is easy to install, minimally invasive to the intervention area, allows optimized adhesion to the skin of the patient 50, allows limiting the disinfection area on the skin of the patient 50, and ensures very precise navigation even if some optical markers 14 are not visible to the positioning device 40.

[0104] It should be noted that the embodiments considered above are described by way of non-limiting examples, and other variants can therefore be envisaged.

[0105] In particular, the selection of a specific size, shape or composition of the substrate 11 of the monitoring device 10 is merely a variation of the present application. The same applies to the selection of a specific shape of the marking region 13 or a specific position of the marking region 13 on the substrate 11. It also applies to the selection of a specific size, shape or position of the intervention region 12 on the substrate 11.

[0106] As mentioned above, the optical marker 14 of the monitoring device 10 can also be an active marker or a passive marker.

[0107] For the optical navigation method 100, various procedures for identifying at least one visible optical marker 14 from all optical markers 14 of the monitoring device 10 have been described. However, other procedures may be used in the method 100, and the selection of a particular procedure is merely a variation of the present application.

Claims

1. An optical monitoring device (10) for monitoring the movement of a target anatomical structure of a patient (50) during a minimally invasive medical intervention, the optical monitoring device comprising a base layer (11), the base layer (11) being used as a sterile drape and having an inner surface (11a) for facing the skin of the patient (50) and an outer surface (11b) opposite to the inner surface (11a), the base layer (11) comprising an intervention area (12) and a marking area (13), the intervention area (12) corresponding to an opening or intended to be cut to expose an area on the skin of the patient (50) where intervention is to be performed, the marking area (13) at least partially surrounding the intervention area (12), the marking area (13) comprising: - an adhesive material (16) on the inner surface (11a) for fixing the optical monitoring device (10) to the skin of a patient (50), - at least three optical markers (14) or at least three fixing brackets on the outer surface (11b), each fixing bracket being used to accommodate an optical marker (14), - an optical fiber sensor (15) fixed to said substrate layer (11) and comprising at least one measuring point associated with each of said optical markers (14) or said fixing support, said optical fiber sensor (15) comprising an optical fiber incorporating a Bragg grating.

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

3. The optical monitoring device (10) according to claim 1 or 2, wherein the intervention area (12) is pre-cut in the substrate layer.

4. The optical monitoring device (10) according to any one of claims 1 to 3, wherein the substrate layer (11) comprises a visual indication defining the marking area (13).

5. The optical monitoring device (10) according to any one of claims 1 to 4, wherein the adhesive material (16) is in the form of an adhesive tape, connecting together various points where the optical marker (14) or the fixing bracket is located.

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 radiopaque markers, each marker being rigidly connected to a corresponding optical marker (14) or a corresponding fixing support.

8. The optical monitoring device (10) according to any one of claims 1 to 7, wherein the optical markers (14) are active, each active optical marker (14) being configured to emit a differently modulated infrared signal.

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

10. An optical navigation system (20), comprising: - The optical monitoring device (10) according to any one of claims 1 to 7, provided with an optical marker (14), a measuring device (30) configured to cooperate with the optical fiber sensor (15) to determine the relative position of each of the optical markers (14) in a reference frame of the measuring device (30), - a positioning device (40) configured to cooperate with said optical markers (14) to determine the position of each of said optical markers (14) in a reference frame of said positioning device (40).

11. An optical navigation method (100) using the optical navigation system (20) of claim 10, the method (100) comprising: - determining (101) the position of at least one optical marking (14) visible to the positioning device (40) by means of the positioning device (40), - identifying (102) the at least one visible optical marking (14) from among all optical markings (14), - determining (103) the positions of all optical markings (14) relative to one another by means of the measuring device (30), - determining (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 markers (14) and the positions of the optical markers (14) relative to each other, - estimating (105) the position of the optical monitoring device (10) based on the positions of at least three optical markers (14).

12. The optical navigation method (100) according to claim 11, wherein the optical markers (14) are active, each optical marker (14) is configured to emit differently modulated infrared signals, 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).

13. The optical navigation method (100) according to claim 11, wherein the optical marker (14) is passive, the optical marker device (10) comprises at least four passive optical markers (14), the distance between two optical markers (14) differs by at least one predetermined margin value, and the method (100) comprises: - determining (101) the positions of at least three optical markings (14) visible to the positioning device (40) by means of the positioning device (40), - identifying (102) the three optical markers from among all the optical markers (14) based on the distances between two optical markers (14) determined for at least two pairs of different optical markers (14) formed from the at least three visible optical markers (14).

14. The optical navigation method (100) according to claim 11, comprising a preliminary step of generating a model for each optical marker (14) by means of the positioning device (40) and the measuring device (30), the model representing the basic periodic movement of the optical marker (14), wherein the at least one visible optical marker is identified (102) by identifying the model corresponding to the movement of the visible optical marker (14).

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