Hybrid simulator for neurosurgery procedures combining virtual reality and anatomical models

Abstract

The present invention discloses a hybrid simulator that uses physical and virtual models of a patient undergoing simulated surgery to train people in neurosurgical procedures. It combines physical and virtual components into a scaled, ergonomic workstation that mimics the actual physical environment of a patient realistically positioned on an OR table and reproduces surgical procedures in virtual environments and scenarios enhanced with visual and physical realism. Also, it comprises various physical and virtual elements combined in different configurations to provide hybrid simulation scenarios of other surgical procedures in neurosurgery in a single multipurpose workstation. Additionally, it makes use of spatial and virtual augmentation techniques that combine a physical model of the patient, visual input with virtual elements, such as three-dimensional anatomies and organ simulation of the patient to virtual models of surgical tools, robotic devices with assembled replicas or real surgical instruments to perform virtual surgical procedures while providing the tactile sensation of manipulating tissue and tracking sensors to spatially integrate all elements within a unified frame of reference therein.

Description

HYBRID SIMULATOR FOR NEUROSURGERY PROCEDURES COMBINING VIRTUAL REALITY AND ANATOMICAL MODELS TECHNICAL FIELD The present invention relates to the field of virtual reality simulators combined with realistic mannequins, to recreate realistic surgical scenarios of invasive neurosurgical procedures including interventions of aneurysms, tumors, nerves, spine and ventricles, for the purpose of medical training and skills enhancement. STATE OF THE ART In modern medicine, training methods are changing due to ethical and legal considerations related to patient safety, restrictions on working with human cadavers, limitations on surgical practice time, the risks associated with inexperienced personnel, and the costs associated with operating room use. These factors have compelled medical residency programs to innovate and find new ways to teach and shorten learning curves. New immersive technologies such as virtual reality (VR) and augmented reality (AR), and their combinations as mixed reality (MR), are enabling surgical skills training through simulated environments, giving trainees an inside view of the patient without the need for risky invasive procedures.VR simulation has focused on simulating complex surgical tasks in graphical scenarios that have demonstrated the visualization of three-dimensional anatomies simulating soft and rigid tissues. These tissues are manipulated using teleoperated virtual instruments to reproduce surgical interventions involving tissue deformation, resection, dissection, cutting, and suturing, among other procedures. Neurosurgery and neurology treatments require special skills and abilities, involving subtle tactile gestures, as well as accurate spatial perception combined with adequate knowledge of the anatomical structures of the head, in order to perform basic and complex surgical gestures and procedures. Neurosurgery simulators exist, such as the NeuroTouch system, the NeuroVR system, and the ImmersiveTouch system. A limitation of current neurosurgery systems is that they are designed for specific, unique clinical cases, limiting training possibilities for different types of interventions and scenarios. This is because they require the use of more than one simulator per clinical case, increasing costs and the physical space needed to house multiple simulators. Current simulators are designed to train users in single stages of surgical intervention but do not include scenarios for most of the stages involved in actual surgeries.For example, some simulate vascular interventions for aneurysm repair, but they do not include essential aspects of the microsurgical process, such as patient head positioning, microscope manipulation, complete soft tissue interactions of the brain, craniotomy of the skull bone, or tumor removal. Others include endoscopic cortical tumor resection, but not combined with vascular interventions. A significant limitation of current virtual reality neurosurgery simulators is their lack of ergonomic physical configurations that would allow clinical staff to practice the full phases of surgical procedures in realistic, full-scale scenarios where surgeons, anesthesiologists, nurses, and surgical assistants work as a team. Current simulators include simulation scenarios for training advanced, later phases for residents and senior surgeons, but are not designed for novice residents in the early stages of their training. Furthermore, current simulators do not model the correct physical positioning and securing of the patient.This is a fundamental skill to develop, as it will impact the correct identification, location, and access to anatomical pathology within the surgical site using surgical instruments (a tumor, aneurysm, or other critical anatomical structures located deep within the surgical field and difficult to access). Another limitation of current simulators is the lack of manual palpation of physical anatomical landmarks to identify the correct insertion point and orientation of a needle or catheter during virtual reality (VR) surgery simulation. Furthermore, the absence of physical elements prevents the use of visual features that can enhance training, such as augmented reality (AR). There is a need for new methods and technologies to provide better surgical simulation systems for neurosurgical procedure training. There is also a need to improve existing VR surgical simulation scenarios to include more realistic phenomena and other phases of interventions than current systems. DESCRIPTION OF THE FIGURES Figure 1 shows a view of a simulator setup for vascular microsurgery simulation that includes a patient model, haptic devices, a Mayfield-type stand, a surgical microscope-type instrument, a surgical-type pedal, virtual reality, and biomechanical simulations of aneurysm clipping. Figure 2 shows a view of a patient model that includes anatomical replicas of tissues in soft and rigid materials, as well as neck and back joints. It is equipped with electronic components to detect contact points with a surgical tool. Figure 3 shows a view of the Mayfield-type clamp-shaped patient support that includes joints for positioning the patient head model and electronic instrumentation with position sensors to provide feedback on the posture of the mechanism. Figure 4 shows a view of the surgical microscope instrument that provides VR / AR visualization of the neurosurgical intervention and includes a stereoscopic viewer to simulate the microscope view and two handheld controllers for scene parameters. Figure 5 shows a configuration of the devices that provides tactile feedback of tissues. They have mechanical tool adapters for mounting surgical instruments and communicate their position to the VR / AR simulation units. Figure 6 shows a view of the surgical tools optionally with mechanical adapters for mounting on haptic devices or with tracking markers for locating them with the motion tracking system. Figure 7 shows the craniotome-type instrument mounted on a haptic device and provides vibrotactile sensations during virtual skull drilling. Figure 8 shows an AR setup with the tracking elements of the surgical tools, such as a stereovision camera and an optical tracker. Figure 9 shows a diagram of the complete system architecture and the interconnection between the different elements. Figure 10 shows the computer simulation cycle involving biomechanical simulation of tissues and interactions with surgical instruments. DETAILED DESCRIPTION In at least one configuration, the Hybrid Simulator for Invasive Neurosurgical Procedures 2000 includes a patient head model 0100, consisting of a physical representation of the head 0110, which includes realistic anatomical replicas of the skull 0111, maxilla 0112, nasal cavities 0113, eye sockets 0114, along with all the details of the bony structures of the skull. The structures may be fabricated from rigid materials such as plastic, polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), nylon, or other suitable materials that are processed by stereolithography, 3D printing, molding and sculpting, or other suitable manufacturing techniques. In at least one configuration, the patient head model 0100 includes soft tissue reproductions of body parts 0115 of the face, head, and neck, and other structures such as the eyes 0116, ears 0117, nose and nostrils 0118, mouth and tongue 0119, among others. The soft tissue models are made of hypoallergenic, hygienic, and easily washable materials such as rubber, silicone, or other suitable materials. In at least one configuration, the patient head model 0100 includes an articulated neck mechanism 0120 and back 0130, allowing it to be mounted on the hybrid simulator's workstation 2000, replicating a real head positioned on a surgical table as in actual neurosurgery. The patient head model 0100 provides ways to ergonomically adjust the correct position and orientation of the patient head model 0110 before the simulated surgical procedure. The articulated neck 0120 consists of a series mechanism with a ball joint 0121 for rotating the head 0110, with rigid links 0122 joined by at least two articulated joints 0123 for tilting the head 0110, and a joint 0124 with at least two degrees of freedom (DoF) in a link 0125 at the base of the neck 0120 simulating the patient's back 0130, through a mechanical rail 0131, a rail 0136, attached to the link 0135, to mechanically restrict neck tilts within the anatomical range of movement of the human neck. The sliding mechanism on the mechanical rail 0131 allows adjustment of the axial depth or horizontal movement of the entire head 0110 and neck 0120 of the patient head model 0100, resulting in an anatomically constrained articulated mechanism with at least three degrees of freedom. The articulated backrest 0130 consists of two support plates 0132, 0133 joined by connecting means 0134 and at least one mechanically constrained joint 0135 with at least one degree of freedom to simulate the angular elevation of the backrest 0130 by means of a hand crank. The backrest 0130 is fixed to the hybrid simulator 2000 workstation via the lower plate 0133. In one embodiment of the invention, the hybrid simulator 2000 includes an electronic contact detection unit 0150 for determining the correct identification of a series of anatomical landmarks 0142, as well as with instrumented surgical tools 0600 and an electronic control unit with a microcontroller (for example, Arduino board, Programmable Integrated Circuit PIC, or other similar microcontroller) with wired or wireless communication with the virtual reality and augmented reality (VR / AR) simulation unit 1300 and the human tissue biomechanical simulation unit 1400 to send data on the positions and orientations of the surgical instruments or tools and map virtual surgical instruments within the scenarios of the VR / AR simulation units. The electronic contact detection unit 0150 may comprise electronic circuits 0141 with electronic sensors located at said anatomical landmarks 0142 within the patient head model 0100. Said surgical tools 0600 have complementary electronic circuits that transmit confirmation signals to the sensors located at the anatomical landmarks 0142 of the patient model 0100. The electronic contact detection unit 0150 may comprise means for emitting visual and / or audible alarms that are activated by the signals emitted when a contact is made or proximal contact is made at any of the anatomical landmarks 0142 of interest. In at least one configuration, the hybrid simulator 2000 has recording means 0160 which features an algorithm that counts contacts and attempts made near anatomical reference target points 0142 and provides reports or analyses on the number of contacts, location, frequency of correct and incorrect contacts, among other related useful information. In at least one configuration, the hybrid simulator 2000 includes a patient head model attachment bracket 0200, which may consist of a Mayfield-type bracket. The patient head model fixing bracket 0200 comprises a mechanism with at least eleven links 0201-0211 articulated by at least three 1-DoF rotational joints 0220-0222, one 2-DoF translational and rotational joint 0223, and one 1-DoF translational joint 0224. The patient head model fixing bracket 0200 features means for fixing the patient head model 0110 in the correct posture, closely resembling that used in actual surgery, via a clamp 0230 and a tensioning mechanism 0231. The instrument 0200 is mounted to the workstation via links 0201 and 0202. The instrument 0200 is made of a rigid material, such as plastic, PLA, nylon, ABS, or other suitable material, or manufactured using another suitable technique.In at least one configuration, the joints of the patient model 0200 fixing bracket are equipped with at least four motion sensors 0240-0243 that measure the angular positions of each joint link and transmit them to the VR / RA 1300 simulation unit. These motion sensors 0240-0243 provide placement data by means of communication, which may be wired or wireless, such as Bluetooth, TCP-IP or UDP, to a patient model 0200 positioning unit for comparison by means of an algorithm with the correct, ideal or suggested position of the patient model 0200 and provide feedback information to the user on the correct or incorrect placement of the patient model 0200 by means of an audible or visual signal.The 02400243 motion sensors are implemented as inertial motion units (IMUs, or other suitable sensors) communicating with the 1300 VR / RA simulation units and 1400 human tissue biomechanics units. In at least one configuration, the hybrid simulator 2000 comprises a display media or unit that includes a surgical microscope-type instrument 0300, which has a microscope-type head 0310 mounted on the workstation 2200 via a multi-degree-of-freedom articulated passive arm 0301, a stereoscopic viewer 0311 providing immersive stereographic display of graphical information in various VR, AR, or MRI modalities such as models and scenes of simulated neurosurgical interventions generated by the VR / AR simulation units 1300 and biomechanical simulation of human tissues, 1400. This information includes patient anatomies, surgical instruments or virtual tools 1600, and other useful visual information. The microscope-type head 0310 simulates the head of an actual physical surgical microscope, such as the Cari Zeiss Rentero microscope, or any similar one, and comprises a custom bracket 0302 that holds said stereoscopic viewer 0311, such as the Oculus Rift, the HTC Vive, or another suitable three-dimensional display device, including a mobile device, which simulates microscope lenses 0312 and 0313. The stereoscopic viewer 0311 is connected to the bracket 0302 via at least one rotary joint 0351 of at least one DoF. The microscope head bracket 0302 can have one or more handheld controllers 0320-0330, each with at least three buttons 0321-0323, 0331-0333 for adjusting the viewpoint's position and direction, turning visual information on / off, turning lights on / off, and controlling the light intensity and focus of the virtual reality or augmented reality simulated microscopic scene. The two handheld controllers 0320, 0330 consist of handheld-type video game controllers, or a similar solution, with appropriate buttons and wired or wireless communication. Each handheld controller 0320, 0330 can be attached to the microscope head 0310 via two rigid links 0340, 0341 connected to bracket 0302. In at least one configuration, the microscope-type head 0310 is mounted on the hybrid simulator 2000 workstation by means of an articulated passive arm mechanism 0301 with several rotational degrees of freedom, as described below. The articulated passive arm 0301 is connected to the hybrid simulator 2000 workstation structure via a mechanism with at least two rotational degrees of freedom and consists of at least two serial links joined by joints of at least one degree of freedom. The microscope-type head 0310 is attached from the support 0302 to the end of the articulated passive arm 0301 by means of a rotary joint 0352 of at least one degree of freedom. In this way, the surgical microscope-type instrument 0300 allows the microscopic viewpoint to be moved, positioned, and directed as in a real surgical microscope. The instrument head 0310 microscope type, the instrument's articulated passive arm 0301 and its components, such as the rotational elements, are constructed of rigid material such as aluminum, carbon fiber, rigid plastic or 3D printed in nylon or PLA material, or using another suitable manufacturing technique. Similar to the Mayfield 0200 type support, the 0300 microscope type instrument and its components, as well as the 0301 arm, can be instrumented with motion sensors that indicate to a positioning unit the correct, ideal or suggested position of the microscope that triggers visual / auditory cues to the operator. In at least one configuration, the hybrid simulator 2000 includes data display devices 0400, such as computer monitors, LCD screens, mobile devices, or other suitable devices. At least one graphic display device 0401 provides the graphical user interface (GUI) 0402 and the display of images and graphics 0403. This display is attached to a passive arm 0410 with at least 2 degrees of freedom (DoF), formed by at least two linkages 0411-0412 and three joints of at least 1 DoF each 0413-0415, and mounted to the workstation 2000 by another linkage 0410. In this way, the operator can manually position the display 0401 in an ergonomic position similar to that used in actual endoscopic neurosurgery, for example. Additional passive arms can be configured in at least one way to mount data input / output devices such as mobile devices, mice, and alphanumeric keyboards.Data output devices can also display image visualization and graphics 0403 with anatomical information such as medical magnetic resonance imaging (MRI), computed tomography (CT), ultrasound or other suitable biomedical imaging modality, in addition to three-dimensional models processed by the VR / AR simulation units 1300 and human tissue biomechanics 1400. The hybrid simulator 2000 includes robotic technology devices to provide kinesthetic force feedback 0500 through at least one or two haptic devices 0501, 0502, such as the Touch or Touch X Haptic device or other available devices. With these devices, the Hybrid Simulator 2000 can provide the user with the tactile sensation of manipulating real soft and rigid biological tissues during VR / AR 1300 surgery simulation. The haptic devices 0501, 0502 provide a means of interacting with the surgical tools 0600 mounted on their end effector, to simulate the virtual surgical tools 1600 in the VR / AR 1300 simulation unit and in the human tissue biomechanical simulation unit 1400.In at least one configuration, one or both haptic devices 0501,0502 provide the position and orientation of the instrument in correspondence with the location of at least a part of the mounted surgical tool 0600, which is then mapped to the positions and orientations of the virtual surgical instruments 1600 within the VR / AR simulation unit 1300 and in the human tissue biomechanical simulation unit 1400. As a result of interaction with the virtual anatomies 1100, the hybrid simulator 2000 provides visual feedback of the movements of the virtual surgical tools 1600 in sync with respect to the movements of the surgical tools 0600 mounted on the end effectors 0503,0504 of the haptic devices 0501,0502.The tactile sensations 1407 provided include the sensation of elasticity, stiffness, dynamic and static friction, plasticity, roughness, shape, or other haptic characteristics of the virtual anatomies 1100 and virtual surgical tools 1600. The force feedback 0500 includes other haptic signals or guidance mechanisms to increase user dexterity or facilitate learning and practice of manual tasks with the virtual tools 1600. Depending on the configuration and the specific neurosurgery being simulated, the haptic devices 0501, 0502 can be mounted on the Hybrid Simulator 2000 workstation structure in different locations on a plate that can have a circular internal shape 0510 around the patient model 0100. To this end, one or two mechanical platforms 0521, 0522 are included to support the haptic devices 0501, 0502. The mechanical platforms 0521, 0522 are height-adjustable with millimeter precision to ensure that the neurosurgeon's work area is fully covered. Together with the patient model 0100 and the Mayfield-type support 0200, the user can define ergonomic positions for performing a simulated procedure. The plate 0510 may consist of two or more separable semicircular pieces 0511,0512. In one configuration, it consists of two pieces, each mounted on two structures 2100, 2200 of the hybrid simulator workstation 2000, each as a mobile cart joined by any suitable means, for example, an articulated hinge 2300. A first structure 2100 can house the patient model 0100, the Mayfield-type patient stand 0200, the surgical-type instrument 0300, the data display device 0400, at least one of the haptic devices 0501, 0502, a motion-tracking device 0900, and a video camera 0910. A second structure 2200, which can be of the mobile type for ease of including different devices according to the desired configuration, can house at least one of the haptic devices 0501, 0502.The second structure 2200 can be removed or rotated with respect to the fixed structure 2100 in different configurations, to allow the operator to stand parallel to the patient model 0100 in a sagittal or frontal plane, as a patient would be positioned in the actual operating room, depending on the clinical case, for example, for vascular microsurgery for aneurysm repair, transsphenoidal endoscopic tumor removal, or others. In at least one configuration of the hybrid simulator 2200, the haptic devices 0501, 0502 include at least one mechanical tool adapter 0700 for attaching a surgical instrument 0600 to each of its end effectors 0503, 0504. The surgical instruments 0600 may include needles, catheters, clip applicators, aspirators, bipolar coagulators, micro-dissectors, retractors, and other surgical instruments commonly used in neurosurgery. Additionally, it may mount an endoscope-type instrument 0620 used in endoscopic procedures, such as tumor resection or neuroendoscopic biopsy interventions. The mechanical tool adapter 0700 consists of a rigid mechanism made of solid parts manufactured from aluminum, plastic, nylon, or other rigid material, using 3D printing, molding, or another suitable manufacturing method. A cylindrical part 0710 of the tool adapter 0700 fits into the end effector 0503 or 0504 of a haptic device 0501 or 0502. This part is coupled by a sliding rail 0711 to a second part 0712, the function of which is to support two bars 0713, 0714 with removable nut heads 0715, 0716 at the end of each bar 0713, 0714. The sliding rail 0711 is designed to manually hold and separate the two parts 0710 and 0712 by fitting them perfectly together, allowing sliding in the tangential direction and immobilization in the normal direction, and adapting to the end effectors 0503,504 of the haptic devices 0501,0502 by means of a circular guide 0717 at the lower end of part 0712.The diameter of the nut heads 0716,0717 can be of different sizes in order to serve as guides for fixing the shaft 0610 of various surgical instruments 0600 or the endoscope-type instrument 0620. In at least one configuration, the Hybrid Simulator 2000 has a craniotome-type instrument 0800 mounted on at least one of the end effectors 0503, 0504 of the haptic devices 0501, 0502. The instrument 0800 provides haptic feedback in the form of vibrations during the drilling of the skull of the virtual patient model 1100, as perceived during actual craniotomies. In at least one configuration, the Hybrid Simulator 2000 integrates a simulated VR / AR craniotomy intervention with the anatomies of the virtual patient 1100. While the user interacts with the craniotome-type instrument 0800, the VR / AR simulation unit 1300 replicates the drilling of the bone tissue and the removal of the skull fragment in the virtual patient model 1100, and then exposes the internal soft brain tissues in the human tissue biomechanical simulation unit 1400. The vibrotactile feedback provided by the craniotome-type instrument 0800 replicates the vibrations of drilling real bone tissue samples with an actual craniotome. The craniotome-type instrument 0800 is attached to a haptic device 0501, 0502 by means of a ring-shaped piece 0801. The sensation of bone structure rigidity is provided by the kinesthetic force feedback 1407 provided by the haptic device 0501 or 0502, which houses the craniotome-type instrument 0800, during bone penetration in the head of the physical model 0100 and the virtual model 1100 of the patient during drilling. For vibrotactile feedback, a series of miniaturized vibratory motors 0810 are mounted inside a handle-shaped clamping piece 0802 of the craniotome-type instrument 0800. The vibratory motors 0810 may be in the form of eccentric mass vibratory motors or other feasible small vibratory actuators.The operator ergonomically holds the craniotome-type instrument 0800 with his thumb and index finger supported on the supports 0803,0804 of the handle 0802, respectively. The vibration frequency of the 0810 vibratory motors can be precisely calibrated using reference vibration signals acquired with a digital signal acquisition system by an operator performing an actual craniotomy with a real craniotome at different positions and angles on a biological sample of bone tissue. For this purpose, the vibration signals can be measured using pressure sensors, accelerometers, or other suitable sensors. The craniotome-type instrument 0800 is controlled by an electronic control unit 0850, which communicates electronic signals and commands from the instrument 0800 to a signal processing unit or computer 1000 that runs the VR / AR simulation 1300, and vice versa. The electronic control unit 0850, which communicates with the processing unit or computer 1000 that houses the VR / AR simulation 1300 and human tissue biomechanics 1400 units via a communication connection 0805 (a serial port cable or Bluetooth wireless connection, among others), is responsible for activating the vibratory motors by the operator. The electronic control unit 0850 consists of electronic elements such as printed circuit boards, at least one commercial microcontroller (such as, but not limited to, an Arduino board, a programmable integrated circuit PIC, or another similar commercial microcontroller), and other components.The 0850 unit can be powered by a wired connection to the serial port or other communication port, a lithium-ion battery pack for wireless communication, or by a connection to the electrical power line. The craniotome-type instrument 0800 is constructed of rigid material such as rigid plastic or 3D printed with materials such as nylon, PLA, or ABS, or using another suitable manufacturing technique. In at least one configuration, the hybrid simulator 2000 includes a surgical instrument activator 0650, such as a surgical-type foot pedal, or other suitable devices, instrumented with electronic buttons and electrical signals to trigger the activation of the craniotome-type instrument 0800, or other surgical instruments 0600, for tissue resection, blood coagulation, and other manipulations of the virtual tissues of the virtual patient model 1100. In at least one configuration, the Hybrid Simulator 2000 includes an endoscope-type instrument 0620, which enables the execution of simulated neuroendoscopic interventions on the patient model 0100. For example, in one configuration, transsphenoidal tumor resection is simulated by introducing a surgical tool 0600 and the endoscope-type instrument 0620, mounted on haptic devices 0501 and 0502 using mechanical tool adapters 0700, through the nostrils of the patient model 0100. This simultaneously simulates the viewpoint of the endoscopic camera and displays the virtual endonasal cavity within the VR / AR simulation 1300. In another configuration, the position and orientation of the endoscope-type instrument 0620, and consequently its viewpoint of the endoscope lens, can be determined and communicated by the haptic devices 0501 and 0502, or by a motion-tracking device. 0900. In at least one configuration, the hybrid simulator 2000 includes a motion-tracking device 0900, such as optical tracking, magnetic tracking, industrial motion unit tracking, or other suitable technology, to detect and communicate in real time the location and spatial orientation of the surgical tools 0600, the patient model 0100, and the global reference frame 0901, fixed to the cart 2100 via a rigid frame 2400 positioned above the cart 2100. Depending on the motion-tracking device 0900, communication with the processing unit or computer 1000, which may house the VR / AR simulation units 1300 and the human tissue biomechanical simulation units 1400, can be carried out via wired or wireless means, such as Bluetooth, TCP / IP, UPD, or other suitable communication protocol. For hybrid simulator 2000 configurations using the optical tracker 0900, the tracker 0900 locates the elements involved in the actual physical scenario in real time. To do this, the tracker 0900 positions the elements as movable rigid physical objects by attaching rigid structures 0901-0903 (tracking frames typically designed in a cross shape) with visual markers 0904 mounted on their structure in different configurations. These markers consist of small, highly reflective spheres. Detecting the visual markers 0904, and knowing the geometric CAD design of the frames 0901-0903, an algorithm determines the location and orientation of the rigid physical objects and sends this information to the VR / AR simulation unit 1300 and the human tissue biomechanical simulation unit 1400.Thus, in at least one configuration, the hybrid simulator 2000 attaches a tracking frame 0902 to the patient model 0100, another frame 0903 to at least one surgical tool 0600, and other frames 0904 to other elements of the hybrid simulator 2000 such as the video camera 0910 or the stereoscopic viewer 0311 of the microscope-type instrument 0310. In some configurations, the Hybrid Simulator 2000 integrates the position and orientation of physical elements within the VR / AR 1300 simulation into a unified spatial reference frame (global coordinate system). This establishes a single coordinate system for accurately locating the position and orientation of all elements in real time with respect to a common 0901 frame base. In some configurations of the Hybrid Simulator 2000, the VR / AR simulation module 1300 includes a means for registering the physical patient model 0100 and the virtual patient model 1100. Registration involves finding a mathematical transformation (typically a rigid or affine transformation) to match the position and shape of the virtual patient model 1100 with respect to the virtual reference frame (local coordinate system in the virtual environment) to the position and shape of the physical patient model 0100 with respect to the global reference frame 0901. The transformation is calculated using an optimization algorithm that minimizes the alignment error between the selected landmarks in both models. The landmarks in the physical patient model 0100 can consist of small spheres 0904 placed on the model and identified by the tracking system 0900, or specific anatomical landmarks.For registration, the operator can locate the actual position of the reference points by manually touching certain points on the patient model 0100 with the tips of the surgical tools 0600 using the tracking devices 0903, and then aligning the virtual patient model 1100 with the identified virtual and real point sets. Optionally, registration also includes other computer vision-based alignment methods, such as using depth point clouds detected on the physical patient model 0100 with the video camera 0910 or image-based methods. Thus, it is possible to locate points of interest within the virtual anatomical models 1100, with respect to the patient model 0100, or to precisely locate the position of the surgical instruments 0600 within the virtual anatomies 1100. Registration also enables the hybrid simulator 2000 to activate visual and haptic guidance with error and success feedback to help the user acquire dexterity and learn gestural skills. In at least one configuration, the Hybrid Simulator 2000 includes a video camera 0910 to record and provide real-time augmented reality visual information from the VR / AR simulation 1300 and the biomechanics of human tissues 1400 on the physical scene of the patient model 0100 and its interaction with surgical instruments 0600. The video camera 0910 can be a two-dimensional or stereoscopic visual camera, providing standard 2D or three-dimensional visualization for augmented reality spatial perception in the VR / AR simulation 1300. The video camera 0910 can provide depth map information for elements of the Hybrid Simulator 2000 by using visual computation estimation techniques, infrared sensors, or other suitable technology capable of estimating the spatial location of all points in the visual scene. The Hybrid Simulator 2000 includes the VR / AR simulation module 1300 and the biomechanical simulation of human tissues module 1400, integrated in a logical sequence of steps according to elements 1301-1307 and 1401-1407. The VR / AR simulation module 1300 integrates three types of three-dimensional models of surgical anatomies and instruments: graphical models, collision models, and physics-based models. Without loss of generality, the graphical models consist of geometric representations of patient-specific organs and anatomies, either manually modeled or automatically reconstructed from medical image sets such as MRI, CT, CT, ultrasound, or other biomedical modalities. Collision models consist of discrete representations of the spatial occupation of virtual objects in virtual scenes and their contact interactions. They are generally, but not exclusively, constructed from occupation maps in the form of recursive tree data structures of bounding geometric elements (spheres, aligned boxes, oriented boxes, among others) that spatially contain the virtual objects. Physics-based models integrate three types of computer-simulated objects: rigid bodies (including simple and multi-rigid bodies), soft-body deformation models, and particle models. Multi-rigid bodies are used to simulate virtual surgical tools and articulated solid anatomies, while simple rigid bodies are used to model non-articulated solids. Particle models are used to simulate the presence of fluids as water or blood flows. Depending on the configuration, some rigid objects of bone anatomies can be considered static, while endoscopic and surgical instruments are mobile and dynamic rigid objects.Soft body deformation models simulate the interaction of surgical and endoscopic tools with soft tissues, allowing deformation, tearing, resection, dissection, suturing, or similar surgical gestures in real time, of virtual deformable anatomical tissues in the 1400 Human Tissue Biomechanical Simulation Unit. To achieve the physical simulation of objects, an available computer physics simulation engine, such as the NVIDIA PhysX or SOFA engine, or any other suitable engine, can be used. Within the computer simulation engine, object geometries can be approximated using solid primitives such as spheres or boxes. It is also possible to directly employ triangular meshes or convex geometries to simplify the original geometries of rigid models, such as the virtual skull, endoscope, and 1600 virtual surgical instruments, to accelerate collision detection. The biomechanical simulation of the viscoelastic behavior of human tissue 1400 is implemented using the Finite Element Method (FEM), where the physical simulation of tissue behavior is based on biophysically valid models with the integration of computer simulation tools such as SOFA, or other suitable computer simulation tools. Soft tissue behavior is not limited to FEM. The hybrid simulator 2000 considers the use of other novel or existing methods, such as mesh-free or particle-based methods, in which the shape of anatomical structures is discretized into particles, each of which contains information about its position, mass, and velocity. This makes it possible to simulate a wide range of materials, from solids to fluids, while also allowing real-time simulation by solving the physical equations in parallel on the GPU or using other suitable paralysis methods. The logical sequence of the VR / AR simulation 1300 and biomechanical simulation 1400 is performed in discrete time steps as follows. First, using the tracking device 0900 or directly via the haptic devices 0501, 0502, the tracking position (and sometimes orientation) 1301 of the actual surgical instruments 0600 is obtained. With the position (and sometimes orientation) of the instruments, an inverse kinematics method 1302 estimates the complete posture of the virtual surgical instruments 1600, which will be reproduced within the biomechanical VR / AR simulation 1300. Next, the postures of the virtual surgical instruments 1600 are updated to follow the movements of the actual instruments 0600 by means of a soft coupling mechanism 1303, and the simulation checks for any collisions between the rigid and deformable objects in the simulation. If a collision is detected, the positions and orientations of the virtual surgical instruments 1600 are updated to the last non-collision, non-penetration posture 1304 with respect to the solid tissue models. The corresponding reaction forces 1305 are then calculated and applied 1306 to both the virtual instruments 1600 and the tissue models 1100. Without loss of generality, the intensity and direction of the collision reaction forces depend on factors such as the level of penetration within the tissue, the dynamic state of the rigid and deformable models, the material properties of the tissues such as viscoelasticity and friction, and spatial and mathematical constraints imposed on the interactions to ensure the stability and interpenetration of the objects. Next, depending on whether or not a collision occurs, the deformation of the soft tissue models 1401 is calculated for the current time step. Collision forces, if any, or other external forces such as gravity or internal forces such as pressure, initial stresses, or others are applied to the tissue models 1100. At this time step, if the current deformation or external loads or stresses on the tissues exceed a biomechanical threshold, tissue rupture 1402 can be simulated, splitting the geometric elements of the tissue models into fragments. Then, if the surgical instrument activator 0650 enables a tissue cutting operation (generally including dissection, resection, cutting, perforation, or other tissue intervention), a geometric algorithm divides the elements of the tissue model involved into tissue fragments 1403 consisting of geometric elements or particles. The resulting fragments are then removed 1404 from the biomechanical models, and the graphical models are updated 1405 in the VR / AR simulation scenes 1300. After calculating tissue deformation and tissue cutting, the hybrid simulator 2000 calculates the resulting forces to be exerted 1406 by the haptic devices 0501,0502 due to the interaction of the virtual surgical instruments 1600 with the tissue models 1100. The application of two haptic modalities 1407 is considered: kinesthetic forces applied by the haptic devices 0501,0502, and vibrotactile feedback with the craniotome-type instrument 0800. At the end of each time step during the simulation cycle, the current metrics of interaction 1307 are recorded and stored for post-session reporting and analysis of the user's intervention skills. Metrics 1307 include, but are not limited to, kinematic information on the movements of the virtual surgical instruments 1600 (position, velocity, acceleration, pull, smoothness, etc.), forces exerted, amount of tissue displacement, amount of deformation and tissue removal, resection, accuracy, duration of the intervention, hit and miss contacts, and other performance information. The simulation then continues with the next cycle of time steps or terminates. The hybrid simulator 2000 also stores all recorded metrics 1307 in a database, allowing users to query information from different sessions and users.The 1307 metrics are used to assess learner progress based on user level, depending on the selected configuration, for example, novice and expert, or novice, intermediate, and expert. This allows for quantitative comparisons between the skills acquired by an individual user and those of intermediate users or the majority of expert users. In at least one configuration, the Hybrid Simulator 2000 can assess the user's skill level using various methods to classify their acquired level through Artificial Intelligence, Machine Learning, or other appropriate technologies. Additionally, in at least one scenario within at least one configuration, the Hybrid Simulator 2000 can progressively adjust the training difficulty level, from low to high, according to an adaptive algorithm. Alternatively, the Hybrid Simulator 2000 allows the user to manually adjust the difficulty level.Differences in the difficulty level of the Hybrid Simulator 2000 may include, among others, different clinical cases, different parameters of the tasks assigned during training, such as the time given to complete a movement, the allowed level of forces exerted on the tissues, the allowed speed of movement, among others. REFERENCES AlZhrani, G., Alotaibi, F., Azarnoush, H., Winkler-Schwartz, A., Sabbagh, A., Bajunaid, K., Lajoie, SP, & Del Maestro, RF (2015). Proficiency performance benchmarks for removal of simulated brain tumors using a virtual reality simulator NeuroTouch. Journal of Surgical Education, 72(4), 685-696. https: / / do¡.org / 10.1016 / j .j su rg .2014.12.014 Banerjee, PP, Luciano, CJ, Alaraj, A., & Charbel, F.T. (2015). Haptic augmented reality for simulation of surgical procedure (Patent No. WO2014052158A3). Chan, S., Conti, F., Salisbury, K., & Blevins, N. H. (2013). 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Real-time surgery simulation of intracranial aneurysm clipping with patient-specific geometries and haptic feedback. 9415.

Claims

1. A hybrid simulator for neurosurgical procedures combining virtual reality and anatomical models comprising: a workstation to house all elements of said hybrid simulator; a patient head model comprising reproductions of body parts of the head anatomy in hard and soft materials and reproducing the joints of the head, neck and back of a real patient; a support for fixing the patient head model; one or more instrumented surgical tools; an electronic control unit; communication media; a virtual reality and augmented reality simulation unit; a human tissue biomechanical simulation unit; and an image display unit.

2. The hybrid simulator of claim 1 characterized in that said workstation is formed by a mobile cart and a fixed cart.

3. The hybrid simulator of claim 1 characterized in that said patient head model has reproductions of body parts of the head anatomy in hard and soft materials, which reproduce the joints of the head, neck and back of a real patient.

4. The hybrid simulator of claim 1 characterized in that said patient head model fixing support comprises a mechanism with at least eleven links articulated by at least three rotational joints 1 DoF, one translational and rotational joint 2 DoF, one translational joint 1 DoF, and means for fixing said patient head model.

5. The hybrid simulator of claim 1 characterized in that said VR / AR simulation unit integrates virtual models of the anatomies and said surgical instruments and to reproduce the natural deformable behavior of real tissues, allowing operations such as cuts, resections, dissections and other common surgical gestures and manipulations.

6. The hybrid simulator of claim 1 characterized in that said VR / AR simulation unit simulates the surgical procedures of endoscopy, open surgery and microsurgery: bone drilling, tissue dissection and membrane resection, tumor resection, tissue removal and displacement, vascular anastomosis, aneurysm clipping, catheter insertion, needle insertion.

7. The hybrid simulator of claim 1 characterized in that said patient head model has at least four motion sensors for measuring the angular positions of each joint link and means for transmitting said positions to said VR / RA simulation unit.

8. The hybrid simulator of claim 1 characterized in that said simulator comprises a mechanical tool adapter on haptic devices for coupling different models of surgical instruments commonly used in neurosurgery.

9. The hybrid simulator of claim 8 characterized in that said adapter allows the attachment of an endoscope-type instrument.

10. The hybrid simulator of claim 1 characterized in that the positions and orientations of said instrumented surgical tools are mapped onto virtual surgical instruments within the scenarios of the virtual and augmented reality units.

11. The hybrid simulator of claim 1 characterized in that said patient head model support is equipped with motion sensors to determine the angular positions of each of its joint links.

12. The hybrid simulator of claim 11 characterized in that said sensors transmit data to the VR / AR simulation units to determine the position of the patient model.

13. The hybrid simulator of claim 1 characterized in that said image display unit comprises a surgical microscope-type instrument.

14. The hybrid simulator of claim 13 characterized in that said surgical microscope-type instrument includes two portable controllers for adjusting scene parameters and executing control commands in the VR / AR simulation.

15. The hybrid simulator of claim 1 characterized in that said instrumented surgical tools comprise a craniotome-type instrument 16. The hybrid simulator of claim 1 characterized in that said instrumented surgical tools are mounted on a terminal effector of the haptic devices.

17. The hybrid simulator of claim 1 characterized in that said instrumented surgical tools include an activator.

18. The hybrid simulator of claim 17 characterized in that said activator consists of a surgical-type pedal.

19. The hybrid simulator of claim 1 characterized in that said instrumented surgical tools transmit their position by means of haptic devices to said virtual reality and augmented reality simulation unit.

20.

19. The hybrid simulator of claim 1 characterized in that said instrumented surgical tools transmit their position by means of a motion-tracking device.

21. The hybrid simulator of claim 1 characterized in that said virtual reality and augmented reality simulation unit includes a computer vision-based method for accurately and in real time locating said instrumented surgical tools and said patient head models with respect to a global coordinate system.

22. The hybrid simulator of claim 1 characterized in that said virtual reality and augmented reality simulation unit provides augmented graphic visual information of 5 real scenes of said patient model by means of 2D or 3D video cameras.

23. The hybrid simulator of claim 1 characterized in that said deployment unit comprises a screen or mobile devices.

24. The hybrid simulator of claim 1, characterized in that said control unit calculates metrics for each training session and stores them for each user. 10 25. The hybrid simulator of claim 24 characterized in that said control unit comprises an intelligent algorithm that determines the user level.

26. The hybrid simulator of claim 24 characterized in that said control unit allows adjusting the level of difficulty of the training.