(cid:6)(cid:27)&(cid:11)(cid:11)(cid:12)(cid:12) (cid:15)(cid:15)(cid:19)(cid:18)(cid:24)(cid:12)(cid:6)
`EP 1 124 487 B1
`
`(11)
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`(19)
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`(12)
`
`(45) Date of publication and mention
`of the grant of the patent:
`23.05.2007 Bulletin 2007/21
`
`(21) Application number: 99952782.3
`
`(22) Date of filing: 01.11.1999
`
`EUROPEAN PATENT SPECIFICATION
`(51) Int Cl.:(cid:3)
`A61B6/00(2006.01)
`
`A61B6/14(2006.01)
`
`(86) International application number:
`PCT/IL1999/000577
`
`(87) International publication number:
`WO 2000/025677 (11.05.2000 Gazette 2000/19)(cid:3)
`
`(54) DENTAL IMAGE PROCESSING METHOD AND SYSTEM
`
`VERFAHREN UND VORRICHTUNG ZUR VERARBEITUNG VON DENTALBILDERN
`
`PROCEDE ET SYSTEME DE TRAITEMENT D’IMAGE DENTAIRE
`
`(84) Designated Contracting States:
`AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU
`MC NL PT SE
`
`(30) Priority: 01.11.1998 IL 12683898
`
`(43) Date of publication of application:
`22.08.2001 Bulletin 2001/34
`(73) Proprietor: Cadent Ltd.(cid:3)
`60372 Or Yehuda (IL)(cid:3)
`
`(72) Inventors:
`• KOPELMAN, Avi
`Ganei Tikva 55900 (IL)(cid:3)
`
`• TAUB, Eldad
`71908 Reut (IL)(cid:3)
`(74) Representative: Joly, Jean-(cid:3)Jacques et al
`Cabinet Beau de Loménie
`158, rue de l’Université
`75340 Paris Cédex 07 (FR)(cid:3)
`
`(56) References cited:
`EP-(cid:3)A- 0 488 987
`US-(cid:3)A- 5 151 856
`
`EP-(cid:3)A- 0 741 994
`US-(cid:3)A- 5 278 756
`
`3SHAPE EXHIBIT 2005
`Exocad v. 3Shape
`IPR2018-00785
`
`Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give
`notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in
`a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art.
`99(1) European Patent Convention).
`
`Printed by Jouve, 75001 PARIS (FR)
`
`EP1 124 487B1
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`EP 1 124 487 B1
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`Description
`
`FIELD OF THE INVENTION
`(cid:3)[0001] The present invention is generally in the field of
`dentistry and provides an image processing method and
`system useful as a tool by the dentist or orthodont.
`
`BACKGROUND OF THE INVENTION
`(cid:3)[0002] There are a wide variety of imaging techniques
`used routinely in orthodontics. One important imaging
`technique is the so-(cid:3)called radiographic cephalometric
`technique. A radiographic cephalometric image is then
`used for a cephalometric analysis. Such an analysis is
`essentially a measurement system designed to describe
`relationships between the various parts of the skeletal,
`dental and soft tissue elements of the craniofacial com-
`plex. The two cephalometric images typically used are a
`lateral cephalometric image, which is of prime use in or-
`thodontic and a front cephalometric image which is of
`somewhat less importance.
`(cid:3)[0003] Cephalometric methods enable to define cer-
`tain norms of a skeletal, dental and soft tissue of the
`craniofacial complex. A cephalometric measurement of
`individuals can then be compared with norms for age,
`sex and population group. A cephalogram is in effect a
`two-(cid:3)dimensional representation of a three-(cid:3)dimensional
`craniofacial structure. It is thus difficult in an analysis per-
`formed on such an image to distinguish between bi-(cid:3)lat-
`eral structures to trace them independently. Additionally,
`facial aspects are not entirely symmetrical, this may add
`a further inaccuracy to an analysis of this kind. Other
`sources of errors in a cephalometric image include dif-
`ferent magnification of different aspects depending on
`the distance from the film and imperfect positioning of
`the patient in the cephalostat. These all add up to con-
`siderable errors in cephalometry.
`(cid:3)[0004] An orthodont, prior to beginning the orthodontic
`treatment typically takes a teeth impression on the basis
`of which a plaster model may be prepared. There are
`also known a number of imaging techniques which allow
`to obtain, within a computer environment, a virtual three-
`dimensional image of the teeth. Such techniques are de-
`scribed for example in WO 97/03622 and DE-(cid:3)C-(cid:3)414311.
`A three-(cid:3)dimensional teeth image provides a different in-
`formation than that obtained by a cephalometric analysis.
`Particularly, a virtual teeth image allows better appreci-
`ation of the three-(cid:3)dimensional structure of the teeth and
`the relative position of different teeth.
`(cid:3)[0005] EP-(cid:3)A-(cid:3)0 488 987 discloses a procedure for dis-
`playing movable bodies. Here, images of the body are
`acquired with a camera precisely located with respect to
`a magnetic field source (coils). To locate the body with
`respect to the camera, a magnetic response assembly
`is attached to the body, and a magnetic stylus is used to
`mark three measurement points on the body. This ena-
`bles to display points on the body that cannot be imaged
`
`by the camera.
`(cid:3)[0006] EP-(cid:3)A-(cid:3)0 741 994 discloses a technique for plan-
`ning a surgical intervention in the area of the patient’s
`jaw by means of a model. The technique utilizes a posi-
`tion-(cid:3)determining device inserted in a patients oral cavity.
`This positioning device is formed with marking points to
`be located in at least one image of the oral cavity.
`(cid:3)[0007] US-(cid:3)A-(cid:3)5 151 856 discloses a method of display-
`ing cardiac function which forms a 3-(cid:3)D model of a heart
`on which is superimposed an arterial diagram obtained
`from a patient angiogram.
`(cid:3)[0008] For the purpose of proper design of orthodontic
`treatment it would have been high advantageous to have
`a method and system whereby information which can be
`acquired from one type of image can be transferred or
`superpositioned to information available from another
`type of image.
`
`GENERAL DESCRIPTION OF THE INVENTION
`(cid:3)[0009]
`In accordance with the invention a novel meth-
`od and system is provided in which information and data
`available from one type of teeth imaging technique is
`transferred and used in an image obtained by another
`kind of teeth imaging technique. This transfer of informa-
`tion provides the dentist or the orthodont with a powerful
`tool for designing of orthodontic treatment
`(cid:3)[0010]
`In accordance with the invention there is pro-
`vided an image processing method comprising:(cid:3)
`
`(a) applying at least a first imaging technique and a
`second imagining technique to acquire a first, two-
`dimensional image of at least a first portion of teeth
`and a second, three- dimensional virtual image of at
`least a second portion of the teeth, respectively,
`there being at least a partial overlap between said
`first and second portions; and
`(b) defining a set of basic landmarks in either one of
`the two images, locating said set in the other of the
`two images and registering said set in the two imag-
`es.
`(cid:3)[0011] By another of its aspects the present invention
`provides an image processing system, comprising:(cid:3)
`
`(i) a first utility for receipt of first data representative
`of a first two-(cid:3)dimensional image of at least a first
`teeth portion;
`(ii) a second utility for receipt of second data repre-
`sentative of a second three-(cid:3)dimensional virtual im-
`age of teeth of at least a second teeth portion;
`(iii) a module for defining basic landmarks in both
`images and for generating data representative there-
`of; and
`(iv) a processor associated with said first and said
`second utility and with said module, for receiving said
`first and said second data and for mapping elements
`in one of the two images to the other of the two im-
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`ages according to the data representative of said
`basic landmarks.
`(cid:3)[0012]
`In accordance with one embodiment of the in-
`vention, the imaging method and system is used to obtain
`orthodontic-(cid:3)relevant information, namely information to
`be used by an orthodont within the framework of an or-
`thodontic treatment or for the design of such a treatment.
`This embodiment involves a registration of at least two
`images, one being a three-(cid:3)dimensional virtual image of
`a teeth model and the other being a two-(cid:3)dimensional im-
`age, e.g. a cephalometric image. Occasionally, other im-
`ages may also be brought into registration consisting, for
`example of one or more of a lateral videographic image,
`a frontal videographic image and a frontal cephalometric
`image.
`(cid:3)[0013]
`In accordance with another embodiment of the
`invention, the method and system are used for proper
`design of a dental implant or of a crown. For proper place-
`ment of an implant, the bone has to be carefully studied
`beforehand and examined whether it can receive the
`dental implant. In addition, the exact position and orien-
`tation of the dental implant has to be properly pre-(cid:3)de-
`signed. Typically, for a proper design of an implant, a
`three-(cid:3)dimensional virtual image of a teeth model is
`brought into registration with both a lateral cephalometric
`image and at times also with a frontal cephalometric im-
`age. This will allow to properly predict the manner of re-
`ceipt of the implant within the bones of the jaw.
`(cid:3)[0014]
`In the following, the invention will be described
`with particular reference to imaging for the purpose of
`design of the orthodontic treatment. It will however be
`appreciated, that the invention applies, mutatis mutandis
`also to its application for the purpose of proper design of
`tooth implants.
`(cid:3)[0015] The first image is preferably an x-(cid:3)ray image,
`typically a cephalometric image obtained by radiographic
`cephalometric technique. The x-(cid:3)ray image is preferably
`a lateral image although at times the image may be from
`another orientation, e.g. a frontal image. In a cephalom-
`etric image, some facial profile aspects may at times be
`seen. However, typically, before an orthodontic treat-
`ment also a third, side elevational view of the face is taken
`from the same direction in which the radiographic cepha-
`lometric image was obtained. In accordance with an em-
`bodiment of the invention, such a third image, comprising
`at least a profile of facial aspects, is also obtained and
`used in the imaging technique of the invention. The side
`elevational image may be obtained, for example, by video
`cephalometry.
`(cid:3)[0016] The term "virtual three-(cid:3)dimensional teeth im-
`age" refers to an image, represented within the computer
`environment which consists primarily of the teeth of one
`or both jaws. For example, a virtual three-(cid:3)dimensional
`teeth image may be represented in a manner resembling
`an image of a plaster model. A virtual three-(cid:3)dimensional
`image may be obtained by a variety of techniques, e.g.
`those described in the references mentioned above. Par-
`
`EP 1 124 487 B1
`4
`ticularly, the three-(cid:3)dimensional virtual image may be ob-
`tained by the method described in WO 97/03622, which
`is an example of the manner of obtaining a three-(cid:3)dimen-
`sional virtual image for use in the method and system of
`the invention. It should be understood that the invention
`is not limited to a specific type of image obtained by one
`imaging technique or another. For example, the two-(cid:3)di-
`mensional image may be obtained by a variety of different
`imaging techniques including magnetic resonance imag-
`ing (MRI), computerized tomography (CT) various radio-
`imaging techniques, etc. Similarly, the three-(cid:3)dimensional
`teeth image may be obtained by any one of a number of
`imaging techniques available including those disclosed
`in the aforementioned references as well as others such
`as those making use of a scanning probe, various pho-
`tographic techniques, techniques in which teeth are
`scanned by a probing light beam, etc.
`(cid:3)[0017] The term "image" as used herein should not be
`understood only as referring to the image as acquired in
`the imaging technique but rather may be also a result of
`initial image processing, e.g. an image processing in-
`tended to define boundaries of various objects in the im-
`age. Thus, the term "image" encompasses also a repre-
`sentation, prepared on the basis of an acquired image,
`of boundaries of objects, e.g. teeth, bones, a profile of
`facial aspects, etc.
`(cid:3)[0018] Often, the imaging technique and analysis in
`accordance with the invention will make use of a third
`image, which may be the elevational image mentioned
`above, or any other image useful in improving the ortho-
`dontic analysis. Thus, by way of example, where said
`first image is a lateral two- dimensional image, said third
`image may be one or both of the afore- mentioned lateral
`elevational image or a frontal x-(cid:3)ray or videographic im-
`age.
`(cid:3)[0019] The basic landmarks which are used for regis-
`tering the two sets of images, are typically defined points
`at either the base or the apex of certain selected teeth
`e.g. the incisors and the first molars. Such basic land-
`marks may be selected by the user or may be automat-
`ically selected by the system’s processor, e.g. based on
`established norms. After selecting the basic landmarks
`and marking them in one of the images, then the land-
`marks may be marked in the other images to allow to
`register both images. The term "registering" should not
`necessarily be understood as meaning a physical regis-
`tration of the two images but rather as meaning the map-
`ping of each feature in one image to a corresponding
`feature in another. The outcome of such registration is
`that any manipulation made on one image will yield a
`corresponding manipulation in the other image. For ex-
`ample, if one image is manipulated by displacing one
`tooth, this should result in a corresponding displacement
`of the same tooth in the other image.
`(cid:3)[0020] At times it may be desired to view both images
`on a screen superimposed one on the other. As two or
`more images have to be superimposed may be present-
`ed initially at a different scale, an initial step which is
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`EP 1 124 487 B1
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`necessary to be taken by the system is to either enlarge
`or reduce the scale of one image until there is an essential
`complete overlap of the basic landmarks in the two im-
`ages. It should however be noted that registering of dif-
`ferent images may not necessarily imply superposition-
`ing, but rather at times the two registered images may
`be represented separately, e.g. side-(cid:3)by-(cid:3)side. The impor-
`tant result of the act of registering is that manipulation
`made on one of the images will effect the other as well.
`(cid:3)[0021]
`In the following, the invention will be described
`with particular reference to an embodiment in which the
`first image is a cephalometric image and the second im-
`age is a virtual three-(cid:3)dimensional image. This specific
`reference should not however be construed as meaning
`that the invention is limited thereto. On the contrary, by
`applying the general teaching of the invention, informa-
`tion may be transferred between images obtained by oth-
`er imaging techniques.
`(cid:3)[0022]
`In accordance with one embodiment of the in-
`vention, after landmarks have been defined in the three-
`dimensional virtual images and in the cephalometric im-
`age, the correct orientation of the virtual three-(cid:3)dimen-
`sional teeth model has to be determined so as to allow
`it to be brought into conformity with the cephalometric
`image. This may at times require extensive computation-
`al time. It has however been found that the process of
`registration of the two images can be considerably ac-
`celerated by defining the cephalometric image to overlap
`the mid palatal plane of the virtual three-(cid:3)dimensional
`teeth image. In other words, the cephalometric image is
`defined to lie on the mid palatal plane and the cephalo-
`graphic image is then adjusted until the basic landmarks
`overlap with the projection of the corresponding basic
`landmarks of the virtual three-(cid:3)dimensional image onto
`the mid palatal plane.
`(cid:3)[0023] The invention permits also an analysis of the
`effect of teeth displacement on various aspects of the
`cranofacial complex. For example, teeth may be dis-
`placed on the virtual three-(cid:3)dimensional image of teeth
`model in a manner they are expected to be shifted during
`the course of the orthodontic treatment. Thus, for exam-
`ple, by marking various landmarks on a displaced teeth
`and marking and then displacing the same landmarks in
`the cephalometric model, it may be possible to check on
`both images whether the orthodontic treatment achieves
`a result which matches a certain acceptable norm or how
`changes should be made to achieve such a norm. If, for
`example, a desired result as viewed in an amended ce-
`phalometric image (namely a cephalometric image after
`a tooth has been displaced) does not match the desired
`results, it is possible to go back to the virtual three- di-
`mensional teeth model and proceed with a simulation
`and then map the results onto the cephalometric image,
`and so forth.
`(cid:3)[0024] By way of example, in order to achieve the same
`degree of displacement in one image, the shifting of a
`certain landmark which is associated with a displaced
`object is then compared to some basic landmarks and
`
`the same relation of displacements is then related to the
`other image.
`(cid:3)[0025] One particular example of analysis which can
`be made by such simulation is to determine the effect of
`such displacement on soft facial tissue, particularly outer
`facial tissue. This will allow an estimation of the effect of
`the orthodontic treatment on the esthetic appearance of
`the individual.
`(cid:3)[0026] A simulation of the treatment and then transla-
`tion of the results to a cephalometric image allows also
`to determine whether shifts in various elements such as
`the jaw, are within permitted physiological or aesthetical
`limits. An uncontrolled shifting of a tooth or a jaw in an
`orthodontic treatment may give rise to various physiolog-
`ical and functional problems.
`(cid:3)[0027] The invention will now be illustrated below with
`reference to some specific, non-(cid:3)limiting embodiments,
`with occasional reference to the accompanying draw-
`ings.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`(cid:3)[0028]
`
`Fig. 1A shows an example of a radiographic cepha-
`lometric image.
`Fig. 1B shows a virtual three-(cid:3)dimensional image of
`teeth, presented in the manner resembling a plaster
`teeth model.
`Fig. 2 shows a super-(cid:3)position of a three-(cid:3)dimensional
`teeth model and a cephalometric image.
`Figs. 3A and 3B show two examples of super-(cid:3)posi-
`tion of a three-(cid:3)dimensional model and a video ce-
`phalometric image.
`Fig. 4A shows a cephalometric image with some
`basic landmarks marked thereon.
`Fig. 4B shows a three-(cid:3)dimensional virtual image of
`the same teeth as those shown in the cephalometric
`image of Fig. 4A, with the same basic landmarks
`marked thereon.
`Fig. 5 shows a super-(cid:3)position of the two images.
`Fig. 6 is a block diagram representation of a system
`in accordance with the invention.
`Figs. 7A and 7B are flowcharts showing the manner
`of mapping elements from a three-(cid:3)dimensional vir-
`tual teeth model to a cephalometric image. Fig. 7A
`shows the user’s interaction modules whereas Fig.
`7B shows the software functionality underlying the
`manner of performing of displacement and mapping
`the displacement from the three-(cid:3)dimensional virtual
`teeth model to the cephalometric image.
`Figs. 8A and 8B are flowcharts showing the manner
`of mapping elements from a cepthalometric image
`to a three-(cid:3)dimensional virtual teeth model. Fig. 8A
`shows the user’s interaction modules whereas Figs.
`8B shows the software functionality underlying the
`manner of performing of displacement and mapping
`the displacement from the cephalometric image to
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`the virtual three-(cid:3)dimensional teeth model.
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`DETAILED DESCRIPTION OF SPECIFIC EMBODI-
`MENTS
`(cid:3)[0029]
`In accordance with the present invention imag-
`es are acquired including at least one two-(cid:3)dimensional
`teeth image and at least one three-(cid:3)dimensional teeth im-
`age and both are combined for the purpose of improving
`the orthodont’s ability to predict the effect of orthodontic
`treatment on various parameters. This combination al-
`lows the orthodont to considerably increase the depth of
`his understanding on the outcome of the orthodontic
`treatment. Hitherto, analysis which was made on a ce-
`phalometric images could not have been readily trans-
`lated to the other tools available to him - this being the
`three-(cid:3)dimensional teeth model, typically a plaster model.
`In the reverse, information gained by him from studying
`a three-(cid:3)dimensional teeth model, could not have been
`readily translated to a cephalometric image. As is well
`known to the artisan, each one of the images allows a
`limited range of analysis which can be made and a true
`analysis can only be gained from thorough analysis
`based on the two types of images.
`(cid:3)[0030]
`It is only with the present invention that a proper
`analysis becomes feasible.
`(cid:3)[0031] An image, once acquired and converted to a
`representation within a computer environment can be
`manipulated, e.g. by displacing certain elements, such
`as one or more teeth or even an entire jaw. The cepthalo-
`metric image allows to view the interrelation between
`some elements and may be used, for example, to test
`the effect of the treatment on some physiological or func-
`tional parameters as well as the aesthetic parameters.
`There is, however, a significant deficiency in that it is
`impossible to fully translate this information to the three-
`dimensional real-(cid:3)life environment. The present invention
`permits a proper analysis of the effect of displacement
`of elements and or better understanding of how changes
`will effect the real-(cid:3)life situation.
`(cid:3)[0032] Reference is first being made to Figs 1A and
`1B, showing respectively, a cephalometric radiograph
`and a three-(cid:3)dimensional virtual teeth image. The virtual
`teeth image which is shown in Fig. 1B, is represented in
`a manner resembling a plaster teeth model. As will no
`doubt be appreciated by the artisan, this is but an exam-
`ple, and the two-(cid:3)dimensional or the virtual three dimen-
`sional teeth image may be represented in a different way.
`(cid:3)[0033] Prior to the present invention, each of these dif-
`ferent images, was represented separately. The three-
`dimensional virtual image was represented either as a
`plaster model or a three-(cid:3)dimensional virtual representa-
`tion in a computer environement. In accordance with the
`invention, two different images, one being a two-(cid:3)dimen-
`sional image, e.g. a cephalometric radiograph, is com-
`bined with a three-(cid:3)dimensional teeth image. A super-(cid:3)po-
`sition of two such images is represented in exemplary
`Fig. 2. As can be seen, the cephalometric image is com-
`
`EP 1 124 487 B1
`8
`bined with the three-(cid:3)dimensional virtual teeth image such
`that it lies on the mid palatal plane of the three-(cid:3)dimen-
`sional virtual teeth image. The relative position of the two
`images is fixed such that basic landmarks defined in the
`two images concur, as will be described further below.
`(cid:3)[0034] Another implementation of the invention can be
`seen in exemplary Figs. 3A and 3B. In these figures, a
`three-(cid:3)dimensional virtual teeth image is superpositioned
`with a lateral or profile picture of an individual. The profile
`pictures in Figs. 3A and 3B are each from a slightly dif-
`ferently orientation and accordingly the virtual three-(cid:3)di-
`mensional teeth model in Fig. 3B is rotated with respect
`to the orientation of the model in Fig. 3A.
`(cid:3)[0035]
`In order to combine a cephalometric image and
`a three-(cid:3)dimensional virtual model, basic landmarks have
`to be defined and marked in both images. These basic
`landmarks may be entered manually by the user, al-
`though alternatively, they may be automatically generat-
`ed by a computer, based on standard image analysis
`method, or based on an earlier user input. Generally,
`such basic landmarks may be arbitrary landmarks or may
`be orthodontic relevant landmarks which may be used
`later in a cephalometric analysis, in accordance with one
`of the acceptable norms therefor. (For review on a ce-
`phalometric analysis see Radiographic Cephalometry,
`From Basics to Videoimaging, Jacobson A., et al., Quin-
`tessence Publishing Co., Inc., Chicago, Berlin, 1995).
`(cid:3)[0036] A cephalometric radiograph and the three-(cid:3)di-
`mensional teeth model from the same individual, are
`shown in Figs. 4A and 4B. In these figures, two basic
`landmarks have been marked - L1 and L2. After these
`landmarks have been marked, the two images are
`brought into registration which results in super-(cid:3)position-
`ing as can be seen in Fig. 5 (the same two landmarks L1
`and L2 can also be seen here). The registration in the
`manner shown in Figs. 4A, 4B and 5 is performed using
`two defined landmarks. Obviously, it is possible at times
`to use more landmarks for this purpose to increase ac-
`curacy of registration.
`(cid:3)[0037]
`In order to reduce computational time, the ce-
`phalometric radiograph is combined with the three-(cid:3)di-
`mensional virtual teeth image by placing (in a virtual
`sense) the cephalometric image on the mid palatal plane.
`For proper registration, the scale of the two images has
`to be adjusted and then one image has to be shifted ver-
`sus the other until the projection of the basic landmarks
`of the three-(cid:3)dimensional virtual image of teeth model onto
`its mid palatal plane are in register with the corresponding
`landmarks in the cephalometric image.
`(cid:3)[0038] The cephalometric radiograph and the cepha-
`lometric videograph as shown herein, are images as ac-
`quired by the utilized imaging technique. It should how-
`ever be noted that at times it is advantageous to produce
`initially a representation of the image, e.g. a graphic rep-
`resentation of boundaries of objects of interest within the
`image. For example, rather than a full cephalographic
`image, a representation comprising boundaries of some
`major bones and several teeth, e.g. the first and second
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`EP 1 124 487 B1
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`molar teeth and the incisors. These aforementioned teeth
`are usually the important teeth for the cephalometric
`analysis, as their position is relatively sensitive to dis-
`placement of teeth and jaws. Furthermore, the position
`of these teeth is an important marker for studying or gaug-
`ing the effect of teeth position on various functional as
`well as aesthetical facial aspects.
`(cid:3)[0039] Producing a graphical representation of some
`aspects of an image, particularly of a cephalometric im-
`age, is very useful for the purpose of a virtual displace-
`ment of the teeth in the image so as to study the effect
`of the treatment on functional or facial aesthetic param-
`eters, as generally known per se.
`(cid:3)[0040] A system in accordance with the embodiment
`of the invention can be seen in Fig. 6. It comprises a
`central computing unit 20 with three input utilities 22, 24
`and 26, which may be integral within module 28. These
`utilities may comprise, as known per se, a data entry port
`and the necessary data transfer software. Furthermore,
`rather than importing of data through a data entry port,
`the data to these utilities may be imported from a storage
`media or from an information carrier, e.g. a magnetic or
`an optical disk. As will no doubt be further understood,
`module 28 may also comprise a scanner for scanning
`images, may comprise a camera for direct image acqui-
`sition, etc.
`(cid:3)[0041] The system still further comprises a module 30,
`connected to a user input interface 32 e.g. a keypad, a
`cursor driver, etc. By means of interface 32 the user may
`define the landmarks or may induce the system to enter
`into various operational modes, some of which will be
`explained below.
`(cid:3)[0042] Module 30 and utility 28 are connected to a
`processor 40 for image processing so as to combine the
`two images as described, for example further below.
`Processor 40 may be connected to monitor 50 and may
`be also connected to other display means, e.g. a printer.
`(cid:3)[0043] A flowchart of an embodiment of the manner of
`linking between a three-(cid:3)dimensional virtual teeth model
`and a cephalometric image can be seen in Figs. 7A and
`7B. Fig. 7A is a flowchart of the user interaction steps
`whereas Fig. 7B is a software functionality flowchart on
`the manner of combining the two images. At a first step
`100, the system receives an input of data representative
`of a three-(cid:3)dimensional virtual teeth model. Then at 110,
`basic landmarks are marked on discernable objects in
`the three-(cid:3)dimensional virtual teeth model as represented
`in image 111. Such basic landmarks may, for example,
`be points on crowns and roots of upper and lower first
`molars (landmarks 1-4 of image 111) as well as on
`crowns and roots of upper and lower centrals (landmarks
`5-8 in image 111). Landsmarks 1 and 4 as well as land-
`marks 5 and 8 mark the approximate position of the roots
`of the teeth. The real root position cannot be seen in such
`a model but the orthodont, based on his experience, can
`relatively accurately mark their roots’ position.
`(cid:3)[0044] At a next step 120, a cephalometric image of
`the same patient is input and on this image, the same
`
`key points are then marked (see 131). Then, the two
`images may be matched, which may be by way of super-
`position as shown above, which can be represented on
`a screen, or by any other way of mapping of each location
`in one image to that of the other image.
`(cid:3)[0045] At a next step 140 teeth and jaws in the three-
`dimensional model may be displaced on the three-(cid:3)dimen-
`sional model to receive a desired result. Then, as repre-
`sented in the flowchart of Fig. 7B, the software at next
`steps 150 and 160 moves skeletal elements and teeth,
`respectively, according to movement performed by the
`user on the three-(cid:3)dimensional virtual teeth model. Then,
`at 170, a cephalometric analysis can be made on the
`amended (after displacement) cepthalometric image to
`see whether desired proportional measurements have
`been reached in such teeth displacement or whether any
`medication should be made.
`(cid:3)[0046] The reverse sequence of operation, namely the
`mapping of each point from a cephalometric image to a
`three-(cid:3)dimensional virtual teeth model is seen in Figs. 8A
`and 8B. In Figs. 8A and Fig. 8B, each of steps 200-270
`corresponds, mutatis mutandis to the steps 100-170 in
`Figs. 7A and 7B. This eventually results in mapping of
`each point in a cephalometric image to the corresponding
`location of the three-(cid:3)dimensional virtual teeth model to
`allow to translate any displacement performed on the
`former image to that in the latter.
`
`Claims
`1. An image processing method comprising :(cid:3)
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`(a) defining a set of basic landmarks (110) in
`one of two images consisting of a first two-(cid:3)di-
`mensional image of at least a first portion of a
`patient’s teeth and a second three-(cid:3)dimensional
`virtual image of at least a second portion of the
`teeth, there being at least a partial overlap be-
`tween first and second portions, said set of basic
`landmarks being in an overlapping region of the
`two images;
`(b) locating the set of basic landmarks in the
`other of the two images (130); and
`(c) combining said two images together by reg-
`istering said basic landmark with each of the two
`images retaining its respective two-(cid:3)dimensional
`or three-(cid:3)dimensional characteristics (140).
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`2. A method according to Claim 1, wherein said first
`image is a longitudinal cross-(cid:3)sectional image.
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`3. A method according to Claim 2, wherein said first
`image is a radiographic x-(cid:3)ray image.
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`4. A method according to Claim 3, wherein said first
`image is a cephalometric image.
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`EP 1 124 487 B1
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`13. A method according to Claim 12, wherein the dis-
`placement of said soft tissue is predicted using a
`third image of at least a profile of facial aspects.
`14. An image processing system comprising :(cid:3)
`
`(i) first and second utilities (22, 24) for receipt
`of, respectively, first data representative of a first
`two-(cid:3)dimensional cross-(cid:3)sectional image of at
`least a first teeth portion, and second data rep-
`resentative of a second, three-(cid:3)dimensional vir-
`tual image of teeth model of at least a second
`teeth portion, an overlapping region existing be-
`tween said first and second portions;
`(ii) a module for defining basic landmarks (30)
`in at least one of the first and second teeth por-
`tions as selected locations within the overlap-
`ping region, and for generating data represent