JPH02306234A - Digital x-ray device - Google Patents

Abstract

PURPOSE:To prevent an erroneous diagnosis by comparing the initial state of a stimulable phosphor sheet with the state thereof at the time of being used and displaying the state individually or after superposing it on an X-ray image. CONSTITUTION:Among one line of correction factors obtained by normalizing the respective image elements of X-ray image data read out from a frame memory 3, the correction factor obtained in a state where an object does not exist just when the stimulable phosphor sheet is exchanged is expressed by a continuous line and stored in a memory 5 for initial correction factor, and the correction factor obtained in a state where the object does not exist when the sheet is used is expressed by a dotted line and stored in a memory 6 for correction factor. Since brightness in the parts A and B of the dotted line is darker to be equal to or exceeding a thershold, the image elements in such parts are counted by an abnormal image element distribution processing part 9 and data on abnormal image element distribution is stored. An image processing part 13 superposes the data on the X-ray image data on a screen so as to display the abnormal image element distribution by using gradation or changing colors. Thus, accurate X-ray image information is obtained and the erroneous diagnosis is prevented.

Description

[Detailed Description of the Invention] [(Already required)] Regarding a digital X-ray device that exposes a photostimulable phosphor plate to X-rays that have passed through a subject and scans this with excitation light to obtain a digital X-ray image, The purpose is to display the abnormal pixel distribution by comparing the original state of the photostimulated phosphor plate and the state during use, to help prevent misdiagnosis during diagnosis, and to facilitate the management of the photostimulated phosphor plate, etc. When the photostimulable phosphor plate, etc. is initially replaced, the photostimulated phosphor plate is exposed to X-rays in the absence of an object, and this is scanned with excitation light to obtain a digital X-ray image. A memory for the initial y4 correction coefficient that stores the normalized correction coefficient of A correction coefficient memory for storing standardized correction coefficients of a digital X-ray image, and the value of the correction coefficient of each pixel stored in this correction coefficient memory and the initial correction coefficient memory. Compare the stored correction coefficient values of each corresponding pixel to find the distribution of abnormal pixels that have a difference of more than a predetermined darkness value,
The abnormal pixel distribution is displayed superimposed on the X-ray image or displayed in association with the X-ray image.

(Industrial Application Field) The present invention relates to a digital X-ray device that exposes a photostimulating phosphor plate to X-rays that have passed through an object and scans it with excitation light to obtain a digital X-ray image. be.

[Prior art and problems to be solved by the invention] Conventionally, a high-sensitivity, high-resolution X-ray imaging system uses a stimulable phosphor plate (sheet) composed of a stimulable phosphor in the form of a sheet. , which is exposed to X-rays that have passed through the subject. A spot-shaped laser beam is scanned as excitation light on the exposed photostimulable phosphor plate on which the latent image exists, and the light emitted at this time is collected and detected by a PMT (photomultiplier), and then converted into a digital value. There is a method to obtain an X-ray image of a subject by converting it into

When obtaining digital X-ray images using this method, the photostimulated phosphor plate may absorb moisture and its properties may deteriorate, or the photostimulated phosphor plate, the part scanned by the laser beam, or the emitted light may If the collecting part or the light receiving part that converts the collected light into electrical signals is scratched or has dust attached to it, information that does not exist on the subject will appear as if it exists, leading to misdiagnosis. There was a problem with the possibility that

Therefore, it is desired to detect the above-mentioned inconveniences of the X-ray imaging system before performing X-ray imaging on the subject, thereby reducing unnecessary radiation exposure and the possibility of misdiagnosis.

The present invention displays the abnormal pixel distribution by comparing the initial state of the photostimulated phosphor plate and the state during use, which helps prevent misdiagnosis during diagnosis and facilitates the management of the photostimulated phosphor plate. is intended to do.

[Means to solve problems]

Means for solving the problem will be explained with reference to FIG.

In FIG. 1, when the initial correction coefficient memory 5 is used to replace the photostimulable phosphor plate, etc., the photostimulable phosphor plate is exposed to X-rays in the absence of an object, and is then exposed to excitation light. This is a memory that stores standardized correction coefficients for digital X-ray images obtained by scanning.

The correction coefficient memory 6 normalizes both digital X-ray images obtained by exposing a photostimulated phosphor plate to X-rays and scanning it with excitation light in the absence of an object during use. This is a memory that stores correction coefficients.

The comparison calculation unit 7 compares the value of the correction coefficient of each pixel read from the memory 6 for correction coefficients and the value of the correction coefficient of each pixel read from the corresponding memory 5 for initial correction coefficients, This method calculates the distribution of the number of abnormal pixels in which the pixels have a difference of more than a predetermined darkness value.

[Effect]

As shown in FIG. 1, the present invention involves exposing the photostimulable phosphor plate to X-rays in the absence of an object at the beginning of replacing the photostimulable phosphor plate, etc., and then using excitation light to an initial correction coefficient memory 5 for storing standardized correction coefficients of digital X-ray images obtained by scanning; A correction coefficient memory 6 is provided to store normalized correction coefficients of a digital X-ray image obtained by scanning the digital X-ray image with excitation light. The value of the correction coefficient is compared with the corresponding value of the correction coefficient of each pixel read from the initial correction coefficient memory 5, and an abnormal pixel distribution having a difference of more than a predetermined darkness value is determined, and this pixel distribution is calculated. X
The image is displayed superimposed on both line images or separately in association with each pixel.

Therefore, by comparing the initial state of the photostimulated phosphor plate and the state during use and displaying the abnormal pixel distribution,
It becomes possible to help prevent misdiagnosis at the time of diagnosis, and
It becomes possible to manage the photostimulated phosphor plate easily.

〔Example〕

First, an example of the configuration and operation of the X-ray exposure/scanning system will be explained using FIG.

In FIG. 2, X-rays having an energy of, for example, 75 KeV emitted from an XyA generator 21 are transmitted to a photostimulating phosphor plate 2.
Exposure to 3. Then, the laser beam emitted from the laser light source 24 as excitation light is passed through the polygon mirror 25 and the lens 2.
6. Scan the photostimulated phosphor plate 23 at high speed via the reflection mirror 27. In synchronization with this scanning, the photostimulated phosphor plate 23 is moved in a direction perpendicular to the scanning direction to scan the entire surface of the photostimulated phosphor plate 23 in a line. At this time, Figure 3 (a)
As shown in , a glass fiber is provided to collect the light emitted from the scanning line portion, and after the light is collected and subjected to optical-to-electrical conversion by a photoelectric converter (for example, r'MT) 1, It is amplified by an amplifier 2 to generate X-ray image data.

With the above configuration, an image existing as a latent image on the photostimulable phosphor plate 23 is detected as X-ray image data.

Next, the configuration and operation of one embodiment of the present invention will be sequentially explained in detail using FIG. Here, the solid line indicates the connection when performing standard imaging for correction and determining abnormal pixel distribution, etc., and the dotted line indicates the connection when performing imaging of the chest, etc. to obtain an image and displaying the X-ray image. show.

In FIG. 1, a photoelectric converter 1 converts light emitted by excitation light into an electrical signal.

The amplifier 2 amplifies the signal converted by the photoelectric converter 1.

The A/D converter 2-1 converts the analog X-ray image signal amplified by the amplifier 2 into digital X-ray image data.

The frame memory 3 stores X&1 image data in units of frames.

The correction coefficient conversion unit 4 includes an average value calculation unit 4-1 that calculates the average value of the X-ray image data read from the frame memory 3.
, and a normalization calculation unit 4-2 that divides and normalizes the X-ray image data based on the calculated average value. This normalization is carried out by dividing by, for example, the average value of all pixels of the X-ray image, the average value of a plurality of pixels, or the initial average value after replacing the photostimulable phosphor plate 23. .

The initial correction coefficient memory 5 contains X-ray image data obtained when the photostimulated phosphor plate 23 is fully exposed under standard conditions without the original subject after replacing the photostimulated phosphor plate 23. This memory stores correction coefficients after normalization by the correction coefficient conversion unit 4 for the values (degrees of brightness) of each pixel.

The correction coefficient memory 6 stores the value (degree of brightness) of each pixel of X-ray image data obtained when the photostimulable phosphor plate 23 is fully exposed under standard conditions without a subject at the time of use. , a memory that stores the correction coefficients after being standardized by the correction coefficient converter 4.

The comparison calculation unit 7 compares the correction coefficient of each pixel read from the correction coefficient memory 6 and the correction coefficient of each pixel read from the initial correction coefficient memory 5 at the time of replacement of the photostimulable phosphor plate 23, etc. The pixel comparison unit 7-1 includes a pixel comparison unit 7-1 that compares and detects abnormal pixels having a predetermined darkness value or more, and an average value comparison unit 7-2 that compares their average values.

The abnormal pixel number counter 8 counts the number of abnormal pixels detected by each pixel comparing section 7-1.

Abnormal pixel distribution processing unit 9, distribution information (matrix position information, etc.) of abnormal pixels detected by each pixel comparison unit 7-l
It is a collection of information. This abnormal pixel distribution information is expressed in the form of the matrix address of the abnormal pixel, or the start and end addresses of consecutive abnormal pixels in one row.

The cause analysis unit 10, based on abnormal pixel distribution data etc.
For example, if the number of abnormal pixels exceeds 1% of the total number of pixels,
Or the number of consecutive abnormal pixels is 0.1% of the total number of pixels
The system analyzes the cause when the phosphor plate exceeds the limit and displays a corresponding warning message such as ``Replace the phosphor plate.''

The image data correction section 11 corrects the X-ray image data read from the frame memory 3 based on the correction coefficients read from the correction coefficient memory 6.

The interface 12 is an interface for transferring the X-ray image data corrected by the image data correction section 11 and the abnormal pixel distribution data obtained by the abnormal pixel distribution processing section 9 according to this embodiment to the image processing section 13.

The image processing unit 13 performs editing based on the transferred XvA@ image data and abnormal pixel distribution data, and superimposes the abnormal pixel distribution data on the X-ray image (for example, by changing the density or changing the color). (superimposed) or
Image processing is performed to display the abnormal pixel distribution associated with the pixels on a screen separate from the line image. In this way, the abnormal pixel distribution is superimposed and displayed on the X-ray image,
Alternatively, by displaying the abnormal pixel distribution in association on a separate screen, accurate X-ray image information can be obtained.
It becomes possible to prevent misdiagnosis during diagnosis, and it becomes possible to easily manage the photostimulable phosphor plate and the like.

Next, the operation of the configuration shown in FIG. 1 will be explained using FIG.

FIG. 3(a) shows an example of reading out X-ray image data.

This is done by scanning the X-ray image existing as a latent image on the stimulable phosphor plate 23 with a laser beam, emitting the light, condensing it with a glass fiber, and converting it into a photoelectric converter (PMT, etc.). This shows how the data is converted, amplified by the amplifier 2, and X-ray image data is detected.

FIG. 3(B) shows one line of the X-ray image data detected in FIG. 3(A). For example, 1 line is 200
It is composed of 0 pixels, and the curve shown is for exposure under standard conditions without an object. Here, as shown in the figure, the values (brightness) at both ends of one line of X-ray image data become smaller due to fluctuations in laser output in a curved manner.

In addition, due to the property of the photostimulating phosphor plate 23 being exposed to X-rays, which gradually attenuate, the value (brightness) gradually decreases as the detection time in the figure becomes later. Decrease. These detected X-ray image data are stored frame by frame in the frame memory 3 in FIG.

FIG. 3(c) shows a normalized correction coefficient (value corresponding to brightness) for one line for each pixel of the X-ray image data read out from the frame memory 3. In the figure, the solid line is the normalized correction coefficient obtained in the original state without a subject after replacing the photostimulating phosphor plate 23, etc., and is stored in the initial correction coefficient memory 5 in Fig. 1. . Moreover, the dotted line in the figure is the normalized correction coefficient obtained in the absence of a subject during use, and is stored in the correction coefficient memory 6 in FIG. Here, the brightness of the parts marked with dotted lines ■ and ■ is darker than the predetermined darkness value, so the pixels in these parts are counted as abnormal pixels and the matrix number (abnormal pixel distribution data) of this abnormal pixel is memorized. (Performed by the abnormal pixel distribution processing unit 9 in FIG. 1).

The first drawing image processing unit 13, which has received the notification of the stored abnormal pixel distribution data, superimposes the abnormal pixel distribution on the X-ray image data of the chest, etc., displayed on the screen by gradation.
Or display it in different colors.

Furthermore, the abnormal pixel distribution may be displayed on a screen separate from the screen on which the X-ray image of the chest or the like is displayed.

In this way, by superimposing or separately displaying the distribution of abnormal pixels such as the phosphor plate 23 on the X-ray image and referring to it, accurate X-ray image information can be obtained, which is useful during diagnosis. This makes it possible to prevent misdiagnosis.

In addition, if the number of abnormal pixels exceeds, for example, 1% of the total number of pixels, or if the number of abnormal pixels continues to exceed 0,1% of the total number of pixels,
%, a warning message such as "Please replace the photostimulated phosphor plate" may be displayed to indicate that it cannot be used.

Furthermore, even when a plurality of photostimulable phosphor plates 23 are provided in a digital X-ray device, or when the X-ray imaging device and the reading device are separate, the plurality of photostimulable phosphor plates to be used can be determined, Store normalized correction coefficients for these in advance,
It is also possible to switch to display the abnormal pixel distribution of the corresponding one.

〔Effect of the invention〕

As explained above, according to the present invention, a configuration is provided in which the initial state of the photostimulable phosphor plate and the state at the time of use are compared and the abnormal pixel distribution is superimposed on or separately displayed on an X-ray image of a chest or the like. Since this method is adopted, positive X-ray image information can be obtained, which can be used to prevent misdiagnosis during diagnosis. Furthermore, it is possible to easily manage devices including a photostimulable phosphor plate by referring to the abnormal pixel distribution.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of one embodiment of the present invention, and Figure 2 is an X-ray exposure/
An example of a scanning system configuration diagram, FIG. 3 is a diagram illustrating the operation of the present invention. In the figure, 1 is a photoelectric converter, 3 is a frame memory, 4 is a correction coefficient conversion unit, 5 is a memory for initial correction coefficients, 6 is a memory for correction coefficients, 7 is a comparison calculation unit, and 7-1 is each pixel comparison unit ,7
-2 is an average value comparison unit, 8 is an abnormal pixel number counter, 9 is an abnormal pixel distribution processing unit, 10 is a cause analysis unit, 11 is an image data correction unit, 13 is an image processing unit, 21 is an X-ray generator, 22
23 represents a photostimulated phosphor plate.

Claims (1)

[Scope of Claims] A digital X-ray device that exposes a photostimulable phosphor plate to X-rays that have passed through an object and scans it with excitation light to obtain a digital X-ray image, comprising: a photostimulable phosphor plate; At the beginning of the exchange, store the standardized correction coefficients of the digital X-ray image obtained by exposing the photostimulable phosphor plate to X-rays in the absence of an object and scanning it with excitation light. A memory (5) for initial correction coefficients to be used, and a digital A correction coefficient memory (6) for storing standardized correction coefficients, and a correction coefficient memory (5) for each pixel stored in the correction coefficient memory (6) and the initial correction coefficient memory (5). The distribution of abnormal pixels with a difference of more than a predetermined threshold is determined by comparing the values of the correction coefficients of each corresponding pixel stored in the , and this abnormal pixel distribution is superimposed on the X-ray image and displayed or on a separate screen. A digital X-ray device characterized by being configured to display information in association with the above.