JP3989777B2 - X-ray fluoroscopy system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an X-ray fluoroscopic inspection apparatus in a non-destructive inspection apparatus, and in particular, an X-ray fluoroscopic inspection that facilitates inspection of an X-ray detector, an X-ray generator, and a display unit provided in the X-ray fluoroscopic inspection apparatus. Relates to the device.
[0002]
[Prior art]
In recent years, X-ray fluoroscopic inspection apparatuses for inspecting small electronic components and the like with high resolution have been made.
[0003]
The X-ray fluoroscopic examination apparatus displays an X-ray generator that outputs X-rays, an X-ray detector that detects X-rays transmitted through a subject with a two-dimensional resolution, and a detected image as a two-dimensional transmission image. And a display unit.
The X-ray detector is an X-ray I.D. I. A combination of (image intensifier) and a TV camera is used.
[0004]
When inspecting a subject with the X-ray fluoroscopic examination apparatus, first, an X-ray generator and an X-ray I.D. I. A subject is placed between them, and X-rays are output from the X-ray generator toward the subject. The X-rays transmitted through the subject are converted into X-rays I.D. I. Then, the image is visualized with a two-dimensional resolution, and the visualized image is taken with a television camera. The captured transmission image is displayed on a display unit, and the internal state of the subject is inspected by the operator viewing it.
[0005]
[Problems to be solved by the invention]
The X-ray detector is an X-ray I.D. I. In general, it is not limited to a combination of a TV camera and a TV camera. Generally, X-ray irradiation with the same energy spectrum and dose rate associated with X-ray irradiation over a long period of time causes the entire image to deteriorate due to its sensitivity degradation and printing. And some luminance changes.
[0006]
This change in luminance is not uniform on the screen, and changes depending on how many subjects are present and how many times the subject having the same shape is examined. Further, the luminance change is caused by failure or deterioration of the X-ray generator or the display unit.
[0007]
Conventional X-ray fluoroscopic inspection devices have different operators who determine the deterioration of the X-ray detector, X-ray generator and display, and the timing of inquiry to the manufacturer (or the timing of replacement). There was a problem that in some cases, the inspection was continued in a very poor state.
[0008]
The present invention has been made in view of the above problems, and an object thereof is to provide an X-ray fluoroscopic inspection apparatus capable of easily inspecting an X-ray detector, an X-ray generator, and a display unit. .
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the invention described in claim 1 irradiates the subject with X-rays, detects the X-rays transmitted through the subject with an X-ray detector, and transmits a transmission image of the subject. A first transmission image captured in the initial stage of use without placing the subject, and after the passage of an arbitrary period from the beginning of use, the first transmission image A second transparent image taken under the same conditions as when shooting, At the beginning of use, a third transmission image is stored that is captured in a state where the X-rays generated by the X-ray generation means for generating X-rays are changed to a predetermined ratio from the same conditions as when the first transmission image is captured. Storage means for Calculating means for calculating a difference value a between corresponding pixels of the second and first transparent images for each pixel; Calculating means for calculating a predetermined allowable value from a difference value b between corresponding pixels with the third and first transmission images; The difference value a or the evaluation amount calculated from the difference value a is Said The gist of the present invention is to include comparison means for comparing whether or not the value is outside the allowable value, and determination means for determining that the second transmission image is abnormal from the result of the comparison.
[0010]
In the present invention, when a reference transmission image capturing command is input from an external input unit in the absence of a subject at the beginning of use of the X-ray detector, the X-ray tube built in the X-ray generator is A tube transmission voltage and a tube current are set to predetermined conditions, a reference transmission image (first transmission image) is taken and stored in the storage means. When a test transmission image capturing command is input without a subject after an arbitrary period of use, the same conditions as when capturing a reference transmission image (X-ray tube voltage and X-ray tube current are set as predetermined conditions) Then, a test transmission image (second transmission image) is taken and stored in the storage means. Next, the test transmission image and the reference transmission image are read from the storage means, a difference between corresponding pixels is obtained for each pixel, this difference (or an evaluation amount calculated from this difference) is compared with a predetermined allowable value, and X is calculated for each local area. Determine possible degradation of the line detector. If it is detected that the difference exceeds a predetermined allowable value, even if it is determined to be abnormal, the maximum change part is detected not only in a uniform sensitivity change but also in a heterogeneous group-like sensitivity change. It can be determined whether or not the allowable value has been exceeded, and the change is not affected by the image noise accurately.If the pixel value has changed more than the allowable value even in a part of the transmission image, this can be detected and output. For the operator, the temporary inspection of the X-ray detector (and the X-ray generator) can be easily performed automatically.
[0012]
In the present invention, when a reference transmission image capturing command is input from the external input unit in a state where there is no subject at the beginning of use of the X-ray detector, the X-ray generator determines from the conditions of the reference transmission image capturing. Only the generated X-rays are changed by a predetermined percentage, and then a reference transmission image (third transmission image) is taken and stored in the storage means. On the other hand, a reference transmission image (first transmission image) is taken before and after the reference transmission image is taken, a difference between corresponding pixels of the reference transmission image and the reference transmission image is obtained, and a predetermined allowable value is obtained from this difference. Obtain and store in the storage means.
[0013]
The invention described in claim 2 for solving the above-described problem is the invention described in claim 1, wherein the predetermined allowable value is calculated from the maximum value b of the absolute value of the difference value b or the frequency distribution of the difference value b. The gist is that the maximum value equivalent value b.
[0014]
In the present invention, the maximum value of the pixel value change when the X-ray intensity changes by a predetermined percentage is obtained and set as a “predetermined allowable value”. Alternatively, a value corresponding to the maximum value of the pixel value change is statistically obtained from the frequency distribution of the pixel value change, and set as a “predetermined allowable value”. As a result, even if the pixel includes noise, the allowable value is obtained from the distribution of the pixel value change including the noise, so that an allowable value that is not affected by the noise (corresponding to a predetermined percentage) can be obtained. . For this reason, even when the noise is different, the determination can be made based on the same reference.
[0015]
In order to solve the above problems, in the invention described in claim 3 according to the invention described in claim 1 or 2, the evaluation amount is calculated from the maximum value a of the absolute value of the difference value a or the frequency distribution of the difference value a. The gist is the maximum value equivalent value a.
[0016]
In the present invention, the maximum value “a” of the absolute value of the difference value “a” between the test transmission image and the reference transmission image is obtained and set as the “evaluation amount”. Alternatively, the maximum value equivalent value a of the absolute value of the difference value a is statistically obtained from the frequency distribution of the difference value a, and is set as an “evaluation amount”. In particular, when the maximum value equivalent value a is used, stable determination can be performed when the number of pixels is small.
[0017]
In order to solve the above-mentioned modification, the present invention as claimed in claim 4 is the invention as claimed in claims 1 to 3, wherein the evaluation amount is obtained from the difference value a and the allowable value is obtained from the difference value b using the same function. Is the gist.
[0018]
In the present invention, the allowable value is calculated from the difference value b by a certain function (a broad function, which means one calculation routine). For example, the maximum value or a statistically standard deviation of the frequency distribution is used to obtain the maximum value equivalent value and set it as the allowable value, or the allowable value is obtained and stored by an operation such as multiplication by a weight function. Then, the evaluation amount is obtained from the difference value a by the same function, and the determination is performed by comparing with the stored allowable value.
[0019]
In order to solve the above-described problems, a fifth aspect of the present invention provides a display means for displaying a detected transmission image, and a first line having a vertical line and a horizontal line that are substantially lowest and substantially equidistant with respect to a background of intermediate luminance. Or a pattern generating means for generating a second test pattern having vertical lines and horizontal lines at substantially equal intervals and substantially equal intervals on a background of intermediate luminance, and any of the first and second test patterns The gist is to display either one on the display means.
[0020]
In the present invention, when a display test command is input, a test pattern is displayed on the display unit. Test pattern: (1) The horizontal line and the vertical line are all white or black. (2) The horizontal line and the vertical line are parallel to each other. (3) The background brightness is uniform. By displaying based on the conditions (1) to (3), it is possible to inspect the luminance change and distortion of the display device alone.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
FIG. 1 is a diagram showing a configuration of an X-ray fluoroscopic inspection apparatus according to an embodiment of the present invention. As shown in FIG. 1, the X-ray fluoroscopic examination apparatus 1 includes an X-ray generator 10 that outputs an X-ray beam 20 and an X-ray detection that detects the X-ray beam 20 that has passed through a subject 70 with two-dimensional resolution. The device 30, a mechanism unit 71 that changes the fluoroscopic position, the fluoroscopic magnification, and the fluoroscopic angle of the subject 70, an X-ray shielding box 75 that covers them entirely, image processing of the detected transmission image, and control of these functional units. A computer 40, a display unit 50 connected to the computer 40 and externally displaying results processed by the computer 40, and an external input unit 60 connected to the computer 40 and for inputting control commands from the outside are provided. In addition, an X-ray control unit 15 and a mechanism control unit 78 for controlling the X-ray generator 10 and the mechanism unit 71 by signals from the calculator 40 are provided.
[0022]
The X-ray detector 30 is an X-ray detector. I. 31 and a television camera 33. The X-ray detector 30 is not limited to this and may be an X-ray flat panel sensor or the like. The X-ray generator 10 includes an X-ray tube 11 and a high pressure generator 12. The tube voltage and tube current of the X-ray tube 11 are controlled by control from the computer 40. The average energy of X-ray photons generated by the tube voltage changes, and the X-ray dose (number of photons) changes by the tube current.
[0023]
The computer 40 is a general personal computer (hereinafter referred to as a personal computer), a calculation unit 42 that calculates a difference between two types of transmission images, and a comparison unit 43 that compares the calculated difference value with a predetermined allowable value. A determination unit 45 that determines the state of the X-ray detection unit 30 according to the comparison result, a control unit 47 that controls these functional units, a storage unit 49 that stores a predetermined allowable value in advance, and a detection The captured image is converted to digital data and captured by a capture board 41 or the like.
[0024]
As for the calculation part 42, the comparison part 43, the determination part 45, and the control part 47, CPU (central processing unit) generally fulfill | performs the function. The storage unit 49 is a main storage memory that temporarily stores images, an image memory that stores transmission image signals converted by the capture board 41, and other "X-ray detector performance inspection programs" and "display unit inspection programs". Is a magnetic disk device that stores " The display unit (monitor) 50 is an RGB input computer video monitor. The external input unit 60 is a keyboard, a mouse, or the like.
[0025]
The “X-ray detector performance check program” automatically performs a primary check of the transmission image detected by the X-ray detector 30 and displays the result on the display unit. The “display unit inspection program” displays a test pattern on the display unit in order to inspect the deterioration state of the display unit itself.
[0026]
(X-ray detector performance check method)
Next, a method for checking the performance of the X-ray detector 30 according to the embodiment of the present invention will be described with reference to the flowcharts shown in FIGS.
[0027]
The calculation algorithm and abnormality (deterioration) detection of the “X-ray detector performance check program” are automatically processed by each function unit built in the personal computer 40. The “performance check of the X-ray detector” is performed by irradiating the X-ray beam 20, and is therefore an inspection including a change in the dose rate of the X-ray generated from the X-ray generator 10.
[0028]
First, as shown in FIG. 2A, step S10 is a reference transmission image photographing step. At the beginning of use of the X-ray detector 30, a “reference transmission image capturing command” is input from the external input unit 60 in a state where the subject 70 is not disposed between the X-ray generator 10 and the X-ray detector 30. The PC 40 sets predetermined conditions (detection conditions such as X-ray conditions, geometric conditions, and integration time) for the X-ray generator 10, the mechanical unit 71, the X-ray detector 30, and the like, and detects X-rays. The device 30 detects the reference transmission image. The detected output image signal is taken into the personal computer 40 through the capture board, stored in the magnetic disk device, and also displayed on the monitor 50.
[0029]
Next, as shown in FIG. 2B, step S20 is a test transmission image capturing step. After an arbitrary period from the beginning of use of the X-ray detector 30, the subject 70 is not disposed between the X-ray generator 10 and the X-ray detector 30, and the same conditions as the imaging conditions of the reference transmission image are satisfied. Set and detect the test transmission image. The detected test transmission image is taken into the personal computer through the capture board, stored in the image memory, and displayed on the monitor 50 in the same manner as the processing of the reference transmission image. Here, the optional period may be a periodical one month or one year after the start of use, or it may be determined according to the number of times of use, or it may be irregular, or if you feel an abnormality. You may only do it.
[0030]
In step S30, the reference transmission image stored in the magnetic disk is read into the image memory.
[0031]
Next, in step S40, the absolute value of the difference value of the corresponding pixel value is calculated for all the pixels of each image on the image memory, and the allowable value D stored in advance is calculated. _SK Compare with That is, the absolute value of the pixel value difference value is within the allowable range (| pixel value difference value | <allowable value D _SK ), The pixel is determined to be “normal” and the process proceeds to the next pixel. If the absolute value of the difference value of the pixel values is out of the allowable range even for one pixel, at least a part of the image is determined to be “abnormal (deteriorated)” and the process proceeds to step S60. Where tolerance D _SK The term “incident X-ray detector 30 incident X-ray dose” refers to a value that changes by approximately ± 20%. This tolerance D _SK For this, a description thereof will be omitted, and a detailed description will be given separately below.
[0032]
If all the pixels are determined to be “normal”, the process proceeds to step S50. Step S50 is a case where it is determined that all pixels of the test transmission image are “normal”. When the normality is determined as described above, for example, by outputting “normal” to the monitor 50, the operator is encouraged to continue using the X-ray fluoroscopic inspection apparatus 1.
[0033]
On the other hand, step S60 is a case where an abnormal pixel is detected in step S40. In this case, since it was determined that there is at least one abnormal pixel in the X-ray inspection device 30, for example, “a pixel in which the incident X-ray dose of the X-ray detector has changed by about ± 20% or more has been detected. Please ask us to check the X-ray detector and the X-ray generator. ”By outputting an error message such as“ Please check the X-ray detector and the X-ray generator ”, we recommend that the operator check the X-ray detector 30 and the X-ray generator 10 in detail.
[0034]
Accordingly, since the performance check can be automatically performed by checking the X-ray detector 30 using the “X-ray detector performance check program”, the operator can easily connect the X-ray detector 30. Can be checked.
[0035]
(Allowable value D _SK Calculation method)
Next, referring to FIG. 3 and FIG. _SK The calculation method of will be described.
3A and 3B show the allowable value D. _SK 4 is a “distribution of change in pixel value” (when the X-ray tube current is reduced by 20%).
[0036]
As shown in FIG. 3A, step S210 is a reference transmission image capturing step. At the beginning of use of the X-ray detector 30, a “reference transmission image capturing command” is input from the external input unit 60 in a state where the subject 70 is not disposed between the X-ray generator 10 and the X-ray detector 30. The PC 40 sets predetermined conditions (detection conditions such as X-ray conditions, geometric conditions, and integration time) for the X-ray generator 10, the mechanical unit 71, the X-ray detector 30, and the like, and detects X-rays. The device 30 detects the reference transmission image. The detected output image signal is taken into the personal computer 40 through the capture board, stored in the magnetic disk device, and also displayed on the monitor 50.
[0037]
As shown in FIG. 3B, step S220 is a reference transmission image capturing process. In this embodiment, the reference transmission image is captured at the beginning of use and after the reference transmission image is captured, but may be before the reference transmission image is captured at the beginning of use. As a specific method for capturing a reference transmission image, when a “reference transmission image capturing command” is input from the external input unit 60 in a state where the subject 70 is not disposed, the personal computer 40 determines the X-ray tube from the standard image capturing condition setting. Only the current value is reduced by 20%. The X-ray generator 10 outputs an X-ray beam 20 in which the X-ray dose corresponding to this control command is reduced by 20%, and the X-ray detector 30 detects this transmitted image. The detected transmission image is taken into the personal computer 40 through the capture board and stored in a memory device (image memory).
[0038]
Next, in step S230, the standard transmission image and the reference transmission image stored in the magnetic disk are read into the image memory, and a pixel value difference between corresponding pixels is calculated for each pixel (calculation of a difference image).
[0039]
Step S240 is a step of obtaining “a distribution of pixel value changes”. A pixel value distribution (hereinafter referred to as “pixel value change distribution”) in the entire image region (or central portion) of the difference value (difference image) calculated in step S230 is obtained. Here, the distribution of pixel values is a frequency distribution of pixel values. When the “distribution of pixel value change” is plotted in a coordinate system in which the X axis represents the pixel value and the Y axis represents the number of pixels, the “pixel value change distribution” shown in FIG. 4 is obtained. The spread of the “pixel value change distribution” is mainly caused by noise caused by X-ray photon noise and non-uniform characteristics of the X-ray detector 30 in the distribution area. Since the contribution of noise is large, a normal distribution graph is obtained as shown in FIG.
[0040]
In step S250, an allowable value D is calculated from the "distribution of pixel value change". _SK This is a process for obtaining. That is, for example, the “distribution of pixel value change” is assumed to be stored in a database consisting of pixel values and the number of pixels, and the maximum absolute pixel value (absolute value of pixel values) where the number of pixels is not 0 is obtained from this database. This absolute pixel value is converted into an allowable value D. _SK Is stored in the magnetic disk. In other words, tolerance D _SK Is the maximum absolute difference between the pixel values of the reference transmission image and the standard transmission image when image noise and characteristic inhomogeneity are considered. Book D _SK In step S230, the maximum absolute difference may be directly obtained without obtaining the “pixel value change distribution”. D _SK The other way of obtaining will be described later.
[0041]
In the present embodiment, the allowable value D _SK When the incident X-ray dose of the X-ray detector 30 is reduced by 20% by reducing the current value supplied to the X-ray generator 10 by 20% compared to when the reference transmission image was taken. However, on the contrary, even if “the incident X-ray dose of the X-ray detector 30 increases by 20%”, the allowable value D _SK Is substantially the same value as “when the incident X-ray dose of the X-ray detector 30 is reduced by 20%”. Actually, since the X-ray dose and the sensitivity of the X-ray detector 30 decrease with time, the allowable value D when “the incident X-ray dose of the X-ray detector 30 decreases by 20%” _SK Is actually measured.
[0042]
Therefore, the above allowable value D _SK By implementing the calculation method, the allowable value D used for checking the performance of the X-ray detector 30 _SK Can be calculated.
[0043]
(Allowable value D _SK Variation of calculation method)
In the embodiment of the present invention, when the “pixel value change distribution” shown in FIG. 4 is obtained, the difference value used for the pixel value distribution is the entire image area in step S240 of FIG. Alternatively, the “pixel value change distribution” may be generated using only the image information of the part. As a result, even if the wide-area characteristic inhomogeneity (such as shading) of the X-ray detector 30 is large, the allowable amount D _SK It is possible to calculate a representative value in the center without excessively increasing. Also, the calculation time can be shortened.
[0044]
In addition, allowable value D _SK The current change% that is the calculation criterion is ± 20% in the present embodiment, but is not limited to this and may be any percentage. Further, the screen may be divided into a plurality of zones and calculated for each zone. For example, the critical value D is 10% for the central part, 20% for the peripheral part, and 15% for the middle part. _SK May be used. Further, instead of changing the tube current, the reference transmission image may be obtained by changing the tube voltage, the geometric condition, or the X-ray filter.
[0045]
Furthermore, the screen is divided into a plurality of zones, a “pixel value change distribution” is obtained for each zone of the screen, and a different allowable value D for each zone. _SK May be obtained. Thereby, more careful determination is possible.
[0046]
Tolerance D _SK Is calculated by calculating + α (small value) or xk (a value slightly larger than 1) for the maximum absolute pixel value in which the “pixel value change distribution” does not become 0, and giving a large margin. Also good. In addition, the average pixel value, Mean, standard deviation, and σ of “distribution of pixel value change” may be obtained and calculated by Expression (1).
D _SK = ABS (Mean) + 4 * σ Equation (1)
Here, the coefficient of the second term does not necessarily need to be “4”, and may be selected from about “3” to “5”. This D _SK In this calculation, “a maximum absolute pixel value whose distribution does not become zero”, that is, a value corresponding to the maximum absolute difference value is statistically obtained. In the case of a detector with little characteristic inhomogeneity, the allowable value D is stably calculated because it is calculated by the equation (1). _SK Is required.
[0047]
(Inspection method for display)
Next, an inspection method for the monitor 50 according to the embodiment of the present invention will be described with reference to the first and second test patterns shown in FIGS. In FIG. 5 and FIG. 6, the repetition of the pattern is omitted.
[0048]
The “inspection of the display unit” is the first test pattern shown in FIG. 5 or the second test pattern shown in FIG. 6 on the monitor 50 in order to visually inspect the gradation and distortion displayed on the monitor 50. To display. Here, the pattern generating means reads out the first and second test patterns from the magnetic disk or creates them by calculation, writes them directly into the image memory, and outputs them to the display unit.
[0049]
The background of these first and second test patterns is a gray scale of intermediate luminance (“128” when binary 8-bit display is performed). In gray scale “0-255”, “0” is the darkest and “255” is the brightest. Further, there is a straight line every 8 pixels in the horizontal and vertical directions.
[0050]
Since the screen of the monitor 50 is 480 pixels long and 640 pixels wide, these straight lines have 59 horizontal lines and 79 vertical lines. In the first test pattern, the gray scale is 255 (true white), and the second test pattern is gray. Scale 0 (true black). Each of these test patterns is displayed on the monitor,
(1) The horizontal line and the vertical line are all white or black.
(2) The horizontal line and the vertical line are parallel to each other.
(3) The background brightness is uniform.
Is confirmed visually.
[0051]
(Effects of the first embodiment)
Therefore, according to the embodiment of the present invention, the X-ray beam 20 generated from the X-ray generator 30 is converted into the X-ray detector 30 in a state where the subject 70 is not arranged at the beginning of use of the X-ray detector 30. And is stored as a reference transmission image, and then a test transmission image is taken periodically or aperiodically under the same conditions as the reference transmission image shooting conditions, and the corresponding pixels of the reference transmission image and the test transmission image are captured. When the difference between the pixel values is calculated for each pixel and the difference value is within the allowable range, it is determined that the test transmission image is normal, while at least one of the difference values is within the allowable range. When it is outside, it is determined that at least a part of the test transmission image is abnormal, and the fact is displayed on the monitor 50, so that the state of the X-ray detector 30 and the X-ray generator 10 can be easily changed to the outside. Can let you know.
[0052]
The permissible range is a permissible value D that is a value in which the incident X-ray dose of the X-ray detector changes by about 20% even if the absolute value of the difference value of the pixel value is one pixel. _SK If the brightness changes more than the allowable value due to deterioration of sensitivity of the X-ray detector 30, burn-in, etc., by displaying an abnormal message when exceeding the value, this can be detected and displayed. The primary inspection of the X-ray detector 30 and the X-ray generator 10 can be performed automatically and easily.
[0053]
In particular, it is possible to determine whether the maximum change portion exceeds an allowable value not only in a uniform sensitivity change but also in a heterogeneous group-like sensitivity change, and the change is not affected by image noise, and the incident X-ray dose is accurately about ± A value changed by 20% can be determined as an allowable value.
[0054]
Further, in “inspecting the display unit”, by displaying the first test pattern or the second test pattern on the monitor 50, it is possible to visually inspect the luminance change or distortion of only the monitor 50.
[0055]
(Modification)
In the present embodiment, in order to check the deterioration of the X-ray detector 30, the difference between the pixel values of the reference transmission image and the test transmission image is performed for each pixel, and the comparison is sequentially made with the allowable value. However, the deterioration inspection method is not limited to this. For example, even if the difference image between the reference transmission image and the test transmission image is calculated first and the difference image determination process is performed later, the same effect as in the present embodiment can be obtained. Obtainable.
[0056]
The photographing conditions for the reference, reference, and test transmission images are automatically set by the personal computer 40, but some or all of the setting items may be manually set by the operator.
[0057]
Further, as a modification of the determination and calculation method of the allowable value, the allowable value D according to the embodiment of the present invention is applied to the image smoothed by applying a spatial filter. _SK Calculation and determination processing may be performed. In this case, the allowable value D is not calculated by all pixels but by thinning (for example, every other pixel). _SK Calculation and determination can also be performed.
[0058]
In the present embodiment, even a single pixel has an allowable value D. _SK It is determined whether pixels exceeding the threshold value are detected. This is because the maximum difference value is the allowable value D. _SK It is equivalent to determining whether or not. Where D _SK An abnormal message may be output when the number of pixels exceeding the predetermined number exceeds one pixel instead of necessarily one pixel.
[0059]
Here, for example, in the “X-ray detector performance check program”, an addition processing step is performed to perform addition when an abnormal pixel is detected. _SK When a pixel exceeding this value is detected, addition and totalization are performed so that an abnormal message is output to the monitor 50 when the total value exceeds a predetermined number. Further, the number of abnormal pixels may be displayed.
[0060]
In the present embodiment, the difference value calculated from the test transmission image and the reference transmission image and the allowable value D _SK And the difference value and the allowable value D _SK However, it is possible to use other comparison methods including operations. For example, the distribution of the difference image is multiplied by a weight function that increases as the absolute value increases, and the difference is evaluated as a score, and this score is compared with another allowable value to determine abnormality. Like that.
[0061]
Furthermore, in the present embodiment, the allowable value D is calculated from the difference between the standard transmission image and the reference transmission image. _SK By calculating the maximum absolute value of the difference by the allowable value D _SK However, the allowable value can also be obtained by multiplying the “distribution of pixel value change” by multiplying by a similar weight function. Generally speaking, when the evaluation value is obtained by calculating the difference value (difference image) between the test transmission image and the reference transmission image and the like and the comparison is made with the allowable value D, the allowable value D is obtained. As a method, the same calculation is added to the difference value (difference image) between the reference transmission image and the standard transmission image.
[0062]
In addition to the weight function multiplication, various calculations can be considered. For example, the maximum absolute difference value equivalent value is obtained and stored in the above equation (1) to obtain the allowable amount D, and the maximum absolute difference value equivalent value is obtained by using the same equation (1) to obtain the evaluation amount. As an example, calculation and comparison / determination can be shown. In this example, stable determination can be performed when the number of pixels is small.
[0063]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the X-ray fluoroscope inspection apparatus which can perform inspection of an X-ray detector, an X-ray generator, and a display part easily can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an X-ray fluoroscopic inspection apparatus according to an embodiment of the present invention.
FIG. 2 is a flowchart for checking the performance of the X-ray detector according to the embodiment of the present invention.
FIG. 3 shows an allowable value D according to the embodiment of the present invention. _SK It is a flowchart figure which calculates.
FIG. 4 is a “pixel value change distribution” graph according to the embodiment of the present invention;
FIG. 5 is a diagram showing a first test pattern.
FIG. 6 is a diagram showing a second test pattern.
[Explanation of symbols]
1 X-ray fluoroscopy system
10 X-ray generator
11 X-ray tube
12 High pressure generator
20 X-ray beam
30 X-ray detector
31 X-ray I.
33 TV camera
40 Computer (PC)
41 Capture board
42 Calculation unit
43 comparison part
45 judgment part
47 Control unit
49 Memory
50 Display (Monitor)
60 External input section
70 subjects
71 Mechanism
75 X-ray shielding box
78 Mechanism control unit

Claims (5)

An X-ray fluoroscopic examination apparatus that irradiates a subject with X-rays, detects X-rays transmitted through the subject with an X-ray detector, and displays a transmission image of the subject,
A first transmission image taken in the initial stage of use without the subject being placed, and a second transmission taken under the same conditions as the first transmission image after an arbitrary period of time has elapsed since the beginning of use. An image and a third transmission imaged in the initial stage of use, with the X-rays generated by the X-ray generation means for generating X-rays being changed to a predetermined ratio from the same conditions as when capturing the first transmission image Storage means for storing images;
A calculation unit that calculates a difference value a between corresponding pixels of the second and first transparent images for each pixel, and a predetermined allowable value from a difference value b between corresponding pixels of the third and first transparent images. Calculating means for calculating
Comparison means for evaluation quantity calculating from said difference value a or the difference value a is compared whether or not outside the tolerance,
An X-ray fluoroscopic inspection apparatus comprising: a determination unit that determines that the second transmission image is abnormal based on a result of the comparison. The predetermined tolerance is
The X-ray fluoroscopic examination apparatus according to claim 1, wherein the absolute value of the difference value b is a maximum value b or a maximum value equivalent value b calculated from a frequency distribution of the difference value b. The evaluation amount is
The X-ray according to claim 1, wherein the absolute value is a maximum value a of the difference value a or a maximum value equivalent value a calculated from a frequency distribution of the difference value a. Fluoroscopy device.   The fluoroscopic examination apparatus according to claim 1, wherein the evaluation amount is obtained from the difference value a and the allowable value is obtained from the difference value b using the same function. . Display means for displaying the detected transmission image;
A first test pattern having vertical lines and horizontal lines with substantially the lowest luminance and substantially equal intervals with respect to the background of intermediate luminance, or a second test pattern having vertical lines and horizontal lines with substantially the highest luminance and substantially equal intervals on the background of intermediate luminance. 5. The apparatus according to claim 1, further comprising: a pattern generation unit configured to generate a test pattern, wherein one of the first and second test patterns is displayed on the display unit. A fluoroscopic inspection device.

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