FR2814667A1 - Stereotactic frames for use in computer assisted stereotactic surgery or radiology with the frames similar to spectacle frames positioned over the patient's eyes and having an emitter-receiver block - Google Patents

Abstract

Stereotactic frames comprise a rigid bar (1) with a hollow for the nose in the center. Two lateral segments (2) are arranged at each end of the bar with blades (3) arranged on the segments so that they rotate about an axis perpendicular to the lateral segments. The blades have integral earpieces. An Independent claim is made for a surgical navigation method using Stereotactic frames positioned on a patient for acquiring anatomical sections after determination of stereotaxical marker positions. The invention also relates to a surgical navigation device for use with the navigation method using the Stereotactic frames.

Description

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 The invention relates to the field of computer-assisted surgery and in particular for an object a stereotaxic frame, registration means and means for supporting surgical tools, as well as a computer-assisted surgical navigation device.

 Computer-assisted surgery is a known technology and for which several systems are currently marketed. It makes it possible to use the patient's radiological record, most often, in the form of a series of computed tomography or MRI images forming a set of sections describing an anatomical volume, to guide the image of a surgeon, during surgical procedures relating to anatomically complex regions, and for which the chosen surgical approach only offers a limited day on the site to be treated. This is particularly the case for neurosurgical procedures, or even video-guided endo-nasal surgery. In general, these guidance systems are based on the use of a space locator consisting of one (or more) sensor (s) in connection with a system for analyzing the position of (or these) sensors (s). The analysis system provides the spatial coordinates or position (X, Y, Z) and the attitude (angles a, ss, and y) of the sensor, in the coordinate system specific to the spatial locator.

 The spatial location system can in particular be of the type: - mechanical-electronic, such as an articulated arm with 6 degrees of freedom associated with potentiometers, variable capacitors or variable inductances, - optical by infrared link, active or passive, in particular, - continuous or pulsed magnetic, - low frequency electromagnetic, - a combination of several of these means.

délivrées par celui-ci. Le (ou les) capteur de localisation spatiale étant fixé sur l'instrument chirurgical dont on désire connaître la position, le système est alors In addition, the patient's imagery is loaded onto a computer system allowing it to be displayed on a monitor accessible to the surgeon. This computer system is connected to the spatial locator, and receives the coordinates

issued by him. The spatial location sensor (s) being fixed on the surgical instrument whose position is desired, the system is then

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capable d'afficher les images anatomiques du patient dont les plans de reconstructions correspondent au mieux ä la position de l'instrument, et simule la position de l'instrument à l'intérieur de l'organisme du patient sous forme d'une marque graphique.

capable of displaying the anatomical images of the patient whose reconstruction plans best correspond to the position of the instrument, and simulates the position of the instrument inside the patient's organism in the form of a graphic mark .

 However, this is only possible from the moment when coordinate transformation equations can be determined with precision, in order to convert the coordinates of the location sensor, to the coordinate system in which the anatomical guidance images have been produced. surgical. The determination of these equations leads to the obtaining of the rotation and translation matrices which make it possible to make any point in the three-dimensional space of the locator correspond to its counterpart in the space for acquiring the patient's imagery. This operation is called "registration" by Anglo-Saxons, and will be called "reca / age" in the following.

 To determine the relative position of the patient's images in relation to the spatial locator system, several glove solutions used: - use of opaque markers glued to the patient's skull. As the skin is mobile, their precision is limited (around 3 mm) and often requires manual identification on radiological radiographs. They cannot be left in place for more than a few hours.

 - use of screws implanted in the skull bone, after shaving the scalp, under local or general anesthesia. Their precision is of the order of a millimeter.

 - Surface matching, which consists of scanning the surface of the patient's skull and face with a probe, to acquire a matrix of contour points.

A complex algorithm compares these points with the contours of the CT or MRI images of the patient, until a concordance is found which makes it possible to know the passage matrices between the patient reference system and that of the 3D locator. This process is very elegant in theory since it avoids the use of stereotaxic markers, but in practice, it is long for the operator, generates errors or can prove to be without solution (local minimum in mathematical functions, simulating a root). Above all, it supposes that the integuments are not deformable while they have a notable elasticity introducing an error

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pouvant atteindre plusieurs millimètres dans le relevé de ces points lorsqu'ils sont acquis sur la patient par le contact mécanique d'une sonde, et que la morphologie du patient seit immuable, ce qui n'est pas le cas : un léger oedème facial, peut modifier ces repères de plusieurs millimètres. Enfin, le recalage per-opératoire n'est guère envisageable après certains gestes chirurgicaux : lambeaux, incisions, etc... qui font perdre tous ces repères.

can reach several millimeters in the recording of these points when acquired on the patient by mechanical contact with a probe, and the patient's morphology becomes immutable, which is not the case: a slight facial edema, can modify these marks by several millimeters. Finally, intraoperative registration is hardly possible after certain surgical procedures: flaps, incisions, etc ... which cause all these benchmarks to be lost.

 These first three methods impose a short delay, between the imaging acquisition phase and the intervention, ranging from a few hours to 2 or 3 days.

est porté ä la fois lors de la phase d'acquisition du dossier radiologique, et lors de la phase chirurgicale. 11 est basé sur la reproductibilité de ses appuis de référence. Des marqueurs radio-opaques insérés dans la résine plastique qui le constitue, forment les points de repère. La déformabilité nécessaire du casque pour pouvoir être positionné sur le patient, oblige à placer ces repères radio-opaques dans une zone de petite dimension située en regard de la région frontale du patient. Le volume repéré par ses marqueurs se trouvant limité, il en résulte une erreur de parallaxe qui diminue la précision de ce casque, notamment en profondeur. D'autre part, ce casque est encombrant, souvent douloureux pour le patient en raison de la forte

pression exercée sur ces appuis et empêche tout geste chirurgical sur les régions frontale et pariétales du crâne. En outre, ce système de casque étant ä usage unique, il s'avère très onéreux à l'emploi. Enfin, il oblige à une traçabilité vigilante, puisque le casque utilisé pour la procédure chirurgicale doit être le même que celui employé pour l'acquisition des images radiologiques. A fourth method is described in patent US Pat. No. 5,803,089 and marketed by the company VTI, USA. A stereotaxic frame for single use and resting on the naso-frontal region and leg external auditory organs of the patient

is worn both during the acquisition phase of the radiological record, and during the surgical phase. It is based on the reproducibility of its reference supports. Radio-opaque markers inserted in the plastic resin which constitutes it, form the reference points. The deformability necessary for the helmet to be able to be positioned on the patient means that these radiopaque markers must be placed in a small area located opposite the frontal region of the patient. The volume identified by its markers being limited, this results in a parallax error which reduces the precision of this helmet, especially in depth. On the other hand, this helmet is bulky, often painful for the patient due to the strong

pressure exerted on these supports and prevents any surgical gesture on the frontal and parietal regions of the skull. In addition, this helmet system being disposable, it is very expensive to use. Finally, it requires vigilant traceability, since the helmet used for the surgical procedure must be the same as that used for the acquisition of radiological images.

 In addition, with the exception of the system marketed by VTI Inc., which uses an electromagnetic type spatial locator built by the company Polhemus-Inc., the navigation systems currently available use an infrared link based on the use of very bulky special cameras in the operating room and very fragile. These infrared cameras have a delicate optic that a shock can easily disrupt, thus imposing immobilization

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prolongée du matériel pour immobilisation. Ce type de système impose au chirurgien de limiter sa gestuelle opératoire, de manière ä ne pas oblitérer le champ de vision des caméras, faute de quoi, le système devient inopérant. 11 en résulte une gêne sensible pour l'opérateur, notamment en chirurgie endonasale, ou l'étroitesse de la voie d'abord (orifices narinaires), et la nécessité d'utiliser conjointement plusieurs instruments (endoscope, aspirateur, pinces, ...) impose un maniement spécial.

equipment for immobilization. This type of system requires the surgeon to limit his operative gestures, so as not to obstruct the field of vision of the cameras, failing which, the system becomes inoperative. 11 results in a significant discomfort for the operator, especially in endonasal surgery, or the narrowness of the approach (nasal orifices), and the need to jointly use several instruments (endoscope, vacuum cleaner, forceps, ... ) requires special handling.

 In addition, all of the surgical navigation systems currently in existence operate with special computer systems called graphic stations. These machines have the theoretical advantage of having high performance, allowing very fast graphic image processing. However, they are very expensive, fragile and bulky gloves.

des informations graphique de navigation. Leur fréquence de réactualisation de l'écran est de l'ordre de 2 à 4 rafraîchissements par seconde. In addition, these navigation systems do not offer real-time display

graphical navigation information. Their screen refresh rate is around 2 to 4 refreshes per second.

Finally, it should be noted that the system marketed by the company VTI-Inc., does not allow the calibration of surgical instruments, and requires the surgeon to use single-use cannulas pre-calibrated in the factory. Their accidental deformation during intervention, requires replacing them. 11 results again, a high cost of use.

 The object of the invention is to remedy these drawbacks by proposing in particular a surgical navigation system: - offering possibilities of registration of images, simple, fast, precise, versatile; - allowing the use of a standard IT system, so as to reduce the cost of manufacturing and maintaining teig systems; - available in a configuration limiting their size in the operating room and authorizing their transport, which presupposes both robustness, small size, and low weight of the system;

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- autorisant des procédures chiturgicales sur l'ensemble des régions craniofaciales, ce qui suppose, notamment, que le dispositif utilisé pour le recalage des images laisse libre la région frontale du patient ; - permettant, le cas échéant, l'emploi d'un instrument chirurgical

quelconque, à la convenance du chirurgien, sans obligation d'utiliser une panoplie limitée d'instruments précalibrés, prédéfinie par le fabricant ; - offrant un affichage en temps réel.

- authorizing chiturgical procedures on all craniofacial regions, which presupposes, in particular, that the device used for registration of images leaves the frontal region of the patient free; - allowing, if necessary, the use of a surgical instrument

any, at the convenience of the surgeon, without obligation to use a limited range of precalibrated instruments, predefined by the manufacturer; - offering real-time display.

 The solution provided is, according to a first embodiment, a stereotaxic framework in particular for radiological and / or surgical use comprising a rigid transverse bar comprising two ends and a groove in its lower median part, first and second lateral segments disposed respectively at the one and the other of said ends of the rigid transverse bar, of the first and second lateral blades connected respectively to the first and second lateral segments by an axis of rotation, and of the first and second olive ends secured respectively to said first and second blades side.

sont disposés respectivement à l'une et ä l'autre des dites extrémités de la barre rigide transversale, et/ou en ce que les premier et deuxième segments latéraux (2) comportent une partie rigide située du côté de la barre rigide transversale et une partie flexible située du coté opposé. According to a particular characteristic, at least two of said first and second lateral segments or of said first and second lateral blades are flexible,
According to another characteristic, the first and second lateral segments are flexible and in that a first and a second rigid lateral strip

are arranged respectively at one and at the other of said ends of the transverse rigid bar, and / or in that the first and second lateral segments (2) comprise a rigid part situated on the side of the transverse rigid bar and a flexible part located on the opposite side.

 According to an additional characteristic, a frame according to the invention comprises first and second rigid anterior segments disposed respectively at one and at the other of said ends of the transverse rigid bar and forming an angle of at least n / 4 Rd with said transverse rigid bar and with said lateral segments.

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Selon une autre caractéristique, il comporte au moins un marqueur stéréotaxique disposé dans l'une et/ou l'autres des premières et secondes réglettes latérales rigides et/ou dans l'un et/ou l'autre des premier et deuxième segments antérieurs rigides et/ou il comporte au moins un marqueur stéréotaxique disposé dans la barre rigide transversale au moins un des dits marqueurs stéréotaxiques pouvant être disposé ä l'intérieur d'un trou borgne. Par ailleurs il peut comporter des moyens de rappel, par exemple un ressort spiral, de chacun desdits que premier et deuxième segments latéraux sur chacun desdites première et deuxième lames latérales, ces moyens de rappels pouvant ne pas être radio-opaque.

According to another characteristic, it comprises at least one stereotaxic marker placed in one and / or the other of the first and second rigid lateral strips and / or in one and / or the other of the first and second rigid anterior segments. and / or it comprises at least one stereotaxic marker placed in the rigid transverse bar at least one of said stereotaxic markers which can be placed inside a blind hole. Furthermore, it may include return means, for example a spiral spring, of each of said first and second lateral segments on each of said first and second lateral blades, these return means not being able to be radiopaque.

According to another characteristic, the first and second lateral blades are free to rotate about first and second axes of rotation respectively secured to the first and second lateral segments and / or it comprises a secondary transmitter or sensor, said transmitter or said transmitter sensor or picks up, for example, at least one low frequency electromagnetic field
Furthermore, it may include a conical recess point.

 A stereotaxic frame according to the invention makes it possible both to perform the registration of the anatomical images, possibly automatically, and to offer support to a transmitter block or to a so-called secondary sensor of spatial location. This frame rests on three anatomical points known to be fixed and allow a faithful reproducibility of these supports in the 3 planes of the space, after removal and replacement of the frame. Its precision is quite remarkable compared to existing models, and its repositioning, even several days apart, is precise to the millimeter. The frames according to the invention can be designed and / or used in several ways. One can, for example, use only one standard frame, provided with marks, for example, opaque to X-rays if one works with a CT image, or else, very excitable with a magnetic resonance if one works with MRI imagery, etc., which are dispersed in a sufficient volume to allow an accurate analysis of their positioning and to minimize parallax errors. This frame is worn by the patient during the phase of acquiring medical images, and leaves the imprint of its spatial position, thanks to the markers it contains. During the

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phase chirurgicale, ce cadre est remis en p ! ace sur ! e patient. Ses repères sont pointés avec un stylet sur lequel est assujetti un capteur primaire de localisation spatiale, de manière ä identifier la position de ces repères dans le système tridimensionnel propre au localisateur spatial. On obtient alors une matrice de coordonnées, qui permet de déterminer par solution mathématique leg équations de transformation (matrices de rotation et de translation) pour passer du système tridimensionnel propre au localisateur vers le système tridimensionnei propre au volume d'acquisition des images anatomiques du patient.

surgical phase, this framework is put back in p! ace on! patient. Its marks are pointed with a stylus to which a primary spatial location sensor is attached, so as to identify the position of these marks in the three-dimensional system specific to the spatial locator. One then obtains a coordinate matrix, which makes it possible to determine by mathematical solution the transformation equations (rotation and translation matrices) to pass from the three-dimensional system specific to the locator to the three-dimensional system specific to the volume of acquisition of the anatomical images of the patient. .

chirurgie endofaciale sans gêner le chirurgien, il peut être laissé en place durant l'intervention. Dans ce cas, il sert de support au bloc émetteur ou à un capteur appelé secondaire utilisé alors comme référence si le système de localisation utilisé ne peut être directement fixé sur le patient. This framework having been designed to allow most of the interventions of

endofacial surgery without disturbing the surgeon, it can be left in place during the intervention. In this case, it serves as a support for the transmitter unit or a sensor called secondary used then as a reference if the localization system used cannot be directly fixed on the patient.

 By knowing, by construction, the relative position of the stereotaxic marking marks of the frame with respect to the active center of the transmitter block or of the secondary sensor then fixed to this frame, it becomes unnecessary to carry out their manual pointing: the system then allows a registration automatic.

 All the frames according to the invention having, by construction, the same characteristics, in particular as regards their support points, it is not necessary to use during the surgical phase, the same frame as that used to mark the medical images.

 Since the markers are only useful during the image acquisition phase, the stereotaxic framework devolved to the surgical phase can be devoid of it, which results in a simplification of its structure, making it possible further to reduce its size. It is therefore for this reason that the production of this frame game can be envisaged when a single standard stereotaxic frame could also be used as previously mentioned.

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When a frame according to the invention cannot be used in the surgical phase, it can be replaced by a self-reference reference transmitter block device.

An autostatic reference transmitter block device according to the invention is suitable for being placed on the head of a patient and comprises a plate, on which is fixed a transmitter block or a secondary reference sensor, at least one pad integral with the plate and having on its underside, pins allowing support without sliding on the patient's head, and means, such as straps, which in at least one position allow said pins to exert pressure on the patient's head. 11 may further include one or more of the following characteristics: - it comprises two pads disposed on either side of the plate, each of them being articulated on the latter by an axis of rotation.

 - Each of the pads is secured to the axis of rotation by a rigid tongue - said means which in at least one position allow said pins to exert pressure on the patient's head are constituted by straps fixed on said rigid tongue.

 - it includes a secondary transmitter or sensor.

 - Said transmitter or said sensor emits, or captures at least one low frequency electromagnetic field.

 - It has a conical recess.

primaire étant disposés à proximité de ce méplat, I'extrémité distale de ce bloc comportant un alésage ainsi qu'au moins une gorge radiale par rapport ä l'alésage, The invention also relates to a computer-assisted surgical navigation system comprising a spatial location device connected to a computer, characterized in that the spatial location device is associated with a cannula or instrument holder device comprising a block, preferably made of resin. plastic, comprising a flat, means for fixing a sensor

primary being disposed near this flat, the distal end of this block comprising a bore as well as at least one radial groove relative to the bore,

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ainsi que des moyens de blocage d'une canule ou d'un instrument disposés à proximité dudit alésage
Selon une caractéristique additionnelle, lesdits moyens de blocage sont constitués par une bague de blocage, articulée sur un point de rotation fixé audit bloc, manipulable grâce à un ergot, et comportant une encoche apte à coopérer avec une gorge disposée sur l'extrémité distale de la canule ou de l'instrument, des moyens de verrouillage de la bague en rotation lui étant associés, lesdits moyens de verrouillage pouvant être constitués par un picot et/ou l'alésage comporter au moins trois gorges disposées en ailettes.

as well as means for blocking a cannula or an instrument disposed near said bore
According to an additional characteristic, said blocking means consist of a blocking ring, articulated on a point of rotation fixed to said block, manipulated by a lug, and comprising a notch capable of cooperating with a groove disposed on the distal end of the cannula or of the instrument, means for locking the rotating ring being associated with it, said locking means possibly being constituted by a pin and / or the bore comprising at least three grooves arranged in fins.

 The invention also relates to a computer-assisted surgical navigation method using a localization device associated with said computer and comprising an instrument placed in a known position relative to a primary sensor capable of emitting a signal representative of its position in a reference called a reference. of the spatial localization device, as well as of means for displaying information associated with the computer, method consisting, with a view to automatic readjustment of the position of a part of the instrument: - to position on the patient a stereotaxic frame according to the invention and comprising at least one stereotaxic marker, - to use a medical imager with a view to acquiring an anatomical volume in serial sections, - to determine the position of the stereotaxic markers on each of said serial sections and to deduce therefrom the matrix of coordinates of the markers in a frame linked to the images, - to position, su r the patient, a frame according to the invention and comprising a transmitter or a sensor emitting or capturing at least one low frequency electromagnetic field, or a reference block device according to the invention and comprising a transmitter or a sensor emitting or capturing at least one low frequency electromagnetic field, the position of said transmitter or of said secondary sensor being predetermined with respect to that of the stereotaxic markers placed on said previously used frame and comprising at least one stereotaxic marker, - to be calculated in the frame of reference linked to the images, the position of the distal part of said instrument from the coordinates of said primary sensor known in the

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repère du dispositif de localisation spatial et de la position connue de la partie distale de l'instrument par rapport audit capteur primaire, - a afficher sur lesdits moyens d'affichage au moins une coupe sérielle d'un plan ou se trouve ladite partie proximale de l'instrument, ainsi que la position de cette partie proximale dans ladite coupe sérielle.

reference mark of the spatial location device and of the known position of the distal part of the instrument relative to said primary sensor, - to display on said display means at least one serial section of a plane where said proximal part of the instrument, as well as the position of this proximal part in said serial section.

instrument respectivement ä chacune des positions des marqueurs stéréotaxiques utilisés dans la première étape et ä établir la matrice de coordonnées de chacun des marqueurs stéréotaxiques dans le repère du localisateur spatial, - dans une sixième étape ä calculer la matrice de transformation de coordonnées dans le repère du localisateur spatial, en coordonnées du repère lié aux images, - dans une septième étape à calibrer ledit instrument. According to another characteristic, a computer-assisted surgical navigation method using a localization device associated with said computer and comprising an instrument placed in a known position relative to a primary sensor capable of emitting a signal representative of its position in a frame called a frame of the spatial localization device, as well as of means for displaying information associated with the computer, consists, with a view to manual registration of the position of a part of the instrument: - in a first step to position , on the patient, a stereotaxic frame according to the invention and comprising at least three stereotaxic markers, - in a second step to use a medical imager for the acquisition of an anatomical volume in serial sections, - in a third step determining the position of the stereotaxic markers on each of said serial sections and deducing therefrom the coord matrix onnées markers in a frame linked to images, - in a fourth step to position on the patient a frame according to the invention or a self-reference reference block device according to the invention, - in a fifth step to position the end proximal of said

instrument respectively to each of the positions of the stereotaxic markers used in the first step and to establish the matrix of coordinates of each of the stereotaxic markers in the coordinate system of the spatial locator, - in a sixth step to calculate the matrix of transformation of coordinates in the coordinate system of the spatial locator, in coordinates of the reference frame linked to the images, - in a seventh step to calibrate said instrument.

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According to an additional characteristic, the sixth step consists in calculating the transformation matrix from the following equation: P1 = P2. [M,] + [MJ (1) where [MJ is the rotation matrix of coefficients a, b, c, d, e, f, g, h, i, and, where [Mt] is a translation matrix of coefficients Kx, Ky, Kz, and P1 a point of coordinates (Sx, Sy, Sz) in the coordinate system of the spatial locator and P2 the point corresponding to P1 but in the coordinate system linked to the images and coordinates Ix, Iy and Iz, and by solving the following equations (2) to 12 unknowns: Ix = (a. Sx) + (b. Sy) + (c. Sz) + Kx Iy = (d. Sx) + (e. Sy) + (f. Sz) + Ky (2) Iz = (g. Sx) + (h. Sy) + (i. Sz) + Kz According to a particular characteristic, the stereotaxic frame used in the first step comprises at least four markers and in that the sixth step consists in directly solving equation (2) from 12 coordinates of the at least four markers.

According to another particular characteristic, the stereotaxic frame used in the first step comprises at least three stereotaxic markers and in that it comprises a complementary step consisting in reducing the equations (2) to 12 unknowns into a system of 6 unknowns by replacing the coefficients a, b, c, d, e, f, g, h, i of the matrix [MJ by! es coefficient of equation (3), cos (A) cos (E) sin (A) cos (E) -sin (E) [MJ = cos (A) s! n (E) sn (R) -sn (A) cos (R) s! n (A) sin (E) sin (R) + cos (A) cos (R) cos (E). sm (R) (3) cos (A). sin (E) cos (R) + sin (A) sin (R) sin (A) sin (E) cos (R) -cos (A) sin (R) cos (E) cos (R) A, E and R being the Eulerian angles of transformation, Then by solving the trigonometric equation of the third degree then obtained by a known method.

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par exemple un capteur CCD, sensible au spectre dudit rayonnement, - Faxe d'émission du rayonnement laser et l'axe de visée de la caméra forment un angle connu entre eux permettant par simple calcul trigonométrique de déterminer la distance du spot du faisceau laser formé par son impact sur un objet, la position dudit spot perçu par la caméra variant avec la distance. The subject of the invention is also a device for resetting a DL location device for use in a surgical navigation device, location device with which a primary sensor is associated, characterized in that it comprises a telemetric device associated with said primary sensor so that their relative positions are fixed and known and able to measure the distance of an object. 11 may include one or more of the following characteristics: the telemetry device is constituted by a source of laser radiation, for example a diode, and by a camera comprising an element,

for example a CCD sensor, sensitive to the spectrum of said radiation, - The axis of emission of the laser radiation and the line of sight of the camera form a known angle between them allowing, by simple trigonometric calculation, to determine the distance of the spot of the laser beam formed by its impact on an object, the position of said spot perceived by the camera varying with distance.

 - Said emission axis is arranged along an axis of an orthonormal reference linked to said sensor.

aboutissant ä l'obtention d'une matrice de point de contour d'imagerie, disposer un bloc émetteur ou un capteur sur le patient - réaliser un relevé surfacique (surface matching) d'une partie de la face du patient avec un dispositif télémétrique associé audit capteur primaire et apte à mesurer, pour chaque point de ladite partie, la distance séparant ledit dispositif ou ledit capteur de ladite face du patient, The subject of the invention is also a method of resetting a surgical navigation device comprising a DL location device with which a primary sensor is associated, characterized in that it comprises the following steps: - using a medical imager for the purpose of acquiring an anatomical volume in serial sections forming images, performing segmental detection of the contours of these images

resulting in obtaining an imaging contour point matrix, placing a transmitter block or a sensor on the patient - performing a surface matching (surface matching) of part of the patient's face with an associated telemetric device to said primary sensor and capable of measuring, for each point of said part, the distance separating said device or said sensor from said face of the patient,

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 comparing these measurements with the previously obtained contour point matrix in order to find the agreement between them by a mathematical algorithm using known methods, calculating the transformation matrix of coordinates in the coordinate system of the spatial locator, in coordinates of the linked coordinate system to the pictures.

ou provenant de scintigraphies ou de tomodensitométries à émission de positons, ...). Dans ces cas, l'utilisation d'un dispositif autorisant un repositionnement précis du patient grâce ä l'emploi d'un système stéréotaxique non-invasif, couplé ou non ä un localisateur spatial, permet d'arriver à un tel résultat. Furthermore, the means of the invention can be used in other fields of medical applications. As such, we can cite its use: - in diagnostic medical imaging: it may be necessary to follow the evolution of a pathology affecting the craniofacial regions, by iterative examinations. In order to be able to compare accurately examinations carried out at different periods of the disease, it may prove essential to have examinations carried out under incidences that are strictly superimposable over time. Or, to carry out explorations using different methods on an extemporaneous basis (for example, fusion of CT and MRI images,

or from scintigraphy or positron emission tomography, ...). In these cases, the use of a device authorizing a precise repositioning of the patient thanks to the use of a non-invasive stereotaxic system, coupled or not with a spatial locator, makes it possible to achieve such a result.

 - in radiotherapy, there is a need to be able to reposition with precision under the therapeutic X-ray beam, a patient subjected to cephalic irradiation, to deliver in a precise site, in an iterative manner, a dose of ionizing radiation. Different systems currently exist: stereotaxic frames fixed to the patient's skull, scalp tattoos, manufacture of molded masks conforming to the patient's anatomy, ... All these processes are complex, time-consuming, costly and sometimes painful for the patient. patient.

 Other advantages and characteristics of the present invention will appear in the description of various alternative embodiments of the invention, with reference to the appended figures among which:

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- La figure 1 est un schéma d'un système de navigation chirurgicale selon l'invention ; - La figure 2 est un diagramme synoptique exposant le principe de fonctionnement du système de navigation décrit dans la présente invention, découpé en trois étapes chronologiques et procédurales distinctes ; - La figure 3 expose les principes bio-mécaniques sur lesquels repose le fonctionnement du système de cadres stéréotaxiques ; - Les figures 4a et 4b exposent un dispositif porte-canule amovible, constitue d'une partie supportant le capteur primaire et d'une canule amovible métallique stérilisable, à repositionnement précis, grâce à un système d'ailettes de guidage ; - Les figures 5a, 5b et 5c montrent un système porte-instrument universel, permettant, après calibration, d'utiliser un instrument chirurgical quelconque, comme outil de guidage ; - Les figures 6 à 9 présentent les aspects de ce système de cadre (cadre pour la phase radiologique, cadre pour la phase chirurgicale à recalage automatique, cadre pour la phase chirurgicale à recalage manuel ; - Les figures 10 et 11, exposent en détail les éléments des cadres pour la phase radiologique et pour la phase chirurgicale.

- Figure 1 is a diagram of a surgical navigation system according to the invention; - Figure 2 is a block diagram showing the operating principle of the navigation system described in the present invention, divided into three distinct chronological and procedural stages; - Figure 3 shows the bio-mechanical principles on which the operation of the stereotaxic frame system is based; - Figures 4a and 4b show a removable cannula holder device, consists of a part supporting the primary sensor and a removable sterilizable metal cannula, with precise repositioning, thanks to a system of guide fins; - Figures 5a, 5b and 5c show a universal instrument holder system, allowing, after calibration, to use any surgical instrument, as a guide tool; - Figures 6 to 9 present the aspects of this frame system (frame for the radiological phase, frame for the surgical phase with automatic registration, frame for the surgical phase with manual registration; - Figures 10 and 11, detail the elements of the frameworks for the radiological phase and for the surgical phase.

 The framework for the manual resetting surgical phase is not detailed, since it differs from that used for the radiological phase, only by replacing the elastic return system with a spiral spring and fitting out orifices for pointing virtual stereotaxic landmarks; - Figure 12 shows the equipment used and the procedures for using the frames described above, depending on the type of automatic or manual registration chosen by the surgeon; - Figure 13 is a block diagram showing the steps of the algorithm for automatic detection of fingerprints left on the volume series of images, by stereotaxic markers;

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- La figure 14 expose les étapes de calcul, par le micro-ordinateur utilisé, des équations de transformation de coordonnées, permettant le recalage des images ; - La figure 15 expose le principe bio-mécanique sur lequel est basé le fixateur auto-statique universel, utilisé pour solidariser le bloc émetteur ou le capteur

secondaire de référence, sur le scalp du patient dans le cas où le chirurgien décide d'opérer sans le cadre standard ; - La figure 16 détaille les éléments constitutifs de ce même système à fixation auto-statique ;
La figure 17, explique le principe de calibration de l'instrument chirurgical, grâce à une méthode de pivotement autour d'un point fixe P, par exemple, situe sur le cadre chirurgical.

- Figure 14 shows the calculation steps, by the microcomputer used, coordinate transformation equations, allowing the registration of images; - Figure 15 shows the bio-mechanical principle on which the universal auto-static fixer is based, used to secure the transmitter block or the sensor

secondary reference, on the patient's scalp in case the surgeon decides to operate without the standard framework; - Figure 16 details the constituent elements of this same system with self-static fixing;
FIG. 17 explains the principle of calibration of the surgical instrument, using a method of pivoting around a fixed point P, for example, located on the surgical frame.

FIG. 1 shows the means constituting the invention, in this case a surgical navigation device, in an alternative embodiment of the invention usable for the different phases of computer-guided surgery, this device comprising: - means IM for acquiring an anatomical volume in serial sections, - information processing means MO, in this case a microcomputer MO, for example of the PC type comprising a set of software routines, a spatial location device DL,
A set of JCS stereotaxic frames,
A DCA cannula holder device for securing a sterilizable metallic surgical suction cannula (or equivalent instrument) to the block carrying the primary sensor,
A universal DPI device holder,
A DBC secondary transmitter or sensor device.

 Figures 2 and 3 explain the relationships between the various components of the invention. It can be seen in FIG. 2 that the IM means, in this case a medical imager, make it possible to acquire an anatomical volume by

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coupes sérielles formant des images, et que ces images sont traitées puis stockées par le micro-ordinateur MO. Lors de l'utilisation du micro-ordinateur en phase chirurgicale, lesdites images traitées sont chargées en mémoire vive et, en parallèle, les coordonnées du dispositif porte canuie dans le repère du dispositif de localisation spatiale gant transformées en coordonnées dans un repère lié aux dites images. Des routines assurent ensuite l'affichage sur les moyens d'affichage de l'ordinateur MO des coupes anatomiques axiales, coronales et sagittales correspondant à la localisation de l'instrument, par exemple une canule, et, en surimpression un curseur représentant la position de l'instrument sur lesdites coupes.

serial sections forming images, and that these images are processed and then stored by the microcomputer MO. When using the microcomputer in the surgical phase, said processed images are loaded into random access memory and, in parallel, the coordinates of the cane-holder device in the coordinate system of the glove spatial location device transformed into coordinates in a coordinate system linked to said images. Routines then ensure the display on the display means of the computer MO of the axial, coronal and sagittal anatomical sections corresponding to the location of the instrument, for example a cannula, and, in overprinting a cursor representing the position of the instrument on said cuts.

 As shown in FIG. 3, the images acquired during a medical imaging phase and coming from the imager can be transmitted by a network, such as the Internet or Ethernet, or archived on a medium, for example a hard disk, a CD ROM, DAT or ZIP cartridge, Colorado tape, etc. During this phase, the use of a stereotaxic frame according to the invention and comprising radio-sensitive stereotaxic markers makes it possible to generate characteristic points on said images .

 The treatment is carried out by the microcomputer MO during a preoperative phase which may or may not be carried out practically at the same time as the aforementioned medical imaging phase. It consists in searching, in each of the images, for the coordinates of the characteristic points due to the stereotaxic markers, automatically or manually, and optionally includes steps for adjusting the gray levels, formatting, reconstruction and automatic configuration of the characteristics. of these images and elements identifying the patient from a DICOM file to a specific file created for this purpose.

 Finally, during the operational phase, a navigation module produced by programming and coupled to a DL localization device which has been manually or automatically adjusted beforehand, makes it possible to transform the coordinates of the DCA cannula holder device, coming from the spatial localization device. in coordinates in a coordinate system linked to said images. This navigation module also provides display on the display means of the computer MO

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des coupes anatomiques axiales, coronales et sagittales correspondant à la localisation de l'instrument, par exemple une canule, et, en surimpression un curseur représentant la position de l'instrument sur lesdites coupes.

axial, coronal and sagittal anatomical sections corresponding to the location of the instrument, for example a cannula, and, overprinted, a cursor representing the position of the instrument on said sections.

In order to allow the surgeon to control the navigation system at his convenience, without the need for external assistance, the computer graphics navigation interface can be controlled during the intervention using a graphic tablet connected to the microphone. - computer, for example with electromagnetic technology.

During the intervention, it may, for example, be placed under a sterile operating sheet, or else in a disposable plastic cover, commercially available. The stylus associated with the graphic tablet, can also be placed in a small sterile cover, which does not interfere with its grip and operation. In conjunction, a traditional mouse system can be used to control the interface under conditions which do not require microbial sterility, by the surgeon himself, before he puts on sterile clothing, by a third party, during intervention.

 The DL spatial localization device includes a position sensor, hereinafter called the primary sensor, which is linked to the operating instrument whose position is desired. A transmitter unit, or a sensor called a secondary sensor in the following, depending on the configuration chosen, is for example fixedly attached to the patient's skull or on a stereotaxic frame, so as not to modify the registration of the images if the patient's head is mobilized during the surgical procedure.

 The DL spatial localization device can operate, for example, by active or passive infrared coupling, by mechanical connection with 6 degrees of freedom, by ultrasonic coupling, by low or high frequency electromagnetic coupling, by continuous or pulsed magnetic coupling, or even by a hybrid system using, for example, a combination of several of these coupling means.

solution contribue à rendre le navigateur chirurgical, à la fois très robuste, léger et peu encombrant et à permettre la fixation directe du bloc émetteur sur le cadre au lieu d'un capteur secondaire de référence en raison de sa petite taille. In the present alternative embodiment of the invention, a system of spatial location by low frequency electromagnetic field, multiplexed, is used. This

solution contributes to making the surgical navigator, at the same time very robust, light and space-saving and to allow the direct fixing of the transmitter block on the frame instead of a secondary reference sensor because of its small size.

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This three-dimensional localization system returns the position of the primary sensor (x, y, z coordinates) and its attitude (alpha angles (azimuth); beta (elevation); gamma (roll)). These coordinates are transmitted to a microcomputer MO. A software routine ensures: the transformation of these spatial coordinates from the three-dimensional locator, to convert them into the System of coordinates specific to the volume in which the anatomical images of the patient were acquired by the medical imager, namely the axial, coronal images and sagittal corresponding to the position thus converted of the instrument, displays in superimposition on these images, a visual cursor, for example a cross, to indicate to the surgeon the effective position of his instrument with respect to these anatomical images.

 The primary sensor associated with the DL spatial location device can be integrated into several structures. By way of example, we can cite the DCA device which makes it possible to subject a sterilizable metallic surgical suction cannula, or an equivalent instrument, to the block carrying the primary sensor, so as to uniquely and precisely position this cannula relative to to this sensor, while making this cannula removable to allow its cleaning and sterilization, as well as the DPI universal instrument holder device which makes it possible to temporarily fix any surgical instrument chosen by the surgeon (endoscope, forceps, monopolar scalpel tip, for example) to the primary sensor.

A DCA cannula holder device according to the invention makes it possible to subject the position of a set of sterilizable metallic surgical cannula, straight or curved and removable, or an equivalent instrument, to the primary position sensor, allowing identical repositioning said cannulas or instrument, with respect to this primary sensor. The spatial position of their working end being constant relative to the active center of the sensor, their calibration can be pre-established once and for all. These cannulas, made of rigid stainless steel, serve both as a palpatory, suction and surgical guide.

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Leur amovibilité permet leur interchangeabilité selen leg besoins chirurgicaux, et, en fin d'intervention, leur nettoyage et leur stérilisation. La figure 4a montre les éléments du dispositif DCA porte canule. 11 comporte un bloc en résine plastique 41, reçoit un capteur primaire 40 qui est seit fixé par boulonnage, seit rendu amovible par des glissières verrouillables de type connu non- représentées. Sa forme permet une préhension ergonomique. Son extrémité distale est alésée formant ainsi un alésage 47 de manière à permettre le passage d'un embout olivaie 45 d'une canule amovible 42. La canule présente des ailettes disposées en étoile 44 qui prennent place dans des logements aménagés autour de l'alésage central, en l'occurrence des ailettes 48 ménagées en creux dans le bloc de résine 41. Ces ailettes assurent le centrage correct de la canule par rapport à cet alésage 47 et ne sont pas transfixiantes de manière à ce que la partie proximale des

ailettes de la canule trouvent un appui inférieur sur le bloc de résine qui leg reçoit. Une bague de verrouillage 46, montrée en détails sur la figure 4b, articulée sur un point de rotation (51), manipulable grâce à un ergot 50, immobilise la canule en l'enserrant dans son encoche (49). Un picot (53) vient alors bloquer la bague, en pénétrant dans une dépression 52, ménagée sur la partie inférieure du bloc de résine. L'épaisseur de la bague 46 correspondant à la distance existant entre la partie proximale émergeante de la canule et son embout olivaire, la canule se trouve verrouillée sur le bloc de résine par la bague refermée.

Their removable nature allows their interchangeability according to surgical needs, and, at the end of the intervention, their cleaning and sterilization. FIG. 4a shows the elements of the DCA cannula holder device. 11 comprises a block of plastic resin 41, receives a primary sensor 40 which is fixed by bolting, is made removable by locking slides of known type not shown. Its shape allows an ergonomic grip. Its distal end is bored thus forming a bore 47 so as to allow the passage of an olive tip 45 of a removable cannula 42. The cannula has fins arranged in a star 44 which take place in housings arranged around the bore central, in this case the fins 48 formed hollow in the resin block 41. These fins ensure the correct centering of the cannula relative to this bore 47 and are not transfixing so that the proximal part of the

Cannula fins find a lower support on the block of resin which receives it. A locking ring 46, shown in detail in FIG. 4b, articulated on a point of rotation (51), which can be manipulated by a lug 50, immobilizes the cannula by enclosing it in its notch (49). A pin (53) then blocks the ring, by entering a depression 52, formed on the lower part of the resin block. The thickness of the ring 46 corresponding to the distance existing between the proximal part emerging from the cannula and its olive tip, the cannula is locked on the resin block by the closed ring.

Son détail est représenté sur la figure 5a. 11 est constitue d'un bloc en résine (60) présentant un évidement polygonal en son centre (61). Un recessus I latéral (66), permet d'y assujettir le capteur primaire du localisateur, fixé par boulonnage, ou par un système de glissières avec picots de blocage. The universe instrument holder! is intended to receive any instrument, at the operator's choice, the end of which will be used for surgical guidance.

Its detail is shown in Figure 5a. 11 is made of a resin block (60) having a polygonal recess in its center (61). A lateral recessus I (66) allows the primary locator sensor to be secured thereto, fixed by bolting, or by a system of slides with locking pins.

Two clamping screws allow the instrument to be locked against one of the internal walls of this recess.

These screws are arranged along two different axes (F-F ') and (G-G') so as to allow immobilization of IRON or IREC instruments, that is to say of which the section is circular as shown on Figure 5c (axis F-F ', screw (63)), seit

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rectangulaire comme montré sur la figure 5b (axe G-G', vis (62)). Une mollette (64) assure une bonne préhension de ces vis de serrage. Un patin (65), (par exemple en téflon'") et éventuellement articulé sur une rotule, permet d'exercer une pression suffisante sur l'instrument, sans l'abîmer.

rectangular as shown in Figure 5b (axis G-G ', screw (62)). A wheel (64) ensures good grip of these clamping screws. A pad (65), (for example in Teflon '") and possibly articulated on a ball joint, allows to exert sufficient pressure on the instrument, without damaging it.

Once secured in this universal instrument holder, the instrument-sensor pair must be calibrated, performed by the surgeon, according to the methodology described below, so that the navigator no longer works with the positions returned by the active center of the sensor, but with the actual position of the end of the chosen instrument.

The stereotaxic frames according to the invention, presented in FIGS. 6 to 11 serve both as a means of registration of images (registration), manual or automatic, and as a support for the referential system of the spatial locator (transmitter block or secondary reference sensor ).

Three points being necessary and sufficient to define a single support plane, the two external auditory canals and the nasion were chosen and form a support tripod precise and reproducible in time, because of their invanance due to the essentially bony supports . They are part of a plane similar to the radioanatomical plane of Frankfurt. Furthermore, their anatomical configuration forming reliefs oriented along complementary axes of space, promotes the stabilization of an external device. The stereotaxic frame system of the present invention uses these anatomical supports, which are lazy provided that the support and restoring forces exerted are properly distributed.

In order to obtain a system possibly allowing automatic readjustment, the frame comprises rigid segments, such that stereotaxic markers which are disposed therein form a rigid body with the transmitter block (or the so-called secondary sensor) of the spatial locator, such so that the vectors originating from the center of the emitting block and each marker at the end, become constant and definable once and for all, by construction.

Similarly, to allow the most precise spatial identification possible, it is desirable that these stereotaxic markers are distributed in a volume

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englobant le plus complètement possible, le volume de travail chirurgical dans lequel sera exploité le localisateur.

encompassing as completely as possible, the volume of surgical work in which the locator will be operated.

In order to ensure optimum precision for such a stereotaxic frame while keeping its manufacturing cost as low as possible, it is moreover desirable to limit the articulations which it may comprise to strict mechanical requirements.

The frame system of the present invention comprises rigid segments in which are arranged stereotaxic markers encompassing in height, width and depth, the entire surgical volume.

FIG. 6 shows the articulation mechanics of the system, so that it can be put in place and adapted to different anatomical configurations, characterized by variable positioning of the external auditory canals relative to the nasion. The frame comprises a rigid transverse bar (1), which is supported by a curved median notch 9, on the nasion P of a patient. Flexible lateral segments (2) allow the lateral blades (3) to be separated, themselves made of flexible material. An axis of rotation (23) is formed between the lateral segment elements (2) and the lateral lateral blades (3).

The combination of the rotation of the frame along a transverse axis (D-D ') and the rotation along said axis of rotation (23), allows the olive tips (4) to cover a sufficiently wide positioning area, to be able to adapt to different anatomical variations in height and depth, along an anteroposterior axis, external auditory canals that can be encountered in practice.

The spacing of the branches (3) allows the system to be placed on the patient, and at the same time adapts to the anatomical variations in the spacing of the external auditory organs. The zones (10), located in the posterior portion of the lateral branches (2), ensure that the frame is placed against the temporo-occipital regions, and reinforce the stability of the assembly, in particular avoiding rotation around an antero-axial axis. posterior passing through P. A system of return springs, placed between lateral segments (2) and the lateral webs (3)), exerts a force which tends to bring the olive tips (4) towards the nasion (P), and make the orthostatic frame.

The material used to produce the elements of the frame can be a plastic resin, for example polycarbonate, chosen for its relative radio-transparency,

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sa résistance mécanique, sa neutralité électromagnétique, et sa résistance aux températures élevées, permettant son éventuelle stérilisation à l'autoclave. L'axe de rotation (23) est réalisé par, exemple, par boulonnage, rondelle de serrage et contre- écrou.

its mechanical resistance, its electromagnetic neutrality, and its resistance to high temperatures, allowing its possible sterilization in an autoclave. The axis of rotation (23) is produced, for example, by bolting, tightening washer and lock nut.

For the frame intended for the radiological phase, the return spring already described, must not be radiopaque, so as not to artifact the acquisition of the imagery. For this purpose, an elastic rubber band can be used. For the frame intended for the surgical phase, the restoring effect can be obtained by means of a spiral spring, exerting its restoring force around the axis 23, and carrying out a counterclockwise thrust, according to the figure considered, around this same axis.

radiologique, la figure 8 celui utilisé pour la phase chirurgicale ä recalage automatique, et la figure 9, celui utilisé pour la phase chirurgicaie à recalage manuel. Figure 7 shows the general appearance of the stereotaxic frame used for the phase

FIG. 8, that used for the surgical phase with automatic registration, and FIG. 9, that used for the surgical phase with manual registration.

- de deux éléments latéraux antérieurs rigides (5), fixés à t'element (1) par un système de tenons vissés (20), confortés par un collage. A leur partie inférieure, ces éléments comportent des plots vissés (7), destinés à recevoir des marqueurs stéréotaxiques antéro-inférieurs (14) ; - de deux éléments latéraux flexibles 2 destinés ä prendre appui sur les régions temporales du patient et à supporter des lames latérales (3), porteuses d'embouts olivaires (4) s'adaptant sur les conduits auditifs externes du patient. Les lames latérales (3) ont une structure repliée en épingle, pour permettre leur écartement avec effet de ressort. Un axe (23), par exemple boulonné avec rondelle FIG. 10 describes the detail of the constituent elements of the frame used for the radiological acquisition, in top, anterior and right lateral view. 11 consists of: - a rigid transverse bar (1), resting in its center on the nasion of a patient, thanks to a notch 9 in rounded inverted "V", reproducing from front to back the obliquity of bottom to top of the nasal dorsum; This bar (1) has an embossing 8 produced above the nasal notch 9 and, for the surgical phase, two holes 11 intended to fix a secondary sensor or a transmitter block;

- two rigid front side elements (5), fixed to the element (1) by a system of screw studs (20), reinforced by bonding. At their lower part, these elements include screwed studs (7), intended to receive antero-lower stereotaxic markers (14); - two flexible lateral elements 2 intended to bear on the temporal regions of the patient and to support lateral blades (3), carrying olive tips (4) adapting to the external auditory canals of the patient. The side blades (3) have a folded pin structure, to allow their separation with spring effect. An axis (23), for example bolted with washer

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et contre-écrou, permet la rotation d'une la me latérale (3) sur un élément latéral flexible (2) ; - de réglettes latérales rigides (6), fixées au bloc formé par les éléments (1) et (5), rendues indépendantes des éléments latéraux (2), grâce à une découpe

aménagée dans ces mêmes lames. Ces réglettes sont destinées ä recevoir, ä leur partie la plus postérieure, des billes de marquage stéréotaxique (12) ; - des ressorts de rappel (24), constitués par exemple de bandes ou de cordons élastiques (radio-transparents), tendent ä refermer l'angle formé entre les éléments latéraux flexibles (2) et leg lames latérales (3). Leurs forces tendent ä rapprocher les embouts olivaies (4) de la barre transversale (1), et grâce ä l'appui de cette même barre sur le nasion (point P), rendent le système orthostatique ; - des marqueurs de repérage stéréotaxiques sont répartis aux points extrêmes du cadre, pour englober le plus grand volume possible : à savoir un marqueur 14 sur chacun des plots visés 7, un autre 12 sur chacune des réglettes latérales rigides 6 et un cinquième 13 sur la barre transversale rigide 1. Un minimum de trois marqueurs est nécessaire pour pouvoir déterminer leg équations de passage entre le système de coordonnées de l'imagerie, vers le système de coordonnées du localisateur spatial. Dans le cas où l'on désire ne travailler qu'avec des équations linéaires, 4 marqueurs sont nécessaires pour résoudre ces équations de transformation. D'autres marqueurs peuvent y être ajoutés, notamment dans le but d'augmenter la précision, en minimisant les erreurs de localisation, puisque celles-ci sont distribuées de manière habituellement stochastique. Si le nombre de marqueurs est supérieur à celui nécessaire à la solution de ces équations de transformation, on leg réduit par sommation des coefficients des fonctions aux dérivées partielles dont sont extraits ces points. En cas d'utilisation du cadre, en imagerie tomodensitométrique, ces marqueurs sont radio-opaques, par exemple, constitués de micro-billes d'acier inox de 2,5 mm de diamètre. Dans les autres cas, on utilise un matériau présentant une opacité optimale au mode d'imagerie choisi, tels des sels de gadolinium en IRM, etc....

and lock nut, allows the rotation of a lateral beam (3) on a flexible lateral element (2); - rigid lateral strips (6), fixed to the block formed by the elements (1) and (5), made independent of the lateral elements (2), by cutting

arranged in these same blades. These strips are intended to receive, at their most posterior part, stereotaxic marking balls (12); - return springs (24), consisting for example of elastic bands or cords (radio-transparent), tend to close the angle formed between the flexible lateral elements (2) and the lateral blades (3). Their forces tend to bring the olive tips (4) closer to the crossbar (1), and thanks to the support of this same bar on the nasion (point P), make the system orthostatic; - stereotaxic marking markers are distributed at the extreme points of the frame, to encompass the greatest possible volume: namely a marker 14 on each of the studs referred to 7, another 12 on each of the rigid lateral strips 6 and a fifth 13 on the rigid crossbar 1. A minimum of three markers is necessary to determine the transition equations between the coordinate system of the imagery and the coordinate system of the spatial locator. In the case where one wishes to work only with linear equations, 4 markers are necessary to solve these transformation equations. Other markers can be added to it, in particular with the aim of increasing precision, by minimizing localization errors, since these are usually distributed in a stochastic manner. If the number of markers is greater than that necessary for the solution of these transformation equations, we reduce by summing the coefficients of the functions with partial derivatives from which these points are extracted. When using the frame, in computed tomography imaging, these markers are radiopaque, for example, made up of 2.5 mm diameter stainless steel micro-balls. In the other cases, use is made of a material having optimal opacity for the chosen imaging mode, such as gadolinium salts on MRI, etc.

The frame used for the surgical phase is designed in two different versions:

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- seit un cadre ä recalage automatique, totalement dépourvu de marqueurs stéréotaxiques, le bloc émetteur ou le capteur secondaire de référence, étant fixé en un point prédéterminé du cadre, à distances fixes et connue des différents marqueurs stéréotaxiques utilisés dans la phase radiologique d'imagerie médicale.

- an automatically resettable frame, totally devoid of stereotaxic markers, the transmitter block or the secondary reference sensor, being fixed at a predetermined point of the frame, at fixed distances and known to the various stereotaxic markers used in the radiological imaging phase medical.

This version replaces the element (5) previously described, by an element (5 '), devoid of antero-inferior expansion; - either a frame allowing manual registration, in this case comprising instead of stereotaxic marking balls, blind channels, the coordinates of the bottom of which correspond to the center of the micro-marking balls of the radiological version of this framework system . Manual registration then consists in recording the virtual position of the center of each of these markers, using a tapered stylus system adapted to the diameter of these channels, and subject to a primary position sensor as mentioned in FIG. 12.

In both cases, the return element (24) may be replaced by a spiral spring placed around the axis 23, exerting the same effect.

Arched notches (29) allow the surgeon to exert pressure on the eyeballs, a maneuver frequently used in surgery of the ethmoid complex.

The other components of the frames intended for the surgical phase also remain identical to those used for the imaging acquisition phase.

Figure 11 describes the version of this frame system, used for the automatic resetting surgical phase. 11 has the same characteristics as that described above, with the exception of the stereotaxic markers.

The frame intended for the surgical phase, with manual registration is not shown in detail, because it is in all points similar to the frame used for the radiological phase, with the following exceptions: - the radiological marking beads are eliminated; - the bottom of the blind holes which contain these balls corresponds to the geometric center of the balls of the radiological frame. For example, if the blind holes are 7 mm deep and receive a 2.5 mm ball on the radiological frame, the manual resetting surgical frame will be pierced with the same blind holes, in the same directions, but of depth 7- ( 2.5 / 2) = 5.75 mm;

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- Le système élastique de rappel, est remplacé par un ressort spiral 18.

- The elastic return system is replaced by a spiral spring 18.

The characteristics of these frames are such that they can be used on most anatomical configurations of adult patients. It is nevertheless easy to design upward dimensional variants, intended for patients with hypertrophic craniofacial morphology, or even downward, for pediatric use of this framework system.

étape, qui est décrite en détail sur la figure 13, les coordonnées (x, y, z) de ces centres géométriques sont stockées dans un fichier informatique associé au dossier du patient, en vue d'un éventuel recalage manuel. En même temps, les équations de transformations de coordonnées sont calculées par le micro-ordinateur, en vue d'une utilisation ultérieure du système en mode de recalage automatique. Dans ce dernier cas, la position virtuelle des marqueurs situés sur le cadre, par rapport au centre actif du bloc émetteur du localisateur (ou du capteur secondaire de référence) étant fixe et pré-déterminée par construction, ce calcul peut se faire de manière automatique, à partir des valeurs de coordonnées desdits marqueurs, stocké dans un fichier de paramètres. The methods of using this system of stereotaxic frames are as follows, explained with reference to FIG. 12. In all cases, the patient is carrying a frame No. 1 (radiological acquisition, during the acquisition phase of its anatomical imagery, carried out in a radiology room. A pre-surgical phase, which can take place immediately after the radiological phase, or on the contrary, just before the surgical phase, consists in importing the images thus produced on the hard disk of the microphone -computer, after having reformatted them, reconstructed according to three-dimensional incidences and after having detected the geometric centers of the imprints left by the stereotaxic markers on these images.

step, which is described in detail in FIG. 13, the coordinates (x, y, z) of these geometric centers are stored in a computer file associated with the patient's file, with a view to possible manual registration. At the same time, the coordinate transformation equations are calculated by the microcomputer, with a view to later use of the system in automatic registration mode. In the latter case, the virtual position of the markers located on the frame, relative to the active center of the transmitter block of the locator (or of the secondary reference sensor) being fixed and pre-determined by construction, this calculation can be done automatically , from the coordinate values of said markers, stored in a parameter file.

programmé pour son patient, s'il peut utiliser sans risque d'être gêné durant son geste, le cadre ä recalage automatique. C'est généralement le cas, puisque celui-ci a été conçu de manière ä être compatible avec la plupart des procédures chirurgicales cranio-faciales. During the surgical phase, the surgeon decides, depending on the intervention he has

programmed for his patient, if he can use without risk of being hampered during his gesture, the automatic adjustment frame. This is generally the case, since it has been designed to be compatible with most craniofacial surgical procedures.

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Dans cette hypothèse qui correspond au choix (a) sur la figure 12, la mise en place du cadre et du bloc émetteur, ou du capteur secondaire de référence, suffit au recalage des images, puisque les appuis anatomiques sont les mêmes que ceux utilisés lors de la phase d'acquisition des images, et le système peut fonctionner aussitôt.

In this hypothesis which corresponds to choice (a) in FIG. 12, the setting up of the frame and the transmitter block, or of the secondary reference sensor, is sufficient for the registration of the images, since the anatomical supports are the same as those used during of the image acquisition phase, and the system can operate immediately.

de référence, étant dès lors recalés vis à vis des repères anatomiques précités. In the event that the surgeon wishes to work on an area obliterated by the facial frame, it is possible to get rid of the frame previously described during the operating phase by proceeding as follows: a system with autostatic attachment, described. in the following, is fixed at a distance from the operating site, for example on the patient's scalp (choice (b) of FIG. 12). Then a third type of stereotaxic frame, similar to that used for the radiological phase, that is to say comprising pointing marks, placed at the same locations as the stereotaxic markers, is placed on the patient. Then the virtual coordinates of the frame markers are acquired, thanks to a pointing stylus, then, this "manual surgical registration" frame is removed, the transmitter block or the secondary sensor

of reference, being therefore readjusted with respect to the above-mentioned anatomical landmarks.

 The device carrying the emitter block or secondary sensor allows the stable fixation of the latter at any point of the cephalic end of the patient, if, as explained above, the surgeon decides to get rid of the stereotaxic frame during the surgical phase .

The universal autostatic reference block device is a device complementary to the stereotaxic frames according to the invention and makes it possible to operate without a stereotaxic frame.

du patient, il est plus particulièrement destiné ä être fixé sur le scalp du patient, par exemple en régions temporales, pariétale, ou au sommet du crâne. Although it can be fixed at any stable point on the head end

of the patient, it is more particularly intended to be fixed on the patient's scalp, for example in temporal regions, parietal, or at the top of the skull.

Figure 15 illustrates its principle of support, and Figure 16, the detail of its constituent elements.

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Schématiquement, il est formé d'une platine 75, sur laquelle est fixé un bloc émetteur ou un capteur secondaire de référence 74. Des patins articulés 72 sont disposés de part et d'autre de la platine 75 et présentent à leur extrémité inférieure des picots 77, permettant d'exercer un appui sans glissement sur le scalp. Ils sont suffisamment nombreux et répartis, pour que la pression exercée sur chacun d'entre eux, soit faible et non-vulnérante. Le système est fixé sur l'extrémité céphalique du patient, grâce à une sangle élastique 79 éventuellement munie d'un agrafage rapide type velcro Le scalp présentant habituellement un certain degré de mobilité par rapport à la galéa (os de la voûte crânienne), le système présenté ici, permet d'exercer une traction du scalp de dehors en dedans tendant à immobiliser le scalp sur le plan osseux sous-jacent en le redrappant de part et d'autre des patins d'appuis du dispositif (flèches B et B'), conjointement à l'effort exercé sur la platine (fläche C) ce qui a pour effet d'améliorer la stabilité et l'autostatisme du système.

Schematically, it is formed by a plate 75, on which is fixed a transmitter block or a secondary reference sensor 74. Articulated pads 72 are arranged on either side of the plate 75 and have spikes at their lower end 77, allowing to exert a support without sliding on the scalp. They are sufficiently numerous and distributed, so that the pressure exerted on each of them is low and non-annoying. The system is fixed to the cephalic end of the patient, thanks to an elastic strap 79 possibly fitted with a quick hook-and-loop fastening. The scalp usually exhibits a certain degree of mobility relative to the galea (bones of the cranial vault), the system presented here, allows to exert a traction of the scalp from outside inside tending to immobilize the scalp on the underlying bony plane by grabbing it on either side of the support pads of the device (arrows B and B ' ), together with the force exerted on the plate (arrow C) which has the effect of improving the stability and autostatism of the system.

The manual registration frame is then temporarily positioned on the patient, and. respecting a pre-established order, a manual resetting stylus, consisting of a primary position sensor, a push button and a tapered part whose cross section is adapted to the size of the pointing blind holes described above, is connected to the locator and then its working end introduced into each pointing hole. The coordinates of the bottom of each of these holes, is entered by the microcomputer cut to the space locator, when the operator presses the push button of the stylus.

All the holes pointed, it is therefore possible to remove the manual registration frame: the transmitter block (or the secondary reference sensor) relocated, for example on the patient's scalp, are readjusted by the same calculation algorithm as that used for automatic registration (figure 14).

 In addition, the set of software routines ensures: - the loading of images from the medical imager, their reconstruction according to axial coronal and sagittal planes, and their storage on the hard disk of the microcomputer;

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- la lecture des paramètres stockés dans l'en-tête du fichier de ces images, comportant notamment leg caractéristiques de ces images (épaisseur des coupes, taille des pixels, format de la matrice des images, identification du patient,...).

- the reading of the parameters stored in the header of the file of these images, comprising in particular the characteristics of these images (thickness of the sections, size of the pixels, format of the matrix of the images, identification of the patient, etc.).

- - - déterminer les composantes (Vx, Vy, Vz) du vecteur ayant pour origine le centre du capteur primaire, et pour extrémité, la partie distale de l'instrument opératoire dont on désire connaître la position de l'extrémité lors de la phase chirurgicaie ; - une routine permettant l'appel des coupes anatomiques correspondant aux coordonnées réelles de l'instrument, et l'affichage en surimpression d'un curseur indiquant sur les dites coupes, la position effective de cet instrument par rapport à l'anatomie du patient ; - un utilitaire permettant la gestion des dossiers patients, et notamment leur suppression du disque dur, lorsqu'ils sont devenus inutiles ; - différents utilitaires permettant un planning pré-chirurgical, c'est à dire, permettant une navigation virtuelle dans le volume anatomique constitue par l'imagerie du patient dans le but de perfectionner le diagnostic, étudier les éventuelles anomalies et préparer une stratégie opératoire, en mesurant angles et dimensions relatives des structures anatomiques, et éventuellement, en délimitant au moyen, par exemple, d'une souris ou d'une tablette graphique, certaines structures à réséquer ou au contraire à respecter impérativement, et en définissant, éventuellement des alarmes qui se déclencheront sous forme d'un message avertissant le chirurgien si son instrument s'approche d'une zone à haut risque chirurgical. - a utility for calibrating the surgical instrument used, allowing

- - - determine the components (Vx, Vy, Vz) of the vector originating from the center of the primary sensor, and for the end, the distal part of the operating instrument, the position of the end of which is desired during the phase surgery; - a routine allowing the call of the anatomical sections corresponding to the real coordinates of the instrument, and the display in superimposition of a cursor indicating on the said sections, the effective position of this instrument relative to the anatomy of the patient; - a utility allowing the management of patient files, and in particular their deletion from the hard disk, when they have become useless; - various utilities allowing pre-surgical planning, that is to say, allowing virtual navigation in the anatomical volume constituted by the patient's imagery with the aim of perfecting the diagnosis, studying any anomalies and preparing an operating strategy, measuring angles and relative dimensions of the anatomical structures, and possibly, by delimiting by means, for example, of a mouse or a graphic tablet, certain structures to be resected or on the contrary to be imperatively respected, and by defining, possibly alarms which will be triggered in the form of a message warning the surgeon if his instrument approaches an area with high surgical risk.

automatique étant basée, par exemple, sur l'intensité des pixels représentant les marqueurs, sur le secteur de l'image à laquelle ils appartiennent, ainsi que sur leur géométrie. - the automatic detection of the stereotaxic markers, shown in FIG. 13, the analysis of their order, and the recording of the coordinates of their respective centers so as to be able to subsequently recreate the equations of registration of the images relative to the coordinates of the spatial locator , this detection

automatic being based, for example, on the intensity of the pixels representing the markers, on the sector of the image to which they belong, as well as on their geometry.

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Ce procédé de détection automatique des marqueurs stéréotaxiques sur les images issues de la phase radiologique comporte une première étape consistant à charger toutes les images, par exemple en mémoire vive de l'ordinateur MO, puis, pour chacun des pixels de chaque image à lire l'intensité de ce pixel puis, à comparer sa valeur avec une valeur de consigne. Cette valeur de consigne est choisie de sorte

qu'aucun élément du corps humain ne puisse avoir une telle valeur, sauf peut-être une prothèse métallique.

This method of automatic detection of stereotaxic markers on images from the radiological phase comprises a first step consisting in loading all the images, for example into the RAM of the computer MO, then, for each of the pixels of each image to be read. intensity of this pixel then compare its value with a set value. This setpoint is chosen so

that no element of the human body can have such a value, except perhaps a metallic prosthesis.

In the case where the intensity value is less than the set value, the coordinates of said pixel are not retained and the next pixel is analyzed.

In the case where the intensity value is greater than the set value, the coordinates (x, y, z) of said glove pixel stored in memory, for example in an array. then the next pixel is analyzed.

When all the pixels of all the images have been compared with the set value, the second step consists in sorting said pixels stored in memory according to increasing or decreasing values of values of x and then in storing the coordinates of the first groups of pixels. juxtaposed and then sorting said groups of pixels stored in memory according to increasing or decreasing values of values of y then storing the coordinates of the second groups of pixels also juxtaposed according to y, so as to constitute zones of contiguous pixels, then to compare each of the zones thus obtained with a setpoint zone corresponding to the shape of the stereotaxic markers in the x and y directions.

In a third step, and for the zones conforming to said setpoint zone, a zone table of indexed coordinates (x, y, z) is generated and the center of each zone is determined, then a sorting is carried out according to z to determine all the zones which have this same center, then the center of the three-dimensional zones then obtained is determined and each of these zones corresponding to a stereotaxic marker and then identified for example by ordinal numbering.

A comparison of said three-dimensional zones with a setpoint value for the volume of the markers makes it possible to eliminate the detection of elements having the same shape as the markers along x and y. In addition, a comparison between the number of three-dimensional areas detected and the number of markers used in phase

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radiologique est faite de façon ä s'assurer qu'il y a identité entre les deux nombres. Par ailleurs, un calcul de la distance euclidienne entre leg différentes zones et une comparaison de ces distances avec des valeurs de consignes permettent de déterminer si la détection est correcte.

X-ray is done to ensure that there is identity between the two numbers. Furthermore, a calculation of the Euclidean distance between the different zones and a comparison of these distances with setpoint values makes it possible to determine whether the detection is correct.

 In its version intended to carry out iterative radiological explorations deferred in time and carried out according to the same incidences, the system can be limited to the isolated use of the stereotaxic frame comprising marking markers which will be used in a protocol for positioning the skull of the patient vis-à-vis the imager using for example a "scout-view" mode of the imager.

 In another configuration, the complete system can be used, the space locator, or an aiming system (for example by clogged laser beams) being fixed to the stand of the imager.

 In this case, rigorously superimposable radiological incidences can be obtained, by adjusting the inclination of the stand of the imager, the relative displacement of the radiological table, and the position of the cephalic end of the patient.

 In its version intended to perform craniofacial radiotherapy sessions by positioning the patient's head in a rigorously reproducible manner with respect to the radiogenic system, the system includes the use of a stereotaxic frame on which is fixed a primary position sensor and a spatial locator stably fixed to the stand of the X-ray system and associated with a microcomputer configured to allow the position analysis of the stereotaxic frame, or else a sighting system by laser beams, making it possible to dispense with the spatial locator.

 Whatever the mode of registration chosen, automatic or manual, the registration phase is carried out by an automatic calculation algorithm performed by the microcomputer MO. It consists in determining the rotation and translation matrices, which make it possible to match a point in geometric space (OxS, OyS, OzS) specific to the locator, to its counterpart in the system of

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repères géométriques (oxyl, Oyl, Ozl) propre au volume dans lequel a été acquise l'imagerie du patient.

geometric markers (oxyl, Oyl, Ozl) specific to the volume in which the patient's imagery was acquired.

 Let (Sx, Sy, Sz) be the Cartesian coordinates of a point P in the system (OxS, OyS, OzS) of the spatial locator and (Ix, Iy, Iz), the coordinates of the point P'which corresponds to it, in the system (0x1, 0y1, 0z1).

 The coordinates of the point P 'can be expressed by: P' = P. [MJ + [MJ (1) where [Mr] is a rotation matrix and [MJ a translation matrix.

Kz), où les lettres a à g représentent les coefficients de la matrice de rotation et Kx, Ky, Kz, les élements de la matrice de translation. The developed form of equation (1) leads in practice to the following parametric equations:
Ix = (a. Sx) + (b. Sy) + (c. Sz) + Kx Iy = (d. Sx) + (e. Sy) + (f. Sz) + Ky (2) Iz = (g. Sx) + (h. Sy) + (i. Sz) + Kz is a system of equations with 12 unknowns (a, b, c, d, e, f, g, h, i, Kx, Ky,

Kz), where the letters a to g represent the coefficients of the rotation matrix and Kx, Ky, Kz, the elements of the translation matrix.

 Thus, 4 distinct points (ie 4 * 3 scalar values of coordinates) are therefore necessary and sufficient, to solve this system of linear equations. In other words, the stereotaxic system must include a minimum of 4 markers to be matched between the system (Oxl, Oyl, Ozl) and the system (0xS, OyS, OzS).

 However, the rotation matrix [Mr] having the expanded form: cos (A) cos (E) sm (A) cos (E) -sm (E) [M,] = cos (A) sm (E) sm ( R) sin (A) cos (R) sm (A) sin (E) sm (R) + cos (A) cos (R) cos (E) sm (R) (3) cos (A) sm (E) cos (R) + sm (A) sm (R) sm (A) sm (E) cos (R) -cos (A) sm (R) cos (E) cos (R)

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translation d'origine, du système (OxS, OyS, OzS) vers le système (Oxl, Oyat, Ozl). 11 en résulte que, ä condition de pouvoir résoudre des équations trigonométriques du troisième degré, le système d'équations linéaires initial ä 12 inconnues, peut être réduit ä un système d'équations ä 6 inconnues, c'est ä dire, pouvant être résolu avec seulement 6 valeurs de coordonnées. Toutefois, un plan ne pouvant être défini géométriquement avec seulement 2 points, les 6 valeurs scalaires de coordonnées devront être extraites de trois points distincts, pour trouver une solution à ces équations. and the matrix [Mt] [Mt] = (Kx, Ky, Kz) (4) equation (2) can be expressed by only 6 unknowns: (A, E, R), the Eulerian angles of passage and ( Kx, Ky, Kz), the components of the vector of

original translation from the system (OxS, OyS, OzS) to the system (Oxl, Oyat, Ozl). It follows that, provided that trigonometric equations of the third degree can be solved, the initial system of linear equations with 12 unknowns can be reduced to a system of equations with 6 unknowns, that is to say, which can be solved with only 6 coordinate values. However, a plane cannot be defined geometrically with only 2 points, the 6 scalar values of coordinates will have to be extracted from three distinct points, to find a solution to these equations.

 However, mathematical algorithms of resolution by method of iterative directional gradients (for example, algorithm of Levenberg-Marquardt), make it possible to solve by incremental substitution of the equations impossible to solve otherwise, on condition of defining an interval of solution to the algorithm of calculation, to avoid blocking of calculation loops in a local minimum.

 The method for calculating the transformation matrices necessary for registration of the images of the present invention uses a combination of these two methods.

 The stereotaxic frames being provided with five stereotaxic markers (a lower or higher number of markers is possible), a first calculation is carried out by linear method (for example, method of the pivots of substitution of Gauss-Jordan) starting from 4 markers, for define the calculation intervals of the second method (trigonometric equations of the third order), more efficient since it allows a direct definition of the Eulerian angles of transformation.

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The five marking points represented by the five stereotaxic references are then optimized by the method of least squares, after calculation of the coefficients of the partial derivatives of the functions of transformations which they represent, to be reduced into 6 scalar values of coordinates.

 The second advantage of the method using a resolution by trigonometric equations, is that it is thus possible to make a possible readjustment during intervention starting from only 2 points or less, depending on the drift to be corrected, by using a matrix d 'preliminary approximation.

The calibration process is as follows:
The primary position sensor is not introduced inside the patient's body, but fixed on a surgical instrument, and forms with it a rigid body (or sufficiently rigid, to be considered as such).

 By calibration, we mean the operation making it possible to determine the components of the vector V originating from the active center of the fixed primary sensor on the surgical instrument used for locating, and for its end, the distal part of this instrument, of which it is desired. deduce the coordinates from those of the primary sensor.

d'une matrice de rotation [Mrl et d'une matrice de translation [MJ, de la forme : p = C. [M,] + [MJ (5) Où la matrice de rotation [M,] permet de décrire la transformation des coordonnées d'un point quelconque soumis à un jeu de rotations combinées d'angles (d'azimut : A ; d'élévation : E et de roulis : R) sur ses axes eu ! riens (OX, OY, OZ). Sa forme développée s'exprime par la matrice trigonométrique d'ordre 3 : Seit C, the active center of the sensor, P the end of the surgical instrument, and (Vx, Vy, Vz) the components of the vector V. The coordinates (Px, Py, Pz) of P are related to the coordinates (Cx, Cy, Cz) of C, by the combination, again,

a rotation matrix [Mrl and a translation matrix [MJ, of the form: p = C. [M,] + [MJ (5) Where the rotation matrix [M,] allows to describe the transformation coordinates of any point subjected to a set of combined rotations of angles (azimuth: A; elevation: E and roll: R) on its axes eu! nothing (OX, OY, OZ). Its developed form is expressed by the trigonometric matrix of order 3:

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cos (A) cos (E) sin (A). cas (E)-sin (E) [M,] = cos (A). sin (E). sm (R)-sin (A). cos (R) sin (A). sin (E). sin (R) + cos (A). cos (R) cos (E). sin (R) (6) cos (A). sin (E) cos (R) +sin (A) sin (R) sin (A) sin (E) cos (R)-cos (A). sin (R) cos (E). cos (R)

où la matrice de translation [Mt] permet de décrire la transformation des coordonnées d'un point quelconque soumis à un déplacement quelconque par rapport à l'origine de ses axes eulériens (OX, OY, OZ). Sa forme développée s'exprime par : [MJ = (x, y, z) (7)
Le localisateur spatial étant capable de renvoyer ä la fois les coordonnées de position (x, y, z) et les angles d'attitude (A, E, R), décrivant le point C, il est possible

de connaître les composantes du vecteur V, en résolvant l'équation matricielle : [MJ = C. [MJ-P (8) et où la matrice [MJ représente ici, les composantes (Vx, Vy, Vz) du vecteur V, c'est ä dire, leg caractéristiques de dimensions de l'instrument utilisé pour le guidage chirurgical.

cos (A) cos (E) sin (A). case (E) -sin (E) [M,] = cos (A). sin (E). sm (R) -sin (A). cos (R) sin (A). sin (E). sin (R) + cos (A). cos (R) cos (E). sin (R) (6) cos (A). sin (E) cos (R) + sin (A) sin (R) sin (A) sin (E) cos (R) -cos (A). sin (R) cos (E). cos (R)

where the translation matrix [Mt] makes it possible to describe the transformation of the coordinates of any point subjected to any displacement relative to the origin of its Eulerian axes (OX, OY, OZ). Its expanded form is expressed by: [MJ = (x, y, z) (7)
The spatial locator being able to return both the position coordinates (x, y, z) and the attitude angles (A, E, R), describing point C, it is possible

to know the components of the vector V, by solving the matrix equation: [MJ = C. [MJ-P (8) and where the matrix [MJ represents here, the components (Vx, Vy, Vz) of the vector V, c that is, the dimensional characteristics of the instrument used for surgical guidance.

 The development of equation (4), formed of a matrix [3 * 3] and a matrix [3 * 1], leads to the constitution of a system of 6 equations with 6 unknowns, 3 of these unknowns being the scalar values of (Vx, Vy, Vz), the other 3 unknowns being the coordinates Px, Py, Pz of the point P. 11 it is therefore theoretically necessary to obtain a minimum of 6 measures of coordinates of C, while P must be kept fixed on a pivot point, to be able to solve the system of equations formed by the development of the matrix equation (4). To do this, the coordinates of P are kept constant, and the block formed by the sensor fixed on the operating instrument is moved around this fixed pivot point (Figure 17). The surgical frames include a standard conical obviously point (reference 15, Figures 8 and 11), intended for this purpose.

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On obtient (en écriture non-développée) le système d'équations : (c y z,). [Mr] + [MJ = P (c2, y2, z2).[Mr] + [Mt] = P (9) (c y z,). [Mr] + [MJ = P (C4, y4, z4).[Mr] + [Mt] = P (c5,y5,z5).[Mr]+[Mt]=P (c6, y6, z6).[Mr] + [Mt] = P
En pratique, le point de pivot étant imparfait, l'instrument comportant toujours un certain degré de flexibilité et les mesures étant toujours affectées d'un certain niveau de bruit, la solution mathématique obtenue est le plus souvent incohérente ou trop éloignée de la dimension réelle du vecteur V, pour être exploitable. La solution consiste alors à réaliser un nombre de mesures n # 6, dont la sommation permet de minimiser suffisamment ces erreurs, pour aboutir à une solution physiquement cohérente et suffisamment précise.

We obtain (in undeveloped writing) the system of equations: (cyz,). [Mr] + [MJ = P (c2, y2, z2). [Mr] + [Mt] = P (9) (cyz,). [Mr] + [MJ = P (C4, y4, z4). [Mr] + [Mt] = P (c5, y5, z5). [Mr] + [Mt] = P (c6, y6, z6). [Mr] + [Mt] = P
In practice, the pivot point being imperfect, the instrument always comprising a certain degree of flexibility and the measurements being always affected by a certain level of noise, the mathematical solution obtained is most often inconsistent or too far from the real dimension of the vector V, to be usable. The solution then consists in carrying out a number of measurements n # 6, the summation of which makes it possible to minimize these errors sufficiently, to arrive at a physically coherent and sufficiently precise solution.

 To be able to reduce the measurement values to the number of equations required for the resolution of the system they form (6), we consider that each of these 6 equations forms a function of type f (Vx, #y, Vz, Pc, Py, Pz) converging towards a minimum, very close to the solution.

comme des coefficients d'un nouveau système de 6 équations aux dérivées partielles, et ainsi, d'introduire un nombre quelconque (mais > 6) de mesures. The calculation of the partial derivatives of these functions then makes it possible to consider the measurement values of Cc, Cy, Cz, Ca, Ce, Cr (which respectively describe the coordinates and the angles of attitude of the sensor C with respect to the pivot point) ,

as coefficients of a new system of 6 partial differential equations, and thus, to introduce any number (but> 6) of measures.

After solving these equations by an algorithm, for example based on the iterative Gauss-Jordan substitution method (linear solver), or even based on a Levenberg-Marquardt type gradient solver (n order solver),

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on aboutit ainsi ä un résultat dont la précision croît avec le nombre de mesures effectuées.

this results in a result whose precision increases with the number of measurements made.

 Subject to respecting a correct operation of the instrument without leaving the pivot point P, a calibration is obtained, the precision of which remains on the order of the intrinsic precision of the spatial locator. The universal instrument holder system (FIG. 5) makes it possible to create a rigid body by associating a primary sensor with any surgical instrument, of circular or rectangular section.

est bonne, seit qu'elle est acceptable, ou bien, qu'elle doit être recommencée. Si la v-F calibration est validée, les valeurs ("y, Vz) sont stocköes dans un fichier, de manière ä éviter t'operateur d'avoir ä refaire cette calibration en cas d'interruption du système informatique de navigation. Furthermore, knowing the coordinates of the points P, makes it possible to carry out statistical tests to ensure the validity of the values (#x, Vy, Vz), by comparing the coordinates of this point P recalculated for each measurement, with the dimensions of the vector V. According to the dispersion of the measurements thus obtained, a message is displayed on the screen of the microcomputer, indicating, that the calibration

is good, whether it is acceptable, or whether it must be repeated. If the vF calibration is validated, the values ("y, Vz) are stored in a file, so as to avoid the operator having to redo this calibration in the event of an interruption of the computer navigation system.

Glove pre-surgical planning tools annexed to the navigation program.

chirurgie, réputée difficile tant sur le plan de sa gestuelle, que des structures anatomiques-repères, à prendre en compte. They consist of: - A graphical interface module (software) allowing the surgeon, thanks to the simultaneous use of the locator, or else thanks to cursors, to move in the anatomical volume represented by the series of images, and to visualize step by step the structures it will encounter, in vivo, during the intervention. This modality can also be very useful, for example to train a student in this type of

surgery, deemed difficult both in terms of its gestures and anatomical landmarks to take into account.

 - Graphic tools, allowing the measurement of distances, angles, volumes (for example, forecasting the volume of a lesion to be resected.

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- Graphic tools allowing to delimit, for example azide of a computer mouse or a graphic tablet, the dangerous anatomical zones (internal carotids, cerebral floor, olfactory placode, orbital cone, optic nerves, ...) and set alarms. An audio message can then be generated by the computer, if the end of the working instrument approaches these structures below a determined value.

 The navigation system can also be programmed to record in a computer file, the position of the operating instrument inside the patient's body, throughout the intervention. This subsequently makes it possible to know the entire anatomical volume in which the end of the instrument has evolved, or even to update the imagery used, during the intervention.

 Of course, numerous modifications can be made to the embodiment described above without departing from the scope of the invention.

marqueurs stéréotaxiques radio-opaques selen la méthode précédemment décrite. Thus, the registration of the images, in the present invention, can also be carried out by a more sophisticated device, but making it possible to overcome the

radiopaque stereotaxic markers according to the method previously described.

mécanique avec leg téguments, et éliminant également, pour les même raisons, la nécessité d'utiliser un système stérile, ce qui autorise, sans contrainte, son emploi même après que l'intervention ait débuté. As explained above in the present invention, the essential problem of the technique of registration of images by the technique of surface matching, lies in the deformation of the integuments by the probe used to collect registration points on the patient. The following technique offers a solution to this problem, thanks to the use of a collimated light spot, eliminating all contact.

mechanical with leg integuments, and also eliminating, for the same reasons, the need to use a sterile system, which allows, without constraint, its use even after the intervention has started.

 This variant uses a small box handled by the surgeon or an assistant before the intervention, or during the intervention, if an intraoperative registration of the images proves necessary.

 This box contains a primary position sensor connected to the DL location device, an aiming device using a laser beam emitting in visible radiation, and a telemetric system allowing to know the distance separating a zero point located in the box, from the light spot generated by the beam

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 aiming laser. This distance is coded, for example in binary form, and addressed to the microcomputer via an appropriate port.

zéro du système télémétrique, et d'autre part le système télémétrique étant agencé de telle sorte par rapport à ce capteur primaire que son axe de mesure seit situe sur l'un des axes orthogonaux du système orthonormé propre à ce capteur primaire, par exemple l'axe 0-X, le faisceau laser de visée étant rendu coaxial ä l'axe de mesure dudit système télémétrique, il est dès lors possible de connaître la position du spot de visée Pv situe à une distance dx du point zéro du système télémétrique, ä partir des valeurs de position (x, y, z) et des angles d'attitude (alpha, bêta, gamma) dudit capteur primaire par l'équation suivante :
Pv = (x + x, + dx, y + Y1, z + z) [Mr] où [Mr] est la matrice de rotation trigonométrique construite à partir des angles d'attitude du capteur, comme précédemment exposé. Knowing on the one hand, by manufacturing, the components (x1, y1, z1) of the vector having for origin the center of the primary sensor and for end the point

zero of the telemetric system, and on the other hand the telemetric system being arranged so with respect to this primary sensor that its measurement axis is located on one of the orthogonal axes of the orthonormal system specific to this primary sensor, for example l axis 0-X, the aiming laser beam being made coaxial with the measurement axis of said telemetric system, it is therefore possible to know the position of the aiming spot Pv located at a distance dx from the zero point of the telemetric system, from the position values (x, y, z) and the attitude angles (alpha, beta, gamma) of said primary sensor by the following equation:
Pv = (x + x, + dx, y + Y1, z + z) [Mr] where [Mr] is the trigonometric rotation matrix constructed from the attitude angles of the sensor, as previously exposed.

 According to this principle, this device is capable of acquiring a set of skin contour points on the cephalic end of the patient, while a reference transmitter block or a secondary sensor is fixed, as previously described in the present invention, any point on the patient's head end.

 This matrix of points, compared with the matrix of surface contour points of the anatomical images used for surgical guidance, then makes it possible to determine the equation of registration of the images, according to known calculation methods carried out by the microcomputer.

d'autre part, d'une caméra CCD associée ä un filtre correspondant ä la longueur d'onde du laser. Cette caméra CCD présente une angulation connue par construction par rapport à l'axe de ce faisceau laser. Des lors, connaissant le temps The telemetry system used can for example be made up of a visible diode laser beam also serving in this case as an aiming system and

on the other hand, a CCD camera associated with a filter corresponding to the wavelength of the laser. This CCD camera has a known angulation by construction with respect to the axis of this laser beam. From then on, knowing the weather

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lequel défini par construction, il est alors possible de déduire la distance séparant le spot laser de la surface active du capteur CCD. separating the start of image synchronization top from the video signal peak corresponding to the laser spot, which time is measured by a chronometric system and on the other hand the angle formed between the camera and the laser beam

which defined by construction, it is then possible to deduce the distance separating the laser spot from the active surface of the CCD sensor.

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deuxième lames latérales (3). 1. Stereotaxic frame in particular for radiological and / or surgical use comprising a rigid transverse bar (1) comprising two ends and a groove in its lower median part, first and second lateral segments (2) disposed respectively at one and at the other of said ends of the transverse rigid bar (1), first and second lateral blades (3) connected respectively to the first and second lateral segments (2) by an axis of rotation, and first and second olive end pieces respectively secured to said first and

second side blades (3).

2. stereotaxic frame according to claim 1, characterized in that at least two of said first and second lateral segments (2) or of said first and second lateral blades (3) are flexible
3. stereotaxic frame according to claim 2, characterized in that the first and second lateral segments (2) are flexible and in that a first and a second rigid lateral strip (6) are disposed respectively at one and at the other of said ends of the transverse rigid bar (1), and / or in that the first and second lateral segments (2) comprise a rigid part situated on the side of the transverse rigid bar and a flexible part situated on the opposite side.

 4. stereotaxic frame according to any one of claims 1 to 3, characterized in that it comprises first and second rigid front segments (5) disposed respectively at one and at the other of said ends of the rigid bar transverse (1) and making an angle of at least n / 4 Rd with said transverse rigid bar (1) and with said lateral segments (2).

 5. stereotaxic frame according to any one of claims 3 and 4, characterized in that it comprises at least one stereotaxic marker disposed in one and / or the other of the first and second strips

Claims (6)

rigid lateral (6) and / or in one and / or the other of the first and second rigid anterior segments (5).  6 stereotaxic frame according to any one of claims 1 to 5, characterized in that it comprises at least one stereotaxic marker disposed in the transverse rigid bar (1).  7. stereotaxic frame according to any one of claims 5 and 6, characterized in that at least one of said stereotaxic markers is disposed inside a blind hole.  8. stereotaxic frame according to any one of claims 1 to 7, characterized in that it comprises return means (24) of each of said first and second lateral segments (2) on each of said first and second lateral blades ( 3).  9. stereotaxic frame according to claim 8, characterized in that said return means are not radiopaque and / or said return means consist of a spiral spring.  10. stereotaxic frame according to any one of claims 1 to 9, characterized in that the first and second lateral blades (3) are free to rotate about first and second axes of rotation secured respectively to the first and second lateral segments (2 ).  11. stereotaxic frame according to any one of claims 1 and 10, characterized in that it comprises a transmitter or a secondary sensor.  12. Stereotaxic frame according to claim 11, characterized in that said transmitter or said sensor emits or captures, at least one low frequency electromagnetic field.  13 stereotaxic frame according to any one of claims 1 and 12, characterized in that it comprises a conical recess point (15). <Desc / Clms Page number 42>

14 Method of computer-assisted surgical navigation using a localization device associated with said computer and comprising an instrument placed in a known position relative to a primary sensor capable of emitting a signal representative of its position in a reference called reference of the spatial localization device , as well as means for displaying information associated with the computer, method consisting, with a view to automatic registration of the position of a part of the instrument: - positioning a stereotaxic frame according to claim 6 on the patient, - to use a medical imager for the acquisition of an anatomical volume in serial sections, - to determine the position of the stereotaxic markers on each of said serial sections and to deduce therefrom the matrix of coordinates of the markers in a reference frame linked to the images, - positioning a frame according to any one of Claims 12 and 13 on the patient , the position of said transmitter or of said secondary sensor being predetermined with respect to that of the stereotaxic markers placed on the frame according to claim 6 used, - to calculate in the reference frame linked to the images, the position of the distal part of said instrument from the coordinates of said primary sensor known in the frame of the spatial location device and of the known position of the distal part of the instrument relative to said primary sensor, - to be displayed on said display means at least one serial section of a plane or is located said proximal part of the instrument, as well as the position of this proximal part in said serial section.  15 Method of computer-assisted surgical navigation using a location device associated with said computer and comprising an instrument placed in a known position relative to a primary sensor capable of emitting a signal representative of its position in a reference called reference of the spatial location device , as well as means <Desc / Clms Page number 43>

 display of information associated with the computer, method consisting, with a view to manual readjustment of the position of a part of the instrument: - in a first step of positioning, on the patient, a stereotaxic frame according to any one of claims 5 and 6 and comprising at least three stereotaxic markers, - in a second step to use a medical imager for the acquisition of an anatomical volume in serial sections, - in a third step to determine the position of the stereotaxic markers on each of said serial sections and to deduce therefrom the matrix of coordinates of the markers in a frame linked to the images, - in a fourth step of positioning on the patient a frame according to any one of claims 1 to 13, - in a fifth step to position the proximal end of said instrument respectively at each of the positions of the stereotaxic markers used in the first step and to establish the matrix of coordinates of each of the stereotaxic markers in the coordinate system of the spatial locator, - in a sixth step to calculate the matrix of transformation of coordinates in the coordinate system of the spatial locator, in coordinates of the

 benchmark linked to the images, - in a seventh step to calibrate said instrument.  16. Method according to claim 15, characterized in that the sixth step consists in calculating the transformation matrix from the following equation: P1 = P2. [MJ + [MJ (1) where [Mr] is the rotation matrix of coefficients a, b, c, d, e, f, g, h, i, and where [MJ is a translation matrix of coefficients Kx, Ky , Kz, and P1 a point of coordinates (Sx, Sy, Sz) in the coordinate system of the spatial locator and P2 the point corresponding to P1 but in the coordinate system linked to the images and of coordinates Ix, Iy e1 Iz, <Desc / Clms Page number 44>  and by solving the following equations (2) to 12 unknowns: Ix = (a. Sx) + (b. Sy) + (c. Sz) + Kx Iy = (d. Sx) + (e. Sy) + (f. Sz) + Ky (2) Iz = (g. Sx) + (h. Sy) + (i. Sz) + Kz 17 Method according to claim 16, characterized in that the stereotaxic frame used in the first step comprises at least four markers and in that the sixth step consists in solving directly equation (2) from 12 coordinates of the at least four markers. 18 Method according to claim 17, characterized in that the stereotaxic frame used in the first step comprises at least three stereotaxic markers and in that it comprises a complementary step consisting in reducing the equations (2) to 12 unknowns in a system with 6 unknown by replacing the coefficients a, b, c, d, e, f, g, h, i of the matrix [Mr] by the coefficients of equation (3),

 cos (A) cos (E) sin (A) cos (E) - sin (E)

 [M,] = cos (A) sm (E) sm (R) -sm (A) cos (R) sm (A) sin (E) sm (R) + cos (A) cos (R) cos (E ) sm (R) (3) cos (A) sm (E) cos (R) + sin (A) sm (R) sin (A) sm (E) cos (R) -cos (A) sm (R) cos (E) cos (R) A, E and R being I the Eulerian angles of transformation, Then by solving the trigonometric equation of the third degree then obtained by a known method.  19 Surgical navigation device for implementing a method according to any one of claims 14 to 18, comprising a spatial location device DL connected to a computer, characterized in that the spatial location device DL is constituted by a DCA cannula or instrument holder device comprising a block (41), preferably made of plastic resin, comprising a flat, means for fixing a primary sensor being disposed near this flat, the distal end of this block comprising a bore (47) as well as at least <Desc / Clms Page number 45>

 a radial groove (48) relative to the bore, as well as means for blocking a cannula or an instrument disposed near said bore 20. Surgical navigation device according to claim 19, characterized in that said blocking means consist of a blocking ring (46), articulated on a point of rotation (51) fixed to said block (41), which can be manipulated by a lug (50), and comprising a notch (49) capable of cooperating with a groove disposed on the distal end of the cannula or of the instrument, locking means (53) of the rotating ring being associated with it 21. Surgical navigation device according to claim 20, characterized in that said locking means (53) consist of a pin (53).  22. Surgical navigation device according to claim 19, characterized in that the bore (47) comprises at least three grooves arranged in fins (48).