JPH02306233A - 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 giving warning when an abnormal image element exceeds a threshold. CONSTITUTION:A normalized correction factor(continuous line) obtained in a state where an object does not exist just when the phosphor sheet is ex changed is stored in a memory 5 for initial correction factor. Then, a normalized correction factor(dotted light) obtained in a state where an object does not exist when a power source is turned on in the morning is 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 the specified threshold, the image elements in such parts is counted to be displayed as the abnormal image ele ment. When the abnormal image elements, for example, exceeds 1% total image elements or when the abnormal image elements consecutively exceeds 0.1% total image elements by number, the warning message such as the exchange of the stimulable phosphor sheet is displayed by judging that the sheet can not be used. Thus, the state of an X-ray image detection system is accurately displayed and the device serves the prevention of the erroneous diagnosis.

Description

[Detailed Description of the Invention] Required by Cm] Regarding 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, Compares the condition of the phosphor plate and its condition during use, displays the number of abnormal pixels, etc., displays a warning message when the threshold is exceeded, displays the status of the device, and helps prevent misdiagnosis during diagnosis. With the aim of An initial correction coefficient memory for storing normalized correction coefficients for line images; Digital X obtained from
A correction coefficient memory that stores normalized correction coefficients for line images, and a correspondence between the correction coefficient value of each pixel stored in the correction coefficient memory and the correspondence stored in the initial correction coefficient memory. Compare the correction coefficient value of each pixel, count and display the number of pixels with a difference of more than a predetermined threshold, and if necessary, display a warning message when this counted value is greater than a predetermined threshold. Configure it as follows.

[Industrial application field]

The present invention relates to a digital X-ray apparatus that exposes a photostimulable phosphor plate to X-rays that have passed through an object and scans the plate with excitation light to obtain a digital X-ray image.

[Prior art and problems to be solved by the invention] Conventionally, as a high-sensitivity, high-resolution X-ray imaging system, a stimulable phosphor plate (sheet) composed of M-loaded phosphors in the form of a sheet has been used. X-rays that have passed through the object are exposed to the object. 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 a digital X'fIIA image using this method, the photostimulable phosphor plate may absorb moisture and deteriorate its characteristics.
If the phosphor plate, the part where the laser beam scans, the part that collects the emitted light, the light receiving part that converts the collected light into an electrical signal, etc. is scratched or has dust attached, There has been a problem in that information that does not exist on the subject appears as if it does, leading to the possibility of misdiagnosis.

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

The present invention compares the initial state of the photostimulable phosphor plate and the state during use, displays the number of abnormal pixels, etc., displays a warning message when a threshold is exceeded, displays the state of the device, and diagnoses the device. The aim is to help prevent misdiagnosis.

[Means to solve problems]

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

In FIG. 1, the initial correction coefficient memory 5 is configured to expose the photostimulable phosphor plate to X-rays when there is no subject at the beginning of replacing the photostimulable phosphor plate, etc., and to use it as excitation light. This is a memory that stores standardized correction coefficients for digital X-ray images obtained by scanning.

Prior to use, the correction coefficient memory 6 normalizes a digital X-ray image obtained by exposing a photostimulable phosphor plate to X-rays in the absence of an object and scanning this with excitation light. This is a memory that stores the corrected correction coefficients.

The abnormality detection unit 7 determines whether the value of the correction coefficient for each pixel read from the memory 6 for correction coefficients and the value of the correction coefficient for each pixel read from the memory 5 for initial correction coefficients are equal to or higher than a predetermined threshold value. This is to detect whether there is a difference.

(Function) As shown in FIG. 1, the present invention exposes the photostimulated phosphor plate to X-rays in the absence of an object at the beginning of replacing the photostimulated phosphor plate, etc. An initial correction coefficient memory 5 for storing normalized correction coefficients of a digital X-ray image obtained by scanning with excitation light; A correction coefficient memory 6 is provided to store normalized correction coefficients of a digital XvA image obtained by exposing a plate and scanning it with excitation light, and the abnormality detection unit 7 reads from the correction coefficient memory 6. The correction coefficient value of each pixel and the corresponding initial correction coefficient memory 5
Detects and counts the difference between the correction coefficient value of each pixel read out by more than a predetermined threshold, displays this counted value, and displays a warning message when the counted value is more than a predetermined threshold. I am trying to display the following.

Therefore, by comparing the initial state of the phosphor plate and the state during use, displaying the number of abnormal pixels, etc., and displaying a warning message when the number of abnormal pixels exceeds a threshold value. In addition to displaying the status of the device, it is also possible to prevent misdiagnosis during diagnosis.

〔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 emitted from an X-ray generator 21 and having an energy of, for example, 75 KeV are transferred to a stimulable phosphor plate 23.
exposed to light. Then, the laser beam emitted from the laser light source 24 as excitation light is transferred to a polygon mirror 25 and a lens 26.
, scans the photostimulated phosphor plate 23 at high speed via the reflecting mirror 27. In synchronization with this scanning, the photostimulated phosphor plate 23 is moved in a direction perpendicular to the scanning direction, and the photostimulated phosphor plate 23 is
Line scan the entire surface of 3. At this time, as shown in FIG. 3(a), a glass fiber is provided to collect the light emitted from the scanning line part, and the light is collected into the charging converter (
For example, after photo-electrical conversion is performed by PMT) I, it is amplified by amplification WS2 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 an X-ray image.

Next, the configuration and operation of one embodiment of the present invention will be sequentially explained in detail using FIG.

In FIG. 1, a photoelectric converter l converts light corresponding to an X-ray image emitted by excitation light into an electrical signal.

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

The frame memory 3 stores detected and AD-converted X-ray image signals (X-ray image data) in units of frames.

The correction coefficient conversion unit 4 converts the X-ray image data read from the frame memory 3 into standardized values (brightness degrees) of each pixel. For example, the average value of all pixels of an X-ray image, the average value of multiple pixels, or the photostimulable phosphor plate 23
Convert to a normalized value by dividing by the initial average value of the exchange.

The initial correction coefficient memory 5 stores each of the This memory stores correction coefficients that have been normalized by the correction coefficient conversion unit 4 for pixel values (degrees of brightness).

The correction coefficient memory 6 stores the photostimulable phosphor plate 23 under standard conditions with no subject present before using the photostimulated phosphor plate 23, for example, when turning on the power every morning or at regular intervals. The value of each pixel of the X-ray image obtained when the entire surface was exposed with
This is a memory that stores correction coefficients after being standardized by the correction coefficient conversion unit 4 regarding the degree of brightness.

The abnormality detection unit 7 reads out the correction coefficient for each pixel read from the correction coefficient memory 6 and the correction coefficient for each pixel at the time of replacement of the photostimulable phosphor plate 23, etc., read out from the initial correction coefficient memory 5. The number of pixels whose difference is equal to or greater than a predetermined threshold value is detected.

The abnormal pixel number/warning generating section 8 displays the abnormal pixel number notified from the abnormal pixel detection section 7 on the panel of the digital %, or if there are consecutive abnormal pixels of 0.1% or more), a warning is displayed indicating that the characteristics of the photostimulable phosphor plate 23 have deteriorated and should be replaced. .

The image data correction unit 9 corrects the X-ray image read from the frame memory 3 based on the correction coefficient read from the correction coefficient memory 6.

The image processing section 10 edits the image data input from the image data correction section 9 and displays the edited image data on the screen.

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.

In this case, the X-ray image existing as a latent image on the photostimulable phosphor vi23 is scanned with a laser beam, the light emitted is focused by a glass fiber, and the light is converted into electricity by a photoelectric converter (PMT etc.) 1. This shows how the data is 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, v! Image data is 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. . In addition, the dotted line in the figure is the normalized correction coefficient obtained in a state where there is no subject, such as when the power is turned on in the morning.
It is something to remember. Here, since the brightness of the portions marked with dotted lines ■ and ■ is darker than a predetermined threshold value, the pixels in these portions are counted and displayed as abnormal pixels. Also, the number of abnormal pixels is, for example, 1% of the total number of pixels.
If the number of abnormal Wi pixels exceeds 0.1% of the total number of pixels in a row, the device is deemed unusable and a warning message such as "Please replace the phosphor plate" is displayed. I try to do this.

Incidentally, a plurality of phosphor plates 23 are provided in the digital X-ray apparatus,
Alternatively, even if the X-ray imaging device and reading device are separate, determine the multiple photostimulable phosphor plates to be used, store the standardized correction coefficients for these in advance, and switch to the appropriate one. You may also exchange it for something else.

〔Effect of the invention〕

As explained above, according to the present invention, the number of abnormal pixels is displayed by comparing the initial state of the photostimulable phosphor plate and the state at the time of use, and when the number of abnormal pixels exceeds a threshold value, Since it is configured to display warning messages, it is possible to accurately display the status of the X-ray image detection system such as the phosphor plate, and it can also be used to prevent misdiagnosis during diagnosis. .

[Brief explanation of the drawing]

, FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is a block diagram of an example of an X-ray exposure/scanning system, and FIG. 3 is an explanatory diagram of 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 an abnormality detection unit, 8 is the number of abnormal pixels/warning occurrence 21 represents an X-ray generator, 22 represents an object, and 23 represents a photostimulable 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 normalized correction coefficients of an image is provided.
The value of the correction coefficient for each pixel stored in 6) is compared with the value of the corresponding correction coefficient for each pixel stored in the initial correction coefficient memory (5), and the difference is greater than a predetermined threshold. A digital X-ray apparatus characterized in that it is configured to count and display a certain number of pixels, and further to display a warning message when the counted value exceeds a predetermined threshold value, if necessary.