JPH0514814A - Medical x-ray radiographic equipment - Google Patents

Abstract

PURPOSE:To prevent the deterioration of a display picture due to halation, and simultaneously, to realize picture analysis processing free from an error in a medical X-ray radiographic equipment. CONSTITUTION:A histogram generation circuit 16 generating the histogram of density information in respect of picture data read out of a frame memory 6 in which the collected digital picture data is stored is provided, and simultaneously, a CPU 9 controlling every component is made capable of controlling a look-up table 7 so that the picture displayed on the television monitor 13 of a display means 8 does not cause the halation by using the data of the histogram generated by the histogram generation circuit 16. Thus, the deterioration of the display picture can be prevented, and simultaneously, the density information of the picture data can be obtained under a certain condition, and the picture analysis processing free from error can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a medical X-ray imaging apparatus which radiates X-rays to a subject and obtains a transmitted X-ray image to perform X-ray fluoroscopy, and particularly prevents deterioration of a display image due to halation. The present invention relates to a medical X-ray imaging apparatus capable of performing image analysis processing that does not include an error.

[0002]

2. Description of the Related Art As shown in FIG. 4, a conventional medical X-ray imaging apparatus of this type includes an X-ray tube apparatus 2 which is supplied with a high voltage from an X-ray high-voltage apparatus 1 and emits X-rays. X-ray tube device 2
A video system device 4 for converting an X-ray image emitted from the subject 3 and passing through the subject 3 into visible light and an electric signal, and an A / D converter for converting an output signal from the video system device 4 into a digital signal. 5, storage means (6) for storing the digital image data from the A / D converter 5, and contrast enhancement means (7) for enhancing the contrast of the image data read from the storage means (6). And a display means 8 for converting the image data subjected to the contrast enhancement by the contrast enhancement means (7) into a video signal and displaying it as an image, and a control means (9) for controlling each of the above components. It was made up of The video system device 4
Is composed of an image intensifier (hereinafter abbreviated as “II”) 10 and a television camera 11, and a display means 8
Is composed of a D / A converter 12 and a television monitor 13.
Reference numeral 14 indicates a CPU bus.

The II 10 and the television camera 11 as described above
In the medical X-ray imaging apparatus using the video system apparatus 4 including the above, if the X-ray condition is set so that the display image of a certain diagnostic region can be seen at an appropriate density, X-rays can pass through better than that. When a part comes into the visual field, the display image may cause halation at that part. When the halation occurs in this way, the diagnostic information is lost in the halation portion of the image, which makes it difficult to see the diagnostic image and accurate diagnosis may not be possible.

Therefore, in order to prevent halation of the display image, conventionally, the amplification degree of the television camera 11 of the video system device 4 has been manually set to a low level in advance. However, in this case, the entire display image on the television monitor 13 is dark and has low contrast, and the diagnostic image may be difficult to observe. Therefore, in response to this, recently, the television camera 1 of the video system device 4 is provided.
A device has been proposed in which the amplification factor characteristic of No. 1 is changed in real time according to the degree of halation generated in the display image ("National Cine Imaging Technology Research Group" 1991).
Year No.3, pp.37-38).

[0005]

However, in the above-proposed medical X-ray photographing apparatus, the amplification factor characteristic of the television camera 11 is changed in real time according to the degree of halation of the image displayed on the television monitor 13. Therefore, the density information of the obtained image data also changes according to the change of the amplification degree characteristic of the television camera 11. However, for example, in an angiographic examination of the heart, X-ray fluoroscopy is performed while injecting a contrast agent into the subject 3, the video signal output from the television camera 11 is digitized, and the density information of the obtained image data is obtained. Based on C
The image analysis processing is performed by the PU 9, but in this case, it is necessary to obtain the density information of the image data while keeping the amplification degree characteristic of the television camera 11 constant. In this respect, in the proposed medical X-ray imaging apparatus, since the amplification characteristic of the television camera 11 is changed in real time, the television camera 11 is added to the density information which is the basis of the image analysis processing by the CPU 9.
Since the change of the density information due to the change of the amplification degree characteristic is also included, the image analysis result includes an error. Therefore, for example, an angiographic examination of the heart may not be performed accurately.

Therefore, the present invention provides a medical X-ray imaging apparatus which can cope with such a problem and prevent the display image from being deteriorated due to halation and which can perform an image analysis process without error. The purpose is to

[0007]

In order to achieve the above object, a medical X-ray imaging apparatus according to the present invention is an X-ray tube apparatus which is supplied with a high voltage from an X-ray high voltage apparatus and emits X-rays.
A video system device for converting an X-ray image emitted from the X-ray tube device and transmitted through the subject into visible light and an electric signal, and an A / D for converting an output signal from the video system device into a digital signal. A converter, storage means for storing the digital image data from the A / D converter, contrast enhancement means for enhancing the contrast of the image data read from the storage means, and contrast enhancement by the contrast enhancement means. An image read out from the storage means in a medical X-ray radiographing apparatus comprising display means for converting the image data subjected to exposure to a video signal and displaying it as an image, and control means for controlling the above-mentioned respective components. A histogram creating means for creating a density information histogram is provided for the data, and the control means is a histogram creating means. Using data made histogram, in which the image displayed on the display means is assumed capable of controlling the contrast enhancement means so as not to cause halation.

[0008]

In the medical X-ray imaging apparatus thus constructed, the histogram of the image data read from the storage means is created by the histogram creation means provided on the output side of the image data storage means, and the histogram is controlled. Using the data of the histogram created by the histogram creating means by the means, the contrast enhancing means is operated so that the image displayed on the display means does not cause halation. As a result, it is possible to prevent deterioration of the display image due to halation without changing the amplification characteristic of the video system device one by one, and it is possible to perform image analysis processing that does not include an error in the density information of the image. ..

[0009]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing an embodiment of a medical X-ray imaging apparatus according to the present invention. This medical X-ray imaging apparatus radiates X-rays to a subject and obtains a transmitted X-ray image to perform X-ray fluoroscopy, and as shown in FIG. 1, an X-ray tube device 2 and an image system device. 4, A / D converter 5, frame memory 6, lookup table 7, display means 8,
A central processing unit (hereinafter abbreviated as “CPU”) 9 is provided, and a buffer memory 15 and a histogram creating circuit 16 are further provided.

The X-ray tube device 2 is designed so that the X-ray tube device 2 directs X-rays toward the subject 3.
It radiates a line and is adapted to apply a high voltage supplied from the X-ray high voltage apparatus 1. The video device 4 is
It converts the X-ray image radiated from the X-ray tube device 2 and transmitted through the subject 3 into visible light and also converts it into an electric signal, and is arranged to face the X-ray tube device 2 with the subject 3 interposed therebetween. It is composed by combining II10 which receives the transmitted X-ray image of the subject 3 and converts it into a visible light image, and a television camera 11 which captures an output optical image of this II10 and converts it into an electric signal.

The A / D converter 5 inputs a video signal output from the television camera 11 of the video system device 4 and converts it into a digital signal. The frame memory 6 serves as a means for storing the digital image data output from the A / D converter 5, and has a storage capacity of, for example, several hundred frames and corresponds to each frame. Image data can be stored one after another.

The look-up table 7 serves as a contrast emphasizing means for inputting the image data read from the frame memory 6 and emphasizing the contrast of the image data. The table data in which the contrast enhancement characteristic which level is set is set is written.

The display means 8 serves as means for converting the image data subjected to the contrast enhancement by the look-up table 7 into a video signal and displaying it as an image.
A D / A converter 12 for converting the image data input from the look-up table 7 into an analog video signal;
The television monitor 13 receives the video signal output from the D / A converter 12 and displays it as an image.
The CPU 9, which serves as control means for controlling the operation of each of the above-described components, reads the image data stored in the frame memory 6 and also performs image analysis processing on the density information. .. In FIG. 1, reference numeral 14 indicates a CPU bus.

Here, in the present invention, a buffer memory 15 is provided between the frame memory 6 and the look-up table 7, and between the output side of the frame memory 6 and the CPU bus 14. A histogram creating circuit 16 is provided. The buffer memory 15 is
The image data transferred from the frame memory 6 to the look-up table 7 is delayed by one frame, and the image data written in the frame memory 6 is immediately read out while the image is being captured, and the buffer memory 15
The image data written in the buffer memory 15 and then read from the buffer memory 15 is sent to the lookup table 7. In addition, the histogram creation circuit 16
Is a means for creating a histogram of density information for the image data read from the frame memory 6, and at the same time as the image data D from the frame memory 6 is written in the buffer memory 15, a histogram of the image is created. It is supposed to do. In this case, in order to create a histogram of density information for an image, all the image data of the image needs to be input into the histogram creating circuit 16. That is, the histogram for the image is completed after all the image data of the image is read from the frame memory 6. Therefore, the buffer memory 15 delays the image data by one frame and inputs the delayed image data to the look-up table 7 so that the contrast enhancement setting contents of the look-up table 7 and the image data are temporally associated with each other. ..

FIG. 2 is a block diagram showing an example of the internal configuration of the above-mentioned histogram creating circuit 16. The histogram creating circuit 16 is a RAM for creating and storing a histogram.
(Random read / write memory) 17, first to third multiplexers 18a, 18b, 18c connected to the data input line, address line and write control line of the RAM 17, and connected to the data output line of the RAM 17. 3 state buffer 19,
And an adder 20.

Next, the operation of the histogram creating circuit 16 having such a configuration will be described. First, while the blanking signal B of the television camera 11 shown in FIG. 1 indicates the blanking period, the three multiplexers 18a, 18b,
The operation of 18c and the 3-state buffer 19 causes RA
Each of the M17 data input line, address line, write control line and data output line is C
It is connected to the PU bus 14. At this time, the CP shown in FIG.
The U9 reads the histogram stored in the RAM 17 during the blanking period via the CPU bus 14 and clears the contents of the RAM 17 in preparation for the creation of the histogram of the next frame. Then, when the blanking period ends, each line of the RAM 17 is switched to the histogram creation state.

In this state, the frame memory 6 shown in FIG.
The image data D read from the second multiplexer 1
By inputting to the address line of the RAM 17 via 8b, the data is read from the address corresponding to the image data D, output from the data output line and input to one input terminal of the adder 20. After adding "1" at, the data is input to the data input line via the first multiplexer 18a and written to the same address as above. At this time, the pixel clock CK is input to the write control line of the RAM 17 through the third multiplexer 18c, the data is read in the first half of one pixel period and output from the data output line, and the adder 20 outputs "1". After adding, the data can be written to the same address as the read address by inputting and writing the data to the data input line via the first multiplexer 18a in the latter half of one pixel period.

By the above operation, the number of times the image data is input to the address corresponding to the image data is stored in the RAM 17. If this operation is performed for one frame period of an image, a histogram of density information is created in the RAM 17 for the image data to be obtained.

Further, in the present invention, the CPU 9
Is the television monitor 1 of the display means 8 using the data of the histogram created by the histogram creating circuit 16.
The contrast enhancement characteristic of the look-up table 7 can be controlled so that the image displayed in 3 does not cause halation.

Next, how to change the contrast enhancement state of the image display according to the histogram of the image created as described above will be described with reference to FIG. First, in FIG. 3, the graph shown in the upper part (a) is a histogram of an image, the horizontal axis indicates the image data value of the image, and the vertical axis indicates the number of pixels.
In addition, the graph shown in the lower part (b) shows the input / output characteristics of the look-up table 7 that applies contrast enhancement to a certain image, the horizontal axis shows the input image data value, and the vertical axis shows the output image data value. Shows. In such a state, under normal conditions, the histogram of the image is set so as to fall within the range A as shown by the solid curve in FIG.
The amplification factor characteristic of the television camera 11 shown in is adjusted in advance. In accordance with this, in the lookup table 7,
As shown by the solid curve in FIG. 3B, the contrast enhancement characteristic is set so that the contrast enhancement is performed in the range A and the halation is caused for the input in the range exceeding A.

Next, in this state, the television camera 11
When a part having a high X-ray transmittance and a bright image is included in the field of view of the image, the data value of the image becomes large. Therefore, the histogram of the image in this case is as shown in FIG.
Changes over the range of A as indicated by the broken curve. At this time, the input / output characteristics of the look-up table 7 for applying contrast enhancement to the image are shown in FIG.
If the curve shown by the solid line is left as it is, halation occurs in the portion A'exceeding the range of A. Therefore, the CPU 9 shown in FIG. 1 refers to the blanking signal B, reads the histogram data from the histogram creation circuit 16 via the CPU bus 14 during the blanking period,
The input / output characteristics of the lookup table 7 are shown in FIG. 3 according to the state of the histogram shown by the broken line curve in FIG.
It is changed as shown by the broken line curve in (b). Then, as is clear from FIG. 9B, the output image data value of the A ′ portion is changed to the contrast enhancement characteristic in which the input image data value is suppressed, and the output is prevented from being saturated. As a result, halation of the image can be suppressed and deterioration of the display image can be prevented without impairing the contrast of the entire display image on the television monitor 13.

In the embodiment shown in FIG. 1, since the buffer memory 15 is provided in the subsequent stage of the frame memory 6 and the time delay required for histogram creation in the histogram creation circuit 16 is adjusted by the buffer memory 15, It is possible to give a change in contrast enhancement characteristics to the image data input to the up table 7 without a tracking delay. However, if the following delay is not a serious problem, the buffer memory 15 may not be provided.

[0023]

Since the present invention is constituted as described above, the image read from the storage means (6) by the histogram creating means (16) provided on the output side of the image data storage means (6). A density information histogram is created for the data, and the control means (9) uses the histogram data created by the histogram creation means (16) to contrast the image displayed on the display means 8 without causing halation. The emphasis means (7) can be controlled. As a result, it is possible to suppress deterioration of the display image due to halation without changing the amplification characteristic of the video system device 4 one by one. Further, during the collection of the image data, the amplification characteristic of the video system device 4 is constant, so that the density information of the image data can be obtained under a constant condition, and the density information of the image does not include an error. Image analysis processing can be enabled. Therefore, for example, an angiographic examination of the heart can be performed accurately.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a medical X-ray imaging apparatus according to the present invention,

FIG. 2 is a block diagram showing an internal configuration example of a histogram creation circuit,

FIG. 3 is an explanatory diagram showing a relationship between a graph showing a histogram of an image and a graph showing an input / output characteristic of a lookup table for applying contrast enhancement to the image;

FIG. 4 is a block diagram showing a conventional medical X-ray imaging apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... X-ray high-voltage device, 2 ... X-ray tube device, 3 ... Subject, 4 ... Image system device, 5 ... A / D converter, 6 ... Frame memory, 7 ... Lookup table, 8 ... Display means, 9 ... CPU, 10 ... II, 11 ... TV camera, 12 ... D / A converter, 13 ... TV monitor,
15 ... Buffer memory, 16 ... Histogram creating circuit.

Claims (1)

Claim: What is claimed is: 1. An X-ray tube device which is supplied with a high voltage from an X-ray high voltage device and emits X-rays, and an X-ray image emitted from the X-ray tube device and transmitted through a subject. System for converting light into visible light and electrical signals, A / D converter for converting output signals from the video system into digital signals, and digital image data from the A / D converter And a contrast enhancing means for enhancing the contrast of the image data read out from the storing means, and the image data subjected to the contrast enhancing by the contrast enhancing means to a video signal and displayed as an image. In a medical X-ray imaging apparatus having a display unit for controlling the above-mentioned components and a control unit for controlling each of the above-mentioned components, the density information of the image data read from the storage unit is displayed. In addition to providing a histogram creating means for creating a program, the control means controls the contrast enhancing means using the data of the histogram created by the histogram creating means so that the image displayed on the display means does not cause halation. A medical X-ray imaging apparatus characterized in that the medical X-ray imaging apparatus is used.