JPH08139996A - X-ray diagnostic device - Google Patents

Abstract

PURPOSE: To attain proper contract processing in response to an X ray voltage by applying a voltage to an X ray tube in response to voltage information obtained based on a detected luminous quantity and controlling prescribed contrast processing. CONSTITUTION: An X ray tube 106 projects an X ray to an image pickup section depending on a voltage from a high voltage generator 107 and the transmitted X ray is converted into an optical image by an I.I. 108 and the image is formed on a TV camera 111. Furthermore, a photo multiplier 111 detects part of the optical image and gives the result to an X ray controller 103. The controller 103 obtains kV information and it is fed to the generator 107 and a signal processing circuit 112. Thus, the dose of the X ray from the tube 106 is adjusted based on the kV information. The circuit 112 converts the video signal and gives the converted signal to an LUT. As a result, the video signal whose contrast is processed is displayed by a display system 105 as an X-ray image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray diagnostic apparatus for diagnosing a subject by displaying an image of a video signal obtained from a transmitted X-ray transmitted through the subject.

[0002]

2. Description of the Related Art Conventionally, an X-ray diagnostic apparatus is used for diagnosing a subject by displaying an image of a video signal obtained from a transmitted X-ray transmitted through the subject, for example, movement of a catheter inside the subject or a contrast agent. It is used for various diagnoses because it can observe the flow etc. The video signal is
Obtained by converting transmitted X-rays that have passed through the subject into an optical image with an image intensifier (hereinafter referred to as II), and converting the optical image with a TV camera that uses a pickup tube, CCD, or the like. To be Further, a camera control unit (hereinafter, referred to as CCU) that controls various characteristics of the video signal is connected to the TV camera.

Generally, in an X-ray diagnostic apparatus, there is a method called automatic exposure control for adjusting the X-ray exposure amount.
Specifically, it is performed as follows. The transmitted X-ray transmitted through the imaging region is I. Is converted into an optical image by means of a photomultiplier tube (hereinafter referred to as "photomul") and a part of the light amount of the optical image is converted.
Detect with. Subsequently, the photomultiplier outputs a signal corresponding to the detected light amount to the X-ray controller, and the X-ray controller obtains appropriate tube voltage information from the signal. The tube voltage information thus obtained is input to the voltage generator, and the voltage generator changes the X-ray dose by adjusting the X-ray tube voltage supplied to the X-ray tube based on this tube voltage information. (Hereinafter, this tube voltage information is referred to as kV information.) On the other hand, the CCU is composed of a signal processing circuit that performs signal processing on a video signal and a control unit that controls the operation of the TV camera,
The video signal output from the CCU is displayed on the monitor as an X-ray image. Further, the image displayed on the monitor is subjected to signal processing such as contrast adjustment by a signal processing circuit as needed. The signal processing circuit includes an A / D converter and a look-up table (hereinafter referred to as LUT). The LUT stores a conversion coefficient for converting a predetermined input / output characteristic of the video signal. FIG. 15 shows an example of an input / output characteristic curve (hereinafter referred to as a γ curve) based on the conversion coefficient. Image brightness modulation (contrast processing) is performed by this γ curve. Also, as another contrast processing method, Japanese Patent Application Laid-Open No. 56-75138
Japanese Patent Laid-Open No. 60-134991 and Japanese Patent Laid-Open No. 60-134991 are known.

[0004]

However, each of the conventional methods has merits and demerits, and an appropriate contrast processing has not been realized yet. Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide an X-ray diagnostic apparatus capable of performing appropriate contrast processing that cannot be achieved by the conventional method.

[0005]

In order to achieve the above object, an X-ray diagnostic apparatus according to the present invention includes an X-ray source that irradiates an object with X-rays, and a transmission that passes through the object. Optical image conversion means for converting X-rays into an optical image, detection means for detecting the light quantity of the optical image, imaging means for picking up the optical image and outputting a video signal, and detected light quantity detected by the detection means Control means for obtaining voltage information based on the voltage information, voltage generation means for supplying a voltage to the X-ray source according to the voltage information, and contrast processing means for performing a predetermined contrast process on the video signal according to the voltage information. And display means for displaying the output of the contrast processing means.

In order to achieve the above object, the X-ray diagnostic apparatus according to the present invention has an X-ray irradiating an X-ray toward a subject.
A radiation source, an optical image conversion unit that converts the transmitted X-rays that have passed through the subject into an optical image, an image capturing unit that captures the optical image and outputs a video signal, and voltage information based on the output of the image capturing unit. , A voltage generating means for supplying a voltage to the X-ray source according to the voltage information, a contrast processing means for performing a predetermined contrast processing on the video signal according to the voltage information, and the contrast processing. Display means for displaying the output of the means.

In order to achieve the above object, the X-ray diagnostic apparatus according to the present invention has an X-ray that irradiates an object with X-rays.
A radiation source, an optical image conversion unit that converts the transmitted X-rays that have passed through the subject into an optical image, a detection unit that detects the light amount of the optical image, and an imaging unit that captures the optical image and outputs a video signal. A control means for obtaining voltage information based on the amount of light detected by the detection means;
Voltage generation means for supplying a voltage to a radiation source, extraction means for extracting a predetermined frequency component of the video signal, subtraction means for subtracting the extraction frequency component extracted by the extraction means from the video signal, and the extraction A compression unit that processes the frequency component so that the pixel value distribution width is narrowed, an emphasis unit that emphasizes the output from the subtraction unit, and an addition that adds the output from the emphasis unit and the output from the compression unit. Means and
Display means for displaying the addition result of the addition means.

Further, in order to achieve the above object, an X-ray diagnostic apparatus according to the present invention provides an optical image of an X-ray source that irradiates an object with X-rays and a transmitted X-ray that has passed through the object. Image conversion means for converting the optical image into image data, image pickup means for picking up the optical image and outputting a video signal, control means for obtaining voltage information based on the output of the image pickup means, and the X-ray source according to the voltage information. Voltage generating means for supplying a voltage to the video signal, extraction means for extracting a predetermined frequency component of the video signal, subtraction means for subtracting the extraction frequency component extracted by the extraction means from the video signal, and the extraction frequency component A compression means for processing so that the width of the pixel value distribution is narrowed, an emphasis means for emphasizing the output from the subtraction means, and an addition means for adding the output from the emphasis means and the output from the compression means. , This addition means In which a display unit for displaying the result of the addition.

[0009]

According to the present invention, the X-ray is emitted from the X-ray source toward the subject.
Line, the transmitted X-rays transmitted through the subject are converted into an optical image by the optical image conversion means, the optical image is picked up by the image pickup means to output a video signal, and the light quantity of the optical image converted by the detection means Is detected, the voltage information is obtained by the control means based on the detected light quantity, and the voltage supplied from the voltage generation means to the X-ray source and the predetermined contrast processing of the video signal by the contrast processing means are controlled according to the obtained voltage information. By outputting the output of the contrast processing means by the display means, it is possible to perform appropriate contrast processing according to the X-ray tube voltage.

Further, according to the present invention, X-rays are radiated from the X-ray source toward the subject, the transmitted X-rays transmitted through the subject are converted into an optical image by the optical image conversion means, and the optical image is converted by the imaging means. An image is taken, a video signal is output to the contrast processing means and the control means, voltage information is obtained based on the output by the control means, and X is output from the voltage generation means in accordance with the obtained voltage information.
By controlling the voltage supplied to the radiation source and the predetermined contrast processing of the video signal by the contrast processing means, and outputting the output of the contrast processing means by the display means,
Appropriate contrast processing can be performed according to the X-ray tube voltage.

Further, according to the present invention, X-rays are radiated from the X-ray source toward the subject, the transmitted X-rays transmitted through the subject are converted into optical images by the optical image conversion means, and the image pickup means optically. An image is picked up and a video signal is output, the light quantity of the optical image converted by the detecting means is detected, voltage information is obtained based on the detected light quantity by the control means, and X-rays are generated from the voltage generating means according to the obtained voltage information. While controlling the voltage supplied to the source, the extraction means extracts a predetermined frequency component of the video signal, the subtraction means subtracts the extraction frequency component from the video signal, and the compression frequency means compresses the extraction frequency component into a pixel value distribution width. Is performed so that the output from the subtraction unit is enhanced by the enhancement unit, and the output from the enhancement unit and the extracted frequency component compressed by the compression unit are added by the addition unit, By displaying on display means the calculated result, it is possible to perform compression processing of the pixel value distribution width of enhancement and a low-frequency component of the high frequency components at the same time in real time.

Further, according to the present invention, X-rays are emitted from the X-ray source toward the subject, the transmitted X-rays transmitted through the subject are converted into an optical image by the optical image converting means, and the optical image is converted by the imaging means. An image is taken and the video signal is output to the control means, the extraction means, and the subtraction means. The control means obtains voltage information based on the output, and the voltage supplied from the voltage generating means to the X-ray source is controlled according to the obtained voltage information, while the extracting means extracts a predetermined frequency component of the video signal. After subtracting the extracted frequency component from the video signal by the subtracting means, the extracting means performs processing so that the width of the pixel value distribution is narrowed by the compressing means, and the emphasizing means performs emphasizing processing on the output from the subtracting means. The output from the emphasizing means and the extracted frequency components compressed by the compressing means are added by the adding means, and the addition result is displayed on the display means, thereby emphasizing the high frequency component and compressing the pixel value distribution width of the low frequency component. The processing can be done simultaneously in real time. As described above, according to the present invention, it is possible to perform an appropriate contrast process, and it is possible to improve the diagnostic ability and the inspection ability.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an X-ray diagnostic apparatus according to the first embodiment of the present invention. The apparatus according to the embodiment shown in FIG. 1 includes an X-ray generator 101 that irradiates X-rays, an image pickup apparatus 102 that detects a transmitted X-ray that has passed through an imaged region and picks up an X-ray transmission image, and the image pickup apparatus 102. Based on the detection, the kV information is obtained, and the X-ray generator 101 and the CCU 104 described later are controlled according to the kV information.
The line control device 103, the CCU 104 that controls various characteristics of the video signal output from the image pickup device 102, and the CCU
The display system 105 is configured to display the output of the image 104.

Each component of the apparatus of the embodiment thus constructed will be described. X-ray generator 101
Is for irradiating X-rays corresponding to the X-ray tube voltage toward the imaging region, and the X-ray tube 106 for irradiating the imaging region with X-rays and the X-ray tube voltage for the X-ray tube 106. And a high voltage generator 107 for supplying Imaging device 102
Is for outputting a video signal corresponding to the transmitted X-rays from the imaged region, and I.I. for converting the transmitted X-rays from the imaged region into an optical image. I. 108, I. I. The optical system 1 that adjusts the light quantity of the optical image from the 108 and guides it to the TV camera 110 in the subsequent stage.
09, a part of an optical image guided from the optical system 109 to the TV camera 110, and outputs a signal corresponding to the detected light amount to the X-ray controller 103 described later. It is configured by a TV camera 111 that captures an image and outputs a video signal. Incidentally, TV
As the camera 110, an image pickup element such as a CCD element or an image pickup tube can be used. The X-ray control device 103 obtains kV information based on the amount of light detected by the photomultiplier 111, the X-ray condition of the X-ray generator 101 that is exposed according to the kV information, and the video signal of the CCU 104 in the subsequent stage. It controls signal processing. The kV information here is I.V. I. When an optical image from 108 is picked up by the TV camera 110, an optical sensor such as a photo sensor 111 is provided in the optical system 109 to detect the optical image, and a method for obtaining the optical image based on the signal output from the optical sensor is used. It is also possible to detect the signal level of the video signal (or a part thereof) output from the TV camera 111 and obtain the kV information based on the video signal. However, using Photomaru 111 etc., k
The method of obtaining V information is preferable because it can be faster by the read time (for example, one frame) of the TV camera 110 than the method of using the video signal. As described above, the kV information is preset with a pixel value level at which the operator can easily see the display screen, or the operator sets a control target level while looking at the display image, and the pixel value varies depending on the tube voltage. The average luminance value of the distribution is calculated so as to reach the control target level,
It is used for automatic exposure control such as being output to the high voltage generator 107.

The CCU 104 controls the operation of the TV camera 110 and performs signal processing including contrast processing on the video signal output from the TV camera 110 as necessary. The signal processing circuit 112 and the control unit 1 are provided.
It is composed of 13. The signal processing circuit 112 performs a predetermined contrast process on the video signal, and
It has a D converter (not shown) and an LUT (not shown). This contrast processing may be performed with either a digital signal or an analog signal, but a digital signal is preferable because it can perform contrast processing with high reproducibility and at high speed. In the present embodiment, the contrast is converted to a digital video signal. Perform processing. The LUT brightness-modulates a video signal according to a predetermined input / output characteristic, and a predetermined conversion coefficient is selected according to kV information output from the X-ray controller 103. The control unit 113 is the TV camera 1
Although the operation of the TV camera 110 is controlled, a well-known technique can be used for the operation control of the TV camera 110, and thus detailed description thereof will be omitted. The display system 105 converts a video signal (video signal) from the signal processing circuit 112 into an analog signal by a D / A converter (not shown) and then displays it as an image. , CRT).

Here, the conversion coefficient stored in the LUT will be described. FIG. 2 is an example of a γ curve (input / output characteristic curve) showing this conversion coefficient. Although two types of γ curves 201 and 202 are shown in FIG. 2 as an example, the γ curve 201 has an X-ray tube voltage of V ₁ kV to V ₂ kV (V ₁ <V
₂ ) shows an input / output characteristic curve selected when the range is set to ₂ ), and the γ curve 202 has an X-ray tube voltage of V ₂ kV to V
_The input / output characteristic curve selected when the range is set to ₃ kV (V ₂ <V ₃ ) is shown. The relationship between the set X-ray tube voltage and the video signal will be briefly described below.
When the tube voltage takes _a certain value V _a of V ₁ kV to V ₂ kV, the pixel value distribution of the luminance region of interest in the video signal output from the image sensor is schematically represented as 203, for example. Therefore, when the X-ray tube voltage takes a certain value V _b of V ₂ kV to V ₃ kV, it can be expressed as 204. Both of the pixel value distributions can be converted into the distribution 205 shown on the left side of the graph in FIG. 2 by subjecting these to luminance modulation according to the γ curves 201 and 202, respectively. That is, γ is set so that the peak of the output distribution of the image sensor according to each X-ray condition is almost constant (for example, the central brightness) in the distribution of display pixel values after the brightness modulation and the dispersion is also substantially constant.
A curve (input / output characteristic curve) is set for each appropriate range of X-ray conditions. Therefore, the γ curves 201, 20
2, V ₁ kV~V ₂ kV, respectively, V ₂ kV~V ₃ k
Although it is selected in the case of V, various γ curves may be stored in the LUT so as to be selected every 1 kV or every several kV. Since the luminance distribution of the video signal from the TV camera 110 is estimated and the γ curve based on the luminance distribution is set here, the pixel value distribution in the actual display image may differ from that described above. It can be solved by adjusting the γ curve as appropriate, and each X
Even if the peak of the output distribution of the image sensor according to the line condition is not exactly constant and the variance is not constant in the display pixel value distribution after luminance modulation, if the diagnostic ability is improved as a result, the purpose is Since it can be achieved, it is not necessary to set the input / output characteristic curve so strictly.

The operation of the embodiment apparatus having the above structure will be described. The high-voltage generator 107 supplies the X-ray tube voltage to the X-ray tube 106, and irradiates the X-ray tube 106 with X-rays corresponding to the X-ray tube voltage to the imaging region. Penetration X that penetrates this part
The lines are I. I. It is converted into an optical image by 108. This optical image is adjusted by the optical system 109, and the TV camera 111 is adjusted.
The image is formed on the imaging surface of. On the other hand, a part of the optical image is detected by the photomultiplier 111, and a signal corresponding to the light amount is X
Output to the line control device 103. The X-ray controller 103 obtains kV information based on the signal and outputs it to the high voltage generator 107 and the signal processing circuit 112. The high voltage generator 107 receives the kV information and X
A tube voltage is supplied to the X-ray tube 106. The above-mentioned automatic exposure control can be used for the control here. In this way, the dose of X-rays emitted from the X-ray tube 106 is kV.
It is adjusted appropriately according to the information. On the other hand, the TV camera 111
Converts the optical image formed on the imaging surface into a video signal and outputs the video signal to the signal processing circuit 112. In the signal processing circuit 112, the video signal (analog signal) is converted into a digital video signal by an A / D converter and output to the LUT. In the LUT,
A γ curve is selected according to the kV information sent from the X-ray controller 103, and a predetermined luminance modulation (contrast processing) is performed on the video signal. The video signal subjected to the contrast processing in this way is converted into an X-ray image by the CR of the display system 105.
Displayed on T.

As described above, in this embodiment, the X-ray controller 1
The kV information obtained in step 03 is output to the high voltage generator 107 and the signal processing circuit 112, the X-ray tube voltage is adjusted according to the kV information to change the X-ray dose, and it is suitable for the current X-ray tube voltage. An image having an appropriate contrast according to the X-ray tube voltage can be provided by selecting the conversion coefficient and performing the brightness modulation.

In the above configuration, the input / output characteristic curve is set so that the (estimated) peak value of the pixel value distribution is converted into the central brightness for display, but the control target level of the automatic exposure control is for display. The input / output characteristic curve may be set so as to be converted into the central luminance of and the distribution width becomes substantially constant.

A second embodiment according to the present invention will be described below with reference to the drawings. The second embodiment shows an example of the contrast processing including compression of a part of the pixel value distribution of the low frequency component of the image according to the kV information. FIG.
FIG. 9 is a block diagram of a gradation conversion circuit 301 showing a modification of the signal processing circuit 112 in the first embodiment. The same parts as those in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted. The gradation conversion circuit 301 performs a predetermined contrast process on the video signal from the TV camera 110 according to the kV information. The gradation conversion circuit 301 is used for the TV camera 11
A gradation conversion circuit 302 that performs a predetermined gradation process on a video signal from 0, and a signal processing circuit 303 that emphasizes a video signal (pixel value distribution) that has been subjected to a predetermined gradation process by the gradation conversion circuit 302. Composed.

The gradation conversion circuit 302 is used in the TV camera 110.
It compresses the dynamic range (pixel value distribution) of the low frequency component of the video signal from. Gradation conversion circuit 302
From the TV camera 110 so that the pixel value distribution of the luminance region of interest (luminance region of diagnostic interest) remains unchanged, and the pixel value distribution on the high and low luminance sides of the luminance region of interest is compressed and output. The gradation processing of the video signal is performed. To perform this gradation processing, the gradation conversion circuit 302 uses the TV camera 110.
A / D converter 304 for converting an analog video signal from the digital video signal into a digital video signal, and a frequency range lower than a certain frequency (cutoff frequency) of the digital video signal from the A / D converter 304 (hereinafter, Low-pass filter (hereinafter referred to as LPF) that passes only low-frequency components.
305, an input / output conversion circuit 306 that performs a predetermined input / output conversion on the video signal that has passed through the LPF 305, an output from the A / D converter 304 (a video signal of the original image) and an output from the input / output conversion circuit 306. (Hereinafter, referred to as a converted video signal) is temporarily held in a buffer unit (not shown), is read in synchronization, and is configured by a subtraction circuit 307 which subtracts the converted video signal from the video signal of the original image.

The LPF 305 may be configured to switch the cutoff frequency according to the kV information. This is because the frequency characteristics of the X-ray image can change due to the influence of scattered X-rays as the X-ray tube voltage changes.

The input / output conversion circuit 306 uses an LUT in which a plurality of conversion coefficients are stored. The LUT selects a conversion coefficient according to the kV information from the X-ray controller 103 to determine a predetermined video signal. Perform input / output conversion. Where LUT
The conversion coefficient stored in will be described. The conversion factor is
The subtraction circuit 307 in the subsequent stage does not perform a predetermined conversion on the pixel value distribution of the luminance region of interest, but sets a predetermined conversion only on the pixel value distribution on the higher or lower luminance side than the luminance region of interest. FIG. 4 is an example of an input / output characteristic curve showing this conversion coefficient. In FIG. 4, two types are shown as an example, but 401 has an X-ray tube voltage of V ₁ kV to V ₂ kV (V ₁ kV
An input / output characteristic curve selected when the range is set to <V ₂ ), and 402 represents an X-ray tube voltage of V ₂ kV to V ₃ k.
The input / output characteristic curve selected when set to the range of V (V ₂ <V ₃ ) is shown. However, the input-output characteristic curve 401 and 402, V ₁ kV~V ₂ kV for the same reason as the signal processing circuit 112 of the first embodiment, V ₂ kV~V ₃ kV
However, the selection may be made within an appropriate range of X-ray conditions. Further, as shown in the left side of FIG. 4, each input / output characteristic curve 401,
402 is set so that the pixel value distribution of the luminance region of interest disappears after the input / output conversion, and the pixel value distribution of each region portion on the high and low luminance sides of the luminance region of interest is input / output converted (for example, compressed). Therefore, the input / output characteristic curves 401 and 402
In FIG. 4, all the luminance areas of interest are converted to 0, and the high and low luminance sides of the interest luminance area have the same inclination regardless of high luminance and low luminance. If the pixel value distribution in the region of interest luminance is eliminated and an additional circuit for performing a predetermined input / output conversion is provided in the pixel value distribution in the region other than that, without specifying the input / output characteristic curve shown in FIG. An input / output characteristic curve may be set such that only the low luminance side or the high luminance side is input / output converted.

The relationship between the set X-ray tube voltage and the video signal will be briefly described below. For example, when the X-ray tube voltage is V _c (V ₁
In the case of <V _c <V ₂ ), the pixel value distribution of the video signal output from the image sensor is schematically represented as, for example, 403, and V _d (V ₂ <V _d <V ₃ ) In this case, it becomes 404. These are input / output characteristic curves 401 and 40, respectively.
By performing the brightness modulation according to 2, both of the pixel value distributions are input / output converted into the pixel value distribution 405 shown on the left of FIG.

The signal processing circuit 303 emphasizes the video signal output from the gradation conversion circuit 302 according to the kV information, and uses an LUT in which a plurality of conversion coefficients are stored. The γ curve stored in this LUT is an input / output characteristic curve that emphasizes the pixel value distribution of all regions (including the luminance region of interest), and here, by enhancement, the image values corresponding to each X-ray condition are displayed. The predetermined pixel value does not change even in the display pixel value distribution, and the pixel value distribution of the image is set to be substantially constant in the display pixel value distribution regardless of the X-ray condition.

Here, the change of the pixel value distribution from the time when the video signal (pixel value distribution) of the original image is A / D converted by the A / D converter 304 until the width of the display pixel value distribution is made substantially constant. Explain the process. FIG. 5 is an explanatory diagram for explaining the process of the output distribution (pixel value distribution) of the low frequency components converted by the gradation conversion circuit 301, and the right side of FIG. 5 is the A / D converter 304.
Shows the relationship between the low frequency component of the video signal input to the subtraction circuit 307 and the low frequency component of the video signal output from the subtraction circuit 305. The left side of FIG. 5 shows the input / output conversion stored in the signal processing circuit 303. An example of a line is shown. Two types of relationship lines are shown as an example on the right side of FIG. 5, but this is because the input / output conversion circuit 306 was described using two input / output characteristic curves and is stored in the input / output conversion circuit 306. It goes without saying that as the number of input / output characteristic curves increases, the number of relationship lines also increases. The relation line 506 has an X-ray tube voltage of V ₁ kV
Shows the relationship of the low frequency components of the video signal input to and output from the subtraction circuit 307 when set in the range of V ₂ kV to V ₂ kV, and the relationship line 507 is set in the range of V ₂ kV to V ₃ kV. In this case, the relationship of the low frequency components of the video signal input to and output from the subtraction circuit 307 is shown.

The relationship between the set X-ray tube voltage and the low frequency component of the video signal will be briefly described. For example, when the X-ray tube voltage is V ₁ kV.
In the case of ˜V ₂ kV (V ₁ <V ₂ ), the pixel value distribution of the low frequency component of the video signal in the luminance region of interest output from the image sensor is schematically represented as 501, for example, and X When the line tube voltage is V ₂ kV to V ₃ kV (V ₂ <V ₃ ), the pixel value distribution of the video signal of the luminance region of interest output from the image sensor is schematically represented as 502. These are subjected to predetermined input / output conversion in accordance with the γ curves 401 and 402 shown in FIG. 4, respectively, and the subtraction circuit 307 subtracts the input / output converted low-frequency component from the low-frequency component of the original image. 5 Pixel value distribution 50 shown in the center
Converted to 3,504. That is, the pixel value distributions 501, 5
02 does not change in the luminance region of interest by the gradation conversion circuit 302, and compresses each region portion on the higher and lower luminance sides than the luminance region of interest. Although two types of input / output conversion lines are shown as an example on the left side of FIG.
Reference numeral 08 represents a conversion coefficient selected when the X-ray tube voltage is set in the range of V ₁ kV to V ₂ kV, and the input / output conversion line 5
Reference numeral 09 represents a conversion coefficient selected when the X-ray tube voltage is set in the range of V ₂ kV to V ₃ kV. here,
The relationship between the set X-ray tube voltage and the video signal will be described. For example, when the X-ray tube voltage is V ₁ kV to V ₂ kV as described above, the video signal output from the subtraction circuit 307 (or interest in the video signal). The pixel value distribution of the low frequency component in the luminance region) is schematically represented as 503, and the X-ray tube voltage is V ₂ kV to V
_In case of ₃ kV, it becomes like 504. These are brightness-modulated (emphasized) according to input / output conversion lines 508 and 509, respectively.
By doing so, both of the pixel value distributions can be converted into the pixel value distribution 505 shown on the left side of FIG. That is, here, the input / output conversion line is set to an appropriate X-ray condition so that the peak and the variance of the pixel value distribution compressed according to the respective X-ray conditions become substantially constant (for example, the central brightness) in the display pixel value distribution. It is set in a range.

The operation of the embodiment apparatus having the above configuration will be described. Similar to the first embodiment, the TV camera 110 converts the optical image formed on the image pickup surface into a video signal and converts the gradation signal 301.
On the other hand, the X-ray controller 103 obtains kV information and outputs it to the gradation conversion circuit 301. In the gradation conversion circuit 301, the gradation conversion circuit 302 and the signal processing circuit 303 perform contrast processing (luminance modulation) as follows. In the gradation conversion circuit 302, the video signal (analog signal) from the TV camera 110 is converted into a digital video signal by the A / D converter 304, and the subtraction circuit 307 and the LPF 3 are used.
Output to 05. (For convenience, the video signal output from the A / D converter 304 to the subtraction circuit 307 is S1, and the video signal output from the A / D converter 304 to the LPF 305 is S1.
2). In the LPF 305, the frequency of the video signal to be extracted is set according to the kV information sent from the X-ray controller 103, and the video signal (only the low frequency component) S2 ′ in the low frequency range from that frequency is extracted to input / output conversion circuit. Output to 306. In the input / output conversion circuit 306, the X-ray controller 103
A predetermined γ curve is selected in accordance with the kV information from and the predetermined contrast processing is performed on the video signal. The video signal S2 ″ subjected to the contrast process in this way is output to the subtraction circuit 307. In the subtraction circuit 307, the A / D converter 304 is used.
The video signal S1 from the video signal S1 and the video signal S2 ″ after input / output conversion by the input / output conversion circuit 306 are temporarily held in the buffer unit,
When the synchronization is read and read, the video signal S2 ″ is subtracted from the video signal S1 and output to the signal processing circuit 303. That is, when the video signal S1 of the original image is S1 = S1h (high frequency component) + S1r (low frequency component), The signal S1 is output by the gradation conversion circuit 302 as follows: S1 (= S1h + S1r) −S2 ″ = S1h + (S1r
-S2 ″), the high frequency component S1h is not affected, but the low frequency component is compressed on the high and low luminance sides of the luminance region of interest. The signal is subjected to emphasis processing by a γ curve corresponding to kV information by the signal processing circuit 303. The video signal (digital signal) thus emphasized is an analog signal by a D / A converter (not shown). Is displayed on the CRT of the display system 105 as an X-ray image.

As described above, in this embodiment, the X-ray controller 1 is used.
The kV information obtained in step 03 is output to the input / output conversion circuit 306 and the signal processing circuit 303, and the input / output conversion circuit 306 and the signal processing circuit 303 perform predetermined luminance modulation in accordance with the kV information to reduce the low frequency of the image. It is possible to provide an image having an appropriate contrast according to the X-ray tube voltage when the pixel value distribution of the component is compressed.

In the above configuration, the input / output characteristic curve is set so that the (estimated) peak value of the pixel value distribution is converted into the central luminance for display, but the control target level of the automatic exposure control is for display. The input / output characteristic curve may be set so as to be converted into the central luminance of and the distribution width becomes substantially constant.

The third embodiment of the present invention will be described below with reference to the drawings. In the third embodiment, predetermined contrast processing is performed according to kV information, and low frequency component signal processing and high frequency component signal processing of a video signal are performed independently. FIG. 6 is a block diagram of a gradation conversion circuit 601 showing a modification of the gradation conversion circuit 301 in the second embodiment. The same parts as those in FIG. 3 are designated by the same reference numerals, and detailed description thereof will be omitted. The gradation conversion circuit 601 is
The compression of the low frequency component (pixel value distribution) and the enhancement of the high frequency component are simultaneously performed in real time. This gradation conversion circuit 60
1 is an A / D converter 304 that converts an analog video signal into a digital video signal; I. An LPF 603 that sets a frequency (cutoff frequency) of the video signal to be extracted according to the size information and extracts a frequency (low frequency component) lower than the set frequency, and a predetermined gradation conversion into a video signal according to the kV information. A gradation conversion unit 604 that performs (compression), and
A subtraction circuit 307 that temporarily holds the video signal containing the high-frequency component and the low-frequency component from the / D converter 304 and the video signal containing only the low-frequency component from the LPF 603 in the buffer unit, synchronously reads and subtracts, A plurality of arbitrary (having an amplification factor) amplification coefficients are stored, and a gain generation section 605 that amplifies (emphasizes) the amplification coefficient applied to the video signal (high frequency component) output from the subtraction circuit 307 in the integration section, and this gain generation section An addition circuit 606 for adding the high frequency component amplified by 605 and the low frequency component gradation-converted by the gradation conversion unit 604, and the saturation value (or a value lower than the saturation value) of the image sensor are set in advance, and A / A saturation determination unit 607 for comparing and determining whether the video signal output from the D converter 304 is a saturation value and a plurality of switches are provided, and the determination result from the saturation determination unit 607 is provided. A desired switch is selected based on the above, and when normal (when a value lower than the set value is input to the saturation determination unit 607), the video signal (pixel value) from the addition circuit 606 is output to the display system 105 as it is. However, if it is abnormal (when a pixel value equal to or higher than the set value is input to the saturation determination unit 607), it is replaced with a predetermined gray level (for example, the maximum value or the minimum value in the pixel value) and the replacement value is displayed on the display system 105. It is configured by the output replacer 608.

The X-ray controller 602 obtains kV information in accordance with the light quantity of the optical image, and the kV information is obtained by the gain generator 60.
5 and the gradation conversion unit 604, the input surface field of the image intensifier 108 (I.
I. (Size) is switched, the I.D. I. The size information is output to the LPF 603. This is an I.D. I. By changing the size, I.V. I. This is because the magnifying power of the output optical image of 108 changes and the frequency characteristic of the image changes accordingly. The gradation conversion unit 604 stores an LUT in which a plurality of conversion coefficients are stored.
To use. This LUT selects a predetermined γ curve according to the kV information from the X-ray controller 602 and compresses the low frequency component. Here, the γ curve stored in the LUT will be described. FIG. 7 is an example of a γ curve, and the γ curve has two thresholds THH and TH depending on a threshold (not shown).
L is set. In addition, the γ curve shows the threshold values THH and THL.
The slope is set so that the video signal is output as it is after the gradation conversion in the range of, and the video signal is set to have the relationship of output ≧ input after the gradation conversion in the lower luminance region than the threshold THL. In the higher luminance region, the inclination is set so that the video signal has a relationship of output ≦ input after gradation conversion. This compresses the pixel value distribution width of the low frequency component (including the DC component).

The operation of the embodiment apparatus configured as described above will be described. The TV camera 11 as in the first embodiment.
0 converts the optical image formed on the imaging surface into a video signal and A / D
Output to the converter 304. On the other hand, the X-ray controller 602
Calculates kV information according to the light amount of the optical image, outputs the kV information to the gain generation unit 605 and the gradation conversion unit 604, and I.V. I. If the size is switched, the I.D. I. The size information is output to the LPF 603. A / D
The converter 304 converts the video signal (analog signal) into a digital video signal, and the saturation judgment unit 60 converts the video signal.
7, output to the subtraction circuit 307 or the LPF 603. LP
In F603, the I.D. from the X-ray controller 602 is transmitted. I. The set frequency is set according to the size information, a video signal (low frequency component) in a lower frequency range than that frequency is extracted, and the low frequency component is output to the subtraction circuit 307 and the gradation conversion unit 604. The subtraction circuit 307 subtracts the video signal (low frequency component) from the LPF 603 from the video signal (high frequency component + low frequency component) from the A / D converter 304, and outputs the subtraction result (high frequency component) to the addition circuit 606. To do. At this time, the video signal (high frequency component) is multiplied by the amplification coefficient according to the kV information by the gain generation unit 605, emphasized, and added to the addition circuit 60.
6 is output.

While amplifying the high frequency component in this way,
The gradation conversion unit 604 selects a γ curve according to the kV information from the X-ray controller 602, performs a predetermined contrast process (compression process) on the low frequency component, and outputs it to the addition circuit 606. In the adder circuit 606, the high frequency component emphasized by the gain generation unit 605 and the low frequency component compressed by the gradation conversion unit 604 are once held in the buffer unit, read out in synchronization and added. Simultaneously with this operation, the saturation determination unit 607 compares and determines whether the video signal output from the A / D converter 304 is a saturation value under an arbitrary X-ray condition, and the determination result is output to the replacement unit 608. The replacement unit 608 outputs the addition result from the addition circuit 606 to the display system 105 when it is normal based on the determination result from the saturation judgment unit 607, and when it is abnormal, the adder 606.
The addition result from is replaced with a predetermined gray level and is output to the display system 105. In this way, the video signal is subjected to predetermined contrast processing and displayed on the CRT of the display system 105 as an X-ray image.

As described above, in this embodiment, the low frequency component of the video signal is extracted, and the low frequency component is subtracted from the video signal of the original image to obtain the high frequency component of the video signal. By separately performing the predetermined contrast processing (luminance modulation) on each of the above, the compression of the pixel value distribution width of the low frequency component and the enhancement of the high frequency component are simultaneously realized in real time.

Further, in this embodiment, the setting tube voltage information is input to the gradation converting section 604 and the gain generating section 605, and the gradation converting section 604 and the gain generating section 605 determine the video signal according to the setting tube voltage information. By performing the contrast processing of No. 1, the signal intensity can be kept constant even if the X-ray tube voltage changes under the operation of the automatic exposure control.

In this embodiment, the I.D. I. Characteristics of LPF 603 according to size information (eg cutoff characteristics)
Even if the frequency characteristic of the original image changes, the low-frequency component and the high-frequency component can be separated according to the change, so that the frequency characteristic for the subject can be made constant.

Further, in the present embodiment, the saturation determination unit 607 compares and determines whether or not the video signal (pixel value) from the A / D converter 304 has a saturation value, and the saturation is actually determined from this determination result. When the brightness is modulated, the image signal (pixel value) is replaced with a predetermined gray level (for example, the maximum value or the minimum value) so that the observer is saturated due to the shortage of X-rays or the brightness modulation (contrast processing is performed. ) Makes it easier to distinguish whether the image is saturated or not.

A fourth embodiment according to the present invention will be described below with reference to the drawings. The fourth embodiment has a configuration different from that of the third embodiment and performs signal processing of low frequency components and signal processing of high frequency components of a video signal independently. Figure 8
It is a block diagram of a gradation conversion circuit 801 showing a modification of the gradation conversion circuit 601 in the third embodiment. The same parts as those in FIG. 6 are denoted by the same reference numerals, and detailed description thereof will be omitted. The gradation conversion circuit 801 is for simultaneously emphasizing high-frequency components of a video signal and compressing low-frequency components thereof in real time. The gradation conversion unit 802 and the A / D similar to that of the third embodiment are used.
It is composed of a converter 304, an LPF 305, a subtraction circuit 307, a gain generation unit 605, and an addition circuit 606.
The gradation conversion unit 802 compresses the pixel value distribution of the low frequency component of the video signal, stores the attenuation coefficient a (a <1), and extracts it from the LPF 305 by the multiplier (of the video signal). Attenuation generation unit 803 that multiplies the low frequency component by the attenuation coefficient to attenuate the low frequency component, and a desired threshold value is set by a threshold (not shown), and the relationship between the threshold value and the low frequency component (of the video signal) A comparator 804 that makes a plurality of comparisons (for example, three combinations) and a low frequency component (hereinafter referred to as an attenuation low frequency component) multiplied by the attenuation coefficient a by the attenuation generation unit 803 and the video signal from the LPF 305 are input. ,
A selector 805 that outputs a low-frequency component (a video signal from the LPF 305 or an attenuated low-frequency component) of a desired video signal based on the determination result of the comparator 804, and a comparator 804.
By an offset value generator 806 that outputs a predetermined offset value (for example, three types) based on the determination result of 1. and an addition unit 807 that adds the video signal selected by the selector 805 and the offset value from the offset generator 806. Composed. Further, in this embodiment, the high frequency component is emphasized as in the third embodiment, but the gain generator 6 is used.
05 is the pixel value (video signal) of the original image that emphasizes high frequency components
The video signal of the original image is input so that the high frequency component is emphasized based on the video signal of the original image.

An example of the judgment result of the comparator 804 and the selector 805 and the offset generator 806 for making a desired selection based on the judgment result will be described below. The comparator 804 compares the video signal of the original image extracted by the LPF 305 with the set thresholds THL and THH, (1) the pixel value of the extracted video signal is smaller than the threshold THL, and (2) the pixel value of the extracted video signal is (3) The pixel value of the low-frequency component of the original image that is larger than the threshold THH is from the threshold THL to the threshold THH.
Any one of the three determination results (excluding (1) and (2)) within the range of (1) and (2) is output to the selector 805 and the offset generator 806. When the determination results are (1) and (3), the selector 805 outputs the attenuated low-frequency component multiplied by the attenuation coefficient a in the attenuation generation unit 803 to the addition unit 806, and the determination result is (2). In that case, the low frequency component of the original image is output to the addition unit 806. Offset value generator 806
Is the offset value THL when the determination result is (1).
In case of (1-a) and (2), offset value 0, (3)
In the case of, a predetermined offset value such as the offset value THH (1-a) is output to the addition unit 806.

An example of the input / output characteristic curve set in this way will be described below. FIG. 9 shows an example of the input / output characteristic curve set in the gradation converting unit 802. As shown in FIG. 9, the input / output characteristic curves are thresholds THL and THH.
The slope has been changed since the border. The input / output characteristic curve shows that when the pixel value of the video signal is smaller than the threshold value THL,
Offset value 1 = THL (1-a) is added and inclination is 1
If it is smaller and the pixel value of the video signal is larger than the threshold value THH, the offset value 3 = THH (1-a) is added and the slope is smaller than 1, and the pixel value of the video signal is between the threshold value THL and the threshold value THH. In this case, the slope to which the offset value 2 = 0 is added is set to 1. That is, the pixel value distribution of the video signal output from the LPF 305 is compressed according to the input / output characteristic curve shown in FIG.

The operation of the embodiment apparatus having the above structure will be described. The A / D converter 304 converts an analog video signal into a digital video signal (original image video signal), and then the LPF 305, the subtraction circuit 307, or the gain generation unit 6
Output to 05. The LPF 305 extracts only a desired low frequency region (low frequency component) from the video signal of the original image,
The low frequency component is output to the subtraction circuit 307 and the gradation conversion unit 802. The subtraction circuit 307 subtracts the low frequency component from the video signal of the original image, and outputs the subtraction result (high frequency component) to the addition circuit 606. At this time, the high frequency component is applied with an arbitrary gain (enhancement) by the gain generator 605.

Further, in the gradation converting section 802, the comparator 804
While the low-frequency component of the original image is input to, the selector 8
To 05, the low frequency component of the original image and the low frequency component obtained by multiplying the attenuation coefficient a by the attenuation generation unit 803 are input. Comparator 80
Reference numeral 4 compares predetermined threshold values THL and THH set by a threshold (not shown) with the frequency of the low frequency component of the original image, and outputs the determination result to the selector 805 and the offset value generator 806. The selector 805 outputs either the low frequency component or the attenuated low frequency component of the original image to the adder 807 based on this determination result. Further, the offset value generator 806 outputs the offset value based on the determination result to the addition unit 807. The adder 807 synchronously adds the low frequency component of the video signal from the selector 805 and the offset value from the offset value generator 806, and outputs the result to the adder circuit 606. In this way, the low frequency component and the high frequency component obtained by the gradation conversion unit 802 are synchronized and added by the adding circuit 606, and output to the display system 105 (not shown). The video signal processed in this way is the CR of the display system 105.
Displayed on T.

In this way, in this embodiment, the high-frequency component emphasis processing of the video signal and the low-frequency component compression processing are performed independently and simultaneously in real time. Therefore, it is possible to perform brightness modulation while keeping the video signal (low frequency component) of the main part (for example, the region of interest) of the image important for diagnosis while maintaining the same level as the original image.

In this embodiment, the low frequency component and the attenuated low frequency component of the original image are selected according to the pixel value of the low frequency component of the original image, and the selected low frequency component and the desired offset value are added. By compressing the low frequency component, when the input bit number of the video signal (image) input to the gradation conversion unit 802 is large enough to exceed the bit number of the address of the ROM, as in the first to third embodiments. When the LUT is used, a plurality of them are required, but the need is eliminated, and the configuration can be simplified.

Further, in the present embodiment, by emphasizing the high frequency component of the video signal depending on the pixel value (video signal) of the original image, the amplification factor is reduced in the dark part of the image and conversely in the bright part. Luminance modulation can be performed so as to increase the amplification factor. This makes it possible to avoid emphasizing noise (high-frequency components) in the part that was completely darkened by barium during contrast examination of the digestive tract using barium,
In addition, even if a catheter or guide wire overlaps the mediastinum (dark part) of the human body and becomes difficult to see in a cardiac catheterization test, increase the amplification factor in the dark part of the image and decrease the amplification factor in the bright part of the image. This makes it possible to improve the visibility of high-frequency components (for example, contours) regardless of whether the image is bright or dark.

The fifth embodiment of the present invention will be described below with reference to the drawings. The fifth embodiment is an apparatus for switching the image processing parameter (luminance modulation) according to the X-ray tube voltage (information) as in the first to third embodiments, and the tube voltage frequently changes by automatic exposure control. However, even if the processing parameters change accordingly, hunting of the image is avoided. Incidentally, the fifth embodiment will be described by way of an example of the first embodiment, which has a relatively simple structure among the first to third embodiments in which the brightness modulation is performed according to the tube voltage information.

FIG. 10 is a partial block diagram of the first embodiment including a hysteresis circuit 901 for avoiding image hunting. The same parts as in FIG.
Detailed description is omitted. Hysteresis circuit 901
Is a device in the subsequent stage that performs a predetermined conversion on the kV information from the X-ray control device 103 (which performs a predetermined brightness modulation. Here, the signal processing circuit 112, the input / output conversion circuit 306 and the signal in the second embodiment are used. The processing circuit 303, which in the third embodiment outputs to the gradation conversion unit 604), latches 902 for temporarily storing kV information, and the previous k (one frame before).
A comparator 903 that compares the V information with the current kV information and outputs information on the tube voltage value and the displacement state of the tube voltage (indicating that the tube voltage becomes larger or smaller).
A predetermined input / output characteristic line is stored, and is constituted by a ROM 904 which performs a predetermined conversion on the kV information according to the information from the comparator 903. Here, the input / output characteristic line stored in the ROM 904 will be described. FIG. 11 is an example of an input / output characteristic diagram, and the solid line is selected in the case of kV information that the X-ray tube voltage is larger than that of one frame before, and the broken line is compared with the case where the X-ray tube voltage is one frame before. This is selected when the kV information is small. Here, the relationship between the change of the set tube voltage and the state value selected at the time of change will be described. For example, when the X-ray tube voltage rises from V _g kV to V _h kV, the state value is selected by the solid line, and accordingly the state value is selected. Γ curve is selected. Conversely, the X-ray tube voltage is from V _h kV to V _g kV
If the value falls to, the state value is selected by the broken line, and the γ curve is selected accordingly.

The operation of the embodiment apparatus having the above structure will be described. The TV camera 110 converts the optical image formed on the imaging surface into a video signal and outputs the video signal to the signal processing circuit 112. On the other hand, the X-ray control device 103 uses the light quantity of the optical image detected by the photomultiplier 111. Then, kV information is obtained and output to the hysteresis circuit 901. Hysteresis circuit 901
Then, the kV information is temporarily stored in the latch 902, and the kV information one frame before and the current kV information are read out to the comparator 903. The comparator 903 compares the kV information one frame before with the current kV information and outputs the tube voltage value and the tube voltage displacement state to the ROM 904. The ROM 904 selects a predetermined input / output characteristic line from the tube voltage value fluctuation state of the kV information, and outputs the state value to the signal processing circuit 112 as kV information having hysteresis. Signal processing circuit 112
Performs a predetermined contrast process on the video signal from the TV camera 110 according to the kV information having hysteresis. The video signal subjected to the contrast process in this way is displayed on the display system 105 as an X-ray image.

Thus, in this embodiment, the X-ray controller 1
03 to obtain the kV information, the hysteresis circuit 901 to obtain the tube voltage value of the kV information and the state value of the kV information based on the displacement state, and output the state value to the signal processing circuit 112, thereby performing the automatic exposure control. Even if the voltage changes frequently, the contrast processing parameter does not change frequently, and hunting of the image can be avoided.

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the gist of the present invention. For example, in the second embodiment shown in FIG. 6, a second gradation conversion unit is provided between the subtraction circuit 307 and the multiplier, and the input / output conversion shown in FIG. 12 is performed based on the low frequency pixel value from the LPF 603. You may do it.
Here, FIG. 12A shows the input / output conversion of the high frequency component used when the low frequency pixel value is at an intermediate level (previously set), and FIG. 12B shows the low frequency pixel value at the intermediate level. The input / output conversion of the high frequency component used when the level is larger or smaller than the level is shown. This series of processing is performed independently for each pixel value. In other words, for each pixel
Either 2 (a) or 2 (b) is converted and sent to the multiplier in the subsequent stage. This gradation conversion can prevent the phenomenon that the pixel value of the final processed image exceeds the maximum value or the minimum value due to the amplification of the high frequency component. Further, this gradation conversion unit may perform input / output conversion that also serves as amplification in the multiplier. Further, it is not necessary to use the low-frequency pixel as a criterion here, and by using the pixel value of the original image, almost the same effect can be obtained. Furthermore, FIG.
The input / output conversion shown in 3 can be used. In this case, it is not necessary to set an intermediate level having a certain width, and if the low frequency pixel value is smaller than a certain set value, FIG. 13A may be used, and if it is larger, the same FIG. 13B may be used. As a result, the same effect as when the input / output conversion shown in FIG. 12 is used can be obtained.

Although the present invention has been described with reference to the first to fifth embodiments, the configurations of the respective embodiments can be partially combined as appropriate according to the purpose of the device. If the compression of the low-frequency component and the enhancement of the high-frequency component of the video signal are performed separately (simultaneously in real time), the configuration shown in FIG. 14 may be used.

In this embodiment, the I.D. I. Although a transmission X-ray image is captured using the optical system 108, the optical system 109, and the TV camera 111, a fluorescent body that converts X-rays into an optical image and an output surface of this fluorescent body have substantially the same area as that of the fluorescent body. A plane detector having a semiconductor area sensor that is arranged in a dimension and detects an optical image may be used.

In the third or fourth embodiment, the LPF60
3, the low frequency component of the video signal is extracted, and the subtraction circuit 30
7, the extracted low frequency component is subtracted from the video signal of the original image to obtain a high frequency component, and the obtained high frequency component and low frequency component are separately subjected to predetermined contrast processing. If the predetermined contrast processing is performed separately, the low-frequency component is extracted by the LPF and then the high-frequency component is obtained. The high-frequency component is extracted by the high-pass filter and then subtracted by the subtraction circuit 307. The low frequency component may be obtained. Further, although a CRT is used as the display system 105 in this embodiment, any other display device such as liquid crystal can be used.

[0055]

As described in detail above, according to the present invention, it is possible to perform an appropriate contrast process, and it is possible to improve the diagnostic ability, the inspection ability and the like.

[Brief description of drawings]

FIG. 1 is a block diagram of an X-ray diagnostic apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an example of an input / output characteristic curve stored in an LUT.

FIG. 3 is a partial block diagram of an X-ray diagnostic apparatus according to a second embodiment of the present invention.

FIG. 4 is a diagram showing an example of an input / output characteristic curve stored in an LUT.

FIG. 5 is an explanatory diagram of a changing process of a pixel value distribution.

FIG. 6 is a partial block diagram of an X-ray diagnostic apparatus according to a third embodiment of the present invention.

FIG. 7 is a diagram showing an example of an input / output characteristic curve stored in an LUT.

FIG. 8 is a partial block diagram of an X-ray diagnostic apparatus according to a fourth embodiment of the present invention.

FIG. 9 is an explanatory diagram of a gradation conversion unit 802.

FIG. 10 is a partial block diagram of the first embodiment including a hysteresis circuit for explaining the hysteresis circuit.

FIG. 11 is a diagram showing an example of an input / output characteristic curve stored in a ROM.

FIG. 12 is a diagram showing a modification of the gradation conversion circuit 601.

FIG. 13 is a diagram showing a modified example of the gradation conversion circuit 601.

FIG. 14 is a partial block diagram for separately compressing a low frequency component and enhancing a high frequency component of a video signal.

FIG. 15 is a diagram showing an example of an input / output characteristic curve stored in an LUT.

[Explanation of symbols]

 101 X-ray generator 102 Imaging device 103 X-ray controller 104 CCU 105 Display system 106 X-ray tube 107 High voltage generator 108 I. I. 109 optical system 110 TV camera 111 photomal 112 signal processing circuit 301 gradation conversion circuit 302 gradation conversion circuit 303 signal processing circuit 601 gradation conversion circuit 602 X-ray controller 605 gain generator 801 gradation conversion circuit 802 gradation conversion 901 Hysteresis circuit

Claims (12)

[Claims] 1. An X-ray source for irradiating a subject with X-rays, an optical image conversion means for converting the transmitted X-rays transmitted through the subject into an optical image, and detecting the light quantity of the optical image. A detection unit, an image pickup unit that picks up the optical image and outputs a video signal, a control unit that obtains voltage information based on the amount of detected light detected by the detection unit, and an X-ray source according to the voltage information. An X-ray diagnostic apparatus comprising: a voltage generating unit that supplies a voltage; a contrast processing unit that performs a predetermined contrast process on the video signal according to the voltage information; and a display unit that displays the output of the contrast processing unit. 2. An X-ray source for irradiating a subject with X-rays, an optical image conversion means for converting transmitted X-rays transmitted through the subject into an optical image, and a video signal for picking up the optical image. , A control means for obtaining voltage information on the basis of the output of the image pickup means, a voltage generating means for supplying a voltage to the X-ray source according to the voltage information, and a voltage generator for supplying voltage to the X-ray source according to the voltage information. An X-ray diagnostic apparatus comprising a contrast processing means for performing a predetermined contrast processing on a video signal, and a display means for displaying an output of the contrast processing means. 3. The contrast processing means stores a plurality of predetermined input / output characteristic curves, selects the desired input / output characteristic curve according to the voltage information, and selects the input / output characteristic of the video signal. The X-ray diagnostic apparatus according to claim 1 or 2, wherein a predetermined contrast process is performed according to a characteristic curve. 4. The contrast processing means includes an extracting means for extracting a predetermined frequency low component of the video signal, and an input / output for converting the extracted frequency component extracted by the extracting means into a predetermined input / output according to the voltage information. Conversion means, subtraction means for subtracting the extracted frequency component input / output converted by the input / output conversion means from the video signal, and emphasizing the output of the subtraction means by a predetermined emphasis processing according to the voltage information. The X-ray diagnostic apparatus according to claim 1, further comprising a processing unit. 5. The contrast processing means converts the video signal into the voltage information so that the pixel value distribution width of the X-ray image corresponding to the voltage becomes substantially constant in the display pixel value distribution after the contrast processing. The X-ray diagnostic apparatus according to any one of claims 1 to 4, wherein the X-ray diagnostic apparatus performs a predetermined contrast process in accordance therewith. 6. An X-ray source that irradiates X-rays toward a subject, an optical image conversion unit that converts transmitted X-rays that have passed through the subject into an optical image, and detects the amount of light of the optical image. Detecting means, image pickup means for picking up the optical image and outputting a video signal, control means for obtaining voltage information based on the amount of light detected by the detecting means, and voltage for the X-ray source according to the voltage information. A voltage generating means for supplying a predetermined frequency component of the video signal, a subtracting means for subtracting the extraction frequency component extracted by the extracting means from the video signal, the extraction frequency component, A compression unit that processes to narrow the pixel value distribution width; an emphasis unit that performs an emphasis process on the output from the subtraction unit; and an addition unit that adds the output from the emphasis unit and the output from the compression unit. Addition means X-ray diagnostic apparatus and a display means for displaying the results. 7. An X-ray source that irradiates X-rays toward a subject, an optical image conversion unit that converts transmitted X-rays that have passed through the subject into an optical image, and a video signal that captures the optical image. , A control means for obtaining voltage information based on the output of the image pickup means, a voltage generating means for supplying a voltage to the X-ray source according to the voltage information, and a predetermined frequency of the video signal. Extraction means for extracting a component; subtraction means for subtracting the extraction frequency component extracted by the extraction means from the video signal; compression means for processing the extraction frequency component so that the pixel value distribution width is narrowed; An X-ray having an emphasizing means for emphasizing the output from the subtracting means, an adding means for adding the output from the emphasizing means and the output from the compressing means, and a display means for displaying the addition result of the adding means. Diagnostic device. 8. The X according to claim 4, wherein the extraction means sets a frequency component to be extracted according to the voltage information.
Line diagnostic device. 9. The extracting unit sets the frequency component to be extracted based on the switching of the field of view of the input surface of the optical image converting unit. The X-ray diagnostic apparatus according to item 1. 10. The image pickup means stores a saturation value of an image pickup device and determines whether or not a pixel value of the video signal is the saturation value, and based on a determination result of the determination means. 2. A replacement means for replacing an output with a predetermined gray level.
The X-ray diagnostic apparatus according to claim 1. 11. The aforesaid compressing means, an attenuating means for attenuating the extracted frequency component, a predetermined threshold value, and a comparing means for comparing the pixel values of the threshold value and the extracted frequency component, and the comparing means. Selecting means for outputting either the extracted frequency component or the extracted frequency component attenuated by the attenuating means based on the result of the means, and an offset generating means for outputting a predetermined offset value based on the result of the comparing means. And an adder unit for adding the output of the offset generating means and the output of the selecting means to each other. An X-ray diagnostic apparatus according to the above item. 12. The contrast processing means includes a storage means for temporarily storing the voltage information, and a comparison means for performing a predetermined comparison between the past voltage information read from the storage means and the voltage information from the control means. A conversion means for performing a predetermined conversion on the basis of the result of the comparison means, and a predetermined contrast processing is performed on the basis of the result of the conversion means. The X-ray diagnostic apparatus according to claim 5, or any one of claims 8 to 11.