JPH0654984B2 - X-ray diagnostic device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an X-ray diagnostic apparatus capable of outputting an image and a measurement value that are useful for medical diagnosis by detecting an X-ray transmitted through a subject. Regarding

[Technical background of the invention and its problems]

Among conventional X-ray diagnostic apparatuses, a digital fluorograph apparatus converts the intensity of X-rays transmitted through a subject before contrast into the intensity of an electric signal, and the intensity of these electrical signals is logarithmically converted to obtain a pixel density. The mask image (I _obj ) is stored.

Similarly, a contrast image (I _co ) obtained from the object under contrast is obtained, and subtraction processing is performed between the I _obj image and the I _co image to remove the background overlapping the contrasted tissue, The tissue-only subtracted image (L _SI ) was displayed for diagnosis of cardiovascular disease.

However, when displaying the original shape of the contrasted tissue from the pixel density of the L _SI image or measuring the cross-sectional area, volume, etc., distortion unique to the apparatus due to shading, scattering X
The distortion due to the lines, the distortion due to the hardening of the quality due to the background, and the distortion due to the hardening of the contrast agent itself complicate the combination of the actual thickness of the contrasting tissue and the measured thickness measured from the pixel density value of the above L _SI image. There will be a large gap between them. Therefore, L _SI
Estimating the stenosis rate, infarction rate, heart volume, etc. of the blood vessel from the pixel density value of the image is low in accuracy, and in the extreme case, it has a drawback that it leads to misdiagnosis.

[Object of the Invention]

The present invention has been made in view of the above circumstances, and provides an X-ray diagnostic apparatus capable of obtaining a diagnostically effective image by correcting a non-linear distortion in a subject image or a subject image under contrast. The purpose is.

[Outline of Invention]

In order to achieve the above object, the present invention provides an image acquisition device including an X-ray generator, a two-dimensional X-ray detector, a logarithmic conversion amplifier, an A / D converter and an image storage device, a D / A converter, and In an X-ray diagnostic apparatus including an image display device including a monitor, an air path image (I _o ) when a subject collected by the image acquisition device is not placed and an object obtained when the subject acquired by the image acquisition device is placed A differential image (L _obj ) with respect to the subject image (I _obj ) and a flat plate phantom made of the substance A having a known thickness and a known X-ray transmission characteristic collected by the I _o image and the image acquisition device and the subject were placed. Case subject +
Subtracting means for obtaining a difference image (L _{obj + A} ) from the flat plate A image (I _{obj + A} ) and a L _obj image, the L _{obj + A} image, the thickness of the flat plate phantom and a phantom similar to the subject The scattered X-ray correction coefficient calculation means for calculating, for each pixel, the scattering coefficient (SC) for correcting the scattering of X-rays by the subject from the coefficient for correcting the radiation hardening distortion obtained by using the L _obj image And a scattered X-ray correction means for obtaining an image (M _obj ) corrected based on the scattering coefficient (SC).

Example of Invention

 Hereinafter, the principle and embodiments of the present invention will be described in detail.

First, the principle of the present invention will be described. X according to the present invention
The line diagnostic device basically comprises a device that executes the following four steps.

First, when collecting images, three types of images are obtained as shown in FIGS. 1 (a), (b), and (c). Here, in the figure, 1 indicates an X-ray generator, 2 indicates an object, and 3 indicates a substance A having a known thickness and a known X-ray transmission characteristic (for example, A, A flat plate phantom of Cu, etc., which is shown by 4 is an image intensifier that amplifies an X-ray transmission image and converts it into an optical image (hereinafter, I,
Abbreviated as I). First, as shown in FIG. 1 (a), an X-ray is emitted in a state where neither the subject 2 nor the flat plate phantom 3 is placed in the irradiation area to obtain an air path image I _o . In the following description, “I” indicates a logarithmically converted video signal. Next, as shown in FIG. 1 (c), X-rays are emitted in a state where the subject 2 and the A flat plate phantom 3 are placed in the irradiation area to obtain a subject + flat plate A image I _{obj + A.} Finally, Figure 1
As shown in (b), X-rays are emitted in a state where only the subject 2 is placed in the irradiation area to obtain a subject image (I _obj ).

Secondly, the I _obj image and the I _{obj + A} image are images (L _obj
And L _{obj + A} ). For the L _obj image and the L _{obj + A} image, the difference between the I _obj image, the I _{obj + A} image, and the I _o image may be obtained for each pixel. Therefore, L _obj image, L
_{The obj + A} image is expressed by the following equations (1) and (2).

L _obj = I _o −I _obj ………… (1) L _{obj + A} ＝ I _o −I _{obj + A} ………… (2) _Thirdly, for each pixel for the L _obj image Scattering coefficient (S
Calculate C). This scattering coefficient (SC) is calculated by the following equation (3)
It is represented by.

Here, Z _A is the thickness of the A flat plate phantom 3. The parameters α, β, and γ are coefficients for correcting the radiation hardening strain obtained in advance using a fan made of a substance similar to the subject 2.

Fourth, from the L _obj image and the scattering coefficient (SC), the nonlinear distortion due to scattered X-rays is further corrected for the L _obj image in which the nonlinear distortion unique to the apparatus is corrected. If the object image on which the non-linear distortion correction unique to the apparatus and the distortion correction by scattered X-rays are executed is represented by M _obj , this M _obj image can be obtained by the following formula (4).

M _obj = L _obj / SC (4) As described above, since it is possible to perform the device-specific non-linear distortion correction and the distortion correction by scattered X-rays on the subject image, the corrected image By displaying, a diagnostically effective image can be provided.

Next, the present invention is applied to an X-ray diagnostic apparatus including a contrast agent injecting apparatus and a subtraction processing unit, and a contrast tissue image (subtract image) in which the non-linear distortion peculiar to the apparatus and the non-linear distortion due to scattered X-rays are corrected. ) Can be obtained with reference to FIGS. 2 (a) to 2 (k). 2 (a), (b), and (c) are schematic explanations for obtaining the air path image (I _o ), the pre-contrast subject image (mask image I _obj ) and the subject image during contrast (contrast image I _co ), respectively. It is a figure. 2a in FIG. 2 shows a blood vessel before contrast enhancement, and 2a ′ in FIG. 2 shows a blood vessel during contrast enhancement. Figure 2 (a), (b),
The _Io image, I, obtained by logarithmically converting the collected data in each case of (c)
_{The obj} image and the I _co image are shown in FIGS. 2 (d), (e), and (f). next,
Non-linear distortion peculiar to the apparatus is corrected on the I _obj image and the I _co image to obtain the corrected mask image L _obj and the corrected contrast image L _co . The L _obj image is obtained according to the above equation (1), and the L _co image is similarly obtained according to the following equation (5).

L _co = I _o −I _co …………… (5) Figure 2 shows the L _obj image and L _co image obtained in this way.
Shown in (g) and (h). Next, device-specific non-the-linear distortion has been corrected L _obj image and subtraction image from the L _co image (L
_SI ). This L _SI image is obtained by executing subtraction processing for each pixel according to the following equation (6).

L _SI = L _co −L _obj (6) This subtracted image (L _SI ) is shown in Fig. 2 (i). next,
Non-linear distortion correction by scattered X-rays is performed on this subtracted image (L _SI ) to obtain the corrected subtracted image.
_Find (M _SI ). This M _SI image is obtained from M _SI = L _SI / SC (7) where SC is the scattering coefficient. The scattering coefficient (SC) is calculated by the above equation
It is obtained in advance based on (3). Therefore, as described above, the subject 2 and the A flat plate phantom 3 are placed in the irradiation area and Xed.
A subject + flat plate A image (I _{obj + A} ) when a line is exposed is collected in advance, the above formula (2) is executed to calculate the image L _{obj + A} , and this is used for executing the above formula (3). To do so. The resulting M _SI
The image is shown in Fig. 2 (j). In this way, by obtaining the subtracted image (M _SI ), it is possible to display a subtracted image in which the non-linear distortion peculiar to the apparatus and the non-linear distortion due to scattered X-rays are displayed, and an extremely effective image for diagnosis is provided. can do.

Further, by using the subtracted image (M _SI ) described above, it is possible to obtain the contrasted tissue thickness image ZI _{SI in} which the contrasted tissue thickness and the pixel density have a linear relationship. The contrast-enhanced tissue thickness image ZI _SI is obtained by executing the following equation (8).

Here, the image M _co is an image obtained by correcting the contrast image L _co with nonlinear distortion due to scattered X-rays, and is obtained by the following equation (9).

M _co = L _co / SC (9) Further, the parameters γ, s, and t are obtained in advance using a phantom composed of a substance similar to contrasted blood, and the contrast agent itself and the background 3 shows the coefficient for correcting the ray hardening distortion due to.

In this way, the contrast-enhanced tissue thickness image ZI _SI can be obtained after correcting the non-linear distortion peculiar to the apparatus and the non-linear distortion due to scattered X-rays. Therefore, the thickness of the contrast-enhanced tissue obtained from this ZI _SI image, It is possible to improve the accuracy of measurement values such as thickness shape, cross-sectional area and volume.

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 3 is a block diagram showing an X-ray diagnostic apparatus which is an embodiment of the present invention.

In the figure, the X-ray generator 1, the subject 2, the A flat plate phantom 3 and I.I4 have already been described in FIGS. 1 and 2, and therefore detailed description thereof will be omitted. The A flat plate fan 3 shown in FIG. 3 can be moved in and out of the X-ray irradiation area under the control of the system controller 12 described later. Reference numeral 5 denotes an optical system for condensing the light converted by the I / I4 and adjusting the light intensity thereof, for example, a lens / optical filter system or a lens / diaphragm system, and 6 denotes the optical system. It is a two-dimensional detector such as an image pickup tube for photoelectrically converting the optical image transmitted through the system 5. Reference numeral 7 denotes a logarithmic conversion type amplifier for logarithmically converting and amplifying the electric signal outputted from the two-dimensional detector 6, and numeral 8 denotes an analog signal outputted from the two-dimensional detector 6 as a digital signal. Reference numeral 9 denotes an A / D converter for converting into a signal, 9 denotes an image processing apparatus having an image processor and an image storage device, which will be described later, and 10 denotes the image processing apparatus 9 It is a D / A converter that converts an output digital signal into an analog signal. Reference numeral 11 denotes an image display device that displays an image of the subject based on the analog signal output from the D / A converter 8.
Reference numeral 12 indicates an X-ray generator 1, a contrast agent injection device 14,
A flat plate fan 3, optical system 5, logarithmic conversion amplifier 7,
A / D converter 8 is a system controller for controlling the operation of each part of the device such as the image processing device 9 and the like, and a system controller incorporating a central processing unit. Reference numeral 13 denotes a system controller programmed in advance in the system controller 12. The operation panel has a selection key for selecting an imaging condition, an image processing mode, a sequence, and the like according to the target site in the subject 2. Reference numeral 14 denotes a contrast agent injection device that automatically injects a predetermined amount of a blood vessel contrast agent into the subject 2 at a predetermined time under the control of the system controller 12,
Reference numeral 15 denotes an electrocardiographic measurement device with an A / D converter built therein, which performs electrocardiographic measurement of the subject 2 and outputs the digital data to the image processing device 9.

Next, the image processing device 9 will be described in detail.

As shown in FIG. 4, the image processing device 9 includes an image processing controller 20, a selector 21, and an image preprocessing device 22.
And an image post-processing device 23. The image processing controller 20 receives the digital electrocardiographic measurement data output from the electrocardiographic measurement device 15 and transmitted via the electrocardiographic data bus, and the control signal A ₁ output from the system controller 12, and inputs the image processing device. It is configured to output a control signal for controlling the operation sequence and the like of each unit within 9. The selector 21 outputs the image data output from the logarithmic conversion amplifier 7 and transmitted via the image data bus, and the pre-processing image output from the image post-processing device 23 described later and transmitted via the image data bus. Data is input, one of the image data and the image data for preprocessing is selected by the control signal S ₁ output from the image processing controller 20, and the image is processed by the image preprocessing device 22 described later. It is configured as a switching switch that outputs via the data bus. The image preprocessing device 22 is
The device-specific distortion correction image data (airpass image data) output from the selector 21 is stored,
On the basis of the stored correction image data, the image data output from the logarithmic conversion amplifier 7 via the selector 21 is corrected so as to correct device-specific distortion such as shading distortion. Processing controller 20
Pre-processing is performed by the output control signal P ₁ and the pre-processed image data is output via the image data bus. The image preprocessing device 22 will be described in more detail later. The image post-processing device 23 inputs the pre-processed image data output from the image pre-processing device 22 and input via the image data bus, and outputs the pre-processing by the control signal Q ₁ output from the image processing controller 20. The processed image data is subjected to processing such as calculation of the scattering coefficient SC, scattered X-ray distortion correction processing, subtraction processing, and radiation hardening distortion correction processing to create a contrast-enhanced tissue thickness image in which nonlinear distortion is corrected. , Performs processing for measuring dimensions and functions such as blood vessel thickness, blood vessel cross-sectional area, and heart volume from the contrasted tissue thickness image, and stores the image data, and outputs image data for display to the image display device 11 via the image data bus. In addition, the preprocessing image data is output to the selector 21 via the image data bus.

In this way, the image processing device 9 corrects the device-specific distortion included in the image data by the image pre-processing device 22, inputs the pre-processed image data obtained by the correction by the image post-processing device 23, and scatters the scattered radiation. Post-processing such as distortion correction, radiation hardening distortion correction, dimension measurement, and cardiovascular function measurement processing is performed, and image data for display is output.

Next, the image preprocessing device 22 will be described in detail with reference to FIG.

The image preprocessing device 22 includes a selector 30, an air path image data memory 31, a sum calculator 32, a device-specific parameter memory 33, and a difference calculator 34.
In response to the control signal PS ₁ output from the image processing controller 20, the selector 30 does not place the subject 2 in the image data transmitted via the image data bus X.
The correction image data for correcting the shading distortion or the like obtained by the line exposure is selected, that is, the air path image data is selected and output to the air path image data memory 31, and the image data other than the air path image data is output to the difference calculator 34. This is a switching switch for outputting. The air-pass image data memory 31 is a storage device for storing the air-pass image data, and the device-specific parameter memory 33 is a storage device for storing the X-ray irradiation condition data and the light attenuation degree data in the optical system 5, and the image processing controller. It is rewritable according to the control signal PD ₂ from 20. The sum calculator 32 is
Control signal PC ₂ output from the image processing controller 20
In accordance with this, the air path image data stored in the air path image data memory 31 is input, and the logarithmic conversion value of the ratio between the X-ray exposure condition data and the light attenuation data stored in the device-specific parameter memory 33 is added. And outputs the correction image data to the difference calculator 34. The difference calculator 34 subtracts the image data output from the selector 30 from the correction image data output from the sum calculator 32 in accordance with the control signal PC ₆ output from the image processing controller 20 to perform the screening. The image data in which the distortion and the like are corrected is output to the image post-processing device 23 described later via the image data bus.

Next, the image post-processing device 23 will be described in detail with reference to FIG. The image post-processing device 23 includes a plurality of image calculation units 50-1, ... 50-J composed of a correction calculation unit group and a processing calculation unit group, which will be described later, and a plurality of image storage devices 60-1. , ..., 60-K and a selector 70. The correction calculation unit group is composed of at least a scattering coefficient calculation unit, a scattered X-ray distortion correction calculation unit, a subtraction calculation unit, and a radiation hardening distortion correction calculation unit. The processing operation unit group includes a heartbeat phase fit operation unit, a septum extraction operation unit, a volume operation unit, a cross-sectional area operation unit, a gradation processing operation unit,
It is composed of an image averaging unit, a filter computing unit, a contrast agent concentration curve computing unit, and the like. Then, the image post-processing device 23 processes the image data transmitted via the image data bus into the plurality of image calculation units 50.
, ..., 50-J, and is output by the image processing controller 20 after being driven by being designated by the control signals QP ₁ , ..., QP _J output by the image processing controller 20. The image data on the image data bus is stored in the image storage devices 60-1, ..., 60-K designated by the control signals QI ₁ , ..., QI _K , and the control signal QO ₁ output from the image processing controller 20 is output. …, Image storage device specified by QO _K 60
-1, ..., 60-K outputs the image data to the image data bus or to the image data bus or the image data on the image data bus again for further image processing. --By controlling signal QC ₁ input to J and output from the image processing controller 20, the image data is distributed to either the image data bus for image display or the image data bus for transmission to the selector 21. It is configured.

The image storage devices 60-1, ..., 60-K have pre-contrast subject images whose device-specific distortion is corrected by the image pre-processing device 22.
L _obj and pre-contrast subject + A flat panel image L
Image data such as _{obj + A} and the subject image L _co during contrast pass through without passing through the image calculation unit 50-1 and are sequentially stored.

The image calculation unit 50-1 is composed of L _obj images and L _{obj + A} stored in the blocks defined by the image memories 60-1, ..., 60-K.
Read the image from the image data bus and the above formula
According to (3), the scattering coefficient SC is obtained for each pixel. Then, the scattering coefficient (SC) is stored in a predetermined block of the image storage devices 60-1, ..., 60-K via the data bus.

The scattering distortion correction operation unit 50-2 is used for the image storage device 60-1,
…, Input the scattering coefficient (SC) stored in the specified block of 60-K and the L _obj image, and use the equation (4).
Is executed for each pixel to output the pre-contrast subject image (M _obj ) that has been subjected to the scattered X-ray distortion correction to the blocks determined by the image storage devices 60-1, ..., 60-K. Next, in the same manner, the scattering coefficient (SC) and the L _co image are input, and the calculation of the above formula (9) is executed for each pixel to perform the scattered X-ray distortion corrected in-contrast subject image (M _co ). Create and output.

Subtract operation unit 50-3 is the same as the above M _obj image and M
_co image is input, M _SI = M _co −M _obj is executed, the background is removed for each pixel, and a contrasted tissue image (M _SI ) is created and output. Note that the creation of the contrast tissue image (M _SI), calculated the L _co image and L _obj image with a previously subtracted image by executing the equation (6) from (L _SI), the subtraction image (L _SI) Alternatively, the expression (7) may be executed to obtain the in-contrast subject image (M _SI ). The only difference is the calculation procedure.

Radiation quality curing distortion correction calculation Yunitsuto 50-4, the M _SI image and M
_{The co-} image is input, and the equation (8) is executed to create and output a contrasting tissue thickness image ZI _SI in which the contrasting tissue thickness and the pixel concentration have a linear relationship for each pixel. Incidentally, each of the images M _obj , M _co ,
The M _SI and ZI _SI are stored in the specified blocks of the image storage devices 60-1, ..., 60-K, read out as needed, and provided for image display.

Next, the operation of the X-ray diagnostic apparatus configured as described above will be described.

First, the input procedure of the airpass image data and the device-specific parameters will be described. When the operation panel 13 is operated to depress the apparatus-specific distortion correction data set switch, the system controller 12 causes the X-ray generator 1 to send data indicating X-ray exposure conditions such as tube voltage and tube current to the optical system 5. Data indicating the degree of attenuation of light intensity is output to the image processing apparatus as the processing sequence control signal A ₁ . Then, first, a predetermined X-ray is emitted from the X-ray generator 1 on the operation panel 13 in a state in which the subject 2 and the A flat plate fan 3 are not placed. The X-ray transmission image by the exposed X-ray is I.
Converted to optical rays by I4. This optical image is the optical system 5
It is attenuated to the intensity designated by and input to the two-dimensional detector, for example, the image pickup tube 6. The air path image data as an analog signal output from the image pickup tube 6 is logarithmically converted by the logarithmic conversion amplifier 7, digitized by the A / D converter 8 and input to the image processing apparatus 9. In the image processing device 9, the air path image data is input to the image preprocessing device 22 via the selector 21. In the image preprocessing device 22, the air path image data is stored in the selector 30.
Is stored in the air path image data memory 31 via. On the other hand, the X-ray exposure condition data and the light attenuation data output from the image processing controller 20 are written in the device-specific parameter memory 33. By the above operation,
The input of the device-specific distortion correction data in the image preprocessing device 22 is completed.

Secondly, a processing procedure for displaying a contrasted tissue thickness image of a patient by injecting a contrast agent when the subject 2 is a patient will be described. First, the system control signal from the system controller 12 is an X-ray generator 1, a contrast agent injection device 12, A
The image is sent to the flat plate fan 3, the optical system 5 and the image processing device 9, and the setting of these devices is completed. After that, X-ray irradiation is started by the following procedure. First, the X-rays transmitted through the subject 2 before projection + A flat plate phantom 3 are detected, and then the X-rays transmitted through only the pre-contrast subject 2 excluding the A flat plate phantom 3 after a lapse of T ₁ time from the start of the exposure. The contrast agent is injected into the subject 2 after the lapse of T ₂ time from the start of exposure, and the X-ray transmitted through the subject 2 during contrast is detected. At this time, the electrocardiographic data is sequentially input to the image processing device 9 from the electrocardiographic measurement device 15, and the three types of X-ray transmission images transmitted through the subject 2 are converted from the I.I4 to the A / D converter 8.
Are sequentially input to the image processing apparatus via. The above-mentioned three types of object image data (I _{obj + A} , I _obj , I _co ) are subjected to device-specific non-linear distortion correction, such as doubling distortion, in the image pre-processing device 22. (L
_{obj + A} , L _obj , L _co ) is input to the image post-processing device 23. The image post-processing device 23 simply passes the subject image (L _{obj + A} , L _obj , L _co ) without operating the image calculation unit 50-1, and then a plurality of image storage devices 60-1 ,. It is stored in the designated block of 60-K. Of the subject image data, L _obj
The image and the L _co image are sequentially input to the subtract operation unit 50-3 to obtain the subtract image L _{SI, which} is output to the image display device 11 via the image data bus, the selector 70 and the D / A converter 10, It is displayed as a temporary contrast tissue image. A doctor or the like looks at the displayed provisional contrast-enhanced tissue image and determines whether or not the examination was appropriate.

Next, the device-specific distortion-corrected images (L _{obj + A} and L _obj ) stored in predetermined blocks of the image storage devices 60-1, ..., 60-K
Is input to the scattering coefficient calculation unit 50-1, and the scattering coefficient (S
C) is obtained for each pixel, and this scattering coefficient (SC) is stored in a predetermined block of the image storage devices 60-1, ..., 60-K. Then, the scattering coefficient (SC) and the L _obj image are input to the scattered X-ray distortion correction calculation unit 50-2 to create a pre-contrast image (M _obj ) in which the scattered X-ray distortion is corrected, and the image storage device
60-1, ..., 60-K are stored in a predetermined block. Similarly, an in-contrast image (M _co ) in which the scattered X-ray distortion is corrected is created from the scattering coefficient (SC) and the L _co image and stored. After that, the M _obj image and the M _co image are input to the radiation hardening distortion correction calculation unit 50-4 to create a contrasted tissue thickness image ZI _SI showing a linear relationship between the contrasted tissue thickness and the pixel concentration, and the image storage device Store in the designated block 60-1, ..., 60-K. Then, the contrast tissue thickness image ZI _SI is read out and output and displayed on the image display device 11 via the image data bus, the selector 70 and the D / A converter 10. Furthermore, when it is desired to perform dimension measurement and functional measurement using this contrasted tissue thickness image ZI _SI , the corresponding image calculation unit 50-1,
…, One of 50-J.

Needless to say, the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the present invention. For example, in the above-described embodiment, the A flat plate phantom 3 is arranged between the subject 2 and I / I4, but it may be arranged between the X-ray generator 1 and the subject 2 as long as it is within the X-ray irradiation area. The logarithmic conversion amplifier 7 may be composed of a logarithmic conversion table and a digital logarithmic converter incorporated in the image preprocessing device 22. further,
The acquisition of the air path image is not limited to the one-time X-ray exposure, and the exposure may be performed n times and averaged.

〔The invention's effect〕

As described above in detail, according to the present invention, it is possible to obtain a diagnostically effective image by correcting the non-linear distortion peculiar to the apparatus and the non-linear distortion due to scattered X-rays to the object image or the object image being contrasted. It is possible to provide an X-ray diagnostic apparatus capable of performing the above.

[Brief description of drawings]

FIGS. 1 (a), (b), and (c) are schematic explanatory views showing collection of an air path image, a subject image, and a subject + A flat plate image, and FIG. 2 (a).
2 (k) is an explanatory view of the operation principle when the present invention is applied to an X-ray diagnostic apparatus having a contrast agent injecting apparatus and a subtraction processing unit, and FIG. 3 is a block diagram of an apparatus of one embodiment of the present invention. 4 and 5 are block diagrams of the image processing device, FIG. 5 is a block diagram of the image pre-processing device, and FIG. 6 is a block diagram of the image post-processing device. 1 ... X-ray generator, 2 ... Subject, 3 ... A flat plate phantom, 6 ... Two-dimensional X-ray detector, 7 ... Logarithmic amplification type amplifier, 8 ... A / D converter, 9 ... Image processing device, 14 ...
... Contrast agent injecting device, 22 ... device-specific distortion correction calculating section,
50-1 ... scattered X-ray correction coefficient calculation unit, 50-2 ... scattered X-ray correction calculation unit, 50-3 ... subtraction processing unit, 50-4 ... radiation hardening distortion correction calculation unit.

Claims (6)

[Claims] 1. An image acquisition device comprising an X-ray generator, a two-dimensional X-ray detector, a logarithmic conversion amplifier, an A / D converter and an image storage device, and an image comprising a D / A converter and a monitor. In an X-ray diagnostic apparatus including a display device, an air path image (I _o ) when a subject collected by the image acquisition device is not placed, and a subject image (I _obj ) when a subject collected by the image acquisition device is placed ) the difference image (L _obj with) and the I _o image and when put flat Fuantomu and subject a substance a having a known thickness and known X-ray transmission characteristics collected by the image collecting device subject + flat A image
(I _{obj + A} ) subtraction means for obtaining a difference image (L _{obj + A} ), and the L _obj image, the L _{obj + A} image, the thickness of the flat plate phantom, and a phantom similar to the subject. from the coefficient for correcting the radiation qualities cured strain that is, a scattered X-ray correction coefficient calculating means for calculating a scattering coefficient (SC) for each pixel to correct the scattering of X-rays by the object, the scattering coefficient the L _obj image ( SC) and a scattered X-ray correction means for obtaining an image (M _obj ) corrected based on the above. 2. The scatter X-ray correction coefficient calculation means, wherein Z _A is the thickness of the flat plate phantom, and α, β, γ are ray hardening obtained using a phantom composed of a substance similar to the subject. As a coefficient to correct the distortion, The X-ray diagnostic apparatus according to claim 1, characterized in that the scatter coefficient (SC) is obtained by executing the above. 3. The scattered X-ray correction means is M _obj = L _obj / S
The X-ray diagnostic apparatus according to claim 1, wherein the X-ray diagnostic apparatus calculates C. 4. The subtraction means obtains a difference image (L _co ) between the I _o image and a subject image under contrast (I _co ), and then the L _obj
A difference image (L _SI ) between the image and the L _co image is obtained, and the scattered X-ray correction means obtains an image (M _SI ) obtained by correcting the L _SI image based on the scattering coefficient (SC). The X-ray diagnostic apparatus according to claim 1, wherein the X-ray diagnostic apparatus is provided. 5. The scattered X-ray correction means is M _SI = L _SI / SC
The X-ray diagnostic apparatus according to claim 4, wherein the X-ray diagnostic apparatus is configured to perform the following calculation. 6. The scattered X-ray correction means is M _SI = L _SI / SC
Is calculated, and r, s, and t are used as coefficients for correcting the ray hardening strain obtained by using a phantom composed of a substance similar to the contrast agent, However, M _CO = L _co / SC. The contrast tissue thickness image (Z _ISI ) having a linear relationship between the contrast tissue thickness and the pixel concentration is obtained by executing the above-mentioned method, and the contrast tissue thickness image (Z _ISI ) is obtained. The described X-ray diagnostic apparatus.