Patent Description:
Typically, the correct positioning of a patient may be one of the most time-consuming tasks of a user of an X-ray imaging unit in an X-ray imaging process. Traditionally, the patient may be positioned to the X-ray imaging unit using various supporting methods that are supposed to hold a head of the patient as stationary as possible.

Traditional supporting means may be a chin rest, a static bite stick, and a head support, where the forehead, temple, and/or back of the skull is supported. In addition, different kind of straps may be used to make the patient positioning as rigid as possible. In addition, some X-ray imaging units have such bite sticks that are attached to the X-ray imaging unit such that attachment means allow movements of the bite sticks in some directions.

One approach that can be considered as traditional as well is using scout images. This is a small dose panoramic image or a set of two projection images taken at <NUM> degrees angle that can be used as a targeting aid for a three-dimensional (3D) image.

A rigid setup is very important with this kind of approach. When the patient positioning (targeting) is done, the patient should keep steady for a whole imaging process. If the patient and/or the X-ray imaging unit moves, i.e. the position of the patient with relation to the X-ray imaging unit changes, between the targeting and the X-ray scanning phases, the resulting X-ray image might be diagnostically useless. Motion of the patient and/or the X-ray imaging unit during the scanning phase may cause severe artifacts in the resulting X-ray image and these artifacts caused by the motion needs to be reduced during a reconstruction of obtained image data during the scanning phase to the dental X-ray image, if possible or can be tried to be reduced by using a software, i.e. computer program, -based correction. The artifacts caused by the motion may af-feet the dental X-ray image quality significantly. The result may be e.g. a blurred image or a distorted image.

Moreover, in panoramic imaging the anatomic shapes of the patient's jaws are unknown prior taking a panoramic image. Panoramic image quality is affected heavily based on how well a pre-defined imaging layer corresponds with the actual anatomic shapes, e.g. dental arch, of the patient. Typically, an average shape is used for all patients, which may lead to a non-optimized image quality.

<CIT> may be considered to disclose the preamble of claims <NUM>, <NUM> and <NUM>.

An objective of the invention is to present a controller, an imaging system, a method, a computer program, and a tangible non-volatile computer-readable medium for dental imaging of an object, and a method for using optical image data in dental X-ray imaging of an object. Another objective of the invention is that the controller, the imaging system, the method, the computer program, and the tangible non-volatile computer-readable medium for dental imaging of an object, and the method for using optical image data in dental X-ray imaging of an object improve quality of the dental X-ray images.

The objectives of the invention are reached by a controller, an imaging system, methods, a computer program, and a tangible non-volatile computer-readable medium as defined by the respective independent claims.

According to a first aspect, a controller for dental imaging of an object is provided, wherein the controller comprises: at least one processor, and at least one memory including computer program code, wherein the at least one memory and the computer program code is configured to, with the at least one processor, cause the controller at least to: obtain first image data from an optical scanner unit; obtain second image data from a dental X-ray imaging unit; produce a first surface model from the obtained first image data, wherein the first surface model represents an optical three-dimensional shape of a surface of a first part of the object; and use the first surface model to process the obtained second image data.

The optical scanner unit may be an intra oral scanner unit.

The obtained first image data may comprise first image data previously obtained from the optical scanner unit.

The controller is configured to: detect based on the first surface model a motion of the object occurring during an acquisition of the second image data, and reduce based on the first surface model artifacts caused by the motion in a two-dimensional or a three-dimensional dental X-ray image reconstructed from the obtained second image data.

The detection of the motion may comprise: production of a second surface model from the obtained second image data, wherein the second surface model represents an X-ray 3D shape of a surface of a second part of the object, and wherein the second part of the object overlaps at least partly with the first part of the object; comparison of a similarity of the second surface model and the first surface model; and detection of the motion, if the second surface model differs from the first surface model.

The production of the second surface model may comprise: reconstruction of the obtained second image data to a three-dimensional dental X-ray image, and extraction of the second surface model from the three-dimensional dental X-ray image by using segmentation.

Alternatively or in addition, the detection of the motion may further comprise registration of the first surface model and the second surface model before the comparison.

Alternatively, the controller may be configured to: determine based on the first surface model an anatomic shape of the object, and adjust a reconstruction of a dental X-ray image from the obtained second image data so that a focal trough in the dental X-ray image corresponds to the anatomic shape of the object determined based on the first surface model.

According to a second aspect, an imaging system for dental imaging of an object is provided, wherein the imaging system comprises: a dental X-ray imaging unit for providing second image data, wherein the dental X-ray imaging unit comprises: a gantry part, an X-ray source part for emitting X-rays, and an X-ray imaging detector part for receiving the X-rays from the source part, wherein the gantry part comprises the source part and the detector part; an optical scanner unit for providing first image data; and a controller as described above, wherein the controller is configured to: obtain the first image data from the optical scanner unit; obtain the second image data from the dental X-ray imaging unit; produce a first surface model from the obtained first image data, wherein the first surface model represents an optical three-dimensional shape of a surface of a first part of the object; and use the first surface model to process the obtained second image data.

According to a third aspect, a method for dental imaging of an object is provided, which method is performed by a controller as defined above, wherein the method comprises: obtaining first image data from an optical scanner unit; obtaining second image data from a dental X-ray imaging unit; producing a first surface model from the obtained first image data, wherein the first surface model represents an optical three-dimensional shape of a surface of a first part of the object; and using the first surface model to process the obtained second image data.

According to a fourth aspect, a computer program is provided, wherein the computer program comprises instructions which, when the program is executed by a controller as described above, cause the controller to carry out the method as described above.

According to a fifth aspect, a tangible non-volatile computer-readable medium is provided, wherein the tangible non-volatile computer-readable medium comprises instructions which, when executed by a controller as described above, cause the controller to carry out the method as described above.

According to a sixth aspect, a method for using optical image data in dental X-ray imaging of an object is provided, wherein the method comprises: obtaining optical image data of the object from an optical scanner unit, and using the obtained optical image data in the dental X-ray imaging of the object.

The using of the obtained optical image data comprises: detecting based on the optical image data a motion of the object occurring during an acquisition of X-ray image data of the object, and reducing based on the optical image data artifacts caused by the motion in a two-dimensional or a three-dimensional dental X-ray image reconstructed from the X-ray image data of the object. Alternatively, the using of the obtained optical image data may comprise adjusting a reconstruction of a dental X-ray image from X-ray image data of the object so that a focal trough in the dental X-ray image corresponds to an anatomic shape of the object determined based the optical image data.

Alternatively, the using of the obtained optical image data may comprise defining based on the optical image data an imaging geometry of a dental X-ray imaging unit for an acquisition of the X-ray image data of the object.

In this description we use the following vocabulary concerning different phases of a dental X-ray imaging process. The term radiating means the phase comprising merely the irradiation, i.e. the phase when an X-ray source is providing an X-ray beam that travels through an object to an X-ray imaging detector. The object may be expected to remain as still, i.e. immobile, as possible during the radiating. During the radiating one or more parts of the dental X-ray imaging unit may move. The term scanning, in turn, means the phase comprising the radiating and moving of one or more parts of the dental X-ray imaging unit. The scanning does not comprise positioning of one or more parts of the X-ray imaging unit in a correct place for providing X-ray images. The term imaging means the whole process comprising radiating, scanning and positioning.

<FIG> illustrates an example of an imaging system <NUM> in accordance with the invention. The imaging system <NUM> comprises a dental X-ray imaging unit <NUM> for providing dental X-ray image data, i.e. second image data, of the object, an optical scanner unit <NUM> for providing optical image data, i.e. first image data, of the object, and a controller <NUM>.

The dental X-ray imaging unit <NUM> may be configured for, for example imaging of the dentomaxillofacial complex of the human skull. The dental X-ray imaging unit <NUM> may be configured to provide different types of imaging procedures, including, but not limited to computed tomography (CT) imaging, panoramic imaging (standard, pediatric, orthozone, wide arch, orthogonal and/or the like), and/or cephalomatric imaging (cephalo pediatric lateral projection, cephalo lateral projection, cephalo posterior-anterior, and/or the like). The CT imaging may be Cone beam CT (CBCT) imaging, wherein the beam is a cone-shaped beam, or alternative CT imaging, wherein the beam is a pyramidal-shaped beam, half-moon -shaped cone beam, or any other shaped beam. <FIG> illustrates only one example of a dental X-ray imaging unit <NUM> for use with the concepts in the present disclosure.

The dental X-ray imaging unit <NUM> comprises a housing <NUM> that is moveably supported on a support column <NUM>. The housing <NUM> may be moved up and down in the vertical direction by means of a guide motor (not shown in <FIG>) that is configured to move the housing <NUM> vertically up and down along the supporting column <NUM>. A supporting section, i.e. upper shelf, <NUM> is configured to support a gantry part, i.e. a rotating part, <NUM>, which is rotatable in a horizontal plane with respect to the supporting section <NUM>. The supporting section <NUM> and/or gantry part <NUM> may comprise a rotating motor (not shown in <FIG>) configured to rotate the gantry part <NUM>. Alternatively or in addition, the supporting section <NUM> may comprise a pivot motor (not shown in <FIG>) configured to pivot the gantry part <NUM> around the column <NUM>. Alternatively or in addition, the dental X-ray imaging unit <NUM> may be mounted to a supporting structure (not shown in <FIG>) exemplarily a wall to being supported by the column <NUM>.

The dental X-ray imaging unit <NUM> comprises further an X-ray source housing <NUM> and an X-ray imaging detector housing <NUM>, which are arranged opposite to each other and extending generally vertically from the gantry part <NUM>. The source housing <NUM> comprises an X-ray source <NUM>. The X-ray source <NUM> is positioned to emit X-rays from the X-ray source <NUM> through the object being imaged, e.g. a head of the patient, to an X-ray imaging detector <NUM> locating in the X-ray imaging detector housing <NUM>.

Furthermore, the dental X-ray imaging unit <NUM> may comprise a lower shelf <NUM> that extends from the housing <NUM>. The lower shelf <NUM> may comprise a chin support <NUM> for positioning the object, e.g. a head of the patient (not shown in <FIG>), between the opposed X-ray source <NUM> and the X-ray imaging detector <NUM> as in the example dental X-ray imaging unit <NUM> of <FIG>. Alternatively or in addition, the dental X-ray imaging unit <NUM> may comprise a head support <NUM> extending from the horizontal supporting section <NUM> through the rotating part <NUM> as in the example dental X-ray imaging unit <NUM> of <FIG>. Alternatively, the lower shelf <NUM> may comprise the head support <NUM>. The patient support parts, i.e. chin support <NUM> and the head support <NUM>, may be optional, and positioning of the patient may be carried out in other manners.

The X-ray source <NUM> is configured to project a beam (not depicted in <FIG>) of X-rays towards the X-ray imaging detector <NUM>. The X-ray source <NUM> may comprise a collimator (not shown in <FIG>) to restrict and/or shape the beam of X-rays. The X-rays pass through a portion of the object, for example the patient's anatomy, e.g. patient's head. The anatomical structures through which the X-rays pass may absorb varying amounts of the X-ray energy. After passing through the object, the attenuated X-rays are received by the X-ray imaging detector <NUM>. The X-ray imaging detector <NUM> is configured to convert the magnitude of the received X-ray energy and to produce a digitized output, i.e. X-ray image data, representative of the unabsorbed X-rays at the X-ray imaging detector <NUM>. The collection of digitized outputs from the X-ray imaging detector <NUM> that correspond to a single emission of a beam of X-rays from the X-ray source <NUM> may be referred to a projection image of the object being imaged, for example the head of the patient.

The gantry part <NUM> may be rotated by a rotating motor, for example. The rotation of the gantry part <NUM> rotates the X-ray source <NUM> and the X-ray imaging detector <NUM> around the object to be imaged, for example around a rotation axis. The rotation axis may be a mechanical rotation axis or a virtual rotation axis. The mechanical rotation axis of the gantry part <NUM>, may be oriented, i.e. aligned, with the center of the object to be imaged or with a particular anatomical feature of interest within the object to be imaged, for example patient's head. The virtual rotation axis may be obtained, for example, by moving the mechanical rotation axis along a circular path, whereupon the virtual rotation axis may be formed in the center of said circular path. Non-circular rotation may be produced, for example, by moving the X-ray source <NUM> and the X-ray imaging detector <NUM> along a path deviating from the circular path, for example an elliptic path. Other techniques or alignments for the rotation axis may also be used as will be recognized by a person or ordinary skill in the art. As the X-ray source <NUM> and X-ray imaging detector <NUM> are rotated around the object, for example the head of the patient, the X-ray imaging device <NUM> operates to acquire a plurality of projection images of the object taken at incremental angles of rotation. As a non-limiting example, the projection images may be acquired about a <NUM>° or <NUM>° rotation, e.g. in the CT imaging. According to another non-limiting example, the projection images may be acquired about a <NUM>° rotation, e.g. in the panoramic imaging. Furthermore, the X-ray imaging unit <NUM> may capture, for example between <NUM>-<NUM> projection images in an imaging operation. However, this is not intended to be limiting on the present disclosure. Such increments may represent fractions of a degree of rotation. Other angular increments and other total angles of rotation are contemplated within the scope of the present disclosure. The dental X-ray image may be formed from the plurality of projection images by reconstructing the X-ray image data to the dental X-ray image.

The optical scanner unit <NUM> may be an intra oral scanner (IOS) unit as illustrate in the example of <FIG>. Intraoral scanners are devices for capturing direct optical impressions in dentistry. With the IOS unit <NUM> optical image data of the object may be provided directly inside a mouth of the patient or from a stone model or a dental impression produced from the object. Alternatively, the optical scanner unit <NUM> may be a desktop optical scanner unit. With the desktop optical scanner unit <NUM> optical image data of the object may be provided from the stone model or the dental impression produced from the object. <FIG> illustrates only one example of an optical scanner unit <NUM> for use with the concepts in the present disclosure.

The controller <NUM> is configured to obtain first image data of the object, e.g. the patient's anatomy, e.g. a dental arch of the patient, from the optical scanner unit <NUM>. The first image data may be for example optical image data provided, i.e. acquired, by the optical scanner unit <NUM> as described above. Moreover, the controller <NUM> is configured to obtain second image data of the same object at least partly from the dental X-ray imaging unit <NUM>. The second image data may be e.g. X-ray image data provided, i.e. acquired, by the dental X-ray imaging unit <NUM> as described above. A field of view (FOV) of the optical scanner unit <NUM>, when providing the first image data of the object and a 3D FOV of the dental X-ray imaging unit <NUM>, when providing the second image data of the same object, may overlap at least partly. The controller <NUM> may obtain the first image data directly from the optical scanner unit <NUM> or from a database <NUM> to which the first image data previously obtained from the optical scanner unit <NUM> may be stored to, i.e. the obtained first image data comprises first image data previously obtained from the optical scanner unit <NUM>. For example, the previously obtained first image data may be obtained few minutes or even several years earlier before the image processing with the controller <NUM> and stored to the database <NUM>. Alternatively or in addition, the controller <NUM> may obtain the second image data directly from the dental X-ray imaging unit <NUM> or from a database <NUM> to which the second image data previously obtained from the dental X-ray imaging unit <NUM> may be stored to. For example, the previously obtained second image data may be obtained few minutes or even several years earlier before the image processing with the controller <NUM> and stored to the database <NUM>. The previously obtained first image data and the previously obtained second image data may be stored to separate databases or to the same database <NUM> as illustrated in the example of <FIG>.

According to an example of the invention, in response to obtaining the second image data from the dental X-ray imaging unit <NUM> the controller <NUM> may be configured to check whether a previously obtained first image data of the same object has been stored to the database <NUM>. If the controller <NUM> detects that a previously obtained first image data of the same object has been stored to the database <NUM>, the controller <NUM> is configured to obtain the first image data from the database <NUM>.

The controller <NUM> may further be configured to produce a first surface model <NUM> from the obtained first image data. The first surface model represents an optical three-dimensional (3D) shape of a surface of a first part of the object. <FIG> illustrates a non-limiting example of the first surface model <NUM> produced from the first image data. The controller <NUM> may further be configured to use the first surface model <NUM> to process the obtained second image data. The use of the first surface model <NUM>, by the controller <NUM>, to process the obtained second image data may depend on the type of the imaging procedure, e.g. CT imaging or panoramic imaging, i.e. panoramic modality.

Next an example of the use of the first surface model <NUM>, by the controller <NUM>, to process the obtained second image data is discussed, wherein the imaging procedure used by the dental X-ray imaging unit <NUM> may be e.g. CT imaging, e.g. CBCT imaging. The controller <NUM> may be configured to detect a motion of the object occurring during an acquisition of the second image data, i.e. during the scanning process in which the second image data is provided, and to reduce artifacts caused by the motion in a two-dimensional (2D) or a three-dimensional (3D) dental X-ray image reconstructed from the obtained second image data based on the first surface model <NUM>. The 2D or 3D dental X-ray image may be e.g. a CT image.

The controller <NUM> may be configured to produce a second surface model <NUM> from the obtained second image data. The second surface model <NUM> represents an X-ray 3D shape of a surface of a second part of the object. <FIG> illustrates a non-limiting example of the second surface model <NUM> produced from the second image data. The second part of the object overlaps at least partly with the first part of the object so that the first surface model <NUM> and the second surface model <NUM> are at least partly from the same part of the same object. For example, the first part of the object from which the first surface model <NUM> is provided may comprise upper and/or lower full dental arch of the patient, a part of the upper and/or lower dental arch of the patient, or a single tooth of the patient. Alternatively or in addition, the second part of the object from which the second surface model <NUM> is provided may comprise upper and/or lower full dental arch of the patient, a part of the upper and/or lower dental arch of the patient, or a single tooth of the patient as long as the second part of the object overlaps at least partly with the first part of the object. The production of the second surface model <NUM> may comprise reconstruction of the obtained second image data to a 3D dental X-ray image, and extraction of the second surface model <NUM> from the 3D dental X-ray image by using segmentation.

In order to detect the motion of the object occurring during the acquisition of the second image data, the controller <NUM> may be configured to compare a similarity of the second surface model <NUM> and the first surface model <NUM> and to detect motion, if the second surface model <NUM> differs from the first surface model <NUM>. According to an example, before the comparison of the similarity of the surface models <NUM>, <NUM>, the controller <NUM> may be configured to register, i.e. align, the first surface model <NUM> and the second surface model <NUM>. The registration may comprise determination of at least one reference structure from the second surface model <NUM>, finding the corresponding at least one reference structure from the first surface model <NUM>, and registration of the first surface model <NUM> and the second surface model <NUM> based on the at least one reference structure. Alternatively, the registration may comprise determination of at least one reference structure from the first surface model <NUM>, finding the corresponding at least one reference structure from the second surface model <NUM>, and registration of the first surface model <NUM> and the second surface model <NUM> based on the at least one reference structure. For example, the at least one reference structure may be, but is not limited to, a specific tooth.

As discussed above, the dental X-ray image may be formed from the plurality of projection images. Each projection image has an accurately defined and known imaging geometry. If the object does not stay immobile or the dental X-ray imaging unit <NUM> movements do not follow the defined imaging geometry, the reconstruction result, i.e. the reconstructed dental X-ray image, will be distorted by the artifacts caused by the motion. If the controller <NUM> detects that the second surface model <NUM> differs from the first surface model <NUM>, the controller <NUM> detects motion, i.e. infers that the object has been moved during the acquisition of the second image data. In response to detection of the motion, the controller <NUM> is configured to reduce the artifacts caused by the motion in the dental X-ray image reconstructed from the obtained second image data. Alternatively, if the controller <NUM> detects that there is no substantial difference between the second surface model <NUM> and the first surface model <NUM>, the controller <NUM> detects no motion, i.e. infers that the object has not moved during the acquisition of the second image data, causing that there is no need for performing any corrections, e.g. reduction of the artifacts, of the X-ray image.

According to an example, the reduction of the artifacts caused by the motion may comprise iterative adaptation of a mutual imaging geometry of the plurality of projection images forming the dental X-ray image reconstructed from the obtained second image data in order to provide minimum difference between the first surface model <NUM> and the second surface model <NUM>, i.e. to find the best match between the first surface model and the second surface model causing that the second surface model <NUM> becomes as similar as possible as the first surface model <NUM>.

Next another example of the use of the first surface model <NUM>, by the controller <NUM>, to process the obtained second image data is discussed, wherein the imaging procedure used by the dental X-ray imaging unit <NUM> may be e.g. panoramic imaging. The controller <NUM> may be configured to determine an anatomic shape of the object, e.g. dental arch or jawbone shape of the patient, based on the first surface model <NUM> and to adjust the reconstruction of the dental X-ray image from the obtained second image data so that a focal trough in the dental X-ray image corresponds to the anatomic shape of the object determined based on the first surface model <NUM>. The dental X-ray image may be a 2D dental X-ray image, e.g. 2D panoramic image or a bitewing image. The parts of the patient's anatomy that hit in a sharp layer are sharp in the dental X-ray image and the other parts of the patient's anatomy are blurred.

According to an example embodiment of the invention, wherein the imaging procedure used by the dental X-ray imaging unit <NUM> may be e.g. panoramic imaging, the controller <NUM> may be configured to use the first image data, e.g. the optical image data, obtained from the optical scanner <NUM> in the acquisition of the second image data with the dental X-ray imaging unit <NUM>. The use of the first image data in this example embodiment may comprise that the controller <NUM> may be configured to use the first image data to define an imaging geometry of the X-ray imaging unit <NUM> for the acquisition of the second image data, i.e. for the scanning process in which the second image data may be provided. The controller <NUM> may be configured to obtain the first image data of the object, e.g. the patient's anatomy, from the optical scanner unit <NUM> as discussed above. As also discussed above the controller <NUM> may obtain the first image data directly from the optical scanner unit <NUM> or from a database <NUM> to which the first image data previously obtained from the optical scanner unit <NUM> may be stored to, i.e. the obtained first image data comprises first image data previously obtained from the optical scanner unit <NUM>.

The controller <NUM> may further be configured to produce the first surface model <NUM> from the obtained first image data. The first surface model <NUM> represents an optical 3D shape of a surface of a first part of the object as discussed above. The first part of the object from which the first surface model <NUM> may be provided may comprise upper and/or lower full dental arch of the patient. The controller <NUM> may further be configured to determine the anatomic shape of the object, e.g. dental arch or jawbone shape of the patient, based on the first surface model <NUM> as discussed above.

As discussed above, the controller <NUM> may be configured to define the imaging geometry of the dental X-ray imaging unit <NUM> for the acquisition of the second image data based on the first surface model <NUM>. The imaging geometry of the dental X-ray imaging unit <NUM> may be defined by the controller <NUM> based on the anatomic shape of the object determined based on the first surface model <NUM> so that the focal trough in the dental X-ray image reconstructed from the second image data acquired by using the defined imaging geometry corresponds to the anatomic shape of the object determined based on the first surface model <NUM>. In other words, in this example embodiment the first surface model <NUM> is formed and the the anatomic shape of the object is determined based on the first surface model <NUM> before the acquisition of the second image data by the dental X-ray imaging unit <NUM>, i.e. before the scanning process in which the second image data is provided. The controller <NUM> may further be configured to use information representing positioning of the object to define the imaging geometry of the dental X-ray imaging unit <NUM> so that that the focal trough in the dental X-ray image reconstructed from the second image data acquired by using the defined imaging geometry of the X-ray imaging unit <NUM> corresponds to the anatomic shape of the object determined based on the first surface model <NUM>. The information representing the positioning of the object may comprise for example a position from which the object is supported, e.g. by using one or more of the patient support parts, and/or the center of the object. The information representing the positioning of the object may be defined by using any known techniques. According to a non-limiting example, the position from which the object is supported may be defined based on a bite block, e.g. a bite stick, arranged for example to the chin support <NUM>. The controller <NUM> may be configured to provide the defined imaging geometry of the dental X-ray imaging unit <NUM> to the dental X-ray imaging unit <NUM>, which may then be configured to acquire, i.e. provide, the second image data of the same object by using the defined imaging geometry.

The controller <NUM> may further be configured to obtain from the dental X-ray imaging unit <NUM> the second image data acquired by using the defined imaging geometry of the dental X-ray unit <NUM> and to reconstruct the obtained second image data to a dental X-ray image, e.g. a 2D panoramic image or a bitewing image, wherein the focal trough in the dental X-ray image reconstructed from the obtained second image data corresponds to the anatomic shape of the object determined based on the first surface model <NUM>.

Above, embodiments of the invention are described referring to the controller <NUM>. The invention relates also to a method for dental imaging of the object. The first image data, e.g. the optical image data, may be used in the dental X-ray imaging of the object. The first image data may be used to process the obtained second image data, e.g. the X-ray image data. Alternatively, the first image data may be used in the acquisition of the second image data with the dental X-ray imaging unit <NUM>. The use of the obtained first image data in the acquisition of the second image data, e.g. in the panoramic imaging, may comprise defining based on the first image data an imaging geometry of the dental X-ray imaging unit <NUM> for the acquisition of the second image data. The use of the first image data to process the obtained second image data, e.g. in the CT imaging, comprises detecting based on the first image data a motion of the object occurring during an acquisition of the second image data, and reducing based on the first image data artifacts caused by the motion in a two-dimensional or a three-dimensional dental X-ray image reconstructed from the second image data. Alternatively, the use of the first image data to process the obtained second image data, e.g. in the panoramic imaging, may comprise adjusting a reconstruction of the dental X-ray image from the second image data so that a focal trough in the dental X-ray image corresponds to an anatomic shape of the object determined based the first image data.

Next an example of the a method in accordance with the invention is described by referring to <FIG> schematically illustrates the invention as a flow chart. It is to be recognized that embodiments of the method may be carried out without each of the steps as disclosed herein or in conjunction with additional steps.

At a step <NUM> the controller <NUM> obtains first image data of the object, e.g. the patient's anatomy, from an optical scanner unit <NUM>. The first image data may be for example optical image data. As discussed above, the controller <NUM> may obtain the first image data directly from the optical scanner unit <NUM> or from a database <NUM> to which the first image data previously obtained from the optical scanner unit <NUM> may be stored to, i.e. the obtained first image data comprises first image data previously obtained from the optical scanner unit <NUM>.

At a step <NUM> the controller <NUM> obtains second image data of the same object from e.g. a dental X-ray imaging unit <NUM>. The second image data may be e.g. X-ray image data. According to an example, in response to obtaining the second image data from the dental X-ray imaging unit <NUM> the controller <NUM> checks whether previously obtained first image data of the same object has been stored to the database <NUM>. If the controller <NUM> detects that previously obtained first image data of the same object has been stored to the database <NUM>, the controller <NUM> is configured to obtain the first image data from the database <NUM> at the step <NUM>.

At a step <NUM>, the controller <NUM> produces a first surface model <NUM> from the obtained first image data. The first surface model <NUM> represents an optical 3D shape of a surface of a first part of the object as discussed above.

At a step <NUM>, the controller <NUM> uses the first surface model <NUM> to process the obtained second image data. The use of the first surface model <NUM>, by the controller <NUM>, to process the obtained second image data at the step <NUM> may depend on the type of the imaging procedure, e.g. CT imaging or panoramic imaging, i.e. panoramic modality. The step <NUM> is discussed more in detail by referring to <FIG> and <FIG>. <FIG> illustrates an example embodiment of a method in accordance with the invention, wherein the imaging procedure used by the dental X-ray imaging unit <NUM> may be e.g. CT imaging, e.g. CBCT imaging. <FIG> illustrates another example embodiment of a method in accordance with the invention, wherein the imaging procedure used by the dental X-ray imaging unit <NUM> may be e.g. panoramic imaging. The steps <NUM> to <NUM> of the example methods of <FIG> and <FIG> corresponds to the steps <NUM> to <NUM> of the example method of <FIG>, but the step <NUM>, i.e. the step of using the first surface model <NUM> to process the obtained second image data, is disclosed in more detail manner referring to <FIG> and <FIG>.

Next an example of the use of the first surface model <NUM>, by the controller <NUM>, to process the obtained second image data at the step <NUM> is discussed by referring to <FIG>, wherein the imaging procedure used by the dental X-ray imaging unit <NUM> may be e.g. CT imaging, e.g. CBCT imaging.

At a step <NUM> the controller <NUM> produces a second surface model <NUM> from the obtained second image data. The second surface model <NUM> represents a 3D X-ray shape of a surface of a second part of the object. The second part of the object overlaps at least partly with the first part of the object so that the first surface model <NUM> and the second surface model <NUM> are at least partly from the same part of the object as discussed above.

At the step <NUM> of <FIG>, the controller <NUM> detects a motion of the object occurring during the acquisition of the second image data, i.e. the scanning process in which the second image data is provided, and reduce artifacts caused by the motion in a 2D or a 3D dental X-ray image reconstructed from the obtained second image data based on the first surface model. This will be discussed more in detail by referring to steps <NUM>-<NUM> of <FIG>. The 2D or 3D dental X-ray image may be e.g. a CT image.

At a step <NUM> the controller <NUM> compares a similarity of the second surface model <NUM> and the first surface model <NUM> in order to detect whether the object has been moved during the acquisition of the second image data, i.e. during the scanning process or not. According to an example, before the comparison of the surface models, the controller <NUM> may register, i.e. align, the first surface model <NUM> and the second surface model <NUM>. The registration may comprise determination of at least one reference structure from the second surface model <NUM>, finding the corresponding at least one reference structure from the first surface model <NUM>, and registration of the first surface model <NUM> and the second surface model <NUM> based on the at least one reference structure. Alternatively, the registration may comprise determination of at least one reference structure from the first surface model <NUM>, finding the corresponding at least one reference structure from the second surface model <NUM>, and registration of the first surface model <NUM> and the second surface model <NUM> based on the at least one reference structure. For example, the at least one reference structure may be, but is not limited to, a specific tooth.

If the controller <NUM> detects at a step <NUM> based on the comparison at the step <NUM> that the second surface model <NUM> differs from the first surface model <NUM>, the controller <NUM> detects motion at a step <NUM>, i.e. infers that the object has been moved the acquisition of the second image data. In response to the detection of the motion at the step <NUM>, the controller reduces at a step <NUM> the artifacts caused by the motion in the dental X-ray image reconstructed from the obtained second image data caused by the motion. Alternatively, if the controller <NUM> detects at the step <NUM> based on the comparison at the step <NUM> that there is no substantial difference between the second surface model <NUM> and the first surface model <NUM>, the controller <NUM> detects no motion at a step <NUM>, i.e. infers that the object has not moved during the acquisition of the second image data causing that there is no need for performing any corrections, e.g. reduction of the artifacts, of the dental X-ray image.

According to an example, the reduction of the artifacts caused by the motion at the step <NUM> may comprise iterative adaptation of a mutual imaging geometry of the plurality of projection images forming the dental X-ray image reconstructed from the obtained second image data in order to provide minimum difference or maximum similarity between the first surface model <NUM> and the second surface model <NUM>, i.e. to find the best match between the first surface model <NUM> and the second surface model <NUM> causing that the second surface model <NUM> becomes as similar as possible as the first surface model <NUM>. Next an example of the use of the first surface model <NUM>, by the controller <NUM>, to process the obtained second image data at the step <NUM> is discussed by referring to <FIG>, wherein the imaging procedure used by the dental X-ray imaging unit <NUM> may be e.g. panoramic imaging.

At a step <NUM> the controller <NUM> determines an anatomic shape of the object, e.g. dental arch or jawbone shape of the patient, based on the first surface model <NUM>.

At a step <NUM> the controller <NUM> may further adjust the reconstruction of the dental X-ray image from the obtained second image data so that a focal trough in the dental X-ray image corresponds to the anatomic shape of the object determined based on the first surface model <NUM>. The parts of the patient's anatomy that hit in a sharp layer are sharp in the dental X-ray image and the other parts of the patient's anatomy are blurred. The dental X-ray image may be a 2D dental X-ray image, e.g. a 2D panoramic image.

<FIG> illustrates schematically another example embodiment of a method in accordance with the invention, wherein the controller <NUM> may use the first image data, e.g. optical image data, obtained from the optical scanner <NUM> in the acquisition of the second image data, i.e. in the scanning process in which the second image data may be provided, with the dental X-ray imaging unit <NUM>. For example, in the example method of <FIG> the imaging procedure used by the dental X-ray imaging unit <NUM> may be panoramic imaging.

At a step <NUM> the controller <NUM> obtains first image data of the object, e.g. the patient's anatomy, from an optical scanner unit <NUM> as discussed above referring to the step <NUM>. The first image data may be for example optical image data. As also discussed above, the controller <NUM> may obtain the first image data directly from the optical scanner unit <NUM> or from a database <NUM> to which the first image data previously obtained from the optical scanner unit <NUM> may be stored to, i.e. the obtained first image data comprises first image data previously obtained from the optical scanner unit <NUM>.

At a step <NUM>, the controller <NUM> produces a first surface model <NUM> from the obtained first image data. The first surface model <NUM> represents an optical 3D shape of a surface of a first part of the object as discussed above referring to the step <NUM>. The first part of the object from which the first surface model <NUM> may be provided may comprise upper and/or lower full dental arch of the patient.

At a step <NUM> the controller <NUM> determines an anatomic shape of the object, e.g. dental arch or jawbone shape of the patient, based on the first surface model <NUM> as discussed above referring to the step <NUM>.

At a step <NUM>, the controller <NUM> uses the first image data in the acquisition of the second image data. The use of the first image data in the acquisition of the second image data may comprise that the controller <NUM> defines the imaging geometry of the X-ray imaging unit <NUM> for the acquisition of second image data based on the first surface model <NUM>. The imaging geometry of the dental X-ray imaging unit <NUM> may be defined by the controller <NUM> based on the determined anatomic shape of the object determined based the first surface model <NUM> so that that the focal trough in a dental X-ray image reconstructed from the second image data acquired by using the defined imaging geometry of the X-ray imaging unit <NUM> corresponds to the anatomic shape of the object determined based on the first surface model <NUM>. In other words, in this example embodiment the first surface model <NUM> is formed and the anatomic shape of the object is determined based on the first surface model <NUM> before the acquisition of the second image data by the dental X-ray imaging unit <NUM>, i.e. before the scanning process in which the second image data is provided. The controller <NUM> may further use information representing positioning of the object to define the imaging geometry of the dental X-ray imaging unit <NUM> so that that the focal trough in the dental X-ray image reconstructed from the second image data acquired by using the defined imaging geometry of the X-ray imaging unit <NUM> corresponds to the anatomic shape of the object determined based on the first surface model <NUM>. The information representing the positioning of the object may comprise for example a position from which the object is supported, e.g. by using one or more of the patient support parts, and/or the center of the object. The information representing the positioning of the object may be defined by using any known techniques. According to a non-limiting example, the position from which the object is supported may be defined based on a bite block, e.g. a bite stick, arranged for example to the chin support <NUM>. The controller <NUM> may provide the defined imaging geometry of the dental X-ray imaging unit <NUM> to the dental X-ray imaging unit <NUM>, which may then acquire, i.e. provide, the second image data of the same object by using the defined imaging geometry.

At a step <NUM> the controller <NUM> may further obtain from the dental X-ray imaging unit <NUM> the second image data acquired by using the defined imaging geometry of the dental X-ray unit <NUM>.

At a step <NUM> the controller <NUM> may further reconstruct the obtained second image data to a dental X-ray image, e.g. a 2D panoramic image or a bitewing, wherein the focal trough in the dental X-ray image reconstructed from the obtained second image data corresponds to the anatomic shape of the object determined based on the first surface model <NUM>.

<FIG> illustrates a schematic example of a controller <NUM> in accordance with the invention. The controller <NUM> may comprise a processor part <NUM>, a data transfer part <NUM>, a user interface part <NUM>, and a memory part <NUM>. The processor part <NUM> is configured to perform user and/or computer program (software) initiated instructions, and to process data. The processor part <NUM> may comprise at least one processor. The memory part <NUM> is configured to store and maintain data. The data may be instructions, computer programs, and any data files. The memory part <NUM> may comprise at least one memory. The memory part <NUM> may further comprise at least a data transfer application <NUM> in order to control the data transfer part <NUM>, a user interface application <NUM> in order to control the UI part <NUM>, and a computer program (code) <NUM> in order to control the operations of the controller <NUM>. The memory part <NUM> and the computer program <NUM>, together with the processor part <NUM>, may cause the controller <NUM> at least to implement one or more method steps and/or operations of the controller <NUM> as described above.

The data transfer part <NUM> may be configured to send control commands external units, e.g. the dental X-ray imaging unit <NUM>. In addition, the data transfer part <NUM> may receive data from external units, e.g. the dental X-ray imaging unit <NUM>, the optical scanner unit <NUM>, the database and/or any other external units.

The user interface (UI) part <NUM> may be configured to input control commands, to receive information and/or instructions, and to display information. The UI part <NUM> may comprise at least a display, a screen, a touchscreen, at least one function key, a keyboard, a wired or wireless remote controller, or any other user input and/or output device.

The computer program <NUM> may be a computer program product that may be comprised in a tangible, non-volatile (non-transitory) computer-readable medium bearing the computer program code <NUM> embodied therein for use with a computer, i.e. the controller <NUM>.

Some non-limiting examples of the controller <NUM> may e.g. be a server, cloud server, personal computer, laptop computer, computing circuit, or a network of computing devices. The location of the controller <NUM> is not limited and the controller <NUM> may be located anywhere. For example, the controller <NUM> may be implemented as part of the dental X-ray imaging unit <NUM>. Alternatively, the controller <NUM> may be implemented as an external part, i.e. external unit, of the dental X-ray imaging <NUM>.

The invention enables a simple way to reduce artifacts caused by motion of the object from 2D or 3D dental X-ray images, e.g. 3D CBCT images, by using the optical image data. At least some embodiments of the present invention described above improve the quality of the dental X-ray images, e.g. 3D CBCT images and/or 2D panoramic images, by using the optical image data.

Claim 1:
A controller (<NUM>) for dental imaging of an object, the controller comprising:
at least one processor (<NUM>), and
at least one memory (<NUM>) including computer program code (<NUM>), wherein the at least one memory (<NUM>) and the computer program code (<NUM>) is configured to, with the at least one processor (<NUM>), cause the controller (<NUM>) at least to:
obtain first image data from an optical scanner unit (<NUM>),
obtain second image data from a dental X-ray imaging unit (<NUM>),
produce a first surface model (<NUM>) from the obtained first image data, wherein the first surface model (<NUM>) represents an optical three-dimensional shape of a surface of a first part of the object,
use the first surface model (<NUM>) to process the obtained second image data,
characterised in that the controller is further caused to detect based on the first surface model (<NUM>) a motion of the object occurring during an acquisition of the second image data, and
reduce based on the first surface model (<NUM>) artifacts caused by the motion in a two-dimensional or a three-dimensional dental X-ray image reconstructed from the obtained second image data.