WO2005006966A1

WO2005006966A1 - Scanning head and endoscopic apparatus using such head

Info

Publication number: WO2005006966A1
Application number: PCT/IT2004/000356
Authority: WO
Inventors: Marcello Marzoli
Original assignee: Marcello Marzoli
Priority date: 2003-07-23
Filing date: 2004-06-21
Publication date: 2005-01-27
Also published as: ITRM20030361A0; ITRM20030361A1; WO2005006966B1

Abstract

The invention concerns a scanning head, characterised in that it comprises a first and a second cylinder, joined each other and that can be coupled to an electromagnetic or electro-optical detection device by a flexible element, said second cylinder being inner and coaxial with respect to the first one, said second cylinder rotating during the scanning, the head further providing a scanning optic, inside and integral with the second cylinder, said second cylinder having an opening through which pass the output and reception optical signal managed by the scanning optic, the first cylinder being optically transparent in its surface corresponding to the rotation of said second cylinder. The invention also concerns an endoscopic apparatus, comprising a scanning head, a flexible element, an electromagnetic or electro-optic detection device, characterised in that said scanning head is the head according to the invention.

Description

SCANNING HEAD AND ENDOSCOPIC APPARATUS USING SUCH HEAD

The present invention relates to a scanning head and an endoscopic apparatus using such head. More particularly, the scansion head according to the invention allows, thanks to its particular structure, the volumetric scanning, since it has very reduced dimensions. Thus, it can be advantageously used in an endoscopic apparatus. Technological progress allowed in the recent years a remarkable development of the image diagnostic and has determined a remarkable improvement of the quality of the medical assistance. Realisation of apparatuses allowing to examine the human body, such a the Computerised Tomography and Magnetic Resonance represented a changing in Radiology, previously limited to the study of "shadows" of the body structures, projected on a photographic film. Digital technology and development of electronic and informatics allowed to begin thinking to new solutions to obtain tri- dimensiona) images. These new methods are still at the beginning and in a testing phase. Searching new solutions occurred when the technique had already made some basic improvements. One of this advancements concern an endoscopic image, defined as the capability of distinguishing two very close objects or points, already remarkably improved by the present technique. Human eye can discriminate objects with a diameter ranging between 125 and 165 microns, while high resolution endoscopes allow to discriminate objects with a diameter ranging between 10 and 71 microns. However, up to now it is not possible to surely know their position and the real measurement of what is analysed. Consequently, it is not possible to obtain reliable and realistic tri-dimensional (3D) reconstruction of the scanned part. Instruments are known able to precisely measure relevant distances between the scanning head (more specifically scanning optic) arid the object detected, said instruments lacking a sufficiently reliable determination of the position of the scanning head. One known instrument that can precisely detect the relevant distances is laser radar. Optical radar laser acts in a similar way of a standard laser, with the difference that short pulses or light beams instead of radio waves (both electromagnetic waves, but radar waves have a wavelength from 1 0,000 to 100,000 times longer than the light waves). A reception system picks up and elaborates the reflected light. Distance of the object (or "target") hit by the light beam is thus calculated on the basis of the delay between the emission and the reception (also known as time of flight). If the system is able to register the frequency of the reflected light, possible frequency displacement with respect to the emitted light takes into consideration the relative speed of the target with respect t the scanning head: due to the known "Doppler effect", light reflected from a moving away object will be subjected to a displacement toward higher wavelengths (effect also known as "red shift"), while light reflected from an approaching object will be subjected to a displacement toward smaller wavelengths (also known as "blue shift" effect) . Radar lasers can be of the continuous wave type (CW) or of the pulsed type, focalised or collimated. In case of close target, it is generally preferred the focalised CW , with lower peak power. It can be provided separated positions for transmitting and receiving the signal, or it is possible making them in a single position (as usually is preferred in the scientific field). Thus, a standard radar laser registers the intensity of the picked up radiations and their delay with respect their transmission. Knowledge of the delay (time of flight) and of the sighting direction of the scanning optic allows to localise the target with respect to the same scanning optic (and thus to the scanning head). It has been further recently introduced the "Coherent (Heterodyne) Laser Radar" able to register also the phase the reflected radiation. Form this information it is possible to obtain information about the average frequency, the frequency spectrum and the photon polarisation: from the average frequency it can be obtained the relative speed between the scanning head and the target. . By this technique it is also obtained a remarkable increase of the sensitivity with low signal to noise ratio conditions (SNR), if a further "Local Oscillator (LO) Laser" is added to the radar laser. It involves a higher sensitivity to the alignment and to the phase perturbations by the optical elements (comprising the radar laser) . From the above, it can be understood that instruments exist allowing to detect the distance and the relative speed between the scanning head and the target, as well as the classic physical RGB parameters and intensity of the reflected radiation. If one wishes to realise the 3D relief of the inner walls of a hollow body by a scanning head, the position and attitude of which are not known, different problem will have to be solved, first of all the above mentioned problem concerning the determination of the position of the scanning head. Another important problem is due to the scanning head for the 3D reliefs. In fact, it must be enough compact and must provide sufficiently precise information about the sighting direction of the scanning signal, as well as be pt to scan a sufficiently large and identifiable volume, as it is necessary in endoscopies, particularly colon-recto endoscopy, or laparoscopy. For endoscopy, all the above results must be obtained with very small dimensions of the scanning head. The Applicant does not know efficient solutions to the above problems. It is object of the present invention that of providing a scanning head solving the above drawbacks of the prior art solutions. It is further object of the present invention an endoscopic apparatus employing the scanning head of the present invention. It is specific object of the present invention a scanning head for an endoscopic apparatus, characterised in that it provides a first and a second cylinder, joined each other and that can be coupled to an electromagnetic or electro-optical detection device by a flexible element, said second cylinder being inner and coaxial with respect to the first one, said second cylinder rotating during the scanning, the head further providing a scanning optic, inside and integral with the second cylinder, said second cylinder having an opening through which pass the output and reception optical signal managed by the scanning optic, the first cylinder being optically transparent in its surface corresponding to the rotation of said second cylinder. According to the invention, said opening can be a slot parallel to the axis of said cylinders. Preferably, according to the invention, the scanning optic is a mirror polygon, rotating during the scanning about an axis perpendicular to the axis of said first and second cylinders. Mirror polygon can have, e.g., 4, 5, 6 or 1 2 equal sides. Preferably, according to the invention, the first cylinder, at its end joined to the flexible element, provides an inner base suitable to differently respond to the scanning optical signal with the variation of the angular position of the scanning optic during its rotation with respect to the cylinder axes. According to the invention, the inner base can provide a relief, said relief being a saw tooth relief. Always according to the invention, the inner base can provide a relief, said relief being a toothed relief, the spaces between the teeth having the same width of the same teeth. Preferably, according to the invention each tooth or space covers an angle of 1 °. Preferably, according to the invention, each tooth provides small teeth and spaces. According to the invention, the portions of the inner base can be differentiated by colours. According to the invention, the end of the first cylinder opposed to the end coupled with the flexible element can be closed and optically opaque. According to the invention, a CCD charge coupling optical device can be integrally coupled with said end, suitable to detect the images according to the direction of the cylinder axes. Preferably, according to the invention, optical signals produced or analysed by the detection electro-optical device enter in or exit from the scanning head along the axis of the same. Preferably, according to the invention, the detection electro- optical device is a radar laser. Preferably, according to the invention, the detection electro- optical device is a coherent radar laser. Preferably, according to the invention, the second cylinder is rotated by one or more compressed air turbines. Still preferably, according to the invention, the scanning optic is moved by one or more compressed air turbines. Still, it is specific object of the present invention an endoscopic apparatus, comprising a scanning head, a flexible element, an electromagnetic or electro-optic detection device, characterised in that said scanning head is the head according to the invention. The present invention will be now described, for illustrative but not limitative purposes, according to its preferred embodiments, with particular reference to the figures of the enclosed drawings, wherein: Figure 1 shows the scanning head according to a preferred embodiment of the invention, on the right side being shown the outer cylinder, and on the left side being shown the inner cylinder; Figure 2 shows only the outer cylinder of the scanning head of figure 1 , on the right side the whole cylinder, and on the left side a cut away view, with the possibility of seeing inner parts; Figure 3 shows only the inner cylinder of the scanning head of figure 1 , on the right side the whole cylinder, and on the left side a cut away view, in the latter being shown also the rotating inner polygon reflecting the radar laser signals. Scanning head according to the invention can be used for each scanning of the surface of objects, particularly for the tri- dimensional re-costruction of their surface. However, it is here illustrated with reference to the endoscopic investigation of human or animal body cavities. In fact, in this case the scanning head solves the problems until now not solved but with complicated and dangerous investigations. Consequently, in the following, reference will be made to the sole endoscopy of body cavities, particularly the recto-colonoscopy and the laparoscopy, but it is to be understood that the device described has a more general use. For the 3D recto-colonoscopy, it is deemed that the topological features more suitable for the univocal recognition of a tissue portion correspond to the vascular map of the tissues under examination (as occurs for the scanning of the human eye retina, the pattern comprised of the vascular network is stable and univocal from point to point). Its acquisition is normally possible projecting on the tissues a low intensity light beam in the visible field or in the (close to) infrared and capturing the reflected image with a device similar to a retinoscope placed at the maximum distance of 3 centimetres. To this end, it is possible to use the known radar laser. An endoscopic apparatus for recto-colonoscopy or iaparoscopy can thus be made up of a unit comprising a radar laser, a processing unit, a flexible unit to be introduced within the cavity, comprising an optical fibre, and a scanning unit or head comprising at least a scanning optic for radar laser and other possible sensors (e.g. a

CCD charge coupling optic device). . . The scanning unit or head, having the shape of a small cylinder, will be housed at the end of a flexible body very similar to those of the present endoscopes and will comprise one or more sensors of scanning optics (such as camera, spectrometer, microscope, mirror system) . Within said unit, housings will be provided for the passage of optic fibres and of electric and mechanical cables necessary for the operation of sensors and scanning optic. Radiations reflected by the surfaces of the cavity under investigation are routed by the optic fibre toward the processing unit, that will be thus able to measure the intensity of the radiations picked up and the delay with respect to the transmission. Delay will give a distance that is the sum of the whole optic path (the known part of which comprises the whole length of the connection optic fibre). In case of a recto-colonoscopy, it can be assumed a length of endoscope of about 4-5 meters and a distance between the scanning head and the colon walls varying between 0 and 3 cm, for a total optic path of about 8 - 10 m: standard technology Coherent Laser Radar already ensure nowadays an error smaller than one tenth of millimetre in case of measurements of distances of about two meters. Detection of the position of a moving object by a moving scanning head, can be done only if the typical frequencies of the two motions are uncoupled. In the example described, for the motion of the living tissues must be considered the big peristalsis (3-4 movements each day for a duration of about 30 seconds from esophagus to recto) and micro-peristalsis (3-4 movements for second that are annulled when the walls are spread with air), while for the motion of the scanning head it must be taken into consideration the oscillation about the temporary fulcrum. Being thus necessary to take into consideration only the oscillation frequencies of the scanning head within surfaces that can be considered fixed, scanning parameters will be adjusted in such a way to ensure the required decoupling of the frequencies. More simply, it can be calculated the time interval within which it is possible to consider "stopped" one with respect to the other, the scanning head and the surrounding surfaces, and, at the lapsing of the interval, navigation techniques described in the following must be adopted to refer the detected points and to integrate the obtained surface (frame) with the previous ones. Coming to describe the specific embodiment of the scanning head according to the invention, and making reference to figures 1 , 2 and 3, the scanning head is comprised of two concentric cylinders 100, 200, the inner cylinder 200 housing a scanning head for radar laser comprised of a rotating mirror polygon 300. The other rotation is the rotation of the polygon 300 within the cylinder 200 about an axis perpendicular to the rotation of the same cylinder 200. By this rotation, the tissue is scanned along a direction parallel to the axis of the scanning head. A 360° scanning of the cavity in the vertical direction of the polygonal scanning optic does not correspond the complete rotation of the cylinders (in other words, if the cavity is approximated to a recto cylindrical tube, according to its axis) . The reasons for this choice are substantially two: first, if the axis direction is reached, too far parts are detected, so that the ^■reconstruction of the scanned zone becomes difficult; second, without the data acting as cyclic reference would be difficult suitably rearrange the various pixels, as described in the following. Further, the above is carried out to avoid the excessive irradiation of the walls of the cavity under investigation, as well as to have a density of scanned points that can vary within well defined and sufficiently narrow limits (since distances does not excessively vary). Laser radar coming from the axis of endoscope can thus be addressed from the rotating polygon in such a ay that tissues are scanned in the direction parallel with respect to the same cylinder. The contemporaneous rotation of the same cylinder will allow the scanning of a helicoidal band of the surrounding surfaces. Really, in some cases it could be useful to observe also in the direction of the cylinder axis, for example for laparoscopy. Still, it could be possible to eliminate the scanning beginning and end thanks to an oscillating mirror scanning unit or galvanometric elements able to give the detection angle with a sufficient precision. In order to identify the limits of the scanning angle (detection), the cylinder of the scanning head according to figure 1 has two edges 101 and 102 in correspondence of the basis of the cylinder, on which the laser is incident and detects a date well different from the others. It can also be provided a single edge for scanning end marking, but two edges allow to have a better precision. Making reference to figures 2 and 3, scanning head has an outer cylinder 100 and an inner cylinder 200, the latter provided with a slot 203 positioned in such a way that the rotating polygon 300, which is integral with the inner cylinder, can send and receive laser signals through the same, the outer cylinder 100 being optically transparent in the emission and reception zone 103. In place of the rotating polygon, an oscillating mirror can be provided. It is to be noted a further solution shown in figure 2, provided in order to obtain an always higher scanning precision. They are reliefs 105 that can be alternated in order to detect also the rotation angle of the scanning head about its own axis. It is possible to provide different shapes of the reliefs. For example, equal and alternate teeth can be provided. Otherwise, teeth covering 1 degree can be provided, with further smaller teeth provided on each one of the first mentioned teeth. Bigger teeth could be then realised with different sizes, according to a repeated patters (e.g. one high tooth, one medium tooth, one low tooth, and so on). Alternatively, it is possible to use continuous reliefs, e.g. with a sloped plane, thus obtaining a saw-tooth form. Still, it is also possible to employ colours, in such a way the radar laser responds with different intensity for different zones. At the distance measured by the scanning optic, the relevant angles of the scanning mirrors will be associated (of the scanning optic comprising, e.g., a rotating polygon), in such a way to obtain the sighting direction of the scanning optic and the complete localisation of the surrounding walls, with precision lower than one tenth of millimetre along the three axes - in the reference system associated with the position and the orientation of the scanning optic (and consequently of the head) at the moment of the acquisition. Scanning head optic thus continuously detecting data (data of the intervals beside the above references will be automatically eliminated), obviously with respect to its reference system that will be indicated as "relative" system. Under this system, the data processing unit, to which the scanning head is coupled, receives a continuous flow of data. It is still t be noted that base 106 (or 107) could be covered by the same material of the edge, or it could be uncovered. It could also be covered by a charge coupling device (CCD) directed toward the axis of the cylinder. Detection by the scanning head for the elevation will preferably occur from the bottom toward the upper part. In the scanning head, axial provenience of the laser radar ensures the possibility of carrying out a continuous circular scanning along the whole 360° arc, this not being possible with the known scanning heads, by which the scansions are carried out at most along a 330° arc, with a circular alternate motion along the two directions. Therefore, 360° scanning is possible only thanks to the solution according to the present invention. Motion of a plurality of movable parts of the scanning head can be advantageously ensured by compressed air turbines. This solution can be more simply implemented with respect to the present endoscopes, which are provided with tubes for transporting useful compressed air, for example to spread organs, and because it would avoid the over-heating risk involved in using a small electric motor. Scanning head according to the invention is suitable for detection of 3D surfaces. Application of the scanning head and of the apparatus according to the invention can be, for example: endoscopy, recto- colonoscopy, esophagus-gastro-duodenoscopy, bronchoscopy, otoscopy, rhinoscopy, laryngoscopy, laparoscopy explorative, volumetric mapping and detection of the body surface, such as birt- marks, loss of substances (wounds, burns, ecc), body volume. Scanning head according to the invention has the advantage, thanks to its structure, to be miniaturised for the above uses. Scanning head and endoscopic apparatus according to the invention are not necessarily suggested to replace the present techniques, but to provide a modular platform able to integrate the images detected by the present and future techniques with congruent spatial information, precisely and in a repeatable way localising in the time the area of the object to be analysed. In this way, it is wished to exponentially increase the amount of available information and their readability: it is sufficient to think to the increase of information obtained when passing from a plane view of an aerial photo, even if with an optimum definition, to its 3D representation, thanks to the wrapping of the same about a model truly representing the ground. The present invention has been described for illustrative but not limitative purposes, according to its preferred embodiments, but it is to be understood that modifications and/or changes can be introduced by those skilled in the art without departing from the relevant scope as defined in the enclosed claims.

Claims

1. Scanning head, said head being coupable with an detection electromagnetic or electro-optic device, particularly by a flexible element, characterised in that it comprises a first and a second cylinder, joined each other and that can be coupled to an electromagnetic or electro-optical detection device by a flexible element, said second cylinder being inner and coaxial with respect to the first one, said second cylinder rotating during the scanning, the head further providing a scanning optic, inside and integral with the second cylinder, said second cylinder having an opening through which pass the output and reception optical signal managed by the scanning optic, the first cylinder being optically transparent in its surface corresponding to the rotation of said second cylinder.

2. Scanning head according to claim 1 , characterised in that said opening is a slot parallel to the axis of said cylinders.

3. Scanning head according to claim 1 or 2, characterised in that the scanning optic is a mirror polygon, rotating during the scanning about an axis perpendicular to the axis of said first and second cylinders.

4. Scanning head according to one of the claims 1 - 3, characterised in that the first cylinder, at its end joined to the flexible element, provides an inner base suitable to differently respond to the scanning optical signal with the variation of the angular position of the scanning optic during its rotation with respect to the cylinder axes.

5. Scanning head according to claim 4, characterised in that the inner base provides a relief, said relief being a saw tooth relief.

6. Scanning head according to claim 4, characterised in that the inner base provides a relief, said relief being a toothed relief, the spaces between the teeth having the same width of the same teeth.

7. Scanning head according to claim 6, characterised in that each tooth or space covers an angle of 1 °.

8. Scanning head according to claim 6 or 7, characterised in that each tooth provides small teeth and spaces.

9. Scanning head according one of the claims 4 - 8, characterised in that the portions of the inner base are differentiated by colours.

10. Scanning head according to one of the claims 1 - 10, characterised in that the end of the first cylinder opposed to the end coupled with the flexible element is closed and optically opaque.

1 1 . Scanning head according to claim 10, characterised in that a CCD charge coupling optical device is integrally coupled with said end, suitable to detect the images according to the direction of the cylinder axes.

12. Scanning head according to one of the claims 1 - 1 1 , characterised in that optical signals produced or analysed by the detection electro-optical device enter in or exit from the scanning head along the axis of the same.

13. Scanning head according to one of the claims 1 - 12, characterised in that the detection electro-optical device is a radar laser.

14. Scanning head according to one of the claims 1 - 1 2, characterised in that the detection electro-optical device is a coherent radar laser.

15. Scanning head according to one of the claims 1 - 14, characterised in that the second cylinder is rotated by one or more compressed air turbines.

16. Scanning head according to one of the claims 1 - 15, characterised in that the scanning optic is moved by one or more compressed air turbines.

17. Endoscopic apparatus, comprising a scanning head, a flexible element, an electromagnetic or electro-optic detection device, characterised in that said scanning head is the head according to one of the claims 1 - 16.