WO1995031148A1

WO1995031148A1 - Computer-simulated radioscopy and assistance method for surgery

Info

Publication number: WO1995031148A1
Application number: PCT/FR1995/000620
Authority: WO
Inventors: François Allouche
Original assignee: Allouche Francois
Priority date: 1994-05-13
Filing date: 1995-05-11
Publication date: 1995-11-23
Also published as: FR2719760A1; FR2719760B1; EP0758868A1

Abstract

A computer-simulated radioscopy method for use in surgery, and particularly in microsurgery, wherein an exhaustive volumetric acquisition of digital images of the operating region is performed; a set of static sensors (16) is placed on the patient to determine a referential of at least three-dimensional co-ordinates; the acquired digital images and the referential are correlated; all of the operative features of the microinstruments (24) to be used by the surgeon during the operation are digitally input; a dynamic topological sensor (18) is lockably attached to the microinstrument used (24) in a predetermined position; the position of the dynamic sensor in relation to the referential is constantly monitored and the exact position of the distal end of the microinstrument (24) is calculated; and the exact position of at least the distal end of the microinstrument (24) on the corresponding digital image is displayed in real time on a screen (4) during the operation.

Description

COMPUTER SIMULATED RADIOSCOPY AND SURGERY ASSISTANCE PROCESS

The present invention relates to a method of computer simulated radioscopy and aid to surgery, in particular to microsurgery.

In general, in endocavitary microsurgery, a microscope is used as the operative visualization means for the areas to be operated that are substantially superficial, and an endoscope for areas inaccessible to direct vision. However, microscope vision has its limits since it is a direct vision which sometimes requires the collapse of the surface structures before accessing the deeper structures. Endoscope vision then has the advantage of respecting the anatomical structures explored. However, it can be hindered by bleeding or anatomical changes. In both cases, the neighboring organs remain invisible to the surgeon, who then risks damaging a noble organ without being able to discern it. It is thus obvious that the reliability of the operation depends on the only experience of the surgeon, since there exists in each operation a certain degree of uncontrollable uncertainty.

To help the surgeon, it has become common to carry out radiological tracking by scanography or by means of nuclear magnetic resonance imaging (MRI) before the operation. All these visualization means, however precise they may be, are deferred over time in relation to the intervention. Radioscopy gives, on the other hand, images in real time, but it has many disadvantages linked in particular to its cost, to its gravity which slows the operation and especially the irradiation of the patient and the practitioner. The intraoperative scanner has been considered in exceptional situations, but cannot reasonably become routine. The object of the invention is to overcome these drawbacks and to allow the surgeon to easily locate in real time any micro-instrument which he uses on a previously recorded digital image and this, without intraoperative irradiation. In the Panorama du Médecin n ^B 3905 of 19 November 1993, an article entitled "Medicine affected by virtual reality" describes what surgery will be in the near future with the use of images obtained by CT. In this prospective article, it is specified that the virtual three-dimensional image and the endoscopic image must be connected to achieve the desired goals. It is therefore a simple registration of images.

More pragmatically and less prospectively, document EP-A-0 326 768 describes the use of an electro-goniometer, one end of which is fixed to the surgical instrument and the other to a reference block in the form of an arm. Speak clearly. The latter is maintained in a constant position relative to the patient by means of a screw introduced into the patient's tibia. This document essentially describes how to help the surgeon to position an instrument, essentially a saw blade or a drill, by identifying the precise position of this instrument.

Document WO-A-90/09 141 describes a system using a surgical video microscope making it possible to obtain surgical imaging on a monitor. This imagery consists of a set of views in cross section and in plane obtained by moiré interferometry, and more generally intended for microsurgery of the eye.

In addition, various documents, such as the article "Virtual Reality Surgical Simulator: The First Steps", published in Surg. Endosc, May-June 1993, 7 (3): pages 203-205, which describes various perspectives in microsurgery following the intensive use of flight simulators in aviation, or "Micromachining Technology and Biomedical Engineering ", published in Appl. Biochem. Biotechnol. in March 1993, 38 (3): pages 233-242, which specifies the progress made in micro-technologies notably by stereo-television and virtual images, show that there is nothing really concrete to date in the field of microsurgery.

All of these documents clearly show that you can acquire a digital image by CT or MRI and that the personal computers currently available have sufficient computing power for image processing. On the other hand, it clearly appears that the technologies described in these documents do not control the means of locating the instruments and moving them in an operating field other than by intraoperative irradiation. Furthermore, none of these documents shows how a surgeon can be effectively helped when he has to operate in a sensitive and blind area. The invention therefore relates to a new concept of computer simulated radioscopy ("RSO") which is entirely desirable to suppress all irradiation during the operation, while retaining the same possibilities of visualization in real time. The present invention therefore relates to a new and concrete method of computer-simulated radioscopy and aid to surgery. It finds its preferred applications in micro- endo-nasal or intra-spinal surgery, in intra-cerebral neurosurgery, in particular as a replacement for stereotaxic surgery, and also in orthopedics.

According to the invention, the method comprises the following stages: one proceeds to the exhaustive volumetric acquisition of digital images by scanography, imaging means by nuclear magnetic resonance or equivalent, of the region to be operated; a set of static sensors fixed to a bone tissue fixed to the region to be operated is placed on the patient and determining a reference frame of coordinates at least three-dimensional; a correlation is ensured between the digital images acquired and the above-mentioned reference frame; all the useful characteristics of the micro-instruments that the surgeon has to use during the operation are digitally entered; a dynamic topological sensor is fixed on the micro-instrument used by the surgeon, in a lockable manner and at a determined point; the position of the dynamic sensor is determined at all times with respect to the above-mentioned reference frame and the precise position of the distal end of the micro-instrument used is calculated; and the precise position at least of the distal end of the micro¬ instrument is displayed in real time on a screen during operation on the digital image corresponding to this position.

Preferably, the dynamic topological sensor is fixed to the proximal part of the micro-instrument outside the operating field.

The sensors can use all known physical principles (electromagnetic field, optical field or infrared, ultrasound, microwave, metal detectors, etc.), and combinations thereof. However, electromagnetic type sensors are preferred because they determine a six-dimensional signal including the spatial coordinates and the angular coordinates of the dynamic topological sensor.

Preferably also, prior to the operation, the hazardous areas close to the operated region are determined on the digital image, the coordinates of these areas are recorded, and during the operation, a warning signal is determined as a function of the distance between the micro¬ instrument and, in particular, its distal end, and closest to the danger zones.

The invention will be better understood, and other objects, advantages and characteristics thereof will appear more clearly on reading the following description of the preferred embodiments given without limitation and to which a sheet of drawings is attached. in which: Figure 1 schematically represents the installation required for the implementation of the method according to the invention; and

Figure 2 shows schematically a micro-instrument provided with sensors according to the invention.

Referring now to the drawings and, more particularly to FIG. 1, the installation required for the implementation of the method for assisting the surgeon in microsurgery essentially comprises a computer 2 provided with a large computing capacity for managing images in real time. This computer is connected to a screen 4 forming a monitor for displaying the images processed and stored in an appropriate memory 6. This memory is favorably connected by modulator-demodulator and telephone line of a switched network 8 to a scanning processing center. 10. In Indeed, the CT processing center 10 is generally far from the operating room where the surgeon will practice, and it is necessary for him to receive digitized images. The monitor can also receive images from the microscope and the endoscope 12 via the computer 2.

The control of the computer by the surgeon is done, for example, by voice or by foot, by means of an input device 14 comprising a validation key and means for moving a cursor accessible to the foot.

A set 16 of static sensors is previously fixed on the patient, for example on a bone tissue secured to the region where the surgeon must operate. By the word "sensor" is meant a device making it possible to identify at least one position.

This set 16 of static sensors will make it possible to determine a reference frame necessary for monitoring the micro¬ instrument during the operation. At least one of these static sensors can favorably be secured to a bone area, for example to the skull, before the actual operation, while another will, for example, be secured to the palatal vault by means of a Inflatable balloon intended to fill the intra-oral volume and to limit mechanical stresses. In practice, a single judiciously placed static sensor is sufficient, but the addition of a second sensor makes it possible to validate the information at any time. In fact, if one of the static sensors detaches from the bone tissue, its movement will be automatically detected by the other sensor before it can result in the slightest error. A dynamic topological sensor 18 is locked on the micro-instrument used by the surgeon. Usually, ten instruments are more than enough for the intervention with, at most, two instruments used simultaneously. The preferred system then comprises four sensors, two static 16 and two dynamic 18 temporarily locked to the instrument used.

When the micro-instrument has a mobile part (micro-scissors or pliers, for example), it is necessary to know its degree of opening. An analog potentiometer 20 of potentiometer type is then added to the micro-instrument.

Preferably, these sensors 16 and 18 each separately analyze the ambient electromagnetic field emitted by the interface 22. However, in this case, the micro-instruments are made of a non-ferromagnetic material, for example plastic or titanium.

Alternatively, these sensors 16, 18 will use other aforementioned physical signals.

The static 16 and dynamic sensors 18 are connected to an interface 22 whose output signal is applied to an input of the computer 2. This output signal gives, in real time, the measurement of the precise position of the dynamic sensor 18 in six dimensions including the Cartesian spatial coordinates of the sensor and the angular coordinates of its orientation of the pitch, yaw and roll type.

Obviously, before any operation, the system is calibrated.

FIG. 2 shows, by way of example, a micro-clamp 24 usually used in microsurgery. The opening angle β of the distal end forming a clamp 26 is measured by means of the analog sensor 20, while the dynamic topological sensor 18 is fixed to the proximal part of the micro-instrument at a determined point. It is necessary to relocate the sensor 18, so that the physical signal, for example electromagnetic signal, does not have to pass through the patient's tissues. In addition, a sensor fixed to the distal part of the micro-instrument would be troublesome both for the surgeon's vision and for his manipulation.

Due to the relocation of the dynamic sensor 18, it is necessary to calculate the precise position of the distal end of the micro-instrument as a function of the location signal of the sensor and of the precise point where it is locked. For this purpose, all the useful characteristics of the micro-instruments that the surgeon will use during the operation must have been previously entered in the computer library. Before the operation, it is also necessary to ensure a correlation between the digital image stored in memory 6 and the frame of reference determined by the static sensors 16. To this end, the system is initialized by the surgeon by touching, with his microphone -instrument, a precise point of the patient, for example the inter-incisor gap or an external canthus, point easily deter inable both on the digital image and on the patient.

During the operation, the surgeon can control the computer 2 by means of the input device 14 or by voice to select a function, make an image enlargement, etc. On the screen 4, the precise position of the distal end of the micro-instrument and, simultaneously, the two-dimensional digital image corresponding to this position. Preferably, the screen 4 comprises several zones making it possible to display a plurality of two-dimensional images in different planes so as to make neighboring zones visible to the surgeon. that he cannot physically see directly, and / or three-dimensional images.

According to a preferred embodiment of the invention, before the operation, the surgeon determines on the digital image the dangerous zones close to the place where he is going to operate. The coordinates of these danger zones are then stored in memory 6. During the operation, the computer emits a warning signal when the distal end of the micro-instrument approaches one of these danger zones. Preferably, this warning signal is an audible signal whose frequency is a function of the exact distance between any part of the micro¬ instrument used and the closest to these danger zones. This warning signal can also be a voice signal indicating the precise distance. This ensures security, especially when a dangerous area is absolutely not visible directly to the surgeon.

According to an equally preferred embodiment of the invention, all of the images displayed during the operation are recorded in memory 6. This recording can then constitute a post-operative magnetic report. In addition, the recording can be favorably used for educational or post-operative analysis purposes. For this purpose, the recording must be locked automatically to avoid any subsequent manipulation of the images (by analogy to what is commonly called "black box" in aviation). Such locking is necessary in forensic applications of the invention.

Although it has been shown and described what is currently considered to be the preferred embodiments of the present invention, it is obvious that those skilled in the art can make various changes and modifications thereto without depart from the scope of the present invention as defined below.

R E V E N D I C A T I O N S

1 - Process of computer-simulated radioscopy and surgical aid, according to which: one proceeds to the exhaustive volumetric acquisition of digital images by scanography, imaging means by nuclear magnetic resonance or equivalent, of the region to operate; a set of static sensors (16) fixed to a bone tissue fixed to said region is placed on the patient and determining a reference frame of coordinates at least three-dimensional; a correlation is ensured between the digital images acquired and said reference frame; all the useful characteristics of the micro-instruments (24) that the surgeon is led to use during the operation are digitally entered; a dynamic topological sensor (18) is fixed on the micro-instrument (24) used by the surgeon, in a lockable manner and at a determined point; the position of the dynamic sensor is determined at any time relative to said reference frame and the precise position of the distal end of said micro-instrument (24) is calculated; and displaying in real time on a screen (4) during the operation said precise position at least of the distal end of said micro-instrument (24) on the digital image corresponding to this position.

2 - Method according to claim 1 characterized in that said dynamic topological sensor (18) is fixed to the proximal part of said micro-instrument (24) and outside the field

Claims

so as to eliminate any physical signal passing through a patient's tissue.

3 - Method according to claim 1 or 2 characterized in that said sensors (16, 18) are of the electromagnetic type.

4 - Method according to claim 3 characterized in that said micro-instrument (24) is made of a non-ferromagnetic material.

5 - Method according to claim 1 or 2 characterized in that said sensors (16, 18) use at least one of the physical principles chosen from the group comprising an optical or infrared field, ultrasound, microwaves , metal detectors, and combinations thereof.

6 - Method according to any one of claims 3 or 4 characterized in that said sensors (16, 18) determine a signal in six dimensions comprising the spatial coordinates and the angular coordinates of said dynamic topological sensor (18).

7 - Method according to any of the preceding claims characterized in that the system (2, 22, 16, 18) is calibrated prior to the operation.

8 - Method according to any one of the preceding claims characterized in that Ton determines, in addition, the degree of opening (β) of the micro-instrument (24), if the latter comprises a movable part (26). 9 - Method according to any one of the preceding claims characterized in that Ton displays on said screen (4), during the operation, a plurality of digital images in two dimensions according to different planes or digital images in three dimensions.

10 - Method according to any one of the preceding claims characterized in that it further comprises the following steps: prior to the operation, the hazardous areas close to said region are determined on the digital image; the coordinates of said zones are recorded; and during the operation, a warning signal is determined as a function of the distance between any part of said micro¬ instrument (24) and the closest to said dangerous zones.

11 - Method according to any one of the preceding claims characterized in that, in addition, during the operation, all of the images displayed on said screen are recorded (4).