X-ray imaging device

Provided is an X-ray imaging device for radiographing an object. The X-ray imaging device includes a generator configured to emit X-rays, a sensor unit configured to detect the X-rays using at least one sensor, a gantry having the generator and the sensor unit facing with the object therebetween, and a sensor moving part provided in the sensor unit and configured to move the sensor while the gantry rotates about a rotating axis.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Stage Patent Application of PCT International Patent Application No. PCT/KR2015/007722 (filed on Jul. 24, 2015) under 35 U.S.C. § 371, which claims priority to Korean Patent Application No. 10-2014-0095717 (filed on Jul. 28, 2014), the teachings of which are incorporated herein in their entireties by reference.

TECHNICAL FIELD

The present invention relates generally to an X-ray imaging modality. More particularly, the present invention relates to an X-ray imaging device and an X-ray imaging method that can provide a three-dimensional X-ray image of a field of view having a desired size and shape by using a narrow-width sensor and low-dose X-ray exposure.

BACKGROUND ART

X-rays are attenuated according to an X-ray attenuation coefficient, such as photoelectric effect, Compton scattering, and the like, of a substance placed in a path of the X-rays.

X-ray imaging modality is radiography using permeability of X-rays, in which an X-ray image of an inner structure of a subject is obtained based on an amount of attenuation that is accumulated in the process of the X-rays passing through the subject. To achieve this, an X-ray imaging device includes: an X-ray source emitting X-rays toward a subject; an X-ray sensor disposed to face the X-ray source with the subject therebetween, and configured to receive the X-rays having passed through the subject; and an image processor configured to produce an X-ray image of a field of view (FOV) by using a detection result of the X-ray sensor.

Meanwhile, recently, X-ray imaging modality is being replaced with digital radiography (DR) using a digital sensor thanks to the development of semiconductor and information processing technologies, and an X-ray imaging method has also been developed in various ways.

As an example, a dental X-ray panoramic image is obtained through following process: radiographing by moving the X-ray source and the X-ray sensor along a subject, namely, a jawbone of an examinee while the X-ray source and the X-ray sensor face each other; and showing a transmission image by joining the radiographs and spreading arrangement relationship of a tooth and a tissue therearound of a desired focus layer on a jawbone trajectory. To achieve this, the X-ray source and the X-ray sensor perform rotational movement along a rotating axis therebetween within a predetermined angular range, and perform linear movement in forward and backward directions of the examinee within a predetermined length range.

The X-ray panoramic image is used as a standard image, which is the most familiar to dentists, since the entire arrangement relationship of a tooth and tissue therearound can be easily identified. However, it is problematic in that to obtain the X-ray panoramic image, a multi-axis drive system is required to link the rotational movement with the linear movement of X-ray source and the X-ray sensor.

As another example, a dental X-ray computed tomographic (CT) image is obtained through following process: radiographing by rotating the X-ray source and the X-ray sensor along a subject, namely, a head of an examinee while the X-ray source and the X-ray sensor face each other; and showing a three-dimensional X-ray image of a field of view including the head by reconstructing the radiographs. To achieve this, the X-ray source and the X-ray sensor rotates along a rotating axis passing by a subject within a predetermined angular range while facing each other.

The X-ray CT image is capable of not only displaying a three-dimensional X-ray image of a subject, but also accurately and clearly displaying a tomographic image according to desired location and direction, whereby it is used in fields that require high precision, such as implant procedures, etc. However, it is problematic in that radiation dose irradiated to an examinee is high to obtain a general X-ray CT image, and an expensive X-ray sensor having a large area is required.

To be more specific to the latter, when performing a general X-ray CT, the sensor should receive X-rays of the entire area having passed through a field of view in all directions. Accordingly, a sensor having an area much larger than that of the sensor for a panoramic X-ray image is required.

As an example, in the case of obtaining an X-ray CT image of a field of view having a first height t1 and a first width w1 by using a cone beam X-ray imaging method that is mainly used in dental fields, assuming that the rotating axis between the X-ray source and the X-ray sensor passes by a center of the field of view, a second height t2 of the sensor should be the same as or more than a value of a magnification ratio*the first height t1 (that is, t2≥magnification ratio*t1), wherein magnification ratio is defined as a distance ratio of a distance between the X-ray source and the rotating axis to a distance between the X-ray source and the X-ray sensor; and a second width w2 of the sensor should be the same as or more than a value of the magnification ratio*the first width w1 (that is, w2≥magnification ratio*w1), whereby it is possible to receive the X-rays of the entire area having passed through the field of view. Here, if necessary, a half beam X-ray imaging method can be used, which is configured to reduce the second width of the sensor to a value of a maximum magnification ratio*(w1)/2 by using an asymmetric X-ray beam covering more than a half of the field of view.

However, regardless of the imaging methods, an area of a sensor for X-ray CT is large. Further, cost of a general sensor increases dramatically according to an area thereof, so an X-ray CT imaging apparatus is problematic in that a sensor having a large area is required. Accordingly, the cost thereof increases due to size of the sensor.

DISCLOSURE

Technical Problem

Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and the present invention is intended to propose an X-ray imaging device and an X-ray imaging method that can provide a three-dimensional X-ray image of a field of view having a desired size and shape by using a narrow-width sensor and low-dose X-ray exposure compared to a conventional X-ray CT apparatus including a half beam method.

The present invention is further intended to propose an X-ray imaging device that can expand the field of view or select the same to have a free-form shape by using a single fixed rotating axis without adding or moving a physical rotating axis between an X-ray source and an X-ray sensor, and can even provide a panoramic image.

Technical Solution

In order to achieve the above object, according to one aspect of the present invention, there is provided an X-ray imaging device including: a generator and a sensor unit facing each other with a field of view therebetween; a gantry configured to rotate the generator and the sensor unit that face each other, about a rotating axis between the generator and the sensor unit; at least one sensor provided in the sensor unit, and configured to detect X-rays; a sensor moving part provided in the sensor unit, and configured to move the sensor in a direction of a rotation trajectory of the sensor unit or in a tangential direction of the rotation trajectory when the generator and the sensor unit are rotated about the rotating axis; and an image processor configured to produce a three-dimensional X-ray image of an entire area of the field of view, by using a detection result of the sensor.

Herein, when a width of the field of view is w1, a width w2 of the sensor is less than a value of a magnification ratio*a first width (w1)/2 (that is, w2<magnification ratio*(w1/2)), and the magnification ratio may be defined as a distance ratio of a distance between the generator and the rotating axis to a distance between the generator and the sensor.

The sensor moving part may move the sensor at a constant speed or at an accelerated speed.

The generator may emit the X-rays toward the sensor. In this case, the generator may include: an X-ray source emitting the X-rays; and a collimator adjusting the X-rays to correspond to the sensor. The X-ray imaging device may further include a generator moving part configured to move or rotate the generator such that the generator emits the X-rays toward the sensor.

In order to achieve the above object, according to another aspect of the present invention, there is provided an X-ray imaging method, in which a generator and a sensor unit facing each other with a field of view therebetween, a gantry configured to rotate the generator and the sensor unit that face each other, about a rotating axis between the generator and the sensor unit, and at least one sensor provided in the sensor unit to detect X-rays are used, the method includes: rotating the generator and the sensor unit about the rotating axis, and moving the sensor in a direction of a rotation trajectory of the sensor unit or in a tangential direction of the rotation trajectory, simultaneously; and producing a three-dimensional X-ray image of an entire area of the field of view, by using a detection result of the sensor.

When a width of the field of view is w1, a width w2 of the sensor is less than a value of a magnification ratio*a first width (w1)/2 (that is, w2<magnification ratio*(w1/2)), and the magnification ratio may be defined as a distance ratio of a distance between the generator and the rotating axis to a distance between the generator and the sensor.

Advantageous Effects

According to the present invention having the above-described characteristics, it is possible to provide an X-ray imaging device and an X-ray imaging method that can provide an accurate three-dimensional X-ray image of a field of view having a desired size and shape, for example, a field of view having a width more than twice a width of a sensor, by using a narrow-width sensor and low-dose X-ray exposure compared to a conventional X-ray CT apparatus including a half beam method.

Further, it is possible to provide an X-ray imaging device that can expand the field of view or select the same to have a free-form shape by using a single fixed rotating axis without adding or moving a physical rotating axis between an X-ray source and an X-ray sensor, and can even provide a panoramic image.

MODE FOR INVENTION

Reference will now be made in greater detail to exemplary embodiments of the present invention, an example of which is illustrated in the accompanying drawings. Although preferred embodiments of the present invention have been described for a dental X-ray imaging device, those skilled in the art will appreciate that the present invention can be applied to all X-ray imaging devices, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

FIG. 1is a perspective view showing an X-ray imaging device according to an embodiment of the present invention.

The X-ray imaging device according to the embodiment includes: a base supported on a floor; a column vertically erected from the base; and an elevation part10elevating along the column to correspond to a height of a subject. A rotating arm support20is connected to a side of the elevation part10. The rotating arm support20is rotatably provided with a rotating arm30. The rotating arm30includes: a generator32provided on a first side thereof based on a rotating axis25C; and a sensor unit31provided on a second side thereof based on the rotating axis25C to face the generator32. When an X-ray image is taken, an extension line of the rotating axis25C in a longitudinal direction passes a head of an examinee including a dental arch50as an example of a subject, and a specific location may be adjusted according to an area to be checked.

The X-ray imaging device according to the embodiment may further include an X-ray sensor unit40connected to the elevation part10directly or via the rotating arm support20, in addition to the rotating arm30. For example, the X-ray imaging device may be further provided with the X-ray sensor unit40for a cephalometric image.

Further, not shown in the drawings, the X-ray imaging device according to the embodiment includes an image processor configured to produce an X-ray image by using a detection result of the sensor unit31, wherein the image processor may be provided in the X-ray imaging device, or may be provided apart from the X-ray imaging device and be connected to the X-ray imaging device wirelessly or by wire.

The generator32may include: an X-ray source configured such that, for example, electrons having high kinetic energy are collided against a metal target to emit X-rays; and a collimator adjusting an irradiation direction or an irradiation range of the X-rays. The X-ray source may be classified into two types according to electron emission method: a filament type, in which thermoelectrons are emitted by using high current; and an electric field emission type, in which field emission effect of a nanostructure, such as a carbon nanotube (CNT), is used.

The sensor unit31is configured to generate electric signals according to strength by locations, by receiving the X-rays having passed through the subject. In the embodiment of the present invention, a generally known technology may be widely applied according to an X-ray conversion method, for example, a direct conversion method of directly obtaining electric signals from the X-rays without an intermediate step, or an indirect conversion method of indirectly obtaining electric signals by converting the X-rays into visible rays.

The rotating arm30and/or the rotating arm support20is provided with a rotation driver25configured to connect the rotating arm with the rotating arm support, and to rotate the rotating arm30about the rotating axis25C by using moving power. The rotation driver25serves to rotate the rotating arm30by a desired angle when the field of view (FOV) of the subject is radiographed. In other words, the X-ray imaging device of the embodiment, as a device configured to rotate the sensor unit31and the generator32with the subject therebetween, includes a gantry, wherein the gantry includes the rotating arm30and the rotation driver25. Reference will be made in detail to an embodiment of overall configurations of the sensor unit31and the generator32.

FIG. 2is a schematic diagram showing a configuration of an X-ray imaging device according to an embodiment of the present invention and an extension of a field of view according to movement of a sensor.

The sensor unit31is provided with at least one sensor311toward the generator32. Here, when a height and a width of the field of view are t1, and w1, respectively, a height t2 of the sensor311is the same as or more than a value of a magnification ratio*a first height t1 (that is, t2≥magnification ratio*t1), and a width w2 of the sensor311is less than a value of the magnification ratio*a first width (w1)/2 (that is, w2<magnification ratio*(w1/2)).

Further, the sensor311is movably provided to move in a direction of a rotation trajectory of the sensor unit31, for example, in a direction of a circular trajectory or in a tangential direction of the circular trajectory during radiography, that is, during rotation of the generator32and the sensor unit31about the rotating axis25C; and the generator32emits an X-ray beam XC aimed toward the sensor311, in conjunction with movement of the sensor311.

InFIG. 2, concentric circles F, FA, FB, and FC that are centered on the rotating axis25C show field of views according to a range of movement of the sensor311. For example, in a state where the sensor311is fixed in the initial location marked with a solid line, an X-ray image is taken while the generator32and the sensor unit31are rotated by predetermined angles, whereby it is possible to obtain a three-dimensional X-ray image of a first field of view F that is the smallest of the concentric circles. This is the same as a conventional half beam X-ray CT apparatus.

Further, during radiography centered on the rotating axis25C, in the case where the sensor311is moved from a location marked with the solid line by a width311A thereof in a direction of the rotation trajectory or in a tangential direction of the rotation trajectory, a radius of a second field of view FA is expanded by a width of the sensor311. Likewise, during radiography, when the sensor311is moved by twice311B or three times311C of its width, the field of view is expanded to third and fourth field of views FB and FC respectively corresponding thereto. Accordingly, even when the width of the sensor311is less than a value of a radius of the entire field of views F, FA, FB, and FC*a magnification ratio, it is possible to obtain a three-dimensional X-ray image of the entire field of views F, FA, FB, and FC.

For reference, in the above description and the drawings, for convenience of understanding, the sensor311is moved by a width of itself step by step during rotation of the generator32and the sensor unit31, that is, during radiography, but it is preferred that sensor311is moved at a constant speed or at an accelerated speed in conjunction with the rotation of the generator32and the sensor unit31during radiography.

In other words, when rotation rates of the generator32and the sensor unit31, and moving rate of the sensor311are adjusted properly, the field of view is actually expanded in a spiral form or in a form similar thereto; and if the rotation rates of the generator32and the sensor unit31, and the moving rate of the sensor311are adjusted to obtain an X-ray image of an entire area of the field of view with a sufficient angular range, it is possible to realize a three-dimensional X-ray image of the entire field of view.

In terms of configuration of the device, the sensor unit31includes a sensor moving part312configured to move the sensor311in the direction of the rotation trajectory of the sensor unit or in the tangential direction of the rotation trajectory, within a limited range. The sensor moving part312may include: a motor315generating power; an driving shaft314transmitting the power; and a connector313connecting the sensor311and the driving shaft314, wherein it is preferred that the sensor unit includes a sensor guide configured to guide movement of the sensor311. However, the above configuration is merely an example, so various shapes and modifications are possible.

Meanwhile, the generator32emits the X-ray beam XC aimed to the sensor311in conjunction with movement of the sensor311by a width corresponding to the width of the sensor311. As an example of configuration to achieve this, the generator32may include: an X-ray source321configured to emit an X-ray beam XT having a wide width to cover the range of movement of the sensor; and a collimator322configured to adjust the wide X-ray beam XT and to emit an X-ray beam XC that has a narrow width corresponding to the width of the sensor311and is aimed toward the sensor in response to movement thereof. The collimator322may include: at least one blade323configured to partially block the X-ray beam; a motor324configured to generate, for example, power to move the blade323; an driving shaft325configured to transmit the power; and a connector326connecting a portion of the blade323with the driving shaft325. The collimator322may be configured such that one blade with slits having a predetermined width, through which the aimed X-ray beam XC is passed, is driven by one motor, or two or more blades are driven by respective motors.

However, the above configuration of the generator32is merely an example, so various shapes and modifications are possible. For example, the generator32may include: an X-ray source configured to emit an X-ray beam that has a narrow width corresponding to the width of the sensor311; and a collimator, wherein the generator32is physically moved and/or rotated such that an irradiation direction of the X-ray beam is in conjunction with location movement of the sensor311. In this case, the generator32may further include a generator moving part for movement and/or rotation. Other than this, various shapes and modifications are possible.

Meanwhile, the X-ray imaging device according to the mentioned embodiment may include a controller60connected to the generator32and the sensor unit31, and configured to control the same such that the generator32emits the X-ray beam XC aimed to the sensor311in conjunction with location movement of the sensor311.

To be more specific, the controller60may be configured to be connected the sensor moving part312to control the motor315, and configured to control a direction of the X-ray beam emitted from the generator32, by using control signals thereof or a signal having been fed back from location information of the sensor311. The control of the direction of the X-ray beam may be performed by controlling the motor324driving the collimator322, as in the embodiment of the accompanying drawings. However, in the case where the generator32is configured through another configuration, a specific component receiving the control signals of the controller60may vary.

Further, the controller60may control of operation of the gantry, as well as the generator32and the sensor unit31. In other words, the controller60may control the rotation of the gantry, the movement of the sensor, and the direction of the X-ray beam from the generator32to be in conjunction with each other, and detailed description thereof has been made hereinbefore.

FIG. 3is a schematic diagram showing selection of a location of the field of view by using movement of the sensor in the X-ray imaging device according to the embodiment ofFIG. 2.

When the X-ray imaging device according to the embodiment ofFIG. 2or according to the above described modified embodiment is used, it is not only possible to expand the field of view, but also possible to freely select a location of the field of view within an available range of movement of the sensor311. Of course, it is possible to expand the field of view by using the movement of the sensor311, based on the selected location.

InFIG. 3, it is shown that during radiography by rotating the generator32and the sensor unit including the sensor311about the rotating axis25C, wide X-ray beams XT, XTD, and XTE at locations32D and32E on the trajectory of the generator32; narrow X-ray beams XC, XCD, and XCE; and a field of view FF generated when the wide X-ray beams and the narrow X-ray beams are overlapped with each other. When the generator32is disposed at the locations32D and32E, the sensor311may receive the aimed X-ray beams XC, XCD, and XCE by being moved to locations311D and311E within the wide X-ray beams XT, XTD, and XTE.

FIG. 4is a view showing an example of a field of view FT having free-form shape realized by the X-ray imaging device of the present invention. When the device is operated as described with reference toFIG. 3, in the state where the subject, for example, a head H of the examinee, stays still, it is possible to freely select a location of the field of view FT; and with reference toFIG. 2, through the combination of operation of the collimator in a vertical direction and the mentioned operation of the device, it is possible to expand the field of view FT having free-form size. Thereby, it is possible to obtain a three-dimensional X-ray image of the field of view FT having free-form shape corresponding to an area to be checked of the head of the examinee.

FIG. 5is a schematic diagram showing taking an X-ray panoramic image by using an X-ray imaging device according to an embodiment of the present invention. As shown inFIG. 5, the generator32and the sensor unit including the sensor311are rotated about the single fixed rotating axis25C, wherein the location of the sensor311is moved in the direction of the rotation trajectory of the sensor unit or in the tangential direction of the rotation trajectory, whereby it is possible to realize the same effect as moving a rotating axis in a conventional panoramic X-ray imaging apparatus, without moving the rotating axis25C in effect.

Accordingly, the X-ray imaging device according to the present invention is capable of not only providing an X-ray CT image and a three-dimensional X-ray image, but also providing a panoramic X-ray image of focus layer corresponding to a dental arch50by using the mentioned properties.