KR20150057970A - X-ray imaging apparatus and control method for the same - Google Patents

Abstract

Provided are an X-ray imaging apparatus which can reduce X-ray dose and minimize degradation of image quality and loss of FOV, and a control method thereof. According to one aspect, the method for controlling the X-ray imaging apparatus comprises the steps of: irradiating little dose of X-ray to an uninterested region in an object region than an interested region; and detecting the irradiated X-ray and obtaining a frame image related to the object region.

Description

[0001] X-RAY IMAGING APPARATUS AND CONTROL METHOD FOR THE SAME [0002]

The present invention relates to an X-ray imaging apparatus for radiating an X-ray to a target and imaging the inside of the X-ray imaging apparatus and a control method thereof.

An X-ray imaging apparatus is an apparatus that can acquire an internal image of an object by irradiating the object with the X-rays and using the X-rays transmitted through the object. Since the transmittance of the X-rays differs depending on the characteristics of the material constituting the object, the intensity or intensity of the X-rays transmitted through the object can be detected to image the internal structure of the object. On the other hand, in order to secure the stability of the X-ray imaging apparatus, it is recognized that it is important to reduce the X-ray dose of the object.

Ray imaging apparatus and its control method capable of reducing the dose of the x-ray and minimizing the loss of the image quality of the x-ray image and the loss of the field of view (FOV).

An X-ray imaging apparatus according to one aspect includes an X-ray source for irradiating X-rays to a target area; An x-ray detector for detecting the irradiated X-rays to acquire a plurality of frame images relating to the object region; And a filtering unit for filtering the X-rays irradiated from the X-ray source so that an X-ray having a dose smaller than that of the ROI is incident on the non-ROI of the object region.

The X-ray imaging apparatus sets the region of interest using the plurality of frame images, and combines the frame image obtained while the X-ray of a small dose is incident on the non-interest region with at least one previous frame image, And an image processor for reconstructing a non-interest area of the image.

Wherein the image processor comprises means for averaging the frame image and at least one previous frame image, summing the frame image and at least one previous frame image, or performing motion compensation temporal filtering on the frame image and at least one previous frame image compensated temporal filtering or motion-compensated spatial filtering may be applied to restore a non-interest area of the frame image.

The image processor may perform a combination of the frame image and at least one previous frame image for the non-interest region.

The image processor may further perform image registration or motion estimation and compensation on the reconstructed non-interest area combined with the at least one previous frame image.

The image processor may further perform an image smoothing algorithm for matching brightness and contrast of the ROI and the non-ROI with respect to the frame image in which the ROI is restored.

The control unit may set an X-ray imaging mode based on information on the frame image, information on the imaging mode, or information on the stage.

Wherein the control unit is further configured to set the X-ray photographing mode to a total photographing mode in which the X-ray photographing mode is irradiated with X-rays of a uniform dose to the ROI and the ROI according to the size of the ROI of the ROI, It can be set to one of the ROI modes to examine the x-rays of the dose.

The control unit may increase the size of the region of interest according to the movement of the object of interest and a total shooting mode in which the X-ray imaging mode irradiates X-rays of a uniform dose to the object region according to the size of the movement of the object of interest The position can be set to one of the static photographing modes to be fixed.

Wherein the control unit controls the X-ray photographing mode according to the size of the movement of the object of interest, the dynamic photographing mode in which the region of interest is moved according to the movement of the object of interest, And the position is fixed.

A method of controlling an X-ray imaging apparatus according to one aspect of the present invention includes irradiating a non-interest area in a target area with an X-ray of a smaller dose than the area of interest; And detecting the irradiated X-rays to acquire a frame image related to the object region.

The method of controlling an X-ray imaging apparatus according to claim 1, wherein the object region irradiates X-rays; Detecting the irradiated X-rays and obtaining a plurality of frame images relating to the object region based on the detected X-rays; And setting a region of interest in the object region using the plurality of frame images.

Irradiating the non-interest region with an x-ray of lesser dose than the region of interest may include filtering the x-rays illuminated to the non-interest region.

The control method of the X-ray imaging apparatus may further include restoring a non-interest area of the frame image by combining the frame image obtained while the X-ray of a small dose is incident on the non-interest area with at least one previous frame image have.

The X-ray dose is reduced, but the X-ray image quality and FOV loss can be minimized.

1 is a control block diagram of an X-ray imaging apparatus according to an embodiment of the present invention.
2 is a cross-sectional view illustrating an internal structure of an X-ray tube included in an X-ray imaging apparatus according to an embodiment.
3 is a control block diagram illustrating a configuration of a video processor included in an X-ray imaging apparatus according to an exemplary embodiment of the present invention.
FIG. 4 is a diagram illustrating an example of a region of interest when a stent is inserted into the aorta using angiography. FIG.
5 is a control block diagram of an X-ray imaging apparatus further including an interest object sensing unit.
6 is a control block diagram illustrating a configuration of a control unit included in the X-ray imaging apparatus according to an exemplary embodiment.
FIG. 7A is a side cross-sectional view of a ROI filter included in a filtering unit of an X-ray imaging apparatus according to an exemplary embodiment, and FIG. 7B is a plan view of an ROI filter.
8 is a cross-sectional view of a filtering unit having a plurality of RO filters.
FIGS. 9A and 9B are diagrams schematically showing the dose of X-rays incident on the ROI and the ROI.
FIG. 10A is a diagram illustrating movement of a ROI according to movement of an object of interest, and FIG. 10B is a diagram schematically illustrating an operation of tracking a ROI.
11 is a control block diagram of an X-ray imaging apparatus further including a source / detector position sensing unit.
12 is a view schematically showing a real-time image combined with a road map.
13A is a diagram illustrating a process of restoring the image quality of a frame image by combining previous images, and FIG. 13B is a diagram schematically illustrating an effect of reducing noise of a frame image by averaging the previous image.
14 is a control block diagram of an X-ray imaging apparatus further including a mode control unit.
15 is an external view of an X-ray imaging apparatus according to an embodiment.
16 is a flowchart illustrating a method of controlling an X-ray imaging apparatus according to an embodiment.
17 is a flowchart of an example of controlling the X-ray imaging mode in the control method of the X-ray imaging apparatus.
18 is a flowchart of another example of controlling the X-ray imaging mode in the control method of the X-ray imaging apparatus.
FIG. 19 is a flowchart of another example of controlling the X-ray imaging mode in the control method of the X-ray imaging apparatus.
FIG. 20 is a flowchart of another example of controlling the X-ray imaging mode in the control method of the X-ray imaging apparatus.

Hereinafter, embodiments of an X-ray imaging apparatus and a control method thereof will be described in detail with reference to the accompanying drawings.

FIG. 1 is a control block diagram of an X-ray imaging apparatus according to an embodiment, and FIG. 2 is a cross-sectional view illustrating an internal structure of an X-ray tube included in an X-ray imaging apparatus according to an embodiment.

1, an X-ray imaging apparatus 100 includes an X-ray source 110 for generating and irradiating an X-ray, an X-ray detector 120 for detecting an irradiated X-ray to acquire a frame image, A filtering unit 140 for filtering the X-rays, an image processor 150 for recovering the image quality of the obtained X-ray image, and a controller 160 for controlling the filtering unit 140.

Referring to FIG. 2, the x-ray source 110 may include an x-ray tube 111 for generating x-rays. An anode 111b and a cathode 111e are provided in the glass tube 111a of the X-ray tube 111 to heat the filament 111h of the cathode 111e to generate a hot electron . The filament 111h can be heated by applying an electric current to the electric wire 111f connected to the filament.

The cathode 111e includes a filament 111h and a focusing electrode 111g for focusing electrons and the focusing electrode 111g is also called a focusing cup. When a high voltage is applied between the anode 111b and the cathode 111e, the thermoelectrons are accelerated and collide with the target material 111d of the anode to generate X-rays. As the target material 111d of the anode, high-resistance materials such as Cr, Fe, Co, Ni, W, and Mo can be used. The generated X-rays are irradiated to the outside through the window 111i, and beryllium (Be) thin film or the like can be used as a material of the window 111i.

The voltage applied between the anode 111b and the cathode 111e is referred to as a tube voltage, and its magnitude can be expressed by the peak value kvp. As the tube voltage increases, the speed of the thermoelectrons increases and consequently the energy (photon energy) of the x-ray generated by collision with the target material increases. In addition, since the energy of the X-ray can be adjusted by arranging the filter in the irradiation direction of the X-ray, the X-ray of a specific energy band can be filtered by placing a filter for filtering the X- have. For example, when a filter such as aluminum or copper is disposed, the X-ray energy of the irradiated X-ray increases while the X-ray of the low-energy band is filtered.

The current flowing through the X-ray tube 111 is referred to as a tube current and can be expressed as an average value mA. When the tube current increases, the dose of the X-ray (the number of the X-ray photons) increases. Therefore, the energy of the X-ray can be controlled by the tube voltage, and the dose of the X-ray can be controlled by the tube current and the exposure time of the X-ray.

The X-ray imaging apparatus 100 can generate an X-ray moving image by applying an X-ray fluoroscopy, and can be applied to an X-ray diagnostic field such as an angiography or various treatment fields using the X-ray imaging apparatus. X-ray videos can be generated and displayed in real time.

The X-ray imaging apparatus 100 continuously performs X-ray imaging to generate X-ray moving images. There are continuous exposure and pulse exposure schemes for continuous X-ray imaging.

In the case of applying the continuous exposure method, a low tube current is continuously supplied to the X-ray tube 111 to continuously generate X-rays, and when the pulse exposure method is applied, an X-ray is generated in a short pulse sequence. Therefore, by applying the pulse exposure method, dose and motion blurring of the X-ray can be reduced. The X-ray imaging apparatus 100 can be applied to both of the above-described systems, but the following description will be made with reference to a pulse exposure system for convenience of explanation.

The x-ray source 110 can irradiate the x-rays a plurality of times according to a predetermined time interval or an arbitrary time interval in a subject area. Here, a predetermined time interval or an arbitrary time interval may be determined according to a pulse rate or a frame rate. For example, the frame rate may be set to 30 frames per second (30 fps), 15 frames per second (15 fps), 7.5 frames per second (7.5 fps), etc. Pulse rate may be set to 30 pulses per second (30 pps) ), 7.5 pulses per second (7.5 pps), and the like.

An object refers to an object to be photographed, in other words, an object to be represented by an X-ray image. An object region means a region including an object and is imaged as an x-ray image. Therefore, the object region may coincide with the photographing region (FOV) of the X-ray imaging apparatus 100 or may include the photographing region of the X-ray imaging apparatus 100.

The object region includes at least one of a region of interest and a region of non-interest. A non-interest area is a non-interest area among the object areas, and a detailed description of the area of interest and the non-interest area will be described later.

The X-ray detector 120 detects an X-ray and acquires a plurality of frame images for the object region. The frame image refers to each of a plurality of X-ray images obtained according to the frame rate of the X-ray imaging apparatus 100. The X-ray detector 120 may have a two-dimensional array structure including a plurality of pixels. When the detected X-rays are converted into electrical signals on a pixel-by-pixel basis, the X-ray detector 120 becomes one X-ray image for the object area.

The X-ray detector 120 can be applied to any of various structures for detecting an X-ray and converting it into an electrical signal. For example, a direct method in which an X-ray is directly converted into an electrical signal by using a photoconductor such as a-Se or a X-ray is converted into a visible light by using a scintillator such as CSI, Or an indirect method in which the signal is converted into a signal.

The filtering unit 140 filters the X-rays irradiated from the X-ray source 110 such that X-rays having a smaller dose than the region of interest are incident on the non-interest area. This is to reduce the dose of the x-ray. The x-rays are applied to the area of interest that contains a lot of useful information about the interior of the object through x-ray filtering. Ray. Since the X-ray is incident on the non-interest area, the FOV is not lost, and a more detailed description of the operation of the filtering unit 140 will be described later.

The image processor 150 reconstructs the frame image obtained while the X-ray having a dose smaller than that of the ROI is incident on the non-interest area using at least one previous frame image. If the dose of the x-ray is small, the signal-to-noise ratio (SNR) of the x-ray image may be lowered. Therefore, the image processor 150 can restore the non-interest area of the current frame image using at least one previous frame image, and a more detailed description about the restoration of the non-interest area will be described later.

In addition, the image processor 150 analyzes the frame image of the object area to obtain information on the ROI. A detailed description of the analysis of the frame image will also be given later.

The control unit 160 may control the X-ray source 110 and the filtering unit 140. For this purpose, the controller 160 may receive information on the region of interest from the image processor 150, 110 and the filtering unit 140 can be determined.

Hereinafter, the operation of each component of the X-ray imaging apparatus 100 will be described in detail.

FIG. 3 is a control block diagram illustrating a configuration of a video processor included in an X-ray imaging apparatus according to an embodiment, and FIG. 4 is a diagram illustrating an example of a region of interest.

Referring to FIG. 3, the image processor 150 includes an image analyzer 151 for analyzing a frame image of an object region to obtain information about a region of interest, and a controller 151 for restoring the image quality of a current frame image using previous frame images And an image reconstruction unit 152. [

As mentioned above, the X-ray imaging apparatus 100 can continuously perform x-ray imaging to obtain x-ray moving images of the object area. The frame images acquired by the X-ray detector 120 are input to the image processor 150 and the image analyzer 151 of the image processor 150 analyzes the inputted frame images to obtain information on the region of interest .

First, in order to set a region of interest, the image analyzer 151 performs an image process such as object recognition on a frame image of the object region to detect an object of interest. In order to detect an object of interest, it is possible to perform image processing on the current frame image, and to perform image processing on the current frame image and one or more previous frame images together. There may be a case where there is no object of interest in the current frame image. Therefore, if one or more previous frame images are used together, the detection performance of the object of interest can be improved.

In order to detect an object of interest, a feature of the object of interest may be stored in advance and an object corresponding to the feature stored in advance from the frame image of the object region may be detected. For example, the features detectable from the x-ray image among features of the object of interest, such as the shape of the object of interest, the x-ray absorption characteristic, and the motion characteristic, can be stored in advance.

The object of interest may be a surgical instrument or a surgical site used for the object, which must be continuously monitored by the user during X-ray imaging. For example, when the x-ray imaging apparatus 100 is used for angiography, when a surgical tool such as a guide wire, a catheter, a needle, a balloon, or a stent is inserted into a blood vessel, Careful observation of tools is needed. Therefore, the procedure tool can be set as an object of interest, and information on the feature can be stored in advance. In addition, when a treatment site is set as an object of interest, stenosis, aneurysm, cancerous region, and the like can be objects of interest.

It is also possible to detect an object of interest by using a marker attached to the object of interest, as well as detecting the object of interest using the features of the object of interest previously stored as described above. The marker can be easily identified in the x-ray image, and the image processor 150 can improve the detection performance by detecting the marker instead of the object of interest. The marker may have radiopaque properties such that it can be identified in an x-ray image, and the material may be at least one selected from the group including stainless steel, steel, gold, platinum and lead.

When an object of interest is detected, the image analyzer 151 sets a certain region including the detected object of interest as a region of interest. The location and size of the region of interest may be determined in consideration of the location, size, or motion characteristics of the object of interest, and may also take into account the uncertainty of the motion characteristics of the object of interest.

As an example, the image analyzer 151 may set the size of the region of interest to be large if the motion of the object of interest is large or the motion characteristics of the object of interest are difficult to predict, and the uncertainty is large.

A specific example of the setting of the region of interest will now be described with reference to FIG.

FIG. 4 illustrates a case where a stent is inserted into a blood vessel using angiography. The stent 13a is injected into the blood vessel to prevent occlusion of the blood vessel, and has a shape like a mesh. The stent 13a is attached to the end of the long tube-shaped stent mechanism 13 in a folded state, injected into the blood vessel, and spreads in the form of a mesh at a necessary position.

Referring to FIG. 4, a guide wire 11 is first inserted to insert a stent mechanism 13 into a blood vessel of a subject area. The stent mechanism 13 is inserted into the blood vessel along the guide wire 11 and the stent mechanism 13, particularly the end portion of the stent 13a, can be an object of interest while the stent mechanism 13 is inserted, A certain region including the region 13a may be the region of interest.

The tip of the guide wire 11 or the guide wire 11 can be an object of interest while the guide wire 11 is inserted and the catheter or the catheter 11 can be inserted while the catheter is inserted to inject the contrast agent into the blood vessel. May be the object of interest.

On the other hand, the image analysis unit 151 may use the information inputted from the outside to detect the object of interest. For example, when information on the type of operation tool, type of procedure, information on the operation site, information on injection of the contrast agent, and the like is input, the object of interest can be detected from the frame image based on the input information.

For example, if the procedure to be performed is a stent insertion of the aorta, and information indicating that the surgical tool to be inserted is a stent mechanism is input, the image analyzing unit 151 analyzes the stored stent characteristic information The stent in the aorta is detected from the frame image.

The image analysis unit 151 can determine the motion characteristics of the object of interest while tracking the detected object of interest, and the information of the object of interest, Can be realized in real time according to the frame rate of the frame. Here, the acquisition of information about the region of interest includes the detection, tracking, and setting of the region of interest based on the detection of the object of interest.

The movement characteristics of the object of interest include information such as the position of the object of interest, the size of the movement, the direction of movement, and the like. The size of the motion may include velocity, but the motion of the object of interest may not have a constant pattern. Therefore, the size of the motion may include various information indicating the degree of motion in addition to the speed.

Since the region of interest is a region including the object of interest, the motion characteristics of the region of interest can be determined according to the motion characteristics of the object of interest, as defined by the object of interest.

Meanwhile, the image analysis unit 151 may be used to set a region of interest by estimating a periodic motion such as respiration or heartbeat of a patient. For example, an object of interest, such as a stent or catheter, may be moved by the patient's movement, even if it is not moving on its own. In this case, since the object of interest moves according to the movement pattern of the patient, the movement of the patient can be predicted and the ROI can be reset using the predicted movement. Specifically, it is possible to reset the region of interest by detecting the object of interest and setting the region of interest, and compensating for the position or size of the region of interest using the amount of movement or the direction of movement according to the periodic movement pattern of the patient.

5 is a control block diagram of an X-ray imaging apparatus further including an interest object sensing unit.

In the embodiments described above, the object of interest is detected and the region of interest is set through the image processing of the x-ray image. However, in order to set the region of interest, a separate sensor May be used. For this purpose, the X-ray imaging apparatus 100 may further include an interest object sensing unit 170 for sensing an object of interest as shown in FIG.

For example, when a variable magnetic field is applied to a certain region including an object of interest and a coil is attached to the object of interest, the voltage applied to the coil varies depending on the movement of the object of interest. Therefore, the voltage applied to the coil can be measured, and the position and movement direction of the coil can be estimated based on the measured voltage. The position and direction of movement of the coil can be treated as the position and orientation of the object of interest. In this case, the object of interest sensing section 170 may include a magnetic field applying device for applying a magnetic field and a voltage sensor for measuring voltage.

Alternatively, an optically recognizable marker may be attached to the object of interest, and the marker may be recognized using an optical sensor to estimate the location and direction of the object of interest. In this case, the object of interest sensing section 170 may include an optical sensor capable of recognizing the marker.

An embodiment of the x-ray imaging apparatus 100 may be mounted on a mounting location of the sensors, such as a voltage sensor or an optical sensor, which may be mounted anywhere that the voltage applied to the coil attached to the object of interest or the marker attached to the object of interest may be recognized. For example.

Those using a voltage measurement sensor or an optical sensor to detect an object of interest are merely examples, and various sensing methods can be used to detect an object of interest.

As described above, when an object of interest is detected using a separate sensor, the object of interest can be detected even when the object of interest is located outside the X-ray irradiation range. The controller 160 warms up the filter driver 143 to quickly move the ROI filter 141 (see FIG. 7A) before the ROI is displayed on the X-ray image And may also move the ROI filter 141 in advance by estimating the moving speed and the moving direction of the object of interest.

The embodiment of the x-ray imaging apparatus 100, on the other hand, includes combining two or more of the above-described methods for the detection of an object of interest, thereby improving the accuracy of detection.

Information such as the position, size, or motion characteristics of the ROI acquired by the image analysis unit 151 is transmitted to the controller 160 and used to control the filtering unit 140.

Meanwhile, the image analyzing unit 151 may acquire not only the information on the region of interest but also information on the image characteristics such as noise and contrast appearing in the frame image. These characteristics are transmitted to the control unit 160, And can be used to control shooting conditions.

6 is a control block diagram illustrating a configuration of a control unit included in the X-ray imaging apparatus according to an exemplary embodiment.

6, the control unit 160 of the X-ray imaging apparatus 100 includes a photographing control unit 161 for controlling the X-ray imaging parameters and a filtering control unit 162 for controlling the filtering unit 140. FIG.

The photographing control section 161 controls various photographing parameters applied to the X-ray photographing. The photographing parameter is also referred to as an exposure parameter, and automatic control of photographing parameters in the X-ray imaging apparatus 100 is referred to as auto exposure control.

The photographing parameters may be at least one selected from the group including the tube voltage, tube current, exposure time, kind of filter, photographing area (FOV), frame rate, pulse rate,

The photographing parameter may be determined based on the frame image for the object area, or may be determined based on the inputted dictionary information before starting the X-ray photographing. Hereinafter, the embodiment related to the case of the former will be described in detail.

The photographing control section 161 can determine the photographing parameters based on the analysis result of the image analyzing section 151. [ For example, when the image analyzing unit 151 analyzes the frame image and determines the characteristics such as the thickness and the density of the object, the photographing control unit 161 determines, based on the determination result, a tube voltage, a tube current, Time, filter type, target material type, and the like.

Further, the photographing control section 161 may determine the photographing parameters based on the information on the region of interest obtained by the image analyzing section 151. [ In one embodiment, the photographing control unit 161 may determine photographing parameters such as a frame rate, a tube current, and a dose per frame according to the magnitude of movement of the object of interest or the characteristic of the image displayed in the region of interest, and may control them individually or simultaneously.

For example, when the size of the motion of the object of interest is large, the shooting control unit 161 obtains the information about the motion of the object of interest as much as possible by increasing the frame rate. If the size of the motion of the object of interest is small, Thereby reducing the exposure of the object.

Also, the photographing control unit 161 may control the dose per frame according to the noise level of the ROI. For example, if the noise level of the region of interest is higher than a preset reference value, the dose per frame may be increased to lower the noise level so that the region of interest may appear more clearly, and if the noise level of the region of interest is lower than a predetermined reference value , The dose per frame can be reduced to reduce the exposure of the object.

The filtering control unit 162 controls the filtering unit 140 based on the information on the region of interest acquired by the image analysis unit 151. To explain the operation of the filtering control unit 162, the configuration of the filtering unit 140 will be described with reference to FIG.

FIG. 7A is a side cross-sectional view of a region of interest filter included in the filtering section, and FIG. 7B is a plan view of an example of a region of interest filter.

Referring to FIG. 7A, the filtering unit 140 includes a region-of-interest filter 141 and a filter-driving unit 143 that moves the region-of-interest filter 141. The filter driving unit 143 may include a motor for generating power and a mechanical structure such as a gear for transmitting the generated power to the ROI filter 141.

The region-of-interest filter 141 is movable on the xy plane or the z-axis by the filter driver 143, the movement on the xy plane is to match the position of the region of interest filter 141 with the region of non-interest, The movement on the axis is to match the size of the ROI with the ROI filter 141.

The collimator 131 may be disposed in the X-ray irradiation direction corresponding to the front of the X-ray source 110. The collimator 131 is made of a material such as lead or tungsten that absorbs or blocks an X-ray, thereby adjusting the range of the FOV corresponding to the X-ray irradiation region of the X-ray source 110 and reducing the scattering of the X-ray.

The ROI filter 141 is located between the collimator 131 and the X-ray detector 120 to filter X-rays emitted from the X-ray source 110. The ROI filter 141 may be made of a material that attenuates the X-rays, and the X-rays are attenuated while passing through the ROI filter 141, thereby reducing the dose. Accordingly, when the ROI filter 141 is positioned at a position corresponding to a non-ROI region of the object region, it is possible to cause an X-ray having a dose smaller than that of the ROI to be incident on the ROI region.

In general, since the ROI is surrounded by the ROIs, the ROI filter 141 may have a ring shape in which the center is empty, that is, the center of the ROI 141b is formed as shown in FIG. 7B.

7B, the opening 141b may have a polygonal ring shape, and the opening 141b may have a ring shape as shown in the right side of FIG. 7B, 141 are not limited thereto, and the ROI filter 141 may have various shapes depending on the characteristics of the ROI, the ROI and the ROI.

The operation of the filtering control unit 162 will be described based on the configuration of the filtering unit 140 described above. The filtering control unit 162 generates a control signal for movement of the ROI filter 141 based on the information about the ROI and transmits the generated control signal to the filter driver 143 to generate the ROI filter 141 And can be moved to a position corresponding to the non-interest area.

As a specific example, the filtering control section 162 controls the movement of the ROI filter 141 on the xy plane so that the opening 141b of the ROI filter 141 is located at a position corresponding to the ROI, It is possible to control the movement of the ROI filter 141 on the z-axis so that the opening 141b of the ROI 141 corresponds to the size of the ROI.

The filtering control unit 162 can control not only the position of the ROI filter 141 but also the type and thickness of the ROI filter 141. [ Hereinafter, the operation of the filtering control unit 162 for controlling the type and thickness of the ROI filter 141 will be described with reference to FIG.

8 is a cross-sectional view of a filtering unit having a plurality of RO filters.

8, the ROI filter 141 may be composed of a plurality of filter layers independently movable on the xy plane or the z axis, and each of the filter layers includes a first ROI filter 141-1, The ROI filter 141-2 and the ROI filter 141-3.

The first ROI filter 141-1, the second ROI filter 141-2 and the third ROI filter 141-3 have the same type of filter material and different thicknesses, The kind and the thickness of the filter material are different from each other, the kind of the filter material is different and the thickness is the same, or the kind and the thickness of the filter material may be the same.

The filtering control unit 162 can determine the dose difference of the X-rays to be incident on the ROI and the ROI based on the image characteristics of the ROI and the ROI such as noise, motion, and contrast, It is possible to variably control the type or the thickness of the film.

As an example, the filtering control unit 162 may use a combination of the first ROI filter 141-1, the second ROI filter 141-2, and the third ROI filter 141-3. First, based on the image characteristics of the ROI and the ROI, a difference in dose of the X-ray to be incident on the ROI and the ROI is determined, and ROIs 141-1 and 141- 2,141-3) is determined.

For example, if it is determined that the second ROI filter 141-2 and the third ROI filter 141-3 are needed, the filtering control unit 162 may determine that the second ROI filter 141-2, The ROI filter 141-1 is positioned at a position where it can be filtered by the X-ray source 110 or passed through the collimator 131 and the first ROI filter 141-1 is excluded from the filtering position . The filtering control section 162 can control the position of the ROI filter 141 by moving it on the z-axis or on the xy plane.

As the ROI filter 141 approaches the X-ray source 110 or the collimator 131, the width of the X-ray passing through the opening 141b of the ROI filter 141 becomes narrower. Accordingly, in the case of increasing the ROI by reducing the ROI, when the ROI filter 141 is moved to the X-ray source 110 or the collimator 131 on the z-axis and the ROI is increased to reduce the ROI And moves the ROI filter 141 on the z-axis to the opposite side of the x-ray source 110 or the collimator 131. [

FIGS. 9A and 9B are diagrams schematically showing the dose of X-rays incident on the ROI and the ROI.

FIG. 9A shows the dose of an X-ray incident on an arbitrary straight line AB passing through the ROI and the ROI. When the filtering control unit 162 moves the ROI filter 141 to a position corresponding to the ROI, an X-ray having a dose smaller than that of the ROI is incident on the ROI as shown in FIG. 9A. Although dose is small, X-rays are incident on un-interested areas, so that information on the whole shooting area can be obtained.

As described above, the X-ray imaging apparatus 100 can acquire a moving image by continuously performing X-ray imaging. As long as the region of interest exists in the object region, the difference in dose between the X- 8b. ≪ / RTI > For example, the dose of an x-ray incident on a non-interest region may be 1/5, 1/10, or 1/20 or less of the x-ray dose entering the region of interest.

FIG. 10A is a diagram illustrating movement of a ROI according to movement of an object of interest, and FIG. 10B is a diagram schematically illustrating an operation of tracking a ROI.

The X-ray moving picture can represent the motion existing in the object area, and if the subject of motion is the object of interest, the area of interest can be moved by the movement of the object of interest. 10A, when the stent 13 is inserted into a blood vessel, the stent 13a, which is an object of interest, moves to a target position in the blood vessel, and the movement of the stent 13a The region of interest is moved together.

As shown in FIG. 10B, when the ROI is moved, the image analysis unit 151 may track the ROI in real time And the filtering control unit 162 controls the ROI filter 141 to move in synchronization with the movement of the ROI.

On the other hand, when the image analyzing unit 151 fails to detect the object of interest or detects it, the reliability may be very low. For example, the reliability of the detection can be obtained by various algorithms for calculating the reliability of the object recognition result, and when the reliability value is less than the preset reference value, it can be determined that the detection result of the object of interest is unreliable. The image analyzing unit 151 can maintain the previous region of interest without resetting the region of interest if the detection of the object of interest fails or its reliability is less than a preset reference value.

11 is a control block diagram of an X-ray imaging apparatus further including a source / detector position sensing unit.

The position of the x-ray source 110 or the x-ray detector 120 may be changed during the x-ray photographing. It is also possible for the user to manually move the x-ray source 110 or the x-ray detector 120 and automatically move the x-ray source 110 or the x-ray detector 120. The relative position between the object of interest and the x-ray source 110 or x-ray detector 120 may vary as the x-ray source 110 or x-ray detector 120 moves, even if the object of interest does not move. In this case, the similarity between the previous frame image and the current frame image may be lowered, and even if the image analyzing unit 151 performs detection and tracking of the object of interest in real time, have. Accordingly, when the X-ray source 110 or the X-ray detector 120 moves, the image analyzing unit 151 detects the object of interest by reflecting a change in the position of the X-ray source 110 or the X-ray detector 120, You can reset it. Specifically, the image analyzer 151 can estimate a positional change relative to the object of interest according to the positional change of the x-ray source 110 or the x-ray detector 120, and reflects a relative positional change So that deterioration of the performance or reliability of detection can be prevented.

The X-ray imaging apparatus 100 may further include a source / detector position sensing unit 180 capable of sensing a change in position of the X-ray source 110 or the X-ray detector 120 as shown in FIG. have. The source / detector position sensing unit 180 may be implemented as a position sensor to acquire positional information of the x-ray source 110 or the x-ray detector 120, and the x-ray source 110 or the x- When the X-ray source 110 or the X-ray detector 120 can automatically move the X-ray source 110, the X-ray source 110 or the X-ray detector 120 may be implemented as a sensor for measuring the driving amount of the driving unit.

When the X-ray source 110 or the X-ray detector 120 is automatically moved under the control of the controller 160, the controller 160 does not include the source / detector position sensing unit 180, It is also possible to obtain information on the movement amount and the moving direction of the X-ray detector 120 or the X-ray detector 120.

In the embodiment of the X-ray imaging apparatus 100, there is no limitation to the configuration or the method of acquiring the information about the positional change of the X-ray source 110 or the X-ray detector 120. In addition to the above- Information about the positional change of the source 110 or the x-ray detector 120 can be obtained.

In the example of FIG. 10B, the region of interest is moved together with the movement of the object of interest. However, according to another example, the size of the region of interest may be changed according to the movement of the object of interest. The image analyzing unit 151 can increase the size of the ROI so that the ROI can include the ROI when the ROI is moved. Therefore, the size increase rate of the region of interest changes according to the size of the movement of the object of interest.

Or, as will be described later, it is also possible to fix the position of the ROI and increase the size only when the size of the movement of the ROI is small.

The X-ray imaging apparatus 100 can perform road mapping, and in performing the road mapping, the X-ray dose can be adjusted by detecting and tracking the region of interest.

12 is a view schematically showing a real-time image combined with a road map.

Referring to FIG. 12, first, a contrast agent is injected into a blood vessel to be inserted with a surgical tool to generate a road map mask. The road map mask serves as a blood vessel map and corresponds to a still image. The image processor 150 may combine the roadmap mask with subsequent live fluoroscopic images to obtain images such that the procedure tool is superimposed on the roadmap.

As an example, the background is removed by subtracting the next real time perspective image from the road map mask, and an image in which the treatment tool and the target vessel are displayed with excellent contrast can be obtained. Alternatively, the roadmap mask may be subtracted from the next real-time perspective image.

The image processor 150 may perform Digital Subtraction Angiography (DSA) on the images before combining the roadmap mask and the real-time perspective image. DSA is a subtraction of the contrast medium before contrast injection, and can improve the recognition rate of blood vessels by removing the background anatomy or tissue.

Here, a real-time perspective image is an image in which a low-dose X-ray is incident on a non-interest region through real-time detection and tracking of a region of interest. By combining low-dose real-time perspective images with road maps, real-time images with excellent contrast between blood vessels and treatment tools can be obtained while reducing the dose.

The image restoration unit 152 may perform image restoration or image enhancement for improving the image quality for a region of interest of the frame image.

The image restoring unit 152 may use a denoising algorithm such as spatial filtering, temporal filtering, spatio-temporal filtering, super-resolution reconstruction, Thereby restoring the region of interest of the frame image. A detailed description of restoration in the area of interest will be given later.

In addition, the image reconstructing unit 152 may enhance the region of interest of the frame image using a histogram, a contrast enhancement algorithm based on wavelet, a detail enhancement algorithm such as an edge enhancement filter, and the like.

On the other hand, since the low-dose X-ray is incident on the non-interest region, the non-interest region of the frame image may have a low signal-to-noise ratio. Accordingly, the image restoring unit 152 performs a restoration operation to improve the image quality of the non-interest area. Hereinafter, an operation of restoring a non-interest area of a frame image will be described in detail with reference to FIGS. 13A and 13B.

13A is a diagram illustrating a process of restoring the image quality of a frame image by combining previous images, and FIG. 13B is a diagram schematically illustrating an effect of reducing noise of a frame image by averaging the previous image.

Referring to FIG. 13A, the image restoring unit 152 may perform image restoration to improve the image quality by combining the current frame image with at least one previous frame image. At this time, the combination of the frame images can be performed for the non-interest area. According to the example of FIG. 13A, a frame image having an excellent signal-to-noise ratio similar to a frame image for a region of interest in which a high-dose X-ray is incident can be obtained by combining and restoring a current frame image with two previous frame images.

As an example of a method of combining a current frame image and at least one previous frame image, a method of summing a current frame image and at least one previous frame image, a method of averaging the current frame image and at least one previous frame image, A method of applying a motion-compensated temporal filtering, a method of applying motion-compensated spatial filtering, and the like may be used. . Here, the sum may be a simple sum or a weighted sum, and the average may be a simple average or a weighted average.

The image restoring unit 152 may use one of the above methods, or may use a combination of two or more methods.

Referring to FIG. 13B, if the current frame image is a frame image m, the frame image m and the frame image m-1 can be averaged to recover the frame image m, and if necessary, the frame image m and the previous frame image m Can be averaged together.

If the number of previous images used in the average is increased, the noise reduction rate of the image is also increased. For example, if the average of the frame image m and the previous frame image of 4 frames is reduced, the noise can be reduced to about 60%. The image reconstructing unit 152 may determine the number of previous frame images used for the average considering the noise of the current frame image and the image lag.

In addition, the image reconstructing unit 152 may perform additional image enhancement on a non-interest area of the reconstructed frame image. As an example, in order to reduce the resolution and image blurring that may occur when a current frame image and a previous frame image are combined, alignment or registration between frame images, or motion prediction / compensation Can be performed.

Algorithms for matching between frame images can be feature-based algorithms, intensity-based algorithms, or algorithms that combine features and signal strengths.

Motion field models for motion prediction / compensation include translational motion, block-based piecewise translational motion, rotation, scaling, non-rigid deformable motion, Etc. may be used.

In addition, the image reconstructing unit 152 may perform image reconstruction on the ROI as well as the ROI. At this time, the image restoration can be performed by combining the current frame image and the previous frame image with respect to the ROI. In restoring both the ROIs and the non-ROIs, it is possible to perform spatial denoising filtering, temporal denoising filtering, and both spatial filtering and temporal filtering in both areas. You may. Here, both spatial filtering and temporal filtering may be motion compensation filtering.

Alternatively, appropriate filtering may be selected according to the motion characteristics of each of the non-interest area and the ROI. As an example, spatial filtering may be applied if the motion is large or fast, and temporal filtering may be applied otherwise. Therefore, if the motion in the region of interest is large or fast, spatial filtering may be applied to the region of interest and temporal filtering may be applied to the regions of no interest.

Alternatively, temporal filtering may be applied to both the ROI and the ROI, and the filtering strengths may be different from each other to optimize the quality of the entire image including the ROI and the ROI. For example, if the similarity between temporally adjacent frame images is small due to a large motion of the object of interest, the temporal filtering may reduce the filtering effect. In this case, temporal filtering of a relatively weak intensity may be applied to the region of interest, and temporal filtering of relatively strong intensities may be applied to the region of non-interest. Thus, it is possible to restore the image quality of a non-interest area irradiated with a relatively low dose of x-rays and to prevent blurring of objects of interest having complex motion.

In order to adjust the intensity of temporal filtering, the number of previous frame images used for restoration of the current frame image may be adjusted, or the weight applied to each previous frame image may be adjusted. For example, to apply temporal filtering of weak intensity, a relatively small number of previous frame images may be used for reconstruction. Alternatively, the same number of previous frame images as in the case of applying strong filtering may be used, but the weight applied to the previous frame image may be adjusted according to the temporal adjacency with the current frame image. For example, a higher weight value may be applied to a previous frame image temporally closer to the current frame image, and a lower weight value may be applied to a temporally farther previous frame image.

The image reconstructing unit 152 may perform an image equalization algorithm to match the brightness and contrast of the ROI with the non-ROI.

On the other hand, when the dose of the X-rays incident on the region of interest and the region of non-interest by the X-ray filtering on the non-interest region is changed, an artifact may occur in the boundary region of the two regions. Accordingly, the image reconstructing unit 152 may reduce the artifacts occurring in the boundary region by performing image processing that applies a boundary correction algorithm to the boundary region between the ROI and the ROI.

The characteristics of the boundary region may vary depending on the material, shape, position, and the like of the ROI filter 141. Therefore, the characteristic of the ROI filter 141 can be considered when the image reconstructing unit 152 performs the image processing by applying the boundary correction algorithm to the boundary region.

As an example of the boundary correction algorithm applied by the image restoring unit 152, a linear blending algorithm may be used. The linear blending algorithm is also referred to as Feathering or Alpha blending. The linear blending algorithm is a method of weighting the values of each pixel in the region where the boundary occurs, and the boundary region can be naturally formed as the weighting region is widened.

As another example of the boundary correction algorithm applied in the image restoring unit 152, a multi band blending algorithm may be used. The multiband blending algorithm separates high frequency and low frequency images for each band through a Gaussian pyramid, separates the band images based on the maximum weight function, and then fuses each band image with different weights. And the low-frequency image is widely fused so that the detail components can be effectively fused.

The above-described boundary correction algorithms are only examples that can be applied to the embodiments of the disclosed invention, and the types of boundary correction algorithms used in the image restoring unit 152 are not limited to these examples.

Meanwhile, when the ROI filter 141 moves while the X-ray is being irradiated, the pattern of the boundary region may be changed. Accordingly, the image reconstructing unit 152 estimates the pattern of the boundary region using the information about the movement speed and the positional change of the ROI filter 141 while the X-ray is being irradiated, and can use the information to correct the boundary region have.

14 is a control block diagram of an X-ray imaging apparatus further including a mode control unit.

Referring to FIG. 14, the control unit 160 of the X-ray imaging apparatus 100 may further include a mode control unit 163 for controlling the X-ray imaging mode. The X-ray photographing mode that can be controlled by the mode control unit 163 includes the ROI mode and the entire photographing mode. As described above, the ROI mode is a mode in which the ROI is differentiated between the ROI and the ROI, and the Full FOV mode has a difference in the X-ray dose between the ROI and the ROI And irradiates an X-ray of a uniform dose with respect to the object area without placing the X-ray.

The mode control unit 163 can control the X-ray imaging mode based on the information about the frame image analyzed by the image analysis unit 151, the information about the imaging mode, or the information about the stage. The mode control unit 163 may consider all or part of these information in controlling the X-ray imaging mode.

The information on the frame image may include information on the region of interest or information on the image characteristics. Hereinafter, the operation of the mode control unit 163 to control the X-ray imaging mode based on the information on the region of interest will be described in detail.

The information on the region of interest includes motion characteristics of the object of interest, and the mode control unit 163 can control the X-ray imaging mode based on the size of the motion of the object of interest.

Specifically, when the motion of the object of interest is large, it may be more efficient to irradiate the X-ray of a uniform dose with respect to the entire imaging region than to change the X-ray dose per region according to the movement of the object of interest. Accordingly, when the movement of the object of interest is large, the mode control unit 163 may set the X-ray imaging mode to the entire imaging mode so that the X-ray of a uniform dose is irradiated to the entire imaging region.

On the other hand, the mode control unit 163 can determine whether the size of the motion is large by comparing the magnitude of motion of the object of interest with a preset reference value, and the reference value can be set based on experiments, statistics, simulations, . A reference value serving as a setting reference of the entire shooting mode, which can determine whether or not the magnitude of the motion is large in order to distinguish it from other reference values to be described later, will be referred to as a first reference value.

If the motion of the object of interest is not large, the mode control unit 163 can set the X-ray imaging mode to the ROI mode, and the ROI mode can be divided into two modes based on the size of the ROI of the ROI .

If the movement of the object of interest is small, it is necessary to finely change the X-ray dose for each region, so that the region of interest is increased by a certain amount to include the movement of the object of interest, and it may be more efficient not to move. In this embodiment, the X-ray photographing mode for performing such an operation will be referred to as a static photographing mode (stationary mode). The mode control unit 163 may set the X-ray photographing mode to the static photographing mode if the magnitude of the movement of the object of interest is smaller than a preset second reference value.

If the movement of the object of interest is intermediate, that is, when the size of the movement of the object of interest is larger than a preset second reference value, the mode control unit 163 moves the ROI according to the movement of the ROI, And sets the photographing mode for adjusting the X-ray dose by moving the photographing lens 141 to a position corresponding to the non-interest area. The photographing mode is set as a dynamic photographing mode.

On the other hand, it is also possible that the mode control unit 163 sets the X-ray photographing mode to only two of the above-described all photographing mode, the static photographing mode, and the dynamic photographing mode or only one mode.

More specifically, the mode control unit 163 sets the X-ray photographing mode to the entire photographing mode if the magnitude of the movement of the object of interest is greater than a preset third reference value, and sets the X-ray photographing mode to the static photographing mode if it is small. Here, the predetermined third reference value may be the same as or different from the first reference value or the second reference value.

Alternatively, if the size of the movement of the object of interest is greater than a preset fourth reference value, the X-ray imaging mode may be set to the entire imaging mode and the X-ray imaging mode may be set to the dynamic imaging mode. Here, the fourth reference value may be the same as or different from the first reference value, the second reference value, or the third reference value.

Alternatively, if the magnitude of movement of the object of interest is greater than a preset fifth reference value, the x-ray imaging mode may be set to the dynamic imaging mode and the x-ray imaging mode may be set to the static imaging mode. Here, the fifth reference value may be the same as or different from the first reference value, the second reference value, the third reference value, or the fourth reference value.

Alternatively, it is possible to set the X-ray photographing mode to the static photographing mode only, or to set the dynamic photographing mode only, regardless of the size of the movement of the object of interest.

Hereinafter, the operation of the mode control unit 163 to control the X-ray imaging mode based on the information about the imaging mode or the information about the stage will be described.

The imaging modes that the x-ray imaging apparatus 100 can perform include a general fluoroscopic mode and a digital subtraction angiography (DSA) mode.

Since the DSA image obtained by the DSA mode can be used to determine the position and shape of the blood vessel to be observed in the entire object region, when the imaging mode of the X-ray imaging apparatus 100 is the DSA mode, the mode control unit 163 You can set the X-ray shooting mode to the full shooting mode.

In the case of the x-ray fluoroscopy mode, it is possible to set the mode of interest region. Therefore, the dynamic shooting mode or the static shooting mode may be set according to the motion characteristics of the object of interest. However, if the movement of the object of interest is large as described above, the entire shooting mode may be set.

The information about the stage includes information about which step of the current step among the various steps for radiography. For example, information on the stage may be information on whether it is a catheter insertion step, a stent insertion step, or a contrast agent injection step.

For example, in the case where the imaging mode is the X-ray fluoroscopic mode, the X-ray imaging mode can be set to the entire imaging mode in order to grasp the overall structure of the object when the present stage is the contrast medium injection stage.

On the other hand, the information on the imaging mode and the information on the stage can be determined by the apparatus itself or can be input by the user. In addition to the above-described example, the mode control unit 163 can also display, on the basis of various information input by the user, Depending on whether the information is important or whether the image information of the area of interest is important, the X-ray imaging mode can be set.

15 is an external view of an X-ray imaging apparatus according to an embodiment.

As an example, the x-ray imaging apparatus 100 may have a C-arm structure as shown in Fig. The X-ray source assembly 107 and the X-ray detector 120 can be mounted at both ends of a C-arm (C-arm) 101, respectively. The C-arm 101 is connected to the main body 103 through the connection shaft 105 and can rotate in the orbital direction.

The X-ray source assembly 107 may include an X-ray source 110, a collimator 131, and a filtering unit 140. When the patient table 109 is positioned between the X-ray source assembly 107 and the X-ray detector 120 and the object is located on the patient table 109, the X-ray source 110 irradiates the X- X-ray images of the object are obtained by detecting the irradiated X-rays.

As described above, the X-ray imaging apparatus 100 can perform X-ray imaging according to various imaging modes and can obtain a real-time moving image of a target object. Thus, the user can have a plurality of screens, It is possible to perform a procedure or diagnosis while viewing the display unit 172 capable of displaying an image.

As described above, when the image analyzing unit 151 obtains information on the region of interest, or the photographing control unit 161 sets photographing parameters or the mode control unit 163 controls the X-ray photographing mode, The input information can be used. The user can input necessary information through the input unit 171 provided in the X-ray imaging apparatus 100.

Hereinafter, an embodiment of a control method of an X-ray imaging apparatus will be described.

16 is a flowchart illustrating a method of controlling an X-ray imaging apparatus according to an embodiment. The X-ray imaging apparatus 100 described above may be used in the control method according to one embodiment. Therefore, it goes without saying that the description of the embodiment of the X-ray imaging apparatus 100 of FIGS. 1 to 15 described above can be similarly applied to the control method of the X-ray imaging apparatus.

Referring to FIG. 16, an X-ray is irradiated at a predetermined time interval in a subject area (310). Although it is also possible to continuously irradiate the X-rays, the present embodiment employs a pulse exposure method in which an X-ray is irradiated at regular time intervals in order to reduce dose of the X-ray and improve temporal resolution. Here, the predetermined time interval may be determined according to the pulse rate. For example, when the pulse rate is 30 pulses per second (30 pps), the X-ray is irradiated 30 times per second.

The examined X-ray is detected to obtain a frame image of the object area (311). Here, the object region may coincide with the X-ray imaging region, and the acquisition of the frame image may be performed in real time in synchronism with the irradiation of the X-ray.

Information regarding the region of interest is obtained from the frame image of the object region (312). Acquisition of information about the region of interest includes detection of the object of interest and setting of the region of interest based on the detected object of interest. Specifically, an object of interest is detected from a frame image of the object area, and a certain area including the detected object of interest is set as an area of interest. The location and size of the region of interest may be determined by considering the location, size, or motion characteristics of the object of interest, and may also take into account the uncertainty of the motion characteristics of the object of interest. The information on the region of interest includes the location, size, or motion characteristics of the region of interest, and the motion characteristics of the region of interest may be defined by the motion characteristics of the object of interest.

The ROI filter is controlled (313) such that x-rays of lesser dose than the ROI are incident on the ROI. The ROI filter 141 is arranged so that positional control is possible between the X-ray source 110 for irradiating the X-ray and the X-ray detector 120 for detecting the X-ray. Accordingly, the ROI filter 141 can be positioned at a position corresponding to the ROI such that an X-ray having a smaller dose than the ROI can be incident on the ROI. The setting of the ROI can be performed in real time according to the frame rate. When the ROI is moved, the ROI is moved to move the ROI filter 141 to a position corresponding to the ROI.

The control of the ROI filter may also include adjusting the dose differences of the X-rays to be incident on the ROI and the ROI based on the image characteristics of the ROI and the ROI such as noise, motion, and contrast.

Since the low-dose X-ray is incident on the non-interest region, the non-interest region of the frame image has a low signal-to-noise ratio. Accordingly, the image quality of the non-interest area is improved by restoring the current frame image using at least one previous frame image (314). Specifically, a current frame image may be combined with at least one previous frame image. As a method of combining a current frame image and a previous frame image, a method of averaging or summing a current frame image and a previous frame image, A method of variably applying a filter applied to a current frame image in consideration of image characteristics such as noise and edge direction, a method of applying motion-compensated temporal filtering, a method of performing motion-compensated spatial filtering ), And the like. Here, the inter-image combining can be performed on the non-interest area.

Then, additional image enhancement can be performed on the reconstructed frame image. As an example, in order to reduce the resolution and image blurring that may occur when a current frame image and a previous frame image are combined, alignment or registration between frame images, or motion prediction / compensation Can be performed.

Meanwhile, the restoration work for improving the image quality of the image can be performed on the region of interest of the frame image as well. The spatial filter, the temporal filter, the spatio-temporal filter, A denoising algorithm such as a super-resolution reconstruction can be used to restore a region of interest of a frame image and a histogram or a wavelet-based contrast enhancement algorithm or an edge enhancement filter A detail enhancement algorithm can be used to enhance the region of interest of the frame image.

Then, an image equalization algorithm is performed to match the brightness and contrast of the ROI and the non-ROI of the frame image, and the restored frame image is displayed on the display unit in real time (315).

The control method of the X-ray imaging apparatus according to an exemplary embodiment can automatically control the X-ray imaging mode based on the information on the frame image, the information on the imaging mode, or the information on the stage. An embodiment for controlling the X-ray imaging mode based on the magnitude of the movement of the object of interest will be described.

17 is a flowchart of an example of controlling the X-ray imaging mode in the control method of the X-ray imaging apparatus.

Referring to FIG. 17, an X-ray is irradiated at a predetermined time interval in an object area (320), and a frame image related to the object area is obtained (321) by detecting the irradiated X-rays. Information about the ROI is obtained from the frame image of the object region (322). Here, the information on the region of interest includes the magnitude of the movement of the object of interest.

If the size of the movement of the object of interest is larger than the first reference value (YES in 323), the X-ray photographing mode is set to the entire photographing mode (324) and the X-ray photographing is performed accordingly. The Full FOV mode is a normal imaging mode in which there is no difference in X-ray dose between the ROI and the ROI.

If the size of the movement of the object of interest is smaller than the first reference value (No in 323), it is determined whether it is larger than the second reference value (325). If the size of the movement of the object of interest is greater than the second reference value (325), the X-ray photographing mode is set to the dynamic photographing mode (326) and the X-ray photographing is performed accordingly. The dynamic imaging mode is a mode for moving the region of interest according to the movement of the object of interest among the ROI modes that differ in the X-ray dose of the ROI and the ROI.

If the size of the movement of the object of interest is smaller than the second reference value (NO in 325), the X-ray photographing mode is set to the static photographing mode (327) and the X-ray photographing is performed accordingly. The static photographing mode is a mode in which only the size of the region of interest is increased by a certain amount to include the movement of the object of interest, and does not move.

18 is a flowchart of another example of controlling the X-ray imaging mode in the control method of the X-ray imaging apparatus.

Referring to FIG. 18, an X-ray is irradiated (330) at a predetermined time interval in the object area, and a frame image related to the object area is obtained (331) by detecting the irradiated X-rays. Information about the ROI is obtained from the frame image of the object region (332). Here, the information on the region of interest includes the magnitude of the movement of the object of interest.

If the size of the movement of the object of interest is larger than the reference value (YES in 333), the X-ray photographing mode is set to the entire photographing mode (334) and the X-ray photographing is performed accordingly.

If the size of the movement of the object of interest is smaller than the reference value (NO in 333), the X-ray photographing mode is set to the dynamic photographing mode (335) and the X-ray photographing is performed accordingly. Here, the reference value may be the same value as the first reference value or the second reference value in the example of FIG. 17, or may be another value.

FIG. 19 is a flowchart of another example of controlling the X-ray imaging mode in the control method of the X-ray imaging apparatus.

Referring to FIG. 19, an X-ray is irradiated at a predetermined time interval in an object area (340), and a frame image related to the object area is acquired (341) by detecting the irradiated X-rays. Information about the ROI is obtained from the frame image of the object region (342). Here, the information on the region of interest includes the magnitude of the movement of the object of interest.

If the size of the movement of the object of interest is larger than the reference value (YES in 343), the X-ray photographing mode is set to the dynamic photographing mode (344) and the X-ray photographing is performed accordingly.

If the size of the movement of the object of interest is smaller than the reference value (No in 343), the X-ray photographing mode is set to the static photographing mode (345) and the X-ray photographing is performed accordingly. Here, the reference value may be the same as or different from the first reference value, the second reference value, or the reference value in the example of FIG. 17 in the example of FIG.

FIG. 20 is a flowchart of another example of controlling the X-ray imaging mode in the control method of the X-ray imaging apparatus.

Referring to FIG. 20, an X-ray is irradiated at a predetermined time interval in an object area (350), and a frame image related to the object area is acquired (351) by detecting the irradiated X-rays. Information about the ROI is obtained from the frame image of the object region (352). Here, the information on the region of interest includes the magnitude of the movement of the object of interest.

If the size of the movement of the object of interest is larger than the reference value (YES in 353), the X-ray photographing mode is set to the entire photographing mode (354) and the X-ray photographing is performed accordingly.

If the size of the movement of the object of interest is smaller than the reference value (NO in 353), the X-ray photographing mode is set to the static photographing mode (355) and the X-ray photographing is performed accordingly. Here, the reference value may be the same as or different from the first reference value, the second reference value, the reference value in the example of FIG. 18 or the reference value in the example of FIG. 19 in the example of FIG.

Further, according to another example of controlling the X-ray photographing mode, it is also possible to set the X-ray photographing mode only to the static photographing mode or to set only the dynamic photographing mode regardless of the size of the movement of the object of interest.

Hereinafter, an example of a control method of the X-ray imaging apparatus for controlling the X-ray imaging mode based on the information about the imaging mode or the information about the stage will be described.

In the imaging mode, there are a general fluoroscopic mode and a digital subtraction angiography (DSA) mode. Information about the stage includes the current stage of the catheter insertion step, the stent insertion step, And may include information as to whether or not it is a step.

For example, when the imaging mode is the DSA mode, the X-ray photographing mode is set to the entire photographing mode. When the X-ray photographing mode is selected, the X-ray photographing mode is set to the default region of the dynamic photographing mode or the static photographing mode, Mode.

On the other hand, in the X-ray fluoroscopy mode, it is also possible to set one of the entire photographing mode, the dynamic photographing mode, and the static photographing mode based on the magnitude of the movement of the object of interest, as shown in FIGS.

According to the X-ray imaging apparatus and its control method described above, it is possible to reduce the dose of all the X-rays by entering the X-rays of low dose into the unattended area and to perform the image restoration on the non- Can be improved. Therefore, it is possible to reduce the dose of the X-ray and acquire a high-quality X-ray image.

In addition, since the ROI filter is automatically moved according to the position of the ROI, no separate user operation is required, and the continuity of the procedure using the X-ray imaging apparatus can be ensured.

100: Medical imaging device 110: X-ray source
120: X-ray detector
140:
150: image processor
160:

Claims (49)

An X-ray source for irradiating an X-ray to a subject area;
An x-ray detector for detecting the irradiated X-rays to acquire a plurality of frame images relating to the object region; And
And a filtering unit for filtering the X-rays irradiated from the X-ray source so that an X-ray having a dose smaller than that of the region of interest is incident on the non-interest area of the object area. The method according to claim 1,
The method of claim 1, further comprising: setting the ROI using the plurality of frame images; combining the frame image obtained while the X-ray of a small dose is incident on the ROI with at least one previous frame image, And an image processor for performing image restoration on the X-ray image. 3. The method of claim 2,
And a control unit for controlling the filtering unit,
The image processor includes:
And acquires information on the ROI from the frame image and transmits the information to the controller. 3. The method of claim 2,
Wherein the filtering unit comprises:
A region of interest filter comprising a filter material that attenuates x-rays; And
And a filter driver for moving the ROI filter. 3. The method of claim 2,
The image processor includes:
Detecting an object of interest from the frame image, and setting the region of interest based on a position, size or motion characteristic of the object of interest. 6. The method of claim 5,
The image processor includes:
And detects the object of interest from the frame image by recognizing a marker attached to the object of interest. 6. The method of claim 5,
The image processor includes:
Estimating a periodic motion pattern of the object, and resetting the region of interest using the estimated motion pattern. 5. The method of claim 4,
And an interest object sensing unit for sensing the object of interest. 9. The method of claim 8,
Wherein,
And pre-heating the filter driver based on the position of the object of interest. 5. The method of claim 4,
The image processor includes:
Estimating a moving direction and a moving speed of the object of interest based on the position of the object of interest,
Wherein,
And moves the ROI filter according to a moving direction and a moving speed of the estimated ROI. 6. The method of claim 5,
The image processor includes:
And detecting the object of interest and setting the region of interest in real time according to a frame rate. The method of claim 3,
The image processor includes:
Detecting an object of interest from the frame image, setting the region of interest based on the position, size, or motion characteristics of the object of interest, acquiring information about the set region of interest and transmitting the information to the controller,
The information about the region of interest may include,
The position of the ROI, the size of the ROI, and the motion characteristics of the ROI. 13. The method of claim 12,
Wherein the filtering unit comprises:
A region of interest filter comprising a filter material that attenuates x-rays; And
And a filter driver for moving the ROI filter,
Wherein,
And controls the filter driver to move the ROI filter to a position corresponding to the ROI based on the ROI information. 3. The method of claim 2,
The image processor includes:
The method of claim 1, further comprising: averaging the frame image and at least one previous frame image, summing the frame image and at least one previous frame image, or performing motion-compensated temporal filtering on the frame image and at least one previous frame image filtering or motion-compensated spatial filtering to perform the image reconstruction. 15. The method of claim 14,
The image processor includes:
And performs image restoration on the non-interest area and the ROI. 16. The method of claim 15,
The image processor includes:
And selects a kind of filtering to be applied to the non-interest area and the ROI based on a motion characteristic of the ROI. 3. The method of claim 2,
The image processor includes:
And performing image registration, motion estimation, and compensation on the non-interest area in which the image reconstruction is performed, in combination with the at least one previous frame image. 3. The method of claim 2,
The image processor includes:
And an image smoothing algorithm for matching the brightness and contrast of the ROI and the non-ROI with respect to the frame image on which the image restoration is performed on the ROI. 14. The method of claim 13,
Wherein,
And sets an X-ray imaging mode on the basis of information on the frame image, information on the imaging mode, or information on the stage. 20. The method of claim 19,
The information about the frame image is,
And the information about the region of interest. 21. The method of claim 20,
Wherein,
An X-ray photographing mode in which the X-ray photographing mode is irradiated with X-rays of a uniform dose to the ROI and the ROI according to the magnitude of the movement of the ROI, and an X- An x-ray imaging device set to one of the area of interest investigated. 22. The method of claim 21,
Wherein,
And sets the X-ray imaging mode to the entire imaging mode if the size of the movement of the object of interest is greater than a first reference value. 23. The method of claim 22,
Wherein,
And sets the X-ray imaging mode to the ROI mode if the magnitude of movement of the object of interest is smaller than the first reference value. 24. The method of claim 23,
Wherein,
And sets the x-ray photographing mode to a dynamic photographing mode in which the region of interest is moved according to a movement of the object of interest when the size of the movement of the object of interest is smaller than the first reference value and larger than the second reference value. 25. The method of claim 24,
Wherein,
Ray imaging mode in which if the size of the movement of the object of interest is smaller than the second reference value, the X-ray imaging mode is set to a static imaging mode in which the size of the ROI is increased in accordance with the movement of the ROI, . 21. The method of claim 20,
Wherein,
A radiographic mode in which the X-ray imaging mode is irradiated with an X-ray of a uniform dose on the object area and a dynamic imaging mode in which the ROI is moved according to the motion of the object of interest, X-ray imaging device. 27. The method of claim 26,
Wherein,
Setting the X-ray photographing mode to a dynamic photographing mode if the size of the movement of the object of interest is smaller than a predetermined reference value, and setting the X-ray photographing mode to the entire photographing mode if the size of the movement of the object of interest is larger than the reference value Imaging device. 21. The method of claim 20,
Wherein,
A total photographing mode in which the X-ray photographing mode is irradiated with an X-ray of a uniform dose to the object region, and a size of the region of interest is increased according to the movement of the object of interest, An x-ray imaging device set to one of the static shooting modes. 29. The method of claim 28,
Wherein,
Setting the x-ray photographing mode to a static photographing mode if the size of the movement of the object of interest is smaller than a preset reference value, and setting the x-ray photographing mode to the entire photographing mode if the size of the movement of the object of interest is larger than the reference value Imaging device. 21. The method of claim 20,
Wherein,
A radiographic mode in which the ROI is moved according to a motion of the ROI, and a size of the ROI is increased according to a motion of the ROI, Is set to one of static photographing modes to be fixed. 31. The method of claim 30,
Wherein,
Setting the x-ray photographing mode to a static photographing mode if the size of the movement of the object of interest is smaller than a preset reference value, and setting the x-ray photographing mode to a dynamic photographing mode if the size of the movement of the object of interest is larger than the reference value Imaging device. 14. The method of claim 13,
The image processor includes:
And combines the frame image with a pre-generated road map. Irradiating a non-interest area within the object area with a dose of radiation less than the area of interest;
And acquiring a frame image related to the object region by detecting the irradiated X-rays. 34. The method of claim 33,
And irradiating the non-interest area in the object area with an X-ray having a smaller dose than the area of interest,
And filtering the x-ray incident on the non-interest area. 35. The method of claim 34,
Irradiating the object region with an X-ray;
Detecting the irradiated X-rays, obtaining a plurality of frame images relating to the object region based on the detected X-rays;
Further comprising setting the region of interest using the plurality of frame images. 36. The method of claim 35,
Setting the region of interest comprises:
Detecting an object of interest from the frame image, and setting the region of interest based on the location, size or motion characteristics of the object of interest. 37. The method of claim 36,
The filtering of the x-
And moving the ROI filter attenuating the irradiated X-rays to a position corresponding to the ROI based on the information on the ROI. 36. The method of claim 35,
And combining the acquired frame image with at least one previous frame image while the X-ray of a small dose is incident on the non-interest area to restore the non-interest area of the frame image. 39. The method of claim 38,
Reconstructing the non-interest region comprises:
The method of claim 1, further comprising: averaging the frame image and at least one previous frame image, summing the frame image and at least one previous frame image, or performing motion-compensated temporal filtering on the frame image and at least one previous frame image filtering or motion-compensated spatial filtering of the x-ray image. 40. The method of claim 39,
Reconstructing the non-interest region comprises:
Further comprising performing image registration or motion estimation and compensation on the reconstructed non-interest area combined with the at least one previous frame image. 40. The method of claim 39,
Further comprising performing an image smoothing algorithm that matches the brightness and contrast of the ROI with the ROI for the frame image in which the ROI is restored. 28. The method of claim 27,
And setting an X-ray imaging mode based on information on the frame image, information on the imaging mode, or information on the stage. 43. The method of claim 42,
The information about the frame image is,
And controlling the X-ray imaging apparatus based on the information about the region of interest. 44. The method of claim 43,
The setting of the X-ray photographing mode includes:
An X-ray photographing mode in which the X-ray photographing mode is irradiated with X-rays of a uniform dose to the ROI and the ROI according to the magnitude of the movement of the ROI, and an X- And setting it to one of the ROI modes to be examined. 45. The method of claim 44,
Wherein the ROI mode comprises:
And a static photographing mode for increasing the size of the ROI according to the movement of the ROI or fixing the position of the ROI according to the movement of the ROI. 46. The method of claim 45,
The setting of the X-ray photographing mode includes:
Setting the x-ray photographing mode to the entire photographing mode if the magnitude of the movement of the object of interest is greater than a first reference value, and setting the x-ray photographing mode to the ROI mode if the size of the movement of the object of interest is smaller than the first reference value To the X-ray imaging apparatus. 47. The method of claim 46,
The setting of the X-ray photographing mode includes:
Setting the X-ray imaging mode to the dynamic imaging mode if the magnitude of movement of the object of interest is smaller than the first reference value and greater than a second reference value, and if the magnitude of movement of the object of interest is less than the second reference value, And setting the mode to the static imaging mode. 44. The method of claim 43,
The setting of the X-ray photographing mode includes:
The X-ray photographing mode is set to one of a dynamic photographing mode for moving the ROI according to the movement of the ROI and a static photographing mode for increasing the size of the ROI according to the movement of the ROI and fixing the position thereof Control method of X - ray imaging device. 49. The method of claim 48,
The setting of the X-ray photographing mode includes:
Setting the x-ray photographing mode to a static photographing mode if the size of the movement of the object of interest is smaller than a preset reference value, and setting the x-ray photographing mode to a dynamic photographing mode if the size of the movement of the object of interest is larger than the reference value A method of controlling a video device.

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