JP7208079B2 - X-ray imaging device - Google Patents

Description

An embodiment of the present invention relates to an X-ray imaging apparatus that automatically sets radiation conditions according to the one-pixel size of an acquired image.

In an X-ray imaging apparatus such as an X-ray fluoroscopic examination apparatus or an X-ray CT apparatus, for example, as shown in Patent Documents 1 to 3, X-ray projection conditions are defined by two parameters, a tube voltage value v and a tube current value i. is controlled by In many X-ray generators, increasing the anode power (tube voltage value v×tube current value i) increases the size of the focal point of the X-rays, resulting in blurred images.

In the conventional apparatus, the operator needs to input the values of the tube voltage and the tube current into the apparatus to adjust the focus size while visually confirming the degree of blurring of the image. In this case, if an attempt is made to keep the focal spot size small so as not to blur the image, the anode power will be small, resulting in an acquired image with a poor SN ratio due to an insufficient dose of X-rays output from the X-ray generator. . In this way, the optimal values of the tube voltage and tube current must be set in consideration of both the resolution and the SN ratio that cause blurring. It was difficult.

JP 2003-173895 A JP-A-2004-317368 JP 2005-149762 A

As described above, when determining the X-ray projection conditions in an X-ray imaging apparatus, if the anode power is increased, the focal size will increase and the acquired image may become blurred, that is, the resolution may decrease. As the dose increases, an image with a good SN ratio can be acquired.

For this reason, in order to efficiently obtain a good image in a short imaging time, it is necessary to perform imaging with the maximum anode power at which blurring is not conspicuous with respect to the size of one pixel of the obtained image. However, in the prior art, such a problem could not be solved, and the operator determined the appropriate tube voltage value v and tube current value i while visually judging the blur of the image.

This embodiment has been proposed to solve the problems of the prior art as described above. The object of the present embodiment is to automatically adjust the tube current value following changes in the one-pixel size of an acquired image and the tube voltage value v, so that an X-ray image with a high resolution and a good SN ratio can be acquired with a simple operation. An object of the present invention is to provide an imaging device.

An X-ray imaging apparatus according to an embodiment of the present invention has the following configuration.
(1) X-ray generator for emitting X-rays.
(2) An X-ray detector that receives X-rays emitted from the X-ray generator.
( 3 ) A position setting unit for setting a geometrical positional relationship among the X-ray generator, the subject, and the X-ray detector.
( 4 ) Geometrical positions of the X-ray generator, the subject, and the X-ray detector acquired from the position setting unit, one pixel size of the calculated acquired image, and the anode power of the X-ray generator A tube current calculator for calculating a tube current value i based on the change characteristic of the focus size and the tube voltage value v determined by the subject.
( 5 ) An X-ray control unit that obtains the anode power of the X-ray generator based on the tube current value i and the tube voltage value v, and controls the output of the X-ray generator based on the anode power.

Embodiments of the present invention can have the following configurations.
(1) An image processing unit that corrects the resolution or SN ratio of a captured image, and a tube current correction unit that adjusts the tube current value according to the correction value of the resolution or SN ratio by the image processing unit.
(2) a movement mechanism for moving at least one of the X-ray generator, the subject, and the X-ray detector; a mechanism control unit for controlling the amount of movement by the movement mechanism; a position setting unit that sets changes in geometric positions of each unit of the imaging device after correction by movement of at least one of the object and the X-ray detector; and each unit of the imaging device after correction by the position setting unit It has the tube current calculator for calculating the tube current value i based on the geometrical position.
(3) a thumbnail generation unit that generates thumbnails of images before and after correction, a thumbnail layout unit that displays the thumbnails in a predetermined format, and an input that selects a predetermined thumbnail from the thumbnails laid out by the thumbnail layout unit; and a correction value for focus size and/or tube current value i for obtaining a captured image is selected based on the thumbnail selected by the input device.

1 is a block diagram of an X-ray imaging apparatus according to a first embodiment; FIG. 3 is a block diagram showing the configuration of a data processing unit according to the first embodiment; FIG. 4 is a flowchart showing the operation of the X-ray imaging apparatus of the first embodiment; 8 is a flowchart showing the operation of the X-ray imaging apparatus of the second embodiment; 9 is a flow chart showing the operation of the X-ray imaging apparatus of the third embodiment; FIG. 11 is a diagram showing an example of a display screen when selecting processing for improving the SN ratio and improving resolution in the second embodiment; FIG. 11 is a diagram showing an example of a display screen when selecting processing of edge enhancement correction and noise removal correction in the third embodiment; FIG. 11 is a view showing another display screen example when selecting processing of edge enhancement correction and noise removal correction in the third embodiment; 4 is a graph showing the relationship between focal point size F and 1-pixel size p of an acquired image.

[1. First Embodiment]
Embodiments of the present invention will be described below. This embodiment can be applied to both X-ray CT and fluoroscopy.

[1-1. Determination of tube current value i]
The anode power w(i, v) is defined as the product of the tube current value i and the tube voltage value v. It is desirable that the tube voltage value v be determined only by the properties of the object to be fluoroscopically viewed with X-rays. In this embodiment, the tube current value i is used as a parameter to control the focal spot size.

The focal spot size F(w(i,v)) varies depending on the anode power w(i,v), but the variation characteristics differ depending on the type of X-ray generator. For example, let Fmax and Fmin be the maximum and minimum values of the focal spot size, and Wmax and Wmin be the maximum and minimum values of the anode power.
F(w(i,v))=Fmaxw(i,v)=>Wmax
=f(w(i,v))Wmin<w(i,v)<Wmax
=Fminw(i,v)=<Wmin
When the anode power w (i, v) reaches the minimum maximum value, it becomes a fixed value, and between the minimum and maximum values, f (w ( i, v)).

Also, F(w(i,v))=F1(w1<w(i,v)=<w2)
=F2(w2<w(i,v)<w3)
:
:
=Fn(wn-1<w(i,v)<wn)
, etc., which change stepwise according to the anode power.

Therefore, a relational expression between the focal spot size F and the anode power w(i, v) is modeled according to the type of X-ray generator, and F(w(i, v)) is obtained. … formula (1)

Next, a relational expression between the focus size F(w(i,v)) and the 1-pixel size p of the acquired image is obtained. If the vertical axis is the focus size F(w(i,v)) and the vertical axis is the one-pixel size p of the obtained image, the graph in FIG. 9 is obtained. For example, the boundary at which the image is blurred is F(p)=2p (Equation (2))
Then, the image is not blurred in the region below F(p) in the graph. Also, the larger the focal point size F, the more the X-ray dose and the SN ratio of the image. Expression (2) indicating the boundary can be determined based on the change characteristic of expression (1). Determined by actual measurement or calculation depending on the function.

Here, assuming that the control of the anode power w is performed only by the tube current value i as described above, from the equations (1) and (2), when the tube voltage value v is one pixel size p of the acquired image, Tube current value i(v,p)...Equation (3) is obtained.

A tube current value determined using equation (3) according to the tube voltage value v set by the operator and the one-pixel size p of an acquired image determined from the geometrical position of each component of the X-ray imaging apparatus. By automatically changing the value of i(v, p), the operator can always take an image that maximizes the device performance.

[1-2.1 Calculation of pixel size p]
As a method of calculating the one-pixel size p, for example, the following formula can be adopted.
The field of view FOV of the photographed image shall be as follows. (The calculation shall be performed by the VC function.)
One pixel size p can be calculated by dividing the FOV by the matrix size of the output image.
However, Y=0 for fluoroscopic images.

(1) For full scan and half scan

(2) For offset scanning
With L shift = 0, it is included in (3) described below.

(3) For offset scanning and detector shift scanning

[1-3. Configuration of Embodiment]
In the X-ray imaging apparatus of the first embodiment, as shown in the block diagram of FIG. and the detector 3 are arranged to face each other with the subject 4 interposed therebetween. The X-ray beam 2 is a pyramidal beam with the X-ray optical axis L as the center. The detector 3 detects, with two-dimensional spatial resolution, the X-ray beam 2 that has passed through the subject 4 placed in the X-ray beam 2, and outputs it as a transmission image (transmission data). The X-ray tube 1 and the detector 3 face each other and are supported by a shift mechanism 7 .

A subject 4 is placed on a rotary table 5 via an XY mechanism 8 . The rotary table 5 is rotated around a rotary shaft 18 by a rotating/lifting mechanism 6 arranged at the bottom thereof. The rotation axis 18 is orthogonal to an imaging plane 19 that is a plane containing the X-ray optical axis L within the X-ray beam 2 . The rotary table 5 is moved up and down perpendicularly to the photographing plane 19 by the rotation/lifting mechanism 6 . The subject 4 is moved in two horizontal directions along the imaging plane 19 by the XY mechanism 8 on the rotary table 5 and can change its position with respect to the rotary shaft 18 .

The rotary table 5 is moved together with the object 4 between the X-ray tube 1 and the detector 3 by the shift mechanism 7 along the X-ray optical axis L to change the imaging distance (focus-rotational axis distance) FCD. The detector 3 is moved along the X-ray optical axis L by the shift mechanism 7 to change the detection distance (focus-detector distance) FDD. This changes the imaging magnification FDD/FCD.

In this embodiment, the X-ray tube 1 is a microfocus X-ray tube in which the focal point F of the generated X-ray beam 2 is on the order of μm. I. (image intensifier tube) and television camera, or FPD (Flat Panel Detector), but not limited to this.

A transmission image from the detector 3 is sent to the data processing section 9, and the processing results and the like are displayed on the display section 10. FIG. CT imaging is imaging in which the subject 4 is rotated within the X-ray beam 2, and transmission images of the subject 4 in multiple directions are obtained by the detector 3. From the transmission images obtained by the CT imaging, the data processor 9 A plurality of cross-sectional images within a CT imaging region (cross-sectional image field) are reconstructed. Here, the CT imaging region is the region encompassed by the X-ray beam 2 that is always measured during one rotation of the object 4 in the case of normal volume scanning.

The data processing unit 9 and the display unit 10 are ordinary computers comprising a CPU, a memory, a hard disk, an input device 13 such as a keyboard and a mouse, an interface, etc., and software for reconstructing a cross-sectional image from CT imaging sequences and data. I remember. Using the data processing unit 9 and the display unit 10, the operator selects menus, sets conditions, manually operates mechanical units, displays moving images of transmission images, starts CT imaging, reads device status, displays cross-sectional images, and displays cross-sectional images. Analysis, projection image display, etc. are performed. The display unit 10 also displays data relating to the geometrical positions of each unit of the imaging apparatus such as FCD and FDD values, thumbnails of captured images, and selection screens for various menus and commands.

The data processing unit 9 is connected to a mechanism control unit 11 that controls mechanisms such as the rotation/lifting mechanism 6, the shift mechanism 7, the XY mechanism 8, and the like. The mechanism control unit 11 controls the amount of movement of each unit by the rotation/lifting mechanism 6, the shift mechanism 7, the XY mechanism 8, etc. based on the command from the data processing unit 9, and the FCD value and FDD obtained as a result of movement. A status signal such as a value is sent to the data processing unit 9 .

The data processing unit 9 has, as functional blocks executed by the CPU, a scan control unit 9a for CT imaging and a reconstruction unit 9b for creating a cross-sectional image. The data processing unit 9 includes, as a configuration unique to this embodiment, a position setting unit 9c for setting the geometrical positions of each unit of the imaging apparatus, an X-ray tube 1, a detector 3, and A position calculation unit 9d for calculating the geometric position of the subject 4, a tube current calculation unit 9e, an image processing unit 9f, a thumbnail generation unit 9g, a thumbnail placement unit 9h, and a tube calculated based on instructions from the operator. It has a tube current corrector 9i for correcting the current value.

The position setting unit 9c sets the geometric positions of the respective parts of the imaging apparatus given as data specific to the X-ray imaging apparatus of this embodiment, the geometric positions of the imaging apparatus given by the operator from the input device 13, and Based on the amount of movement of the X-ray tube 1, the detector 3, and the subject 4 obtained by the position calculator 9d, the geometrical positions of the respective parts of the imaging apparatus are set. The position calculation unit 9d controls the X-ray tube 1, the detector 3, and the subject based on control data of each mechanism unit such as the rotation/lifting mechanism 6, the shift mechanism 7, and the XY mechanism 8, which are controlled by the mechanism control unit 11. 4 is calculated and output to the position setting unit 9c.

The tube current calculation unit 9e uses the tube voltage value v, which is set in advance according to the properties of the subject 4 or is set by the operator's input, and the geometry of each part of the imaging apparatus obtained from the position setting unit 9c. Based on the target position, equations (1) through (3) are executed to obtain a tube current value i that determines the anode power of the X-ray tube 1 . Equations (1) and (2), which are values unique to the imaging device, are preset in the tube current calculator 9e by the operator or the manufacturer of the device.

The image processing unit 9f corrects the resolution (the degree of blurring), improves the SN ratio, enhances the contour, removes noise, etc., from the captured image created by the reconstruction unit 9b based on an instruction from the operator. process. The thumbnail generation unit 9g generates thumbnails of the captured image before image processing created by the reconstruction unit 9b, the resolution corrected image, the SN ratio improvement corrected image, the edge-enhanced image, and the noise-removed image performed by the image processing unit 9f. The thumbnail arrangement unit 9h causes the display unit 10 to display the captured images before and after image processing generated by the thumbnail generation unit 9g in a format designated by the operator.

The tube current correction unit 9 i corrects the tube current value i by the operator selecting a thumbnail displayed on the display unit 10 from the input device 13 . Correction of the tube current value i is performed by changing the geometrical position of each part of the imaging apparatus to change the size of one pixel p of the acquired image in the resolution correction and SN ratio improvement correction, thereby changing the focal size of the X-ray. Thus, the tube current value calculated by the tube current calculator 9e is indirectly corrected. The output side of the tube current correction section 9i is connected to the mechanism control section 11 in order to move the X-ray tube 1, the detector 3 and the subject 4 according to the correction amount to adjust the focus size. Further, the input side of the tube current correction section 9i is connected to a position calculation section 9d that calculates the geometrical position of each section of the imaging apparatus changed based on the control data from the mechanism control section 11. FIG.

On the other hand, the correction by edge enhancement and noise removal is performed by image processing software. Correct the current value directly. Therefore, the input side of the tube current correction section 9i is connected to the input device 13, and receives from the input device 13 a selection signal for a predetermined thumbnail arranged on the thumbnail arrangement section 9h. The output side of the tube current corrector 9i is connected to the X-ray controller 12 that calculates the anode power.

Based on the tube current calculated by the tube current calculation unit 9e or the tube current value i corrected by the tube current correction unit 9i and the tube voltage value v set in advance according to the subject 4, the data processing unit 9: An X-ray controller 12 for controlling the anode power of the X-ray tube 1 is connected.

The data processing unit 9 is connected to an input device 13 such as a keyboard, a mouse, and a file reading device through which an operator inputs various data and commands. As the data input from the input device 13 to the data processing unit 9, in addition to various data input in a conventionally known X-ray imaging apparatus, data specific to the present embodiment, such as predetermined data of each unit of the imaging apparatus. There are the geometric position, the tube voltage value corresponding to the subject 4, the thumbnail display format, the type and level of image processing such as edge enhancement and noise removal, and the like.

[1-4. Action of Embodiment]
(1) Basic Operation of CT Apparatus The operation of this embodiment will be described with reference to FIG. First, the operator scans (CT) the subject 4 as follows. The operator places the subject 4 on the XY mechanism 8, turns on the X-rays, displays the transmission image of the subject 4 on the display unit 10 in real time, and raises and lowers the subject with the rotating/lifting mechanism 6 while observing this. Then, the subject is aligned with the imaging plane 19, and the tube voltage value v, the tube current value i, the integration time, and the number of views are set. Here, the integration time is the time to detect one transmission image, and the number of views is the number of acquired transmission images during rotation.

When the operator starts scanning, the turntable 5 is rotated by the scan control section 9a of the data processing section 9, and the transmission image is collected during one rotation to complete the scanning. A CT imaging region included in the X-ray beam 2 is reconstructed by the reconstructing unit 9b from transmission images corresponding to the number of views obtained by scanning in 360° directions, and stored. At this time, the reconstruction unit 9b reconstructs a plurality of cross-sectional images that are orthogonal to the rotation axis 18 and are continuously arranged at equal intervals in the direction of the rotation axis 18, and the plurality of cross-sectional images form three-dimensional data. Three-dimensional data obtained by scanning can be displayed on the display unit 10 by MPR (Multi-planer Reconstruction) display or the like.

(2) Actions of First Embodiment FIG. 3 is a flow chart for explaining actions of the first embodiment. In the present embodiment, first, the anode power and focal spot size equations (1) . . . Next, the geometric position data of each part of the imaging device is inputted to the position setting part 9c (S02). The formula (2) of the image blur boundary . . . F(p)=f(p) is set for the tube current calculator 9e (S03). The subject 4 is placed on the XY mechanism 8 on the rotary table 5 (S04). A tube voltage value v corresponding to the subject 4 is set for the tube current calculator 9e (S05). The processing from S01 to S05 may be performed in any order.

The tube current calculation unit 9e calculates the equation (3) based on the relationship between the one-pixel size p and the focus size F obtained by the set equations (1) and (2), thereby reducing blurring. Moreover, the optimum tube current value i for obtaining an image with an improved SN ratio is calculated (S06). A tube current calculator 9e calculates a tube current value i based on the obtained anode power w(i, v). The tube current value i obtained by the tube current calculator 9e is output to the X-ray controller 12, and the X-ray controller 12 calculates the anode power w ( i, v) are calculated (S07), the X-ray tube 1 is excited with the obtained anode power w(i, v), and a desired amount of X-rays is projected onto the object 4 to be examined. As a result, it is possible to display a picked-up image with less blurring and an improved SN ratio on the display unit 10 (S08).

Specifically, when the tube voltage value v = 100 kV is set in the subject 4 having the focus size F (w (i, v)), the relational expression between the focus size F (w (i, v)) and the anode power is (1) formula is
F(w(i,v))[um]=w(i,v)=i×v[W] (1)
and the formula (2) of the boundary where the image is blurred is
F(p)=2p (2)
From equations (1) and (2), when
F(p)=2p=i×v (3)
From the equation (3), the obtained tube current value i=2p/v.

For example, if one pixel size p of an acquired image at a certain X-ray geometric position is set to p=50 um from equation (3), the tube current value i=1000 uA, and one pixel size p=10 um by changing the X-ray geometry. For example, the tube current value i=200 uA. As described above, according to the present embodiment, when the pixel size p changes each time the imaging position is changed, the tube current value i is automatically changed accordingly.

[1-3. Effect of Embodiment]
This embodiment has the following effects.
(1) The operator can easily perform optimal imaging without considering the resolution and SN ratio of the acquired image.
(2) Since the operator only needs to change the tube voltage value v out of the tube voltage value v and the tube current value i, it is possible to easily obtain an image with a good SN ratio without image blurring.
(3) Since the optimum anode power is obtained according to the geometric position of each part of the imaging device and the tube voltage value v determined by the subject 4, an image with little blurring, that is, high resolution and an improved SN ratio. can be obtained.

[2. Second Embodiment]
In the second embodiment, in addition to the processing of the first embodiment, mechanical processing of changing the position of each part of the image capturing apparatus, that is, hardware processing, is added to the captured image, thereby increasing the resolution or the SN ratio. An image that improves either is obtained. Other configurations of the second embodiment are similar to those of the first embodiment. Components similar to those of the first embodiment are denoted by the same reference numerals, and descriptions thereof are omitted.

As shown in the flowchart of FIG. 4, in the second embodiment, it is selected whether or not to perform resolution or SN ratio correction processing (S51) on the image captured in the first embodiment. This selection is executed by the operator outputting a predetermined command from the input device 13 to the mechanism control section 11 . If it is selected to perform the correction process (YES in S51), the mechanism control unit 11 causes each mechanism unit such as the rotation/lifting mechanism 6, the shift mechanism 7, and the XY mechanism 8 to move by a predetermined amount. Control data for changing the X-ray tube 1, detector 3 and subject 4 are output (S52). The X-ray tube 1, the detector 3, and the subject 4 are moved from the imaging position of the layer before correction to the position after correction based on the control data from the mechanism control unit 11. FIG. The control data from the mechanism control section 11 is also sent to the position calculation section 9d, which calculates the amount of movement of each section of the imaging device accompanying the correction, and sends the calculation result to the position setting section 9c.

The position setting unit 9c introduces the corrected geometric position of each part into the equation (1) based on the amount of movement of each part received from the position calculation unit 9d, and the tube current calculation unit 9e calculates the set correction Based on the relationship between the one-pixel size p and the focal point size F obtained by the following formulas (1) and (2), the corrected tube current value i is calculated by addition of the formulas (S06, S07). That is, by moving each part of the imaging device in the direction of increasing the focal size F, it is possible to obtain an image with higher resolution and less blur, and conversely, moving each part of the imaging device in the direction of decreasing the focal size F. An image with an improved SN ratio can be obtained.

After that, the thumbnail generation unit 9g moves each unit of the imaging apparatus in a direction to increase and decrease the focal size F, and generates thumbnails of the obtained corrected image and the uncorrected standard image. are displayed on the display unit 10 in a format preset by the thumbnail arrangement unit 9h (S09). FIG. 6 shows an example of a display format of thumbnails, where the focal size F is moved in two steps in the direction of increasing and decreasing, and the thumbnails of the captured images at each step are replaced with the standard image (uncorrected image). They are arranged vertically in one row in the center.

In the second embodiment as described above, in addition to standard images, a plurality of thumbnails whose resolution and SN ratio have been corrected by hardware can be displayed on the display unit 10 . As a result, before the actual imaging, a plurality of images with different geometric positions of each part of the imaging apparatus are preliminarily captured, and thumbnails of the captured images are displayed so that the operator can select an optimal thumbnail. Therefore, in actual imaging, a captured image having the resolution and SN ratio required by the operator can be obtained.

[3. Third Embodiment]
In the third embodiment, instead of the resolution correction or SN ratio correction processing of the second embodiment, the image processing unit 9f performs image processing using software such as edge enhancement or noise removal on the captured image. This is to obtain an image with improved quality. Other configurations of the third embodiment are similar to those of the second embodiment. The same reference numerals are assigned to the same configurations as in the second embodiment, and the description thereof is omitted.

As shown in the flowchart of FIG. 5, in the third embodiment, it is selected whether or not correction processing (S53) for edge enhancement or noise removal is to be performed on the image captured in the first embodiment. This selection is executed by the operator outputting a predetermined command from the input device 13 to the mechanism control section 11 . If correction processing is selected (YES in S53), the mechanism control unit 11 causes the tube current calculation unit 9e to calculate a coefficient determined in advance according to the correction amount for edge enhancement or noise removal. The corrected tube current value i is calculated by multiplying by the tube current value i of the standard image (S06, S07). That is, when correction processing such as contour enhancement or noise removal is performed, even an image with low resolution due to a large focal size F but an excellent SN ratio becomes a clear image with high resolution. The S/N ratio is improved even for an image with a poor ratio. Therefore, an image excellent in both resolution and SN ratio can be obtained by performing edge enhancement or noise removal according to the degree of resolution and SN ratio of the obtained standard image.

In the third embodiment, the thumbnail generator 9g generates thumbnails of the standard image and the image that has undergone correction processing such as edge enhancement or noise removal, and these thumbnails are displayed on the display unit 10 in a format preset by the thumbnail layout unit 9h. (S09). In this case, as in the display example of FIG. 6 of the second embodiment, multiple stages of correction processing such as edge enhancement or noise removal are performed, and the thumbnails of the captured images at each stage are displayed around the standard image (uncorrected image). , can be arranged in a row in the vertical direction.

In such a third embodiment, in addition to the standard image, a plurality of thumbnails subjected to software correction such as edge enhancement or noise removal can be displayed on the display unit 10 . As a result, before the actual imaging, a plurality of images with different degrees of edge enhancement or noise removal are preliminarily captured, and the thumbnails of the images are displayed. In actual imaging, a captured image having the resolution and SN ratio required by the operator can be obtained.

FIG. 7 is an example of a thumbnail display format when the second embodiment and the third embodiment are combined. Optimal imaging is achieved by arranging multiple thumbnails on a matrix centered on a standard image, obtained through hardware corrections that adjust resolution and SN ratio, and software corrections such as edge enhancement or noise reduction. Conditions can be easily selected.

FIG. 8 is another example of a thumbnail display format when the second embodiment and the third embodiment are combined. In FIG. 8, the thumbnails obtained by the correction processing of edge enhancement or noise removal are displayed on multiple axes with respect to the individual thumbnails obtained by the hardware correction for adjusting the resolution and SN ratio shown in FIG. . This gives the operator more options.

Note that the display format is not limited to thumbnails, and the optimal image obtained is used as a reference value. Other forms may be adopted as long as the user interface function is capable of obtaining an image in which the size is varied and the S/N ratio and resolution (degree of blurring), or edge enhancement and noise removal are finely adjusted.

[4. Other embodiments]
The present invention is not limited to the above-described embodiments, and can be embodied by modifying constituent elements without departing from the scope of the present invention at the implementation stage. Further, various inventions can be formed by appropriate combinations of the plurality of constituent elements disclosed in the above embodiments. For example, some components may be omitted from all components shown in the embodiments. Furthermore, components across different embodiments may be combined as appropriate. For example, the present invention is applicable to both X-ray CT and fluoroscopy systems. Also, the method for calculating the one-pixel size p in this embodiment is not limited to the one described above.

The following are specific examples of modifications of the present invention.
(1) The X-ray imaging apparatus is provided with a focal spot size when a predetermined anode power is applied to the X-ray generator at a specific geometrical position of each part of the X-ray imaging apparatus. The focus size can be easily determined when the current value is changed by displaying it on a liquid crystal display or the like all the time or at appropriate times.
(2) The focal spot size with respect to the anode power of the X-ray generator in the imaging state is always or timely displayed as a ratio to one pixel size in the X-ray imaging apparatus in the same state. For example, if the size of one pixel calculated from the geometrical position is 100 μm and the focal size in that state is 150 μm, then 1.5 times is displayed.
(3) Instead of the numerical values in (2) above, a color map, symbols, or character strings are used to display at a ratio to one pixel size at all times or as appropriate. For example, color maps such as "ratio < 1: yellow, 1 ≤ ratio ≤ 1.5: green, 1.5 < ratio: red", symbols such as "○, △, ×", character strings such as "good, bad", The status is indicated by a thumbnail image or the like.
(4) When the resolution or SN ratio of the captured image is corrected by the image processing unit, the correction value for the captured image performed by the image processing unit, for example, the numerical value of the correction value itself, or the correction strength based on the correction value is displayed. do.

Reference Signs List 1 X-ray tube 2 X-ray beam 3 Detector 4 Subject 5 Rotating table 6 Rotation/lifting mechanism 7 Shift mechanism 8 XY mechanism 9 Data processing unit 9a Scan control unit 9b Reconfiguration Section 9c Position setting section 9d Position calculation section 9e Tube current calculation section 9f Image processing section 9g Thumbnail generation section 9h Thumbnail placement section 9i Tube current correction section 10 Display section 11 Mechanism control section 12 X Line control unit 13 ... input device

Claims (7)

an X-ray generator that emits X-rays;
an X-ray detector that receives X-rays emitted from the X-ray generator;
a position setting unit that sets a geometrical positional relationship between the X-ray generator, the subject, and the X-ray detector;
geometric positions of the X-ray generator, the subject, and the X-ray detector obtained from the position setting unit; a 1-pixel size of an acquired image calculated based on the geometric positions; a tube current calculation unit for calculating a tube current value i based on a focal spot size change characteristic with respect to the anode power of the X-ray generator at an optical position and a tube voltage value v determined by the subject;
an X-ray control unit that obtains the anode power of the X-ray generator based on the tube current value i and the tube voltage value v, and controls the output of the X-ray generator based on the anode power. and an X-ray imaging device. an image processing unit that corrects the resolution or SN ratio of a captured image;
2. The X-ray imaging apparatus according to claim 1, further comprising a tube current correction unit that adjusts the tube current value according to a correction value of resolution or SN ratio by the image processing unit. a moving mechanism for moving at least one of the X-ray generator, the subject, and the X-ray detector;
a mechanism control unit that controls the amount of movement by the movement mechanism;
setting a change in geometric position of the X-ray generator, the subject, and the X-ray detector after correction by moving at least one of the X-ray generator, the subject, and the X-ray detector; a position setting unit;
2. The tube current calculation unit for calculating the tube current value i based on the geometric positions of the X-ray generator, the subject, and the X-ray detector after correction by the position setting unit. The X-ray imaging apparatus according to claim 2. a thumbnail generation unit that generates thumbnails of images before and after correction;
a thumbnail placement unit that displays the thumbnails in a predetermined format;
an input device for selecting a predetermined thumbnail from among the thumbnails arranged by the thumbnail arrangement unit;
with
4. The X-ray according to any one of claims 1 to 3, wherein a focus size and/or a correction value for tube current value i for obtaining a captured image are selected based on said thumbnail selected by said input device. Imaging device. 3. An X-ray imaging apparatus according to claim 1 or 2, wherein the focal spot size to anode power of said X-ray generator at said geometrical position is displayed. 3. An X-ray imaging apparatus according to claim 1 or claim 2, wherein the focal spot size for the anode power of said X-ray generator at said geometrical position is displayed as a ratio to said one pixel size corresponding to said geometrical position. . 3. The X-ray imaging apparatus according to claim 2, wherein the correction value for the picked-up image performed by the image processing unit on the picked-up image is displayed.

Images