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WO2003053247A1 - Appareil ultrasonore et procede de positionnement et de mise en image d'un objet en guide d'onde a travers un support d'interposition - Google Patents

Appareil ultrasonore et procede de positionnement et de mise en image d'un objet en guide d'onde a travers un support d'interposition Download PDF

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Publication number
WO2003053247A1
WO2003053247A1 PCT/US2002/039690 US0239690W WO03053247A1 WO 2003053247 A1 WO2003053247 A1 WO 2003053247A1 US 0239690 W US0239690 W US 0239690W WO 03053247 A1 WO03053247 A1 WO 03053247A1
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WO
WIPO (PCT)
Prior art keywords
probe
medium
waveguiding
inteφosing
ultrasonic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US2002/039690
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English (en)
Inventor
Dan Cohen
Yuval Jacoby
Garri Passi
Boris Pershitz
Yuval Shay-El
Pavel Smirnov
Uri Stein
Alon Eitan
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Imadent Ltd
Original Assignee
Imadent Ltd
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Filing date
Publication date
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Priority to AU2002364551A priority Critical patent/AU2002364551A1/en
Publication of WO2003053247A1 publication Critical patent/WO2003053247A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/42—Details of probe positioning or probe attachment to the patient
    • A61B8/4272—Details of probe positioning or probe attachment to the patient involving the acoustic interface between the transducer and the tissue
    • A61B8/4281—Details of probe positioning or probe attachment to the patient involving the acoustic interface between the transducer and the tissue characterised by sound-transmitting media or devices for coupling the transducer to the tissue
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/08—Clinical applications
    • A61B8/0875—Clinical applications for diagnosis of bone
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/44—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device
    • A61B8/4483—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device characterised by features of the ultrasound transducer
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
    • A61B2562/16—Details of sensor housings or probes; Details of structural supports for sensors
    • A61B2562/164—Details of sensor housings or probes; Details of structural supports for sensors the sensor is mounted in or on a conformable substrate or carrier

Definitions

  • the present invention relates, in general, to the field of diagnostic imaging, and in particular, it discloses an ultrasonic apparatus and method for locating and imaging a waveguiding object through an interposing medium.
  • the procedure of replacing a tooth with an implant-supported prosthesis has become very common and widely used.
  • the process of fixture (implant) placement entails exposing the jawbone (raising the mucoperiosteal flap), and drilling a receptive site for the fixture.
  • One of the major hazards of drilling into a human lower jaw is the risk of contacting and consequently damaging the mandibular canal, which runs along and inside the lower jaw, and in particular, the inferior alveolar nerve inside the mandibular canal. For this reason, it is widely acknowledged that an implantologist must be able to determine the location of the mandibular canal, and preferably obtain an image of the mandibular canal.
  • Mandible 30 comprises several layers of tissue.
  • the external layer of mandible 30 comprises the gum 32, or the mucoperiosteal tissue covering the jawbone.
  • Beneath gum tissue 32 is a layer of cortical (compact) bone 34, which is normally dense bone tissue.
  • Beneath cortical bone 34 lies an area of trabecular bone 36, which is normally bone tissue softer than cortical bone.
  • Mandibular canal 38 is an elongated tubular cavity, usually comprising dense (cortical type bone) borders. In cases where dense borders are not present, mandibular canal 38 is a conduit within a sponge-like matrix. In the latter case, mandibular canal cavity 38 may be distinguished from the cavities of the trabecular environment 36 by the mandibular canal's regular shape, i.e. an elongated tubular cavity. All cavities inside the cross-section of mandible 30 are normally filled with fluids. Referring to FIG.
  • the gum tissue 32 extends from the lingual side of the mandible upwards toward the alveolar ridge 40, in which teeth 42 are normally situated.
  • the gum tissue is attached to the internal cheek or chin tissue 44, which extends upwards to the lower lip 46 and then outwards to the external cheek or chin skin surface 48.
  • the common procedure prior to installation of a dental fixture involves, inter alia, drilling into the cortical 34 and trabecular 36 bone of mandible 30 using a drill 70, in order to prepare a socket in which a fixture will be anchored. If an implantologist drilling into mandible 30 is not aware of the precise location of mandibular canal 38, then during the drilling procedure drill 70 may contact and damage inferior alveolar nerve 39. Such damage can ultimately lead to severe pain, hemorrhage and even local paralysis, among other undesired consequences. For this reason, as mentioned hereinabove, the implantologist must determine the location of the mandibular canal, usually by obtaining an image of the jaw.
  • Panoramic X-ray Radiography The most common technique currently used in Implantology for imaging and locating the mandibular canal is Panoramic X-ray Radiography.
  • this technology suffers from some significant shortcomings.
  • Panoramic X-ray does not provide a cross-sectional image of the lower jaw, and therefore provides very limited information about the mandibular canal's location.
  • Panoramic X-ray is inherently distorted and inaccurate because it projects the three-dimensional jaw onto a two-dimensional image. It is therefore unreliable for assessing the depth of the bone tissue available for drilling a fixture socket.
  • Third, the X-ray image is not taken. chair-side and consequently does not allow for real-time monitoring of implant procedures.
  • CT Computerized Tomography
  • a CT image of the lower jaw provides a sectional view of the jaw, and is less distorted than panoramic radiography.
  • CT involves a substantially higher dosage of X-ray radiation than conventional radiography, and therefore poses a significantly greater risk to the health of the patient.
  • CT equipment is very expensive and is only rarely found inside the clinic of the implantologist. CT can definitely not provide a chair-side solution for imaging and locating the mandibular canal.
  • Ultrasound is considered to be safe to the health of the patient and the doctor, and is therefore a very common medical imaging technique, for example, in the fields of Embryology and Gynecology. Ultrasound is most commonly used for imaging of soft or fluid-filled tissues, as these possess favorable acoustic properties, such as low acoustic attenuation and low impedance.
  • the ultrasonic imaging of hard tissue is problematic, due to the difficulty in achieving adequate ultrasound penetration in complex solid biological structures such as bone tissue. To date, therefore, a reliable ultrasonic location and imaging of bone structures, such as a jaw, has not been possible.
  • the present invention relates to an ultrasonic apparatus and method for locating and imaging a waveguiding object through an interposing medium.
  • waveguiding object is meant any object, whether natural or manmade, usually having a tubular or duct-like shape, which tends to confine and direct the propagation of ultrasonic waves transmitted toward or into it.
  • interposing medium is meant any material or combination of materials, covering, surrounding, or otherwise separating a waveguiding object from its environment. It is a particular teaching of the present invention, that when an ultrasonic signal is transmitted toward a mandibular canal, through the interposing soft tissue and bone tissue of the lower jaw, the mandibular canal will often serve as a waveguide of the transmitted signal. This waveguide phenomenon can be explained by the following two factors.
  • the mandibular canal is normally filled with nerves, blood vessels and other soft or fluid tissues which possess more favorable acoustic properties (e.g. lower ultrasound attenuation, lower ultrasound impedance) than the surrounding bone tissue.
  • the mandibular canal's tube-like bone tissue borders cause acoustic waves to be repeatedly reflected from the internal walls of the canal, and hence to propagate along and inside the canal.
  • the present invention exploits this waveguiding characteristic of the mandibular canal (or any other waveguiding object, for that matter), for the advantageous purpose of locating and imaging the mandibular canal, as will be explained hereunder in this description.
  • Apparatus 100 comprises a main unit 102, a first probe 104, a second probe 106, a user interface 108, and a display device 110.
  • the main unit further comprises a multiplexor (MUX) 112, a pulser/receiver (PUL/REC) 114, an analog-to-digital converter (A/D) 116, and a digital processing unit (computer) 118.
  • MUX multiplexor
  • PUL/REC pulser/receiver
  • A/D analog-to-digital converter
  • computer digital processing unit
  • the first probe 104 comprises a plurality of transducing elements, 1041, 1042, 1043, etc.
  • Each transducing element comprises a conventional ultrasound transducer capable of emitting and receiving ultrasonic oscillations, for example, a wideband piezoelectric transducer.
  • the interposing medium being scanned comprises biological tissue
  • the first probe must be biocompatible, so that it can be safely put in contact with a living organism, possibly even inside a cavity of the organism, for example, inside the mouth of a patient undergoing dental implant surgery.
  • the transducing elements of the first probe are arranged in a predefined pattern, preferably such pattern which conforms, at least in part, to the surface of the interposing medium inside or behind which lies the waveguiding object of interest.
  • FIG. 4 there is shown an example in which the first probe 104 is applied to a mandible 30.
  • the first probe comprises two essentially L-shaped arrays of transducing elements.
  • the dual L-shape arrangement is suited to conform to a toothless surface of a mandible of a patient who is undergoing dental implant surgery.
  • a first L-shaped array 141 of transducing elements is attached to a second L-shaped array 142 of transducing elements, by means of a U-shaped joint 143.
  • Each of these L-shaped arrays comprises a plurality of linearly arranged transducing elements having a predetermined width (e.g. 1mm each), and being fixed at a predetermined distance (e.g. 1.5mm) from one another.
  • first probe 104 comprises a total of 50 transducing elements, although greater or smaller quantities of transducing elements may equally be employed. It is recommended that the transducing elements be acoustically isolated from one another, in order to prevent a so-called "cross-talking" between them.
  • the first L-shaped array 141 is acoustically coupled to the lingual gum surface and to the toothless alveolar ridge (where drilling is to be performed); the second L-shaped array 142 is acoustically coupled to the cheek and chin skin surfaces opposite the first array, whereas the U-shaped joint 143 conforms to the shape of the lower lip.
  • the first probe 104 is not limited to any particular quantity of transducing elements or arrays, nor to any particular shape, arrangement, or pattern, and that the foregoing description is given solely for illustration purposes.
  • the first probe may comprise a plurality of transducing elements arranged in any two or three-dimensional pattern, including a plurality of separate arrays not attached to each other.
  • the first probe may comprise one or more flexible or adjustable transducing element arrays, whose shape or position can be manually or mechanically altered (e.g. by bending, twisting, sliding, rotating, swiveling, etc.) in order to fit or conform the transducing elements to a particular surface currently being scanned.
  • the pattern of the transducing elements of first probe 104 (e.g. the spacing between the transducing elements, the orientation of each transducing element, the width of each transducing element, and the like) is predetermined and stored in a corresponding memory address in the computer 118.
  • apparatus 100 will further comprise any known means for determining the location and orientation of the transducing elements. For example, if one or more transducing elements are mounted on a step-motor activator, the controller of such activator will communicate to the computer the current location and orientation of such transducing element, upon any change in these parameters. Hence, the computer 118 can retrieve, at any given moment during the operation of apparatus 100, the location and orientation of every transducing element in the first probe.
  • the first probe 104 is operative to perform two main functions that are independent of one another.
  • the first function is to transmit ultrasonic signals toward the surface of a medium interposing between the probe and the waveguiding object, and to receive reflections from the surface of the interposing medium. These reflections will be used for reconstructing the contour of the interposing medium.
  • the second function of the first probe is to receive, from the waveguiding object, ultrasonic oscillations originally transmitted by the second probe. These oscillations will be used for locating the waveguiding object. These two functions will be discussed in greater detail later hereunder.
  • the second probe 106 comprises at least one conventional ultrasound transducer capable of emitting ultrasonic energy, for example, a wideband piezoelectric transducer.
  • the second probe is preferably biocompatible, as explained hereinabove with respect to the first probe.
  • the second probe is operative to convert an input electric signal into an analog ultrasonic signal, and to emit the ultrasonic signal toward a waveguiding object through an interposing medium, for example, toward the mandibular canal through the jaw tissues interposing between the probe and the canal.
  • User interface 108 comprises one or more of a variety of conventional user interface means, such as an on/off switch, a keyboard, a computer mouse, a trackball, a touch pad, a touch screen, and a computer-executable code such as a user interface software program for managing the interaction between a human operator and the apparatus.
  • the user interface is operative to enable a human operator of the apparatus to control the operation of the main unit, and of all the elements comprised therein or coupled thereto.
  • Display device 110 comprises any known visual display means, such as a cathode- ray tube (CRT), a liquid crystal display (LCD), or a flat-panel display, optionally also including a touch screen.
  • the display device may additionally include tangible display means, such as a printer.
  • the display device is operative to display, based on commands rendered by the computer, any information of interest to the user, including but not limited to the location and image of the waveguiding object.
  • the elements comprised in main unit 102 will now be described in greater detail.
  • PUL/REC 114 comprises a conventional pulser circuitry and a conventional receiver circuitry.
  • the pulser circuitry is operative to generate electric signals or pulses, which cause the first or second probe to emit analog ultrasonic signals or pulses.
  • the receiver circuitry is operative to receive from the first probe electric signals representing ultrasonic signals received by the transducing elements.
  • the receiver circuitry is further operative to amplify the electric signals and to transfer them to the AID for digitization.
  • A/D 116 comprises a conventional analog-to-digital converter operative to sample input electric signals at a predetermined sampling rate (e.g. 40 MHz), thus converting them into a stream of digital samples or readings, and to then send the samples to the computer.
  • a predetermined sampling rate e.g. 40 MHz
  • MUX 112 comprises a conventional multiplexor operatively coupled to the transducer of second probe 106, to each of the transducing elements of first probe 104, and to the pulser and receiver circuitries of the PUL/REC.
  • the MUX operates as a switch between the PUL/REC and the various transducers of the first and second probes, and thus eliminates the need to provide, for each transducer, a dedicated receiver and digitizer.
  • Computer 118 comprises conventional digital computing means, for example, an IBM-compatible PC with an Intel® central processing unit, operated by a conventional operating system such as Microsoft® Windows®, further comprising a memory for storing digital data, and an installation of a computer executable code for controlling the operation of the apparatus, for reconstructing the contour of an inte ⁇ osing medium, for determining the location of the waveguiding object, and ultimately, for producing an image of the waveguiding object in relation to the contour.
  • a conventional digital computing means for example, an IBM-compatible PC with an Intel® central processing unit, operated by a conventional operating system such as Microsoft® Windows®, further comprising a memory for storing digital data, and an installation of a computer executable code for controlling the operation of the apparatus, for reconstructing the contour of an inte ⁇ osing medium, for determining the location of the waveguiding object, and ultimately, for producing an image of the waveguiding object in relation to the contour.
  • the aforesaid computer executable code is preferably in the form of one or more software programs, although such code provided in the form of hardware or firmware or any combination thereof, is equally within the scope of the present invention.
  • the functions performed by the computer, according to the teachings of the present invention, will be described in greater detail later hereunder in this description.
  • the main unit causes the first probe to transmit a series of ultrasonic signals toward a surface of a medium interposing between the probe and a waveguiding object of interest.
  • the first probe receives reflections of the transmitted signals, from the surface of the interposing medium.
  • the main unit processes the received reflections, and the computer reconstructs the contour of the interposing medium based on these reflections.
  • the main unit causes the second probe to transmit an ultrasonic signal, through the interposing medium and toward the waveguiding object. A portion of the transmitted signal enters the waveguiding object, and propagates through it, ultimately being received by different transducing elements in the first probe.
  • the main unit processes the received signals, and the computer then determines the location of the waveguiding object, based on the processed received signals.
  • the computer produces and displays an image of the waveguiding object, in relation to the reconstructed contour of the interposing medium.
  • an operator of apparatus 100 acoustically couples first probe 104 and second probe 106 to a surface of an interposing medium covering a waveguiding object of interest.
  • the interposing medium includes the cortical 34 and trabecular 36 bone tissue surrounding the mandibular canal, and the gum tissue 32 surrounding these bone tissues (see also FIG. 1).
  • either or both probes can be acoustically coupled to a surface inside the mouth cavity, such as the buccal or lingual gum surface of the jaw, or to a surface outside the mouth cavity, such as the cheek or chin skin surface.
  • either or both probes may be acoustically coupled directly to a bone surface (cortical or trabecular) of the mandible.
  • the user acoustically couples the second probe 106 to a location that is assumed or known (e.g. empirically) to allow penetration of acoustic emission from the probe into the waveguiding obj ect of interest.
  • the operator should preferably couple the second probe 106 either to the buccal gum surface covering the anterior opening 381 of the mandibular canal, or to the external skin surface covering same. Such coupling will improve penetration of acoustic emission from the probe into the mandibular canal. It is well known, that in a normal adult patient, the anterior opening 381 of the mandibular canal is usually situated a few millimeters below and between the roots of the second bicuspid and first molar teeth (on either side of the mouth).
  • a conventional acoustic coupling material (not shown in the drawings) is preferably applied between each probe and the scanning surface of the inte ⁇ osing medium.
  • the inte ⁇ osing medium is the soft or bony tissue of a mandible, in some cases, the fluids present in the mouth of the patient (e.g. saliva, blood, drill cooling water) will sufficiently serve as an acoustic coupling material. If not sufficient, the user may use another material, for example, a nontoxic ultrasound coupling gel of a known type.
  • inte ⁇ osing medium contour is meant a surface or an outline defining a border of the inte ⁇ osing medium.
  • the waveguiding object being sought for is the mandibular canal.
  • the inte ⁇ osing medium includes the cortical 34 and trabecular 36 bone tissue surrounding the mandibular canal, as well as the gum tissue 32 surrounding these bone tissues (see FIG. 1).
  • the implantologist must determine the location of the mandibular canal, in order to avoid contacting the canal with the drill (see FIG. 2).
  • the implantologist cannot see the mandibular canal, but, as a result of raising the mucoperiosteal flap, he will usually be able to see the cortical borders of the jaw.
  • the implantologist with the location of the mandibular canal, in terms of its distance from the cortical borders of the mandible. It is further desirable to provide the implantologist with an image, wherein the mandibular canal is presented in relation to the cortical contour of the jaw.
  • the contour reconstruction procedure includes the following steps.
  • MUX 112 connects first transducing element 1041 of first probe 104 to the pulser circuitry of PUL/REC 114.
  • the MUX connects the first transducing element to the receiver circuitry of the PUL/REC.
  • the pulser generates an electric signal, which causes the first transducing element to emit an analog ultrasonic signal.
  • the emitted ultrasonic signal is eventually reflected from one or more of the surfaces or contours of the inte ⁇ osing medium.
  • each transducing element in the first probe further comprises a suitable delay line, for improving separation between the transmitted signal and its received reflection.
  • the electric signals representing the received reflections are sent to the receiver circuitry of the PUL/REC, which amplifies them and sends them to A/D 116.
  • the A/D digitizes the received reflections and sends them to the computer.
  • the computer determines based on predetermined criteria (e.g. time-of-flight, amplitude, frequency spectrum), which portion of the plurality of reflections represents a reflection from the contour that is to be reconstructed, for example, a reflection from the cortical contour (as opposed to reflections from the gum tissue contour, or trabecular contour).
  • the computer stores this portion as a first reflection A-scan, in a corresponding memory address.
  • the MUX maintains the connection of the first transducing element to the pulser, but disconnects it from the receiver, and instead, connects to the receiver second transducing element 1042.
  • the procedure described hereinabove is repeated, again with the first transducing element acting as a transmitting element, but this time with the second transducing element acting as a receiving element.
  • the computer stores a second reflection A-scan, in a corresponding memory address.
  • the foregoing procedure is repeated, over and over again, each time with a different transducing element acting as a receiving element, until a desired number or all of the transducing elements have served as receiving elements.
  • the MUX then disconnects the first transducing element from the pulser circuitry, and connects another one of the transducing elements, for example, the second transducing element, to the pulser.
  • the MUX then alternately connects and disconnects different transducing elements, to and from the receiver circuitry of the PUL/REC, all as previously described in respect of the first transducing element, until a desired number of reflection A-scans is stored in the computer.
  • the foregoing procedure is repeated, over and over again, until a desired number or all of the transducing elements have served as transmitting and as receiving elements, so that a desired number of reflection A-scans has been stored.
  • the computer processes the accumulated reflection A-scans, in order to reconstruct the contour of the inte ⁇ osing medium.
  • This result can be achieved, for example, by implementing one of several Synthetic Aperture Focusing Techniques (SAFT) that are known in the art.
  • SAFT Synthetic Aperture Focusing Techniques
  • the computer first prepares a template (e.g. a matrix of coordinates) of the environment in which the contour is situated.
  • the template can be two-dimensional or tliree-dimensional, depending on the needs of the user: if the user desires to ultimately view a three-dimensional image of the waveguiding object in relation to the inte ⁇ osing medium contour, then a tliree-dimensional template will be used for contour reconstruction; however, if the user desires to view a cross-sectional image of the waveguiding object in relation to a cross-section of the inte ⁇ osing medium contour, then a two-dimensional template, such as the x-y coordinate system shown in FIG. 6A, will be used.
  • the computer calculates, for each combination of one transmitting element, one receiving element (which, as previously explained herein, can be the same transducing element currently serving as a transmitting element), and one template coordinate, the total time-of-flight it would take for the transmitted ultrasonic signal to travel from that transmitting element to that receiving element, had the signal been reflected from that coordinate.
  • This total time-of-flight is calculated based on a predefined ultrasonic velocity. For example, if the contour to be reconstructed is the cortical bone contour of the mandible, then the ultrasonic velocity in gum tissue (approximately equal to the ultrasonic velocity in water) can be used. Referring now to FIG.
  • the computer is currently calculating the time-of-flight of an ultrasonic signal transmitted from the third transducing element 1043, reflected from coordinate (xo, yo) and then received by the seventh transducing element 1047.
  • the location of each of the transducing elements of the first probe is predetermined and stored in the computer.
  • the computer can, thus, calculate the distance from each of the current two transducing elements 1043 and 1047, to the current coordinate (xo, yo). Accordingly, the computer can also calculate the time-of-flight between each of the current two transducing elements and the current coordinate, by dividing each of the calculated distances by the predefined ultrasonic velocity.
  • the time-of-flight from third transducing element 1043 to coordinate (x 0 , yo) is denoted as ti
  • the time-of-flight from coordinate (xn, yo) to transducing element 1047 is denoted as t .
  • the total time-of-flight is denoted as to.
  • the computer now retrieves the corresponding reflection A- scan that was produced by using third transducing element 1043 as a transmitting element and seventh transducing element 1047 as a receiving element.
  • the computer checks the amplitude value at time point to in this A-scan. In the current example, the amplitude value for to is a relatively high positive value.
  • the computer stores this amplitude value for coordinate ( o, yo) in a corresponding memory address.
  • the computer repeats the foregoing procedure, for each combination of transmitting element, receiving element, and template coordinate. For each such combination, the computer calculates a first time-of-flight, from the current transmitting element to the current template coordinate, and a second time-of-flight, from the current template coordinate to the current receiving element. The computer sums up the two time-of-flight results, and obtains a total time-of-flight. The computer then checks the current reflection A-scan (i.e. the reflection A-scan that was produced while using the current transmitting element for transmittal, and the current receiving element for reception), and determines what is the amplitude value at the time point corresponding to the calculated total time-of- flight. The computer aggregates, in the memory address that corresponds to the current template coordinate, the sum of all amplitude values from all the combinations that included that coordinate.
  • the current reflection A-scan i.e. the reflection A-scan that was produced while using the current transmitting element for transmittal, and the current receiving element for reception
  • FIG. 6D there is shown an example of a grayscale template of a bone scanned according to the teachings of the present invention.
  • the bone comprises a cortical border confining a trabecular area in which a waveguiding channel exists.
  • the bone simulates a portion of a mandible comprising the mandibular canal.
  • Each pixel represents a coordinate in the contour template.
  • the various grayscale levels represent respective aggregate amplitude values.
  • the computer detects areas in the contour template, which are characterized with relatively extreme aggregate amplitude values. In the current drawing, these areas were traced with a black line. This black line actually represents the reconstructed contour of the inte ⁇ osing medium. The reconstructed inte ⁇ osing medium contour is stored in a corresponding memory address.
  • the apparatus After the contour of the inte ⁇ osing medium has been reconstructed and stored as explained hereinabove, the apparatus turns to locate the waveguiding object.
  • the first step in locating the waveguiding object involves waveguide signal acquisition.
  • the MUX connects the second probe 106 to the pulser circuitry of the PUL/REC, and further connects the first transducing element 1041 of the first probe 104 to the receiver circuitry of the PUL/REC.
  • the pulser generates an electric signal and sends it to the second probe. Simultaneously, the pulser sends a trigger to the A/D to start digitizing incoming signals.
  • the second probe is excited by the electric signal, and consequently, produces and emits an analog ultrasonic signal, through the inte ⁇ osing medium and toward the waveguiding object, for example, toward the mandibular canal.
  • a first portion of the energy of the transmitted ultrasonic signal is lost, for example, due to scattering and attenuation, and is therefore not received by any of the transducing elements (the “lost portion”).
  • a second portion of the transmitted signal propagates through the inte ⁇ osing medium directly toward one or more of the transducing elements, completely bypassing the waveguiding object (the "bypassing portion”).
  • a third portion thereof propagates through the inte ⁇ osing medium, enters the waveguiding object and propagates through it, then propagates outwards from the waveguide, through the inte ⁇ osing medium, and ultimately toward one or more of the transducing elements (the "waveguide portion", portrayed in the drawing by a zigzag).
  • the first transducing element 1041 currently being connected to the receiver circuitry of the PUL/REC, receives any incoming ultrasonic oscillations (possibly including the bypassing portion, the waveguide portion, and mere noise), converts them into analog electric signals, and sends them to the receiver.
  • the receiver amplifies the electric signals, and sends them to the A/D, which samples them at a predetermined sampling rate (e.g. 40MHz), and sends the samples to the computer.
  • the computer stores the digital data representing ultrasonic data acquired by the first transducing element, as a first set of samples, in a first memory address.
  • the A/D stops sampling incoming signals, whilst the MUX disconnects the first transducing element from the receiver, and connects the second transducing element 1042 instead.
  • the signal acquisition procedure described hereinabove is repeated, and the computer ultimately stores a second set of samples, in a second memory address.
  • This procedure is repeated over and over again, each time connecting a different transducing element to the receiver, until a desired number of corresponding sets of samples is acquired and stored.
  • the signal acquisition procedure described heretofore is essentially a "serial" procedure, meaning that ultrasonic signals received from only one transducing element are acquired at every given moment.
  • a MUX is required in order to serially switch between the different transducing elements and the single receiver and digitizing circuitry.
  • the foregoing "serial" signal acquisition procedure is currently the preferred procedure, because it requires only one receiver and digitizing circuitry, and therefore substantially reduces the cost of apparatus 100.
  • a "parallel" signal acquisition procedure in which ultrasonic signals are acquired by several receiving elements concurrently, is equally within the scope of the present invention.
  • a dedicated receiver and digitizer circuitry is provided for each of the transducing elements of the first probe, thus eliminating the need for providing a multiplexor for this procedure.
  • a "parallel" waveguide signal acquisition procedure according to the teachings of the present invention, will now be briefly described.
  • the second probe 106 is directly connected to the pulser circuitry of the PUL/REC.
  • Each transducing element 1041, 1042, 1043, etc. of the first probe 104 is directly connected to a dedicated receiver and A/D circuitry.
  • the pulser generates an electric signal and sends it to the second probe. Simultaneously, the pulser sends a trigger to all the A/Ds to start digitizing incoming signals.
  • the second probe is excited by the electric signal, and consequently, produces and emits an analog ultrasonic signal, through the inte ⁇ osing medium and toward the waveguiding object, for example, toward the mandibular canal.
  • the bypassing portion and waveguide portion are eventually received by one or more of the transducing elements.
  • Each transducing element converts any incoming ultrasonic oscillations (possibly including the bypassing portion, the waveguide portion, and mere noise) into analog electric signals, and sends these to its dedicated receiver.
  • Each dedicated receiver amplifies the electric signals representing ultrasonic signals received by its corresponding transducing element, and sends these to its dedicated A/D.
  • Each dedicated A D samples, at a predete ⁇ nined sampling rate (e.g. 40MHz), the electric signals incoming from its corresponding receiver, and sends the samples to the computer. After a predetermined sampling period has elapsed, all A/Ds stop sampling incoming signals. Finally, the computer stores the samples representing ultrasonic data acquired by each transducing element, as a corresponding set of samples, in a corresponding memory address.
  • the foregoing "parallel" procedure had the advantage of faster data acquisition, with no need for switching between the transducers of the probes and the PUL/REC.
  • FIG. 7 A there is shown an example of a plurality of A-scans, representing a plurality of sets of samples, that were acquired in a signal acquisition session, according to the teachings of the present invention.
  • An ultrasonic signal was transmitted by the second probe 106 toward a mandibular canal, and was then received by the first probe 104 employing a plurality of spaced apart transducing elements 1041, 1042, 1043, etc.
  • the ultrasonic signal as received by each transducing element was digitized and stored as a corresponding set of samples.
  • each of the shown A-scans represents one of these stored sets of samples: a first A-scan Ai represents a first set of samples corresponding to the first transducing element 1041; a second A-scan A represents a second set of samples corresponding to the second transducing element 1042; a third A- scan A 3 corresponds to the third transducing element 1043, an so on until the last A-scan ARIC, corresponding to the last transducing element which participated in the current session, and which is denoted by serial number n.
  • the sets of samples are displayed synchronously, meaning that all sets of samples start and end at the same moment.
  • the computer After having acquired a plurality of sets of samples corresponding to a plurality of transducing elements, the computer processes the acquired sets of samples, in order to determine, for each set of samples, which portion of the set represents a waveguide portion, i.e. a portion of the transmitted signal that has propagated, at least in part, through the waveguiding object.
  • a waveguide portion i.e. a portion of the transmitted signal that has propagated, at least in part, through the waveguiding object.
  • a portion of an ultrasonic signal which has propagated from the second probe to a transducing element of the first probe, through an inte ⁇ osing medium, without having propagated through a waveguiding object referred to hereinabove as the "bypassing portion"
  • typically different ultrasonic characteristics e.g. time-of-flight, ultrasound velocity, frequency spectrum, amplitude, waveform, etc.
  • a portion of an ultrasonic signal propagating through a mandible whilst bypassing the mandibular canal possesses typically different ultrasonic characteristics than the waveguide portion, that is, a portion that has propagated, at least in part, through the mandibular canal.
  • the bypassing portion will sometimes be received earlier than the waveguide portion.
  • the waveguide portion will be typically less attenuated than the bypassing portion, and will therefore be received in greater amplitudes and in higher frequencies.
  • the computer performs cross-correlation between the acquired sets of samples, using any of a variety of cross-correlation techniques widely known in the art.
  • one waveguide portion will be selected from the plurality based on predetermined criteria, for example, by selecting the waveguide portion first to be received or last to be received, or having the greatest overall amplitude or the greatest peak amplitude value.
  • the computer can detect, in a certain set of samples, at least one waveguide portion, that set of samples will be ignored, or optionally, the computer can display a message, on display 110, asking the operator to choose between ignoring and re- acquiring that set of samples.
  • each A-scan includes a portion characterized by a plurality of discernible repeating amplitude peaks.
  • Each such portion is an example of a waveguide portion. After having detected a waveguide portion in each set of samples, the computer stores the portion as a corresponding subset of samples.
  • the subset which represents a waveguide portion in the first A-scan At is denoted as WP l3
  • the subset representing a waveguide portion in the second A-scan A 2 is denoted as WP 2
  • WP 2 the subset representing a waveguide portion in the second A-scan A 2
  • WP 2 the subset representing a waveguide portion in the second A-scan A 2
  • WP 2 the subset representing a waveguide portion in the second A-scan A 2
  • WP 2 the subset representing a waveguide portion in the second A-scan A 2
  • WP 2 the subset representing a waveguide portion in the last A-scan A n .
  • the time-of-flight of the waveguide portion, from the waveguiding object to each of the transducing elements is unknown, because the location of the waveguiding object is yet unknown.
  • the overall time-of-flight of the waveguide portion, from transmittal to reception by each transducing element can be measured.
  • the computer calculates the overall time-of-flight of the waveguide portion, for each, transducing element.
  • the waveguide portion may exhibit differences in duration and in waveform when received by different transducing elements.
  • the time-of-flight should be measured from transmittal time to a distinguishable parameter of the waveguide portion in each transducing element, for example, to the peak amplitude.
  • the computer selects one of the transducing elements to be a reference transducing element, based on a predetermined criterion.
  • a reference transducing element can be selected the transducing element first to receive the waveguide portion (i.e. the transducing element with the shortest overall time-of-flight). It is understood that, alternatively, any other transducing element can be selected as a reference transducing element.
  • the computer determines, for each transducing element, a corresponding relative waveguide portion time-of-flight, that is, the difference between the overall time-of-flight of the waveguide portion, from transmittal to that transducing element, and the overall time-of-flight of the waveguide portion, from transmittal to the reference transducing element.
  • a corresponding relative waveguide portion time-of-flight that is, the difference between the overall time-of-flight of the waveguide portion, from transmittal to that transducing element, and the overall time-of-flight of the waveguide portion, from transmittal to the reference transducing element.
  • the relative waveguide portion time-of-flight of the reference transducing element itself, always equals zero.
  • the computer stores the results as a table of the relative waveguide portion time-of-flight per transducing element.
  • TABLE 1 is an example of a table of relative waveguide portion time-of-flight per transducing element: TABLE 1
  • the twelfth transducing element 1052 was selected to be the reference transducing element.
  • the value next to each transducing element listed in TABLE 1, signifies the time difference (in milliseconds) between reception of the waveguide portion by that transducing element, and reception of same by the reference transducing element.
  • the differences in the relative waveguide portion time-of-flight of the various transducing elements can be explained by the fact that the distance between each transducing element and the waveguiding object may be different. It is well known that time-of-flight is, among others, a function of the distance traveled by the signal, and therefore, the relative waveguide portion time-of-flight of each transducing element, correlates to the distance between that transducing element and the waveguiding object. It can thus be assumed that the greater the relative waveguide portion time-of-flight measured for a certain transducing element, the farther the location of the waveguiding object from the transducing element, and vice versa. Referring now to FIG.
  • the computer processes the accumulated differences in the relative time-of-flight from the waveguiding object to the different transducing elements, whilst considering the known location and orientation of each transducing element, and determines an optimal curve which defines these differences.
  • the computer subsequently determines an optimal focal area of the determined optimal curve.
  • the optimal curve and the optimal focal area can be computed using any of various curve- fitting algorithms known in the art, for example, those provided in MATHEMATICA® software by Wolfram Research Company of Champaign, Illinois.
  • the optimal focal area of the aforesaid optimal curve defines the location of the waveguiding object.
  • the present invention determines the location of a waveguiding object through an inte ⁇ osing medium, for example, the location of the mandibular canal of a patient.
  • the apparatus After having reconstructed the inte ⁇ osing medium contour, and having determined the location of the waveguiding object, the apparatus produces and displays, on display 110, an integrated image showing the waveguiding object in relation to the inte ⁇ osing medium.
  • the image is produced simply by overlapping a representation of the location of the waveguiding object on the previously reconstructed contour image.
  • the waveguiding object image can be either two-dimensional, such a cross- sectional image, or three-dimensional, for example, based on a plurality of two- dimensional images.
  • FIG. 8 A there is shown an example of an image produced according to the teachings of the present invention. It is a cross-sectional image of the same bone previously referred to hereinabove with reference to FIG. 6D. On the previously produced and stored image of the reconstructed cortical contour of the bone, there was added a black circle representing the location of the waveguiding channel.
  • FIG. 8B there is shown a photograph of an actual cross-section of the bone whose image is shown in FIG. 8A. It is clearly evident that the image produced according to the teachings of the present invention appreciably resembles the real object of examination.
  • the image displayed on display 110 can further include dimensions, for example, the depth of the waveguiding object with respect to a certain point on the inte ⁇ osing medium contour.
  • the dimensions can be either default dimensions which are always displayed automatically, or specific dimensions requested by the user (e.g. by clicking and dragging a mouse).
  • the present invention provides a comprehensible and accurate solution to the problem of locating and imaging a waveguiding object through an inte ⁇ osing medium.
  • the present invention provides the dental implantologist with a real-time, chair- side, radiation-free, yet economical tool for the location and imaging of the mandibular canal on the fly.

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Abstract

L'invention concerne un appareil ultrasonore servant à positionner et mettre en image un objet en guide d'onde, à travers un support d'interposition. Le système comprend une unité principale (102) pouvant être connectée de manière fonctionnelle à une première sonde (104); une seconde sonde (106); une interface utilisateur (108); et un dispositif d'affichage (110). L'unité principale (102) comprend un multiplexeur (MUX) (112), un pulseur/récepteur (PUL/REC) (114), un convertisseur analogique-numérique (A/D) (116), et une unité de traitement numérique (ordinateur) (118). La première sonde (104) comprend plusieurs transducteurs ultrasonores pouvant émettre et recevoir des oscillations ultrasonores. La seconde sonde (106) comprend un ou plusieurs transducteur(s) ultrasonore(s) classique(s) pouvant émettre une énergie ultrasonore en direction de l'objet en guide d'onde, à travers le support d'interposition. L'interface utilisateur (108) est conçue et construite de façon à accepter des données entrées par un opérateur du système. Le dispositif d'affichage (110) est conçu et construit de façon à afficher un ou plusieurs objet(s) d'information se rapportant au guide d'onde.
PCT/US2002/039690 2001-12-20 2002-12-12 Appareil ultrasonore et procede de positionnement et de mise en image d'un objet en guide d'onde a travers un support d'interposition Ceased WO2003053247A1 (fr)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019110846A3 (fr) * 2017-12-08 2019-10-17 Lechner, Johann Appareil et procédé de détection de cavitations par échographie alvéolaire à transmission (tau)
US10548567B2 (en) 2016-12-13 2020-02-04 General Electric Company System and method for displaying medical images of an object within a patient
US10799210B1 (en) 2017-09-01 2020-10-13 S-Ray Incorporated Dental imaging apparatus and method
CN115227284A (zh) * 2022-06-22 2022-10-25 四川大学 一种基于高频超声的牙科辅助装置及扫描方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0353209A1 (fr) * 1988-07-25 1990-01-31 GIEMMECI S.r.l. Procédé et dispositif destinés à l'examen dentaire à l'aide d'ultrasons
US5115813A (en) * 1987-10-14 1992-05-26 Hollming Oy Ultrasound method and apparatus for examining dense tissues, in particularly dental tissue
US5806521A (en) * 1996-03-26 1998-09-15 Sandia Corporation Composite ultrasound imaging apparatus and method
US6030221A (en) * 1998-02-11 2000-02-29 Cavitat, Inc. Ultrasonic apparatus and for precisely locating cavitations within jawbones and the like

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5115813A (en) * 1987-10-14 1992-05-26 Hollming Oy Ultrasound method and apparatus for examining dense tissues, in particularly dental tissue
EP0353209A1 (fr) * 1988-07-25 1990-01-31 GIEMMECI S.r.l. Procédé et dispositif destinés à l'examen dentaire à l'aide d'ultrasons
US5806521A (en) * 1996-03-26 1998-09-15 Sandia Corporation Composite ultrasound imaging apparatus and method
US6030221A (en) * 1998-02-11 2000-02-29 Cavitat, Inc. Ultrasonic apparatus and for precisely locating cavitations within jawbones and the like

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10548567B2 (en) 2016-12-13 2020-02-04 General Electric Company System and method for displaying medical images of an object within a patient
US10799210B1 (en) 2017-09-01 2020-10-13 S-Ray Incorporated Dental imaging apparatus and method
WO2019110846A3 (fr) * 2017-12-08 2019-10-17 Lechner, Johann Appareil et procédé de détection de cavitations par échographie alvéolaire à transmission (tau)
US11839508B2 (en) 2017-12-08 2023-12-12 Johann Lechner Apparatus and method for detecting cavitations using through-transmission alveolar ultrasonography (TAU)
US12446851B2 (en) 2017-12-08 2025-10-21 Johann Lechner Apparatus and method for detecting cavitations using through-transmission alveolar ultrasonography (TAU)
CN115227284A (zh) * 2022-06-22 2022-10-25 四川大学 一种基于高频超声的牙科辅助装置及扫描方法

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