Patent Publication Number: US-2021195121-A1

Title: Method and apparatus for changing image magnification power

Description:
TECHNICAL FIELD 
     The present disclosure relates to a method and apparatus of capturing an image, while changing an image magnification power. More particularly, the present disclosure relates to a method and apparatus of changing a magnification power of an X-ray imaging apparatus according to an object. 
     BACKGROUND ART 
     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 1 (Korean Patent Laid-Open Publication No. 10-2007-0017670) 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 2 (Korean Patent Publication No. 10-2016-0056986) 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. 
     DISCLOSURE 
     Technical Problem 
     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. 
     Technical Solution 
     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 a distance between the sensor and the generator is not changed. 
     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 a distance between the sensor and the generator is not changed. 
     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. 
     Advantageous Effects 
     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. 
    
    
     
       DESCRIPTION OF DRAWINGS 
       A detailed description of each drawing is provided to more fully understand the drawings, which are incorporated in the detailed description of the disclosure. 
         FIG. 1  is a reference drawing illustrating terms used in the present disclosure. 
         FIG. 2  is a diagram illustrating an image capturing apparatus according to an embodiment. 
         FIGS. 3 and 4  are conceptual views illustrating a method of changing an image magnification power in an image capturing method performed by an image capturing apparatus according to an embodiment. 
         FIG. 5  is a flowchart illustrating an operation of an image capturing apparatus according to an embodiment. 
         FIG. 6  is a block diagram illustrating a specific configuration of an image capturing apparatus according to an embodiment. 
         FIG. 7  is a block diagram illustrating a configuration of an image capturing system including an image capturing apparatus according to an embodiment. 
     
    
    
     BEST MODES 
     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. These terms are only used to distinguish one element from another. 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. 
     It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. 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. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. 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. It will be further understood that the terms “comprises,” “comprising,” “includes,” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     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. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     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  FIGS. 1 and 2 . 
       FIG. 1  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. 2  is a diagram illustrating an image capturing apparatus  100  according to an embodiment. The image capturing apparatus  100  according to the embodiment includes a generator  110 , a sensor  120 , and a controller  130 . 
     In an embodiment, the generator  110  may generate X-rays. In an embodiment, the generator  110  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  110  determines strength, dose, and the like of an X-ray generated according to an imaging mode and irradiated to the sensor  120 , 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  120  collects X-rays generated by the generator  110 . In detail, the sensor  120  absorbs the X-rays generated by the generator  110  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  120  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  110  may be collected but an image may be generated using only X-rays collected through different active regions. 
     In an embodiment, the controller  130  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  130  may control physical operations of the generator  110  and the sensor  120  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  100  according to an embodiment will be described with reference to  FIGS. 3 and 4 .  FIG. 3  is a diagram illustrating positions of the sensor  120 , the generator  110 , and an object  140 , as an object to be imaged, before a magnification power is changed. In  FIG. 3 , a region of interest (ROI)  141  is set to the entire portion of the object  140 . 
     When X-rays generated by the generator  110  is incident to the sensor  120  after being transmitted through the object  140 , a captured image of the object  140  is acquired by the sensor  120 . In the example shown in  FIG. 3 , as the X-rays transmitted through the entire region of the object  140  are incident on an image plane of the sensor  120 , the entire region  141  shaded for the object  140  is acquired by the sensor. 
       FIG. 4  is a diagram illustrating relative positions of the sensor  120 , the generator  110 , and the object  140  after a magnification power of the image capturing apparatus  100  according to an embodiment is changed. The image capturing apparatus  100  according to an embodiment moves positions of the sensor  120  and the generator  110  according to an imaging mode. Accordingly, the relative positions of the sensor  120 , the generator  110 , and the object  140  located therebetween are changed. Here, the sensor  120  and the generator  110  may move the same distance so that the distance between the sensor  120  and the generator  110  does not change. In this case, although the distance between the sensor  120  and the generator  110  is the same, the magnification power may be changed as the distance between the generator  110  and the object  140  changes. 
     When the relative position of the object  140  in a space between the sensor  120  and the generator  110  is changed, an ODD value is changed as a spatial distance between the sensor  120  and the object  140  is changed and an FOD value is changed as the spatial distance between the generator  110  and the object  140  is changed. However, the sensor  120  and the generator  110  may move the same distance so that the distance between the sensor  120  and the generator  110  does not change. In this case, an FDD value is not changed as the spatial distance between the sensor  120  and the generator  110  is maintained. 
     For example, as shown in  FIG. 4 , when the object  140  and the generator  110  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  120 . That is, compared with  FIG. 3 , as X-rays transmitted through a portion of the object  140  are incident on an image plane of the sensor  120 , the ROI  141  selected to be shaded in the object  140  in  FIG. 4  is acquired as a captured image by the sensor. Accordingly, the image capturing apparatus  100  according to an embodiment may simply acquire the magnified image of the ROI  141  of the object with high resolution without additional software processing. 
     Positioning of the Sensor  120  and the Generator  110   
     In an embodiment, the user may determine a relative position of the object  140  located between the sensor  120  and the generator  110  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  141  of the object  140 , the image capturing apparatus  100  may move the positions of the sensor  120  and the generator  110  to capture the magnified image. 
     In an embodiment, the user may determine a relative position of the object  140  located between the sensor  120  and the generator  110  to acquire a maximum magnification power image of the ROI  141  of the object  140  by an active region of the sensor  120 . 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  120  and the generator  110  for capturing an image of the ROI  141  may be determined based on a position and an area of the ROI  141  in the real world coordinate system. 
     The image capturing apparatus  100  may determine a position of the sensor  120  and the generator  110  to a position where the outermost portion of the ROI  141  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  120  from the generator  110  so that the maximum magnification power image may be acquired using the active region of the sensor  120 . 
     An example thereof is shown in  FIG. 4 .  FIG. 4  illustrates an example in which the uppermost and lowermost portions of the ROI  141  are in contact with upper and lower paths of light incident on the outermost portion of the active region (image plane) of the sensor  120  from the generator  110 . 
     In another embodiment, the positions of the sensor  120  and the generator  110  may be determined based on a position and an area of the ROI  141  in the current image acquired at the current positions of the sensor  120  and the generator  110 . The image capturing apparatus  100  may calculate a position correction value for converting center coordinates of the ROI  141  into center coordinates of the current image and an area correction value for converting the area of the ROI  141  to the area of the current image and determine positions of the sensor  120  and the generator  110  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  140 , the positions of the sensor  120  and the generator  110  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  140  is an amorphous solid body, the image capturing apparatus  100  may calculate the positions of the sensor  120  and the generator  110  at each angle at which the sensor  120  and the generator  110  rotate. The positions of the sensor  120  and the generator  110  for acquiring the maximum magnification power image of the ROI  141  of the object  140  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  100  may calculate relative positions of the sensor  120  and the generator  110  regarding the object  140  located between the sensor  120  and the generator  110  in advance in consideration of a size of the sensor  120 , a position and a size of the ROI  141  in the object  140 , a magnification power, and an FDD value and selectively use the calculated results as necessary. For example, the image capturing apparatus  100  may locate the object  140  spaced apart from the generator  110  than a previously calculated position, at a position at which the entire portion of the ROI  141  is maximally acquired by the sensor  120  so that a phenomenon in which a portion (in particular, the outermost portion) of the ROI  141  set for the object  140  is not acquired by the sensor  120  does not occur. 
     Movement of Positions of Sensor  120  and Generator  110   
     The image capturing apparatus  100  may move the positions of the sensor  120  and the generator  110  relative to the object  140 , while maintaining the same spatial distance between the sensor  120  and the generator  110 . The image capturing apparatus  100  may include a moving unit for moving the sensor  120  and the generator  110 , and the moving unit may include an actuator or the like. The moving unit may be directly coupled to the sensor  120  and the generator  110  or may be coupled to an accommodating module that accommodates the sensor  120  and the generator  110 . 
     In an embodiment, in order to efficiently acquire a magnified image, the image capturing apparatus  100  may change 3D positions of the sensor  120  and the generator  110  so that an image of the ROI  141  acquired by the sensor  120  and the generator  110  is a specific portion of the object. To this end, the image capturing apparatus  100  may further include a moving unit for changing the 3D positions of the sensor  120  and the generator  110 . Alternatively, the image capturing apparatus  100  may change a 3D position of the object  140  so that the image of the ROI acquired by the sensor  120  and the generator  110  may be a specific portion of the object, and the image capturing apparatus  100  may include a moving unit for moving the object  140 . 
     In an embodiment, the sensor  120  and the generator  110  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  120  and the generator  110  in the gantry. The sensor moving unit and the generator moving unit may horizontally/vertically move the positions of the sensor  120  and the generator  110  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  120  and the generator  110  horizontally/vertically. 
     In an embodiment, the sensor  120  and the generator  110  may move to positions at which the center of the sensor  120 , the center of the generator  110 , and the center of the ROI  141  are aligned to maximally acquire a magnified image of the ROI  141  of the object  140 . If necessary, the sensor  120  and the generator  110  may be tilted in order to capture an image in an oblique direction. 
     In another embodiment, the sensor  120  and the generator  110  may be fixed to the gantry. In the present embodiment, the gantry may be moved to move the fixed sensor  120  and the generator  110 . 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  120  and the generator  110 , and only the part connecting the sensor  120  and the generator  110  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  141  of the object  140 , the gantry may move to the position where the center of the sensor  120  and the center of the generator  110  and the center of the ROI  141  are aligned. If necessary, the gantry may be tilted for imaging in the oblique direction. 
     As an alternative embodiment, the image capturing apparatus  100  may move the position of the object  140  between the sensor  120  and the generator  110 . The image capturing apparatus  100  may include a moving unit for moving the object  140 , 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  140  is located. For example, if the object is a human, the module in which the object  140  is located may be a chair on which a person may sit or a bed in which a person may lie down. 
       FIG. 5  is a flowchart illustrating an operation of the image capturing apparatus  100  according to an embodiment. First, the image capturing apparatus  100  determines an imaging mode in operation S 110 . 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  100  may determine an imaging mode according to a user input. Alternatively, the image capturing apparatus  100  may sequentially change the imaging mode in order to acquire an image of an object according to pre-programmed image capturing order. 
     Next, the image capturing apparatus  100  determines a magnification power of the image according to the selected imaging mode in operation S 130 . The magnification power according to the imaging mode may be stored in advance in the image capturing apparatus  100 . Alternatively, the image capturing apparatus  100  may query the user to select a magnification power and determine the magnification power according to the user input. 
     Next, the image capturing apparatus  100  captures an image according to the determined magnification power in operation S 150 . In order to change the magnification power, the image capturing apparatus  100  may change the positions of the sensor  120  and the generator  110  or change the position of the object  140  as described above with reference to  FIG. 4 . 
     In an embodiment, a plurality of independent ROIs for the object  140  may be set. In this case, imaging positions of the sensor  120  and the generator  110  for capturing an image at the maximum magnification power may be set for each ROI. A plurality of imaging positions of the sensor  120  and the generator  110  for imaging the ROIs independently are generated. 
     In order to independently capture an image for each ROI, the sensor  120  and the generator  110  should perform position movement several times. In order to minimize a moving distance of the sensor  120  and the generator  110 , the shortest distance path between the sensor  120  and the generator  110  using the plurality of imaging positions as stops may be calculated. Accordingly, a position movement schedule of the sensor  120  and the generator  110  may be generated. The image capturing apparatus  100  may capture images of the ROIs according to the generated position movement schedule. 
       FIG. 6  is a block diagram illustrating a specific configuration of an image capturing apparatus  100  according to an embodiment. As illustrated in  FIG. 6 , the image capturing apparatus  100  according to an embodiment may include the generator  110 , the sensor  120 , a controller  130 , an object location module  142 , a positioning module  150 , a user interface  160 , and a communication module  170 . The object location module  142 , the user interface  160 , and the communication module  170  may be selectively used and omitted according to an embodiment. 
     As described above, as the generator  110 , an X-ray generator commonly used as a light source for generating X-rays may be adopted and used. If necessary, the generator  110  may further include a collimator. 
     As the sensor  120 , an X-ray sensor generally used to collect X-rays to acquire an image may be adopted and configured as described above. The sensor  120  may be a large area sensor for panoramic or CT imaging. A size of the sensor  120  may be selected in consideration of a size of an ROI in the object  140 , a magnification power, and the FDD value. 
     The controller  130  includes a processor and a memory. The processor controls the image capturing apparatus  100  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  110  and the sensor  120  according to an imaging mode. 
     The object location module  142  accommodates an object, thereby allowing a position of the object to be specified. The object location module  142  may be omitted as an optional component. 
     The positioning module  150  moves positions of the generator  110  and the sensor  120 . According to an embodiment, the positioning module  150  may move a position of the object location module  142 . 
     As the user interface  160 , general input device and output device may be adopted as an interface unit between the image capturing apparatus  100  and the user. As the communication module  170 , a general wired/wireless communication module may be adopted as an interface unit between the image capturing apparatus  100  and an external device. The user interface  160  and the communication module  170  may be omitted as optional components. 
       FIG. 7  is a block diagram illustrating a configuration of an image capturing system  1000  including the image capturing apparatus  100  according to an embodiment. The image capturing system  1000  according to an embodiment may include the image capturing apparatus  100  of  FIG. 6 , a database  200 , and a processor  500 . In addition, the image capturing system  1000  may further include the user interface  300  and the communication module  400 . 
     The image capturing system  1000  may further include the database  200  to store image data of an object acquired from the image capturing apparatus  100  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 may also include, alone or in combination with the program instructions, data files, data structures, and the like. 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. Examples of program instructions include both machine code, such as produced by a compiler, and files containing higher level code that may be executed by the computer using an interpreter. 
     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. 
     Although embodiments of the present disclosure have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are can be made without departing from the scope and spirit of the disclosure as disclosed in the accompanying claims. Therefore, the technical scope of the present disclosure should be defined by the technical spirit and scope of the accompanying claims.