Patent Description:
An X-ray imaging apparatus widely used in the field of medical technology irradiates a human body with X-rays to acquire an image of an inside of the human body, through which abnormalities in the human body are detected.

A principle of the X-ray imaging apparatus is to irradiate an object with X-rays generated by a generator that generates the X-rays and to receive the X-rays that reach a sensor facing the generator after being partially transmitted or not transmitted through the object. Thereafter, the X-ray imaging apparatus converts the received X-rays to generate an image.

Recently, techniques for the X-ray imaging apparatus that may be used for the purpose of panoramic imaging or computed tomography (CT) imaging as necessary have been disclosed. Related Art document <NUM> (<CIT>) discloses a technique for performing two functions of panoramic imaging and CT imaging using one device. According to the Related Art document, a technique of separately adopting a sensor for panoramic imaging and a sensor for CT imaging and switching an imaging mode by detachably attaching the sensors as necessary is disclosed.

However, these techniques involve an inconvenience of detachably attaching the sensors each time the imaging mode is switched for panoramic imaging or CT imaging. In addition, in order to acquire an enlarged image of a specific region, separate post-processing is required after image capturing.

In addition, Related Art document <NUM> (<CIT>) proposes capturing images in various modes by rotating or moving a sensor and a generator of an X-ray imaging apparatus in a longitudinal direction, but there is no specific consideration of a size of a region of interest (ROI) to be actually imaged and a magnification power, and there is a difficulty in implementing a plurality of modes with one sensor without considering an active region within a limited size of the sensor. Related Art document <NUM> (United States Patent Application Publication No. <CIT>) discloses a system and method for forming a virtual isocenter in an imaging system. The method includes determining a distance between a detector and an object to be imaged, determining a distance between a detector and source, varying either or both distances between image exposures, and adjusting image data obtained from the image exposures for a change in magnification between image exposures. The distance is determined using a tracking system.

An aspect of the present disclosure provides a method of acquiring a magnified image of a specific portion of a target to be imaged (or an object) with high resolution at a time of capturing an image, without additional post-image processing on the captured image.

The present disclosure provides an image capturing method performed by an image capturing apparatus, including: acquiring information on first positions which are current positions of a sensor and a generator; moving the sensor and the generator to
second positions which are positions at which an image having a magnification power different from a magnification power of an image of an object acquired when the sensor and the generator are located at the first positions is acquired; and acquiring an image of the object, wherein the sensor and the generator move the same distance so that the distance between the sensor and the generator is not changed at the first positions and the second positions. The distance between the generator and the object at the first positions is different from the distance between the generator and the object at the second positions. The first positions are corresponding to a first imaging mode and the second positions are corresponding to a second imaging mode different from the first imaging mode. The first imaging mode and the second imaging mode respectively include at least one of a panoramic imaging mode and a CT imaging mode.

The present disclosure also provides an image capturing apparatus including: a sensor; a generator; and a processor configured to acquire information on first positions which are current positions of the sensor and the generator, to move the sensor and the generator to second positions which are positions at which an image having a magnification power different from a magnification power of an image of an object acquired when the sensor and the generator are located at the first positions is acquired, and control operations of the sensor and the generator to acquire an image of the object, wherein the sensor and the generator move the same distance so that the distance between the sensor and the generator is not changed at the first positions and the second positions. The distance between the generator and the object at the first positions is different from the distance between the generator and the object at the second positions. The first positions are corresponding to a first imaging mode and the second positions are corresponding to a second imaging mode different from the first imaging mode. The first imaging mode and the second imaging mode respectively include at least one of a panoramic imaging mode and a CT imaging mode.

The present disclosure also provides a computer-readable recording medium having a computer program recorded thereon to perform the foregoing image capturing method.

The present disclosure also provides an image capturing system including: the foregoing image capturing apparatus; and a database configured to store the image captured by the image capturing apparatus together with information of the object, wherein the database stores an image of the object at second positions having a magnification power different from a magnification power of the object at first positions.

Using the image processing method and apparatus according to an embodiment, a magnified image of a specific portion of an object may be acquired with high resolution at a time of capturing an image, without separate post-image processing on the captured image.

In addition, using the image processing method and apparatus according to an embodiment, a user may capture a high-resolution magnified image of a specific area of a subject using a normal radiation dose, and thus, unnecessary exposure of the subject to radiation may be reduced.

A detailed description of each drawing is provided to more fully understand the drawings, which are incorporated in the detailed description of the disclosure.

While a specific structural or functional description with respect to embodiments according to the present disclosure disclosed in this specification is merely provided for the purpose of describing the embodiments of the present disclosure, there are various modifications capable of replacing the embodiments, and the present disclosure is not limited to the embodiments described in this specification.

While the embodiments according to the present disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of examples in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the present disclosure to the particular forms disclosed, but on the contrary, the present disclosure is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure.

It will be understood that, although the terms "first," "second," etc. may be used herein to describe various elements, these elements should not be limited by these terms. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the disclosure.

In contrast, it will be understood that when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present. Other expressions describing a relation between elements, that is, "between" and "directly between", or "adjacent to" and "directly adjacent to", etc. should be similarly understood.

As used herein, the singular forms "a", "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

Unless otherwise defined, all terms used herein including the technical or scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

An embodiment of the present disclosure provides an image capturing method of capturing an image of a subject to be imaged at different magnification powers. First, terms for explaining the present disclosure and a basic configuration of the image capturing apparatus will be described with reference to <FIG> and <FIG>.

<FIG> is a reference drawing for explaining the terms used in the present disclosure. Focal spot to detector distance (FDD) refers to a spatial distance from a generator (focal spot) to a sensor (detector). Focal spot to object distance (FOD) refers to a spatial distance from the generator to an object (to be imaged).

Focal spot to rotation center distance (FCD) refers to a spatial distance from the generator to a rotation axis of a gantry. The rotation axis of the gantry refers to an axis of rotation of the generator and the sensor. Object to detector distance refers to a spatial distance from the object to the sensor. A magnification power described below refers to a value acquired by dividing FDD by FOD.

Field of view (FOV) refers to a size of a region that may be imaged at a time by the sensor, which may be represented by an angle and correspond to a region of interest (ROI) in the present disclosure.

<FIG> is a diagram illustrating an image capturing apparatus <NUM> according to an embodiment. The image capturing apparatus <NUM> according to the embodiment includes a generator <NUM>, a sensor <NUM>, and a controller <NUM>.

In an embodiment, the generator <NUM> may generate X-rays. In an embodiment, the generator <NUM> generates X-rays according to a first mode or a second mode.

In an embodiment, the mode classifies an image capturing method using X-rays. In an embodiment, the first mode may be a computed tomography (CT) imaging mode. A three-dimensional (3D) structure inside a human body may be recognized by capturing a 3D image through a CT image.

The second mode may be a panoramic image capturing mode. An overall teeth condition and structure may be recognized through a panoramic image and used for a diagnosis and a surgical procedure.

In an embodiment, the generator <NUM> determines strength, dose, and the like of an X-ray generated according to an imaging mode and irradiated to the sensor <NUM>, and an irradiation range may also be determined through a separate collimator.

In addition, a focus for a specific subject may be differentiated or an X-ray based on other set imaging conditions may be generated.

In an embodiment, the sensor <NUM> collects X-rays generated by the generator <NUM>. In detail, the sensor <NUM> absorbs the X-rays generated by the generator <NUM> and transmitted through a subject according to the first mode or the second mode and converts the X-rays into an electrical signal. An image may be generated using the converted electrical signal.

In addition, in an embodiment, the sensor <NUM> may change an active region according to each imaging mode. For example, in the first mode and the second mode, X-rays generated by the same generator <NUM> may be collected but an image may be generated using only X-rays collected through different active regions.

In an embodiment, the controller <NUM> may configure an imaging environment based on the imaging mode by controlling the imaging conditions or the active region described above in software. In addition, the controller <NUM> may control physical operations of the generator <NUM> and the sensor <NUM> described above by hardware control to configure the imaging environment according to each imaging mode.

Hereinafter, a method of changing an image magnification power in an image capturing method performed by the image capturing apparatus <NUM> according to an embodiment will be described with reference to <FIG> and <FIG>. <FIG> is a diagram illustrating positions of the sensor <NUM>, the generator <NUM>, and an object <NUM>, as an object to be imaged, before a magnification power is changed. In <FIG>, a region of interest (ROI) <NUM> is set to the entire portion of the object <NUM>.

When X-rays generated by the generator <NUM> is incident to the sensor <NUM> after being transmitted through the object <NUM>, a captured image of the object <NUM> is acquired by the sensor <NUM>. In the example shown in <FIG>, as the X-rays transmitted through the entire region of the object <NUM> are incident on an image plane of the sensor <NUM>, the entire region <NUM> shaded for the object <NUM> is acquired by the sensor.

<FIG> is a diagram illustrating relative positions of the sensor <NUM>, the generator <NUM>, and the object <NUM> after a magnification power of the image capturing apparatus <NUM> according to an embodiment is changed. The image capturing apparatus <NUM> according to an embodiment moves positions of the sensor <NUM> and the generator <NUM> according to an imaging mode. Accordingly, the relative positions of the sensor <NUM>, the generator <NUM>, and the object <NUM> located therebetween are changed. Here, the sensor <NUM> and the generator <NUM> may move the same distance so that the distance between the sensor <NUM> and the generator <NUM> does not change. In this case, although the distance between the sensor <NUM> and the generator <NUM> is the same, the magnification power may be changed as the distance between the generator <NUM> and the object <NUM> changes.

When the relative position of the object <NUM> in a space between the sensor <NUM> and the generator <NUM> is changed, an ODD value is changed as a spatial distance between the sensor <NUM> and the object <NUM> is changed and an FOD value is changed as the spatial distance between the generator <NUM> and the object <NUM> is changed. However, the sensor <NUM> and the generator <NUM> may move the same distance so that the distance between the sensor <NUM> and the generator <NUM> does not change. In this case, an FDD value is not changed as the spatial distance between the sensor <NUM> and the generator <NUM> is maintained.

For example, as shown in <FIG>, when the object <NUM> and the generator <NUM> are close to each other, the FOD value decreases. However, since the FDD value remains the same, an image captured by magnifying a portion of the object is acquired by the sensor <NUM>. That is, compared with <FIG>, as X-rays transmitted through a portion of the object <NUM> are incident on an image plane of the sensor <NUM>, the ROI <NUM> selected to be shaded in the object <NUM> in <FIG> is acquired as a captured image by the sensor. Accordingly, the image capturing apparatus <NUM> according to an embodiment may simply acquire the magnified image of the ROI <NUM> of the object with high resolution without additional software processing.

In an embodiment, the user may determine a relative position of the object <NUM> located between the sensor <NUM> and the generator <NUM> according to an imaging mode to implement a magnification power of an image required for the imaging mode. The imaging mode may include at least one of a panoramic imaging mode and a CT imaging mode.

In addition, if the user wants to capture a magnified image of the specific ROI <NUM> of the object <NUM>, the image capturing apparatus <NUM> may move the positions of the sensor <NUM> and the generator <NUM> to capture the magnified image.

In an embodiment, the user may determine a relative position of the object <NUM> located between the sensor <NUM> and the generator <NUM> to acquire a maximum magnification power image of the ROI <NUM> of the object <NUM> by an active region of the sensor <NUM>. The ROI may be a region of a portion of a mouth of a subject imaged for an X-ray image. For example, the ROI may be an upper jaw (maxilla), a lower jaw (mandible), or a part thereof.

In an embodiment, the positions of the sensor <NUM> and the generator <NUM> for capturing an image of the ROI <NUM> may be determined based on a position and an area of the ROI <NUM> in the real world coordinate system.

The image capturing apparatus <NUM> may determine a position of the sensor <NUM> and the generator <NUM> to a position where the outermost portion of the ROI <NUM> in the real world coordinate system is in contact with a path of light incident on the outermost portion of an active region of the sensor <NUM> from the generator <NUM> so that the maximum magnification power image may be acquired using the active region of the sensor <NUM>.

An example thereof is shown in <FIG> illustrates an example in which the uppermost and lowermost portions of the ROI <NUM> are in contact with upper and lower paths of light incident on the outermost portion of the active region (image plane) of the sensor <NUM> from the generator <NUM>.

In another embodiment, the positions of the sensor <NUM> and the generator <NUM> may be determined based on a position and an area of the ROI <NUM> in the current image acquired at the current positions of the sensor <NUM> and the generator <NUM>. The image capturing apparatus <NUM> may calculate a position correction value for converting center coordinates of the ROI <NUM> into center coordinates of the current image and an area correction value for converting the area of the ROI <NUM> to the area of the current image and determine positions of the sensor <NUM> and the generator <NUM> at which the image of the ROI is maximized using the position correction value and the area correction value.

In another embodiment, if there are a plurality of ROIs in the object <NUM>, the positions of the sensor <NUM> and the generator <NUM> may be determined as positions at which the maximum magnification power image including all the plurality of ROIs may be acquired by the active region of the sensor.

In consideration of the fact that the object <NUM> is an amorphous solid body, the image capturing apparatus <NUM> may calculate the positions of the sensor <NUM> and the generator <NUM> at each angle at which the sensor <NUM> and the generator <NUM> rotate. The positions of the sensor <NUM> and the generator <NUM> for acquiring the maximum magnification power image of the ROI <NUM> of the object <NUM> calculated as described above may be calculated in advance, stored in the memory, and may be loaded to be used as needed later.

In an embodiment, the image capturing apparatus <NUM> may calculate relative positions of the sensor <NUM> and the generator <NUM> regarding the object <NUM> located between the sensor <NUM> and the generator <NUM> in advance in consideration of a size of the sensor <NUM>, a position and a size of the ROI <NUM> in the object <NUM>, a magnification power, and an FDD value and selectively use the calculated results as necessary. For example, the image capturing apparatus <NUM> may locate the object <NUM> spaced apart from the generator <NUM> than a previously calculated position, at a position at which the entire portion of the ROI <NUM> is maximally acquired by the sensor <NUM> so that a phenomenon in which a portion (in particular, the outermost portion) of the ROI <NUM> set for the object <NUM> is not acquired by the sensor <NUM> does not occur.

The image capturing apparatus <NUM> may move the positions of the sensor <NUM> and the generator <NUM> relative to the object <NUM>, while maintaining the same spatial distance between the sensor <NUM> and the generator <NUM>. The image capturing apparatus <NUM> may include a moving unit for moving the sensor <NUM> and the generator <NUM>, and the moving unit may include an actuator or the like. The moving unit may be directly coupled to the sensor <NUM> and the generator <NUM> or may be coupled to an accommodating module that accommodates the sensor <NUM> and the generator <NUM>.

In an embodiment, in order to efficiently acquire a magnified image, the image capturing apparatus <NUM> may change 3D positions of the sensor <NUM> and the generator <NUM> so that an image of the ROI <NUM> acquired by the sensor <NUM> and the generator <NUM> is a specific portion of the object. To this end, the image capturing apparatus <NUM> may further include a moving unit for changing the 3D positions of the sensor <NUM> and the generator <NUM>. Alternatively, the image capturing apparatus <NUM> may change a 3D position of the object <NUM> so that the image of the ROI acquired by the sensor <NUM> and the generator <NUM> may be a specific portion of the object, and the image capturing apparatus <NUM> may include a moving unit for moving the object <NUM>.

In an embodiment, the sensor <NUM> and the generator <NUM> may each be connected to a gantry through the moving unit. A sensor moving unit and a generator moving unit may horizontally and/or vertically move the sensor <NUM> and the generator <NUM> in the gantry. The sensor moving unit and the generator moving unit may horizontally/vertically move the positions of the sensor <NUM> and the generator <NUM> along a movable portion of the gantry. The sensor moving unit and the generator moving unit may extend in a horizontal/vertical direction to move the positions of the sensor <NUM> and the generator <NUM> horizontally/vertically.

In an embodiment, the sensor <NUM> and the generator <NUM> may move to positions at which the center of the sensor <NUM>, the center of the generator <NUM>, and the center of the ROI <NUM> are aligned to maximally acquire a magnified image of the ROI <NUM> of the object <NUM>. If necessary, the sensor <NUM> and the generator <NUM> may be tilted in order to capture an image in an oblique direction.

In another embodiment, the sensor <NUM> and the generator <NUM> may be fixed to the gantry. In the present embodiment, the gantry may be moved to move the fixed sensor <NUM> and the generator <NUM>. A gantry moving unit may move the gantry horizontally/vertically. Here, a position of a rotation axis of the gantry may not change in the real world coordinate system. In order to implement this, the gantry may be divided into a part forming the rotation axis and a part connecting the sensor <NUM> and the generator <NUM>, and only the part connecting the sensor <NUM> and the generator <NUM> may be moved relative to the part forming the rotation axis of the gantry.

In order to maximally acquire the magnified image of the ROI <NUM> of the object <NUM>, the gantry may move to the position where the center of the sensor <NUM> and the center of the generator <NUM> and the center of the ROI <NUM> are aligned. If necessary, the gantry may be tilted for imaging in the oblique direction.

As an alternative embodiment, the image capturing apparatus <NUM> may move the position of the object <NUM> between the sensor <NUM> and the generator <NUM>. The image capturing apparatus <NUM> may include a moving unit for moving the object <NUM>, and the moving unit may be configured as an actuator or the like. The moving unit may be coupled to a module in which the object <NUM> is located. For example, if the object is a human, the module in which the object <NUM> is located may be a chair on which a person may sit or a bed in which a person may lie down.

<FIG> is a flowchart illustrating an operation of the image capturing apparatus <NUM> according to an embodiment. First, the image capturing apparatus <NUM> determines an imaging mode in operation S110. The imaging mode may be previously determined. The imaging mode may be one of a panoramic imaging mode and a CT imaging mode and may further include a separate imaging mode for changing a magnification power for the ROI set according to an embodiment.

The image capturing apparatus <NUM> may determine an imaging mode according to a user input. Alternatively, the image capturing apparatus <NUM> may sequentially change the imaging mode in order to acquire an image of an object according to preprogrammed image capturing order.

Next, the image capturing apparatus <NUM> determines a magnification power of the image according to the selected imaging mode in operation S130. The magnification power according to the imaging mode may be stored in advance in the image capturing apparatus <NUM>. Alternatively, the image capturing apparatus <NUM> may query the user to select a magnification power and determine the magnification power according to the user input.

Next, the image capturing apparatus <NUM> captures an image according to the determined magnification power in operation S150. In order to change the magnification power, the image capturing apparatus <NUM> may change the positions of the sensor <NUM> and the generator <NUM> or change the position of the object <NUM> as described above with reference to <FIG>.

In an embodiment, a plurality of independent ROIs for the object <NUM> may be set. In this case, imaging positions of the sensor <NUM> and the generator <NUM> for capturing an image at the maximum magnification power may be set for each ROI. A plurality of imaging positions of the sensor <NUM> and the generator <NUM> for imaging the ROIs independently are generated.

In order to independently capture an image for each ROI, the sensor <NUM> and the generator <NUM> should perform position movement several times. In order to minimize a moving distance of the sensor <NUM> and the generator <NUM>, the shortest distance path between the sensor <NUM> and the generator <NUM> using the plurality of imaging positions as stops may be calculated. Accordingly, a position movement schedule of the sensor <NUM> and the generator <NUM> may be generated. The image capturing apparatus <NUM> may capture images of the ROIs according to the generated position movement schedule.

<FIG> is a block diagram illustrating a specific configuration of an image capturing apparatus <NUM> according to an embodiment. As illustrated in <FIG>, the image capturing apparatus <NUM> according to an embodiment may include the generator <NUM>, the sensor <NUM>, a controller <NUM>, an object location module <NUM>, a positioning module <NUM>, a user interface <NUM>, and a communication module <NUM>. The object location module <NUM>, the user interface <NUM>, and the communication module <NUM> may be selectively used and omitted according to an embodiment.

As described above, as the generator <NUM>, an X-ray generator commonly used as a light source for generating X-rays may be adopted and used. If necessary, the generator <NUM> may further include a collimator.

As the sensor <NUM>, an X-ray sensor generally used to collect X-rays to acquire an image may be adopted and configured as described above. The sensor <NUM> may be a large area sensor for panoramic or CT imaging. A size of the sensor <NUM> may be selected in consideration of a size of an ROI in the object <NUM>, a magnification power, and the FDD value.

The controller <NUM> includes a processor and a memory. The processor controls the image capturing apparatus <NUM> and performs control to perform the image capturing method described above. The memory includes temporary and non-temporary data necessary for the image capturing apparatus to operate. The memory may include a magnification power of an image and corresponding position data of the generator <NUM> and the sensor <NUM> according to an imaging mode.

The object location module <NUM> accommodates an object, thereby allowing a position of the object to be specified. The object location module <NUM> may be omitted as an optional component.

The positioning module <NUM> moves positions of the generator <NUM> and the sensor <NUM>. According to an embodiment, the positioning module <NUM> may move a position of the object location module <NUM>.

As the user interface <NUM>, general input device and output device may be adopted as an interface unit between the image capturing apparatus <NUM> and the user. As the communication module <NUM>, a general wired/wireless communication module may be adopted as an interface unit between the image capturing apparatus <NUM> and an external device. The user interface <NUM> and the communication module <NUM> may be omitted as optional components.

<FIG> is a block diagram illustrating a configuration of an image capturing system <NUM> including the image capturing apparatus <NUM> according to an embodiment. The image capturing system <NUM> according to an embodiment may include the image capturing apparatus <NUM> of <FIG>, a database <NUM>, and a controller <NUM>. In addition, the image capturing system <NUM> may further include the user interface <NUM> and the communication module <NUM>.

The image capturing system <NUM> may further include the database <NUM> to store image data of an object acquired from the image capturing apparatus <NUM> with respect to the object. For example, when used in a hospital, a doctor may store an X-ray image captured for a patient in the database by designating the patient.

The image capturing method according to the embodiments described above may be implemented in a program instruction form that can be performed through various computing means and recorded in computer-readable medium. The computer-readable medium may also include program instructions, data files, data structures, and the like alone or in combination. The program instructions recorded in the medium may be designed and configured specially for the embodiments or be known and available to those skilled in computer software. Examples of computer-readable medium include magnetic medium such as hard disks, floppy disks, and magnetic tape; optical medium such as CD ROM disks and DVDs; magneto-optical medium such as floptical disks; and hardware devices that are specially configured to store and perform program instructions, such as read-only memory (ROM), random access memory (RAM), flash memory, and the like. Examples of program instructions include both machine code, such as produced by a compiler, and higher level code that may be executed by the computer using an interpreter or the like.

The image capturing method according to the embodiments described above may be recorded in non-transitory computer-readable medium including program instructions to implement various operations embodied by a computer. The media and program instructions may be those specially designed and constructed for the purposes, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of non-transitory computer-readable medium include magnetic media such as hard disks, floppy disks, and magnetic tape; optical media such as CD ROM disks and DVD; magneto-optical media such as floptical disks; and hardware devices that are specially to store and perform program instructions, such as read-only memory (ROM), random access memory (RAM), flash memory, and the like.

Each of the drawings referred to in the foregoing description of the embodiments is merely an embodiment illustrated for convenience of description, and items, contents, and images of information displayed on each screen may be modified and displayed in various forms.

Claim 1:
An image capturing method performed by an image capturing apparatus (<NUM>), the image capturing method comprising:
acquiring information on first positions which are current positions of a sensor (<NUM>) and a generator (<NUM>) in a first imaging mode;
entering to a second imaging mode different from the first imaging mode;
according to the entering to the second imaging mode, moving the sensor (<NUM>) and the generator (<NUM>) to second positions which are positions at which an image having a magnification power different from a magnification power of an image of an object (<NUM>) acquired when the sensor (<NUM>) and the generator (<NUM>) are located at the first positions is acquired; and
performing the second imaging mode to acquire an image of the object (<NUM>),
wherein the sensor (<NUM>) and the generator (<NUM>) move the same distance so that the distance between the sensor (<NUM>) and the generator (<NUM>) is not changed when the magnification power is changed to be different,
wherein the distance between the generator (<NUM>) and the object (<NUM>) at the first positions is different from the distance between the generator (<NUM>) and the object (<NUM>) at the second positions,
wherein the first positions are according to the first imaging mode and the second positions are according to the second imaging mode different from the first imaging mode, and
wherein the first imaging mode and the second imaging mode include respectively a panoramic imaging mode and a CT imaging mode,
wherein the second positions are determined as positions at which a maximum magnification power image of a region of interest (ROI) of the object (<NUM>) is acquired by an active region of the sensor (<NUM>), and
wherein the ROI includes a portion of a mouth of the object (<NUM>).