JP2003052687A - X-ray inspection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray inspection system which carries out the correction of sensitivity, dependence on the size of subjects to be examined and remaining images. SOLUTION: A data processor (1) calculates the attenuation ratios r of the remaining images per measuring time of one transmission X-ray image and subtracts (104) a value, obtained by multiplying output signals of the measurement made once preceding the present measurement by r from the value, obtained by multiplying the output signals of the present measurement by (1+r) and a sensitivity correction term for correcting the sensitivity of the X-ray inspection system as a whole is (2) calculated using measuring conditions of transmission X-ray images determined by operation conditions of an X-ray generator and operation conditions of the X-ray inspection system. The results obtained by the division of the results of the arithmetic processing (1) by the sensitivity correction term undergo an exponential conversion (107) or the sensitivity correction term subjected to the exponential conversion are subtracted from the results of the arithmetic processing (1) to (3) calculate a size depending correction term indicating changes in energy distribution depending on the sizes of the subjects to be examined. Then, the results of the arithmetic processing (2) are multiplied by the size depending correction term (108) to obtain an image 113 processed for correction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray inspection apparatus and an inspection method for a fluoroscopic apparatus, an imaging apparatus, a CT apparatus, a cone-beam CT apparatus including a multi-slice CT apparatus, and the like.

[0002]

2. Description of the Related Art As a known device for measuring an X-ray image using a two-dimensional X-ray detector, a fluoroscope, an imaging device, an X-ray source and a two-dimensional X-ray detector are rotated around a subject. However, there is a cone-beam CT apparatus including a multi-slice CT apparatus that performs rotation imaging.

As a two-dimensional X-ray detector used in these devices, an X-ray image intensifier (hereinafter referred to as X-ray image intensifier) is used.
II) and a TV camera via an optical system in combination with an XII-camera type X-ray detector (for example, "JP-A-10-192267" (Prior Art 1)), a flat type X-ray detector ( For example, “Trends in Flat Panel Detectors” (Seiya Inamura, Video Information, vol.31 (4),
pp. 125-130, 1999 (Prior art 2)),
Etc. As an example of a planar X-ray detector, an amorphous silicon photodiode (aSiPHD) and a TFT are arranged in a square matrix, and a fluorescent plate is used. An amorphous selenium (aSe) semiconductor is formed on an amorphous silicon (aSi) TFT. There is an example of placement. CT devices using one-dimensional X-ray detectors that perform spiral scans, and cone beam CT devices are also well known.

In the CT device and the cone beam CT device,
A three-dimensional reconstruction algorithm that performs a correction process on each of a plurality of data obtained from a plurality of directions and executes a three-dimensional reconstruction process to obtain a three-dimensional image is well known. The cone-beam CT reconstruction algorithm is based on "3D imaging" (Tsuneo Saito, Medical Imaging Technology, vol.
13 (3), pp.183-188, 1995 (Prior Art 3)). In particular, the Feldkamp method uses the “Practical cone
beam algorithm "(LA Feldkamp, Journalof Optic
al Society of America, vol.1 (6), pp.612-619, 1984
(Prior Art 4)).

In the CT device and the cone beam CT device,
Volume rendering processing and surface rendering processing are performed on the three-dimensional reconstructed image, and a two-dimensional image containing three-dimensional information is created and used for diagnosis. ("Application of volume rendering to anatomy" (Masataka Suzuki, Medical
Imaging Technology, vol.13 (3), pp.195-201, 1995
(Prior Art 5)).

There are various correction processing methods for improving the image quality of an image measured by a see-through device, a photographing device, a CT device, and a reconstructed image measured by a cone-beam CT device. In the prior art 1, the detector offset correction processing, sensitivity nonuniformity correction processing, geometric distortion correction processing, saturation (halation) correction processing, diffused light component correction processing, scattered X-ray component Correction processing, correction processing for protruding the subject from the effective field of view of the detector, and the like. Further, in the conventional technique 1, an image that will be measured next time is estimated from the image measured immediately before, and the measurement condition is controlled to optimize the next measurement condition according to the value of the estimated image. .

The afterimage erasing characteristic peculiar to a flat panel detector (FPD) for capturing an X-ray image is stored in advance according to the photographing conditions, and the afterimage erasing characteristic is used to predict the afterimage level in pixel units. , A method of storing a pixel value obtained by subtracting a predicted value of an afterimage level from each image obtained by continuous shooting in a memory and outputting the pixel value to a liquid crystal display or a laser imager has been reported (see Japanese Patent Laid-Open No. 2000-17589).
No. 2 publication "(prior art 6)).

An image processing method and apparatus have been reported in which X-rays are alternately radiated from the left and right focal points between X-rays to the subject to perform stereoscopic fluoroscopy of the subject (see JP-A-08-13.
No. 0752 ”(Prior Art 7)). In the prior art 7,
The digital signal R of the right image (or the digital signal L of the left image) is multiplied by a predetermined coefficient K to obtain K · R (or K ·
L) is calculated, and the right-side processed image RM immediately before and the left-side processed image LM immediately before are multiplied by a predetermined coefficient (1-K) to obtain RM.
(1-K) (or LM (1-K)) is calculated, and the addition signal K · R + RM (1-K) (or K · L + LM (1-
K) is obtained, and the image on the same focus side by the previous exposure and the image obtained this time are superimposed to reduce noise. In the prior art 7, the addition signal K · R + RM (1
−K) (or K · L + LM (1−K), a signal obtained by multiplying the image signal RM (or LM) by the previous exposure by a predetermined coefficient a is subtracted, and K · R + RM (1−K) K) -a
LM (or K.L + LM (1-K) -aRM) is obtained and the afterimage caused by the image by the previous exposure is removed.

An afterimage removing method has been reported in which an afterimage generated in a solid-state image pickup device is removed by signal processing (see Japanese Patent Laid-Open No. 05-2005).
No. 153503 ”(Prior Art 8)). Prior art 8
Then, the signal of the current field is S _n−1 , the signal before the S _n−1 field is S _n−1 , the afterimage coefficient depending on S _n−1 is α (S _n−1 ), and the signal proportional to the amount of incident light is X _n . At this time, the afterimage-removed signal X _n is given by (Equation 1). Further, the signal S _n ′ for which the white balance has been corrected is obtained from (Equation 2). In _{X n = S n -α (S} n-1) · S n-1 ... ( Equation _{1) S n '= X n} + α (S n) · S n ... ( Equation 2) In other words, the prior art 8, 1 An afterimage-removed signal is obtained by subtracting the amount obtained by multiplying the signal before the field by the afterimage coefficient depending on the size of the signal from the signal in the current field. Further, a value obtained by multiplying the signal of the current field by the afterimage coefficient is added to obtain white balance.

An image display device that performs the same afterimage reduction processing as in (Equation 1) has been reported (see "Patent No. 0275208").
No. 5 "(prior art 9)). In the prior art 9, the A / D-converted X-ray image output is alternately stored for each frame, and the frame image through the first and second frame memories is multiplied by the afterimage removal coefficient and added. The afterimage of the camera is removed from the X-ray image output continuously collected for each frame by the camera.

[0011]

In the following description, an image measured by a fluoroscopic device or an imaging device, or a reconstructed image measured by a CT device or a cone beam CT device is simply referred to as an image.

In the prior art 1, since the image measurement conditions are controlled in order to improve the image quality of the image, the image measurement conditions are different for each image, and even if the same inspection target is used, the pixel value of the image is There was a problem that it was different for each. Further, in the prior art 1, various correction processes are performed in order to improve the image quality of the image, but since the change of the measurement condition due to the control of the measurement condition of the image is not taken into consideration, the correction process is accurately performed. There was a problem that it was not done.

In the prior art 8, in order to improve the image quality of the image, the afterimage component is estimated from the previous image and subtracted from the current image to correct the afterimage. However, the afterimage correction process contributes to the signal. S / N of the image due to the decrease in the number of X-ray quantum
There was a problem that it decreased.

In the X-ray fluoroscope, the radiographing apparatus, the CT apparatus, and the cone-beam CT apparatus, the X-ray is gradually absorbed by the inspection object when passing through the inspection object, and the energy distribution of the X-ray changes. In the prior art, since the change of the energy distribution is not corrected, the pixel value of the image is different depending on the distance through which X-rays are transmitted, that is, the size of the inspection target even when the inspection target is made of the same substance. was there.

In the prior art, due to the existence of the above problem, the pixel value for each image is different for the same inspection object, and there is a problem that the quantitativeness deteriorates. Due to this decrease in quantification, there is a problem that it is necessary to adjust the display condition for each image even when measuring the same inspection target. The pixel value of the reconstructed image is a CT showing the X-ray absorption coefficient.
It is a value, and the doctor pays attention to the CT value when making a diagnosis.
There is a problem in that the diagnostic ability is reduced due to the reduced quantitativeness of the reconstructed image.

Further, since the quantitativeness of the reconstructed image is lowered, it becomes difficult to set a threshold value when creating a rendering image by the volume rendering process or the surface rendering process using the reconstructed image, and an area other than the extraction target is extracted. However, there is a problem in that the image quality of the rendered image is deteriorated due to the duplication of images and the loss of the extraction target.

Therefore, a first object of the present invention is to provide an X-ray inspection apparatus and an X-ray inspection method by which an image with improved quantitativeness can be obtained. A second object of the present invention is to provide a sensitivity of the entire X-ray inspection apparatus (hereinafter,
It is called system sensitivity. ), A change in energy distribution depending on the size of the inspection target, and various correction processes in consideration of afterimages generated by the X-ray detection apparatus, and an X-ray inspection apparatus and an X-ray inspection that improve the quantitativeness of the image. To provide a method.

[0018]

An X-ray inspection apparatus of the present invention is an X-ray generation apparatus for generating X-rays for irradiating an inspection target,
An X-ray detection device for measuring a transmitted X-ray image of an inspection object;
And a data processing device for calculating an image to be inspected by performing an arithmetic processing of an output signal of the line detection device, and the data processing device, with respect to the measured output signal, transmits X-ray generated by the X-ray detection device. An afterimage correction calculation process for correcting an afterimage of a line image, and a system sensitivity correction calculation process for correcting a change in sensitivity of the entire X-ray inspection apparatus depending on image measurement conditions;
The calculation processing of size dependence correction for correcting the change in the energy distribution of the X-rays depending on the distance that the X-rays penetrate through the inspection target is executed.

Further, the data processor in the X-ray inspection apparatus of the present invention (1) calculates the attenuation ratio r of the afterimage per measurement time of one transmission X-ray image, and measures it this time (i-th). An operation for subtracting a value obtained by multiplying the output signal measured by (1 + r) times the output signal measured ((i−1) th) one time before the measurement of the current output signal by r times, and executing the afterimage processing. System sensitivity correction term for correcting the sensitivity of the entire X-ray inspection apparatus by using the processing and (2) the measurement conditions of the transmitted X-ray image determined by the operation conditions of the X-ray generator and the operation conditions of the X-ray detector. (2a) the result of the arithmetic processing of (1) or the result of dividing the output signal by the sensitivity correction term is logarithmically converted, or (2b) the logarithmic conversion of (1) is performed. Logarithmically converted from the arithmetic processing result or the logarithmically converted output signal The calculation processing for correcting the system sensitivity by subtracting the degree correction term, and (3) the size dependency correction term (quantity) indicating the change in the energy distribution depending on the distance (size) through which the X-ray penetrates through the inspection object. One of the calculated and logarithmically converted output signal or the calculation process of (2) above and the calculation process of correcting the size dependence of the inspection target by multiplying the result by the size dependence correction term, or Two or three arithmetic processes are executed. One, two, or three correction items selected from the above (1), (2), and (3) are set in the correction setting means. In addition, the measurement modes for measuring the image of the inspection object are fluoroscopic measurement, imaging measurement, and CT.
The measurement mode selected when measuring the image of the inspection target, including measurement, multi-slice CT measurement, cone-beam CT measurement, and spiral scan CT measurement, is set in the measurement mode setting means. Furthermore, the data processing device is the same as the above (1).
A value obtained by multiplying the output signal measured next to the measurement of the current output signal by the coefficient w is added to the result of the arithmetic processing of. At this time, the coefficient w is w = r ² or w = {r ² / (1-
r ² )}.

Further, the data processing device in the X-ray inspection apparatus of the present invention is: (1) X-ray from the air image measured by irradiating X-ray without placing the inspection object and the transmission X-ray image. Calculation processing that performs offset correction processing that subtracts the measured offset image without irradiating
(2) Using the measurement conditions of the transmission X-ray image determined by the operating conditions of the X-ray generator and the operating conditions of the X-ray detector, a sensitivity correction term for correcting the sensitivity of the entire X-ray inspection apparatus is calculated. A saturation judgment value obtained by multiplying the pixel value of the transmission X-ray image subjected to the offset correction processing and the pixel value of the air image subjected to the offset correction processing by a system sensitivity correction term and a coefficient s (where 0 ≦ s ≦ 1) And when the pixel value of the transmission X-ray image subjected to the offset correction processing is larger than the saturation judgment value, the pixel value of the transmission X-ray image subjected to the offset correction processing is set to the system sensitivity correction term as the pixel value of the air image. The afterimage of one transmission X-ray image per measurement time is calculated by using the output signal that has been subjected to the saturation value restoration correction processing and (3) the saturation value restoration correction processing. Calculate the damping ratio r of , The current measured output signal (1+
r) The result of the calculation process of (4) above (3), in which the afterimage correction is performed by subtracting the r-folded value of the output signal measured one time before the measurement of the current output signal from the multiplied value Is logarithmically converted by the sensitivity correction term, or the logarithmically converted result of (3) is subtracted from the logarithmically converted sensitivity correction term to perform system sensitivity correction. ) A calculation process for performing nonuniformity correction by subtracting a logarithmically converted air image from the transmission X-ray image obtained by the system sensitivity correction obtained in (4), and (6)
An arithmetic process for calculating a size dependency correction term indicating a change in energy distribution depending on the size of the inspection target, and multiplying the result of the arithmetic process of (5) by the size dependency correction term to perform size dependency correction. To execute. Further, the data processing device performs an operation of adding a value obtained by multiplying the output signal measured next to the output signal measured this time by the coefficient w to the result of the operation processing of (3), and the coefficient w is w = r ² , or
w = a ^{{r 2 / (1-r} 2)}.

[0021]

1 is a flow chart showing an example of a correction process applied to an X-ray inspection apparatus according to an embodiment of the present invention. For the measured image 101 of the inspection target,
(1) Afterimage correction processing 104, (2) logarithmic conversion processing 10
7, (3) system sensitivity correction processing 108, and (4) size dependency correction processing 111 are executed in this order, and the corrected image 113 of the inspection target is obtained. Image 11
3 is used for the three-dimensional reconstruction processing. Image 101
In contrast, (1) afterimage correction processing 104, (2) system sensitivity correction processing 108, (3) logarithmic conversion processing 107,
(4) The size dependency correction processing 111 may be performed in this order.

The correction parameters necessary for the correction processing are the measurement condition file for storing the measurement conditions of the image, each data stored in the relation file showing the relation between each of the measurement conditions of the image to be adjusted and the pixel value of the image, An attenuation ratio r of the afterimage generated by the X-ray detection device per measurement time of one transmission X-ray image, a size dependence table representing changes in energy distribution depending on the size of the inspection object, and the like. If the components and geometrical arrangement of the inspection device do not change, the correction parameters other than each data stored in the measurement condition file are fixed. That is, it is sufficient to measure and calculate once when the device is installed.

The relationship between each of the measurement conditions of the image to be adjusted and the pixel value of the image is stored as a mathematical expression or a table. By formulating the above relationships into mathematical expressions, the calculation becomes easy, the file size can be reduced, and as a result, the calculation processing can be speeded up. A complicated relationship can be dealt with by tabulating the above relationships.

The measurement condition file is created when measuring an image. The measurement condition file stores the measurement condition of the image measured for each angle. The image measurement conditions are the conditions for operating the X-ray generator (X-ray pulse width, X-ray tube current,
X-ray tube voltage, etc., conditions for operating the X-ray detection device (gain, optical system parameters, etc.), geometric conditions (focus of X-ray tube, inspection target, relative X-ray incident surface of X-ray detection device) (Positional relationship), the configuration conditions of the scattered X-ray shielding grid, and the like.
By using the measurement condition file and the relation file, the correction term of the sensitivity of the entire X-ray inspection apparatus (system sensitivity correction term) depending on the measurement condition of the image is calculated.

(Description of Afterimage Correction Processing) First, the afterimage correction processing 104 is performed on the measured image 101 to be inspected. The afterimage generated by the X-ray detection device decreases exponentially with time. i frame (i: integer) in the image data measured by the X-ray detector is irradiated with X-ray d _i, then, was measured by X-ray detector without irradiating the X-rays (i + 1) frame When the image data is d _{i + 1} , the afterimage attenuation ratio r per measurement time of one frame (one transmission X-ray image) is calculated for each pixel by (Equation 3). r = d _{i + 1} / d _i (Formula 3) In the above-mentioned conventional techniques 8 and 9, the afterimage component is estimated from the previous image data and subtracted from the current image data.
That is, in the prior arts 8 and 9, assuming that the image data measured by the i-th (current) time is d _i , the image data f _i measured after the afterimage correction process is the same as (Equation 1) 4). f _i = d _i −r · d _i−1 (Equation 4) On the other hand, the afterimage correction process in the embodiment of the present invention is performed as follows. As shown in (Equation 5), the (i−1) th (one time before the measurement of the current image data) image data is multiplied by r to estimate the afterimage component (r · d _i−1 ). Then
The afterimage component is subtracted from the value obtained by multiplying the i-th (currently) measured image data by (1 + r). f _i = (1 + r) · d _i −r · d _{i -1} (Equation 5) Comparing (Equation 4) and (Equation 5), in (Equation 5), r · d is provided on the right side of (Equation 4). _{The i} signal is added. The signal of r · d _{i on} the right side of (Equation 5) is a signal lost in the i-th (current) measurement due to the afterimage of the (i-1) -th measurement, assuming that d _i ≈d _i-1. Corresponds to the estimated correction component of. As a result, in (Equation 5), it is possible to maintain the same signal level as that before the afterimage correction process, and it is possible to prevent a decrease in S / N due to the afterimage correction process. Further, in (Equation 5), since the image data measured one time before the measurement of the current image data and the image data measured this time are used for smoothing, the S / N can be improved.

Another afterimage correction process of the embodiment of the present invention is performed as follows. On the right side of (Equation 5), (i +
1) The value obtained by multiplying the image data measured first by w is added. In (Equation 6), smoothing is performed using the image data measured one time before the measurement of this image data, the image data measured this time, and the image data measured next to the measurement of this image data. Therefore, the S / N ratio can be improved by increasing the signal without lowering the accuracy of the afterimage correction processing as compared with the afterimage correction processing according to (Equation 5). The first term on the right side of (Equation 6),
w · d _{i + 1} corresponds to the estimated correction component of the afterimage component of the i-th (current) measurement, which is included in the (i + 1) -th (next to this image data measurement) measurement image data. To do. The equation w is given by (Equation 7) or (Equation 8). The afterimage correction processing according to (Equation 5) and (Equation 6) is performed for all pixels of the image. f _i = w · d _{i + 1} + (1 + r) · d _i −r · d _i-1 (Equation 6) w = r ² (Equation 7) w = {r ² / (1-r ² )} (Equation 8) (Explanation of logarithmic conversion processing) All pixel values of the image subjected to the afterimage correction processing are logarithmically converted (107).

(Description of System Sensitivity Correction Processing) When the system sensitivity correction processing (108) is performed on the image after logarithmic conversion, the system sensitivity correction term (quantity) is calculated from each pixel value of the image after logarithmic conversion. Subtract. Since the logarithmically converted system sensitivity correction term is subtracted from the pixel value of the image after the logarithmic conversion, the correction process is easy and the speedup is possible. When system sensitivity correction processing is performed on an image before logarithmic conversion, each pixel value of the image before system sensitivity correction processing is divided by the system sensitivity correction term. The calculation of the system sensitivity correction term will be described below.

Conditions for operating the X-ray generator (X-ray tube current, X-ray tube voltage, X-ray pulse width) and conditions for measuring transmitted X-rays (sensitivity (gain) in the X-ray detector, optical, System parameters) is used to calculate the system sensitivity correction term. The sensitivity (system sensitivity) of the entire X-ray inspection apparatus changes depending on the image measurement conditions. For example, when measuring an image of the same inspection object, when the system sensitivity is doubled, the pixel value of the image is also doubled.

The sensitivity at the time of measuring an air image (a transmitted X-ray image of air obtained without placing an inspection object) is used as a standard of system sensitivity. That is, the measurement condition of the air image is set as the reference measurement condition, and the sensitivity at the time of measuring the air image is set as the reference sensitivity. The system sensitivity with respect to the reference sensitivity is defined as the system sensitivity correction term. The image measurement conditions optimized for each image to be measured are X-ray pulse width, optical diaphragm, X
When the current is a tube current, the system sensitivity correction term (quantity) Sr in the measured image r is represented by (Equation 9). In addition,
When measuring the image of the inspection object, the X-ray pulse width is pr, the optical aperture efficiency is qr, the X-ray tube current is br, and the X-ray pulse width is pa and the optical aperture efficiency is qa when measuring the air image. X
Let the tube current be ba. Sr = (pr / pa) (qr / qa) (br / ba) (Equation 9) The system sensitivity correction term is for the inspection target with respect to the value of the reference measurement condition at each angle at which the image of the inspection target is measured. It is the ratio of the values of the image measurement conditions. This ratio is converted into the pixel value of the image. That is, it is the result of dividing the estimated pixel value of the image measured under the reference measurement condition by the pixel value of the actually measured image. As the reference measurement condition, the measurement condition of the air image or the measurement condition of the image of the inspection target to be measured first is used.

When the measurement condition of the air image is used as the reference measurement condition, it is not necessary to convert the air image into the image under the reference measurement condition in the saturation value restoration correction process described later, and the calculation process can be speeded up.

When the measurement condition of the image of the inspection object that is initially measured is used as the reference measurement condition, it is not necessary to refer to the measurement condition of the air image when calculating the system sensitivity correction term, and the calculation process can be simplified. . Hereinafter, the system sensitivity correction term using the measurement condition of the air image as the reference measurement condition is used.

(Description of Size Dependence Correction Processing) Size dependence correction processing (111) is performed on the pixel values of the image for which the system sensitivity correction processing has been executed. Logarithmic conversion data P
(X) is represented by (Equation 10). In (Equation 10),
Size of inspection object (distance that X-ray penetrates through inspection object)
x, an average value μave of the X-ray absorption coefficient, and an error e (x) of the Bering glare correction process and the scattered X-ray correction process. P (x) = μave · x + e (x) (Equation 10) Even if the composition to be inspected is uniform, the average energy of X-rays increases as the size x increases, so μave decreases as x increases. Therefore, if x increases, P
(X) deviates from the proportional relationship with x, and P (x) moves downward from the straight line passing through the origin. Also, the effects of Behring glare and scattered radiation on the log transformed image increase as x increases. Therefore, when the Bering glare correction processing and the scattered radiation correction processing are insufficient, the deviation from the above proportional relationship becomes larger. These results,
Even if the inspection target has a uniform composition, the inspection target size x
The X-ray absorption coefficient μ ave changes depending on The size dependency correction process is performed as follows.

An image of a cross section of a cylinder of a cylindrical phantom having various diameters x perpendicular to the target axis is measured, various correction processes are executed on the measured image, and the image after the logarithmic conversion is obtained. Find the maximum value of a pixel. The relational expression P (x) between the diameter x and the maximum value of the pixels of the image is obtained by polynomial fitting. An expression obtained by extracting only the first-order term of the relational expression P (x) is obtained, and is set as logarithmic conversion data Pc (x) that is ideally proportional to the inspection target size x.

FIG. 2 is a diagram showing the relationship between the diameter x and the maximum value of the pixel of the image when a cylindrical phantom in which water is filled in an acrylic frame is used, which is measured in the embodiment of the present invention. Is. As x increases, the maximum value of the pixels of the measured image deviates from the ideal value Pc (x) in the proportional relationship. As shown in (Equation 11), the ratio between Pc (x) and the actual logarithmic conversion data P (x) is defined as a size dependency correction term (quantity) Q {P (x)}. Q {P (x)} = Pc (x) / P (x) (Equation 11) In the size dependence correction process, the logarithmic conversion data P (x) is multiplied by the size dependence correction term Q. Q is P instead of x
By determining as a function of (x), the size dependency correction process can be a table reference process of the input P and the output Q, and the correction process can be simplified and speeded up. Each pixel value of the measured image is multiplied by the size-dependent correction term.

By the above arithmetic processing, the afterimage correction processing 104, the logarithmic conversion processing 107, the system sensitivity correction processing 108, and the size dependence correction processing 11 are performed on the measured image.
The corrected image 113 in which 1 has been obtained is obtained.
The corrected image 113 is used in a three-dimensional reconstruction process 315 shown in FIG. 5 described later.

FIG. 3 shows the XII in the embodiment of the present invention.
FIG. 7 is a flowchart showing an example of a correction process in an X-ray inspection apparatus using a camera type X-ray detector. For the measured image 101, offset correction processing 102, saturation value restoration correction processing 103, afterimage correction processing 104, Behring glare correction processing 105, scattered X-ray correction processing 106, logarithmic conversion processing 107, system sensitivity correction processing 108, The nonuniformity correction process 109, the geometric distortion correction process 110, the size dependency correction process 111, and the protrusion correction process 112 are performed.
The image 113 corrected by these correction processes is used for the three-dimensional reconstruction process 315 shown in FIG. 5 described later.

The correction parameters necessary for the correction process, the measurement condition file, the relational file, the afterimage attenuation ratio r, the size dependency table and the like have been described above.

(Description of Offset Correction Processing) First, the offset correction processing 102 is performed on the measured image 101.
Do. Measure one or more offset images without irradiating X-rays. Irradiate X-rays without placing an inspection object and measure a single or a plurality of air images (transmission X-ray images of air). By using an average image of a plurality of offset images and an average image of a plurality of air images, it is possible to suppress an increase in noise during the correction process. When the temporal variation of the offset image and the air image is large, the accuracy of the correction process can be improved as the offset image and the air image are measured closer to the measurement time of the image to be inspected. Therefore, it is desirable to measure immediately before or after the measurement of the image of the inspection target.

When the offset image and the air image vary greatly for each angle at which the image to be inspected is measured, and the variation of the distortion table described later is large, the offset image and the air image are measured at each angle at which the image to be inspected is measured. It is possible to improve the accuracy of the correction process by measuring and the distortion table.

Further, the offset image and the air image are measured and the distortion table is created at every several angles at which the image of the inspection object is measured. At other angles, the offset image and the air image and the distortion table at the closest angle are used, or the offset image and the air image and the distortion table which are already obtained are used for estimation. As a result,
The memory required for storing the offset image, the air image, and the distortion table can be saved, and the accuracy of correction processing can be improved. Of course, even when there are large fluctuations in other correction processing parameters, the same effect can be obtained as described above.

In the offset correction processing 102 for the measured image, the pixel value of the offset image is subtracted from each pixel value of the measured image and the offset-corrected measured image and each pixel value of the air image are calculated. An air image subjected to offset correction processing is obtained by subtracting the pixel value of the offset image.

In the following description, the system sensitivity correction term (quantity) with the air image measurement condition as the reference measurement condition is used.

(Description of Saturation Value Restoration Correction Processing) Saturation value restoration correction processing 103 is performed on the measured image subjected to the offset correction processing. The following processing is performed on each pixel. The pixel value of the measured image subjected to the offset correction processing and the saturation determination value obtained by multiplying the pixel value of the air image subjected to the offset correction processing by the system sensitivity correction term and the coefficient s (where 0 ≦ s ≦ 1) are set. Compare. If the pixel value of the offset-corrected measured image is larger than the saturation determination value, it is determined that the pixel is saturated, and the pixel value of the offset-corrected measured image is set to the pixel of the air image. Replace the value with the system sensitivity correction term.

Considering statistical fluctuations in image measurement, the coefficient s is set to about 0.8. When the coefficient s is close to 1.0, the accuracy of determining the saturated region can be improved. When the coefficient s is brought close to 0, it is less likely to be affected by fluctuations in noise and the like, and a stable saturated region can be determined. By correcting the discontinuity of pixel values caused by the above replacement, streak artifacts in the reconstructed image can be reduced. When not correcting the discontinuity of the pixel values caused by the above replacement,
Quantitative accuracy can be improved in the area where no artifact occurs.

(Explanation of Afterimage Correction Processing) The above-mentioned afterimage correction processing 1 is applied to the measured image subjected to the saturation value restoration correction processing.
Perform 04. Here, according to (Equation 8), at each pixel, from the value obtained by multiplying the pixel value of the image measured this time (i-th) by (1 + r), one time before the measurement of the current image ((i-1 ) Th) The pixel value of the measured image is multiplied by r, and the value is subtracted to obtain ((i + 1)
(Rth) The measured pixel value of the image is {r ² / (1-
r ² )} The multiplied value is added. Similarly, afterimage correction processing is also performed on the air image subjected to the offset correction processing.

(Explanation of Diffused Light (Beling Glare) Correction Processing) Diffused light correction processing 105 is performed on the measured image subjected to the afterimage correction processing. The diffused light point spread function is convoluted with the measured image on which the afterimage correction process is performed, and the diffused light intensity ratio is further multiplied to obtain the diffused light component image. The diffused light component image is subtracted from the measured image on which the afterimage correction process has been performed to obtain the measured image on which the diffused light correction process has been performed. Similarly, diffused light correction processing is also performed on the air image subjected to afterimage correction processing.

(Explanation of scattered X-ray correction processing) The scattered X-ray correction processing 10 is performed on the measured image subjected to the diffused light correction processing.
Do 6. A scattered X-ray point image distribution function is convoluted with the measured image subjected to the diffused light correction processing, and the scattered X-ray intensity ratio is further multiplied to obtain a scattered X-ray component image. The scattered X-ray component image is subtracted from the measured image subjected to the diffused light correction processing to obtain the measured image subjected to the scattered X-ray correction processing.

(Explanation of Logarithmic Conversion Processing) Logarithmic conversion processing 107 is performed on the measured image subjected to the scattered X-ray correction processing and the air image subjected to the diffused light correction processing.

(Description of System Sensitivity Correction Processing) The system sensitivity correction processing 108 described above is performed on the measured image after logarithmic conversion. At each pixel, the system sensitivity correction term is subtracted from the pixel value of the measured image after logarithmic conversion.

(Description of Non-uniformity Correction Processing) Non-uniformity correction processing 1 is performed on the measured image subjected to the system sensitivity correction processing.
Perform 09. At each pixel, the air image after logarithmic conversion is subtracted from the pixel value of the image subjected to the system sensitivity correction processing.

(Explanation of Geometrical Distortion Correction Processing) The geometrical distortion correction processing 110 is performed on the measured image subjected to the nonuniformity correction processing. The distortion table is a table showing the relationship between the case where there is no distortion and the case where there is distortion in each pixel. For example, the distortion table describes to which pixel an arbitrary pixel when there is no distortion moves when there is distortion, and the value of the pixel described in the distortion table is set to the arbitrary pixel.

(Description of Size Dependence Correction Processing) The above-described size dependence correction processing 111 is performed on the measured image subjected to the distortion correction processing. At each pixel, the pixel value of the distortion-corrected image is multiplied by the size-dependent correction term.

(Explanation of Overhang Correction Processing) Overrun correction processing 112 is performed on the measured image subjected to the size dependency correction processing.

From the various correction processes described above, the necessary correction process can be selected. For example, in a flat panel X-ray detector, the Bering glare correction process and the geometric distortion correction process can be omitted. It is possible to speed up by omitting unnecessary correction processing. The order of the various correction processes described above can be changed.

FIG. 4 is a diagram showing a configuration example of the X-ray inspection apparatus according to the embodiment of the present invention. The X-ray inspection apparatus shown in FIG.
It is an example of a cone beam CT measuring device using an arm.
An X-ray tube 201 of an X-ray generator that generates X-rays that irradiate the inspection target 203, an X-ray detection device 204 that measures a transmitted X-ray image of X-rays that have passed through the inspection target 203, and C
The X-ray tube 201 and the X-ray detection device 20 are controlled by the arm 202.
4 are fixed as a pair, and the X-ray tube 201 and the X-ray detection device 2
The rotation drive device 208 for rotating the device 04 around the inspection object 203, the X-ray tube 201, the rotation drive device 208, and the X-ray detection device 204 are controlled to collect the output of the X-ray detection device 204 as image data. A data collection device 205,
Data processing device 206 for performing arithmetic processing of image data
And a display device 207 that displays image data and / or the result of arithmetic processing.

In addition to the apparatus configuration shown in FIG. 4, a scattered X-ray shielding grid may be arranged in front of the X-ray detecting apparatus 204. Alternatively, a scattered X-ray shielding grid built in the X-ray detection device 204 may be used.

When the images of the inspection object are not measured from a plurality of directions, the rotation driving device 208 is not driven after the rotation driving device 208 sets a specific angle. A processing device having a display in which the data collection device 205, the data processing device 206, the display device 207, etc. are integrated may be used. Further, the data processing device may have a built-in board, chip or the like for executing the correction processing of the present invention.

In the example shown in FIG. 4, as the X-ray detecting device 204, a planar planar two-dimensional X-ray detector in which detecting elements are arranged two-dimensionally is used. For example, fluorescent plate, aSiP
A well-known planar two-dimensional X-ray detector composed of HD and TFT, and a well-known planar two-dimensional X-ray detector composed of aSe semiconductor on aSiTFT can be used. Instead of the planar two-dimensional detector, a multi-row detector in which a plurality of one-dimensional detectors having one-dimensionally arranged detection elements are arranged in a row can also be used. Furthermore, as an X-ray detector, XII, an optical system,
XII-TV camera type X-ray detector composed of TV,
XII- consisting of XII, optical system, CCD camera-
A CCD camera type X-ray detector can also be used.

The correction processing of the present invention is performed by the data processing device 20.
6 is executed. Information on which correction process is to be executed is set in a correction setting means (for example, a switch, a button, a touch panel arranged in the data processing device, or a window of a screen displayed on the display screen of the data processing device). It The typical correction processing of the embodiment of the present invention is (1) afterimage correction, (2) system sensitivity correction, and (3).
1 selected after the correction item of the size dependence correction processing
One, two, or three correction items are set in the correction setting means.

In the configuration example of the X-ray inspection apparatus shown in FIG. 4, as the measurement mode for measuring the image of the inspection object, the fluoroscopic measurement,
Measurement modes such as imaging measurement, CT measurement, multi-slice CT measurement, cone beam CT measurement, and spiral scan CT measurement are possible. The measurement mode selected when measuring the image of the inspection target is a measurement mode setting unit (for example, a switch, a button, a touch panel arranged on the data processing device,
Alternatively, it is set in the window of the screen displayed on the display screen of the data processing device). Hereinafter, a cone-beam CT measurement mode will be described as an example of a typical image measurement mode.

The X-ray tube 201 and the X-ray detection device 204 are rotated around the inspection object 203 by the rotation drive device 208 to perform cone beam CT measurement. Alternatively, the X-ray tube 20
1 and the X-ray detection device 204 are fixed, and a rotary drive device 208
Then, the inspection object 203 is rotated to perform cone beam CT measurement.

Each device shown in FIG. 4 is a data collecting device 20.
5, the image of the inspection object 203 is measured and the image data is acquired. Data collection device 205
Is the detection of the status of each device, acquisition of measurement conditions using external input means such as terminals, calculation of measurement conditions using measured images, setting of conditions for each device, and measurement describing the measurement conditions of images. Create a condition file.

FIG. 5 is a flowchart showing an example of processing including correction processing in the X-ray inspection apparatus for performing cone beam CT measurement in the embodiment of the present invention. The C-arm 202 is moved to the rotation start angle (301). The standby information of the X-ray generator, the X-ray detector, the rotation driving device, etc. is confirmed (302). The rotation of the C-arm is started (303). It is detected that the C arm has reached the angle at which image measurement is started (304), and measurement of the image 101 to be inspected is started. It is detected that the C arm has reached the angle to measure the image (305), X-rays are irradiated from the X-ray tube to the inspection target (306), and the transmitted X-ray image of the inspection target is measured by the X-ray detection device. (307), the output signal of the X-ray detection device is collected as image data (308), the measurement condition of the next inspection object is calculated using the measured image data and the measurement condition (309), and it is obtained. According to the measurement conditions, the pulse width of the X-ray irradiating the inspection target is adjusted (310), and the gain in the X-ray detection device is adjusted (311). From 305 to 311 until it detects that the C arm has reached the angle at which the image measurement is finished (312).
repeat. When it is detected that the C arm has reached the angle at which the image measurement is finished, the rotation of the C arm is finished (313).

The data processing device 206 applies the correction processing 31 shown in FIG. 1 or 3 to the measured image data.
4 is performed, the three-dimensional reconstruction process 315 is performed using the corrected image data 113, and the rendering process 316 is performed on the three-dimensional reconstructed image to obtain a rendered image. The rendering image is displayed on the display device 207 (317).

In the embodiment shown in FIG. 5, the X-ray pulse width and the gain in the X-ray detection device are adjusted for each angle according to the measurement conditions of the image. Either one of the gains in the apparatus may be adjusted, or both the X-ray pulse width and the gain in the X-ray detection apparatus may be constant. Further, the X-ray tube voltage, the X-ray tube current, the thickness of the X-ray attenuation filter, etc. may be changed. In the embodiment shown in FIG. 5, the measurement of the image by the pulse X-ray has been described, but the image can be measured by the continuous X-ray.

The method of adjusting the gain of the X-ray detector 204 depends on the configuration. For example, the X-ray detection device 204
When the optical system is composed of II, an optical system, and a CCD camera, the gain can be adjusted by the opening area of the optical diaphragm installed inside the optical system. The optical diaphragm adjusts the amount of light incident on the CCD camera. For example, when the X-ray detection device 204 is a flat two-dimensional X-ray detector, the gain can be adjusted by an amplifier that adjusts the output intensity of the detection element. The gain can be adjusted by the input / output characteristics of the A / D converter.

In the above description, the X-ray inspection apparatus using the XII-camera type X-ray detector and the cone-beam CT measuring apparatus using the C-arm have been described as specific examples, but the present invention is not limited to these embodiments. It is not limited. The X-ray inspection apparatus of the present invention can be executed in any of measurement modes of fluoroscopic measurement, imaging measurement, CT measurement, multi-slice CT measurement, cone beam CT measurement, and spiral scan CT measurement.

An example of the configuration of the X-ray inspection method of the present invention will be described below. The X-ray inspection method of the present invention includes a step of irradiating an inspection target with X-rays generated from an X-ray generation device, and measuring a transmitted X-ray image of the inspection target by an X-ray detection device,
Calculating the output signal of the X-ray detection apparatus to obtain the image of the inspection target.

In the step of performing the arithmetic processing in the first X-ray inspection method of the present invention, (1) the attenuation ratio r of the afterimage per measurement time of one of the transmission X-ray images is calculated and measured this time. An arithmetic process for subtracting a value obtained by multiplying the output signal by r times the output signal measured one time before the measurement of the output signal this time, from the value obtained by multiplying the output signal by (1 + r), and (2) the X-ray generator. Using the measurement conditions of the transmitted X-ray image, which are determined by the operating conditions and the operating conditions of the X-ray detection device, a system sensitivity correction term for correcting the sensitivity of the entire X-ray inspection device is calculated, and the calculation of (1) is performed. A calculation process of logarithmically converting a result of dividing the processing result by the sensitivity correction term, or a calculation process of subtracting the logarithmically converted sensitivity correction term from the logarithmically converted calculation result of (1); Energy depending on the size of the inspection object Calculating the size dependent correction term indicating the change in the over distribution, and a calculation processing for multiplying the size dependent correction term to the result of the calculation processing (2). Furthermore, (1)
A value obtained by multiplying the output signal measured next to the measurement of the output signal this time by the coefficient w is added to the result of the arithmetic processing of. As the coefficient w, w = r ² or w = {r ² / (1-
r ² )} is used.

The above in the second X-ray inspection method of the present invention
The step of performing the arithmetic processing is the step of calculating one of the transmission X-ray images.
The decay ratio r of the afterimage per measurement time is calculated and measured this time.
The output signal from the value obtained by multiplying the output signal by (1 + r)
The output signal measured one time before the measurement of the force signal is multiplied by r
The calculation process of subtracting the calculated value is included. Furthermore, this arithmetic processing
As a result of, the measurement was made next to the measurement of the output signal this time.
A value obtained by multiplying the output signal by a coefficient w is added. Coefficient w
As w = r², Or w = {r²/ (1-r ²)}
use.

The step of performing the arithmetic processing in the third X-ray inspection method of the present invention is the measurement condition of the transmitted X-ray image determined by the operation condition of the X-ray generator and the operation condition of the X-ray detector. Is used to calculate a system sensitivity correction term for correcting the sensitivity of the entire X-ray inspection apparatus, and a calculation process for logarithmically converting the result of dividing the output signal by the sensitivity correction term, or the logarithmically converted output signal From the logarithmically converted sensitivity correction term.

In the step of performing the arithmetic processing in the fourth X-ray inspection method of the present invention, the size-dependent correction term indicating the change in energy distribution depending on the size of the inspection object is calculated, and the output signal is logarithmically converted. To the size-dependent correction term.

In the step of performing the arithmetic processing in the fifth X-ray inspection method of the present invention, (1) the attenuation ratio r of the afterimage per measurement time of one of the transmission X-ray images is calculated and measured this time. An arithmetic process for subtracting a value obtained by multiplying the output signal by r times the output signal measured one time before the measurement of the output signal this time, from the value obtained by multiplying the output signal by (1 + r), and (2) the X-ray generator. Using the measurement conditions of the transmission X-ray image, which are determined by the operating conditions and the operating conditions of the X-ray detection apparatus, a sensitivity correction term for correcting the sensitivity of the entire X-ray inspection apparatus is calculated,
The result obtained by dividing the result of the operation process of (1) by the sensitivity correction term is logarithmically converted, or the result is logarithmically converted (1).
Calculation processing of subtracting the sensitivity correction term logarithmically converted from the calculation processing result of Further, a value obtained by multiplying the output signal measured next to the measurement of the output signal this time by the coefficient w is added to the result of the arithmetic processing of (1). As the coefficient w, w = r ² or w = {r ² / (1-r ² )} is used.

The step of performing the arithmetic processing in the sixth X-ray inspection method of the present invention is (1) determined by the operating conditions of the X-ray generator and the operating conditions of the X-ray detector.
An arithmetic process of calculating a sensitivity correction term for correcting the sensitivity of the entire X-ray inspection apparatus using the measurement conditions of the transmission X-ray image, and logarithmically converting the result of dividing the output signal by the sensitivity correction term, or A calculation process of subtracting the logarithmically converted sensitivity correction term from the logarithmically converted output signal, and (2) calculating a size dependence correction term indicating a change in energy distribution depending on the size of the inspection target, ), The calculation result of the size dependence correction term is multiplied.

In the step of performing the arithmetic processing in the seventh X-ray inspection method of the present invention, (1) the attenuation ratio r of the afterimage per measurement time of one of the transmission X-ray images is calculated and measured this time. Arithmetic processing for subtracting a value obtained by multiplying the output signal by r times the output signal measured one time before the measurement of the output signal this time, from the value obtained by multiplying the output signal by (1 + r); A size dependent correction term indicating a change in the dependent energy distribution is calculated, and the logarithmically converted result of the operation (1) is multiplied by the size dependent correction term. Further, as a result of the arithmetic processing of (1), a coefficient w is added to the output signal measured next to the measurement of the output signal this time.
The value obtained by multiplying by is added. As the coefficient w, w = r ² or w = {r ² / (1-r ² )} is used.

The eighth X-ray inspection method of the present invention comprises the steps of irradiating an inspection object with X-rays generated from an X-ray generator, and measuring a transmitted X-ray image of the inspection object with an X-ray detector. , A step of performing arithmetic processing of an output signal of the X-ray detection device to obtain an image of the inspection object, and the step of performing the arithmetic processing includes (1) X-ray without placing the inspection object. Image measured by irradiating the
It is determined by an operation process of performing an offset correction process of subtracting an offset image measured without irradiating X-rays from each of the X-ray images, and (2) an operating condition of the X-ray generator and an operating condition of the X-ray detector. , A sensitivity correction term for correcting the sensitivity of the entire X-ray inspection apparatus is calculated using the measurement conditions of the transmission X-ray image, and the pixel value of the transmission X-ray image subjected to the offset correction processing and the offset correction The pixel value of the processed air image is compared with the saturation determination value obtained by multiplying the system sensitivity correction term by a coefficient, and the pixel value of the transmission X-ray image subjected to the offset correction is larger than the saturation determination value. Sometimes, the pixel value of the transmission X-ray image subjected to the offset correction is replaced with a value obtained by multiplying the pixel value of the air image by the system sensitivity correction term,
Using a calculation process for performing a saturation value restoration correction process and (3) using the output signal subjected to the saturation value restoration correction process,
The attenuation ratio r of the afterimage of one transmission X-ray image per measurement time is calculated, and the output signal measured this time is calculated as (1+
r) a calculation process of subtracting a value obtained by multiplying the output signal measured once before the current measurement of the output signal by r from the multiplied value, and (4) a calculation process of (3) And a calculation process of logarithmically converting the result of dividing the result of (1) by the sensitivity correction term, or a calculation process of subtracting the logarithmically converted sensitivity correction term from the calculation result of (3) to perform system sensitivity correction. (5) Calculation processing for performing nonuniformity correction by subtracting the logarithmically transformed air image from the transmission X-ray image obtained by the system sensitivity correction obtained in (4), and (6) the inspection Calculate a size-dependent correction term that indicates the change in energy distribution depending on the size of the target,
The calculation processing of (5) is multiplied by the size dependency correction term to perform size dependency correction. Further, a value obtained by multiplying the output signal measured next to the measurement of the output signal this time by the coefficient w is added to the result of the arithmetic processing of (3). As the coefficient w, w = r ² or w =
Using the ^{{r 2 / (1-r} 2)}.

The ninth X-ray inspection method of the present invention comprises the steps of irradiating the inspection target with X-rays generated from an X-ray generator, and measuring a transmitted X-ray image of the inspection target by an X-ray detector. , A step of performing a calculation process of an output signal of the X-ray detection device in order to obtain the image of the inspection object, and the step of performing the calculation process includes (1) measurement of one transmission X-ray image. A value obtained by calculating an afterimage attenuation ratio r per time and multiplying the output signal measured this time by (1 + r) times the output signal measured one time before the measurement of the output signal this time. A step of performing afterimage processing by subtracting
(2) A sensitivity correction term for correcting the sensitivity of the entire X-ray inspection apparatus is calculated using the measurement conditions of the transmitted X-ray image determined by the operation conditions of the X-ray generator and the X-ray detector. (2a) logarithmic conversion of the result of the arithmetic processing of (1) or the output signal divided by the sensitivity correction term, or (2b) logarithmic conversion of the arithmetic processing result of (1) or logarithmic conversion. Subtracting the sensitivity correction term logarithmically converted from the output signal to correct the system sensitivity, and (3) calculating a size dependence correction term indicating a change in energy distribution depending on the size of the inspection target, One of the steps of correcting the size dependency of the inspection target by multiplying the logarithmically converted output signal or the result of the arithmetic processing of (2) by the size dependency correction term, or two steps. Or three To run the degree. (1),
There is a step of setting one step, two steps, or three steps selected from the steps (2) and (3) in the correction setting means. In addition, the measurement modes for measuring the image of the inspection target are fluoroscopic measurement, imaging measurement, CT measurement,
There is a step of setting the measurement mode selected when measuring the image of the inspection target in the measurement mode setting means, which includes multi-slice CT measurement, cone-beam CT measurement, and spiral scan CT measurement. Further, in the step of performing the arithmetic processing, a value obtained by multiplying the output signal measured next to the measurement of the output signal this time by the coefficient w is added to the result of the arithmetic processing of the step (1). At this time, the coefficient w is w = r
² or w = {r ² / (1−r ² )}.

The X-ray inspection method according to the present invention is a fluoroscopic measurement,
The present invention can be applied to an X-ray inspection apparatus that executes any measurement mode of imaging measurement, CT measurement, multi-slice CT measurement, cone beam CT measurement, and spiral scan CT measurement.

[0079]

As described above, according to the present invention,
X-ray inspection apparatus and X capable of obtaining images with improved quantitativeness
A line inspection method can be provided. Further, according to the present invention, a change in sensitivity of the entire X-ray inspection apparatus (system sensitivity) depending on measurement conditions of an image, a change in energy distribution depending on a size of an inspection target, and an afterimage generated in the X-ray detection apparatus are detected. Thus, it is possible to provide an X-ray inspection apparatus and an X-ray inspection method that improve the quantitativeness of an image by performing correction processing and other various correction processing as necessary. Furthermore, since the quantitativeness of the three-dimensional reconstructed image can be improved, the quality of the rendered image can be improved.

[Brief description of drawings]

FIG. 1 is a flowchart showing an example of a correction process applied to an X-ray inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a diameter x and a maximum value of pixels of an image when a cylindrical phantom is used, which is measured in an example of the present invention.

FIG. 3 is an XII-camera type X according to an embodiment of the present invention.
The flowchart which shows an example of the correction process in the X-ray inspection apparatus using a line detector.

FIG. 4 is a diagram showing a configuration example of an X-ray inspection apparatus according to an embodiment of the present invention.

FIG. 5 is a flowchart showing an example of processing including correction processing in the X-ray inspection apparatus that performs cone-beam CT measurement in the embodiment of the present invention.

[Explanation of symbols]

101 ... Measured image, 102 ... Offset correction process, 103 ... Saturation value restoration correction process, 104 ... Afterimage correction process, 105 ... Behring glare correction process, 106 ... Scattered X-ray correction process, 107 ... Logarithmic conversion process, 108 ... System sensitivity correction processing, 109 ... Non-uniformity correction processing, 110 ... Geometric distortion correction processing, 111 ... Size dependence correction processing, 1
12 ... Protrusion correction processing, 103 ... Correction processed image, 201 ... X-ray tube, 202 ... C arm, 203 ... Inspection object, 204 ... X-ray detection device, 205 ... Data acquisition device, 206 ... Data processing device, 207 ... Display device, 20
8 ... Rotation drive device, 301 ... Rotation start angle movement, 302
... standby information confirmation, 303 ... rotation start, 304 ... image measurement start angle detection, 305 ... image measurement angle detection, 30
6 ... X-ray irradiation, 307 ... Transmission X-ray image measurement, 308 ...
Data collection, 309 ... Measurement condition calculation, 310 ... Pulse width adjustment, 311 ... Gain adjustment, 312 ... Image measurement end angle detection, 313 ... Rotation end, 314 ... Correction processing, 315 ...
Reconstruction process, 316 ... Rendering process, 317 ... Display.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G06T 1/00 460 G06T 1/00 460A 5C077 5/00 100 5/00 100 H04N 1/407 H04N 7/18 L 7/18 1/40 101E 101B F Term (reference) 2G088 EE01 EE02 FF02 GG19 GG20 GG21 JJ05 KK32 KK33 LL11 LL12 LL15 LL17 4C093 AA22 CA03 CA05 CA07 CA09 FB02 FC47 FC11 FC02 FC14 FC02 FC02 FC02 FC02 FC24 FC02 FC02 FC02 FC24 FC02 FC02 FC02 FC02 FC24 FC02 FC02 FC02 FC24 FC02 FC14 FC02 FC02 FC24 FC24 CB22 DC04 DC06 5B057 AA08 BA03 CA02 CA08 CA12 CA16 CB02 CB08 CB12 CB13 CB16 CD12 CE02 CE08 CE11 5C054 CA02 CB00 EJ00 HA05 HA12 5C077 LL02 LL04 MP01 PP10 PP11 PP15 PP16 PP25 PQ12 SS01 TT10

Claims (12)

[Claims] 1. An X-ray generator for generating X-rays for irradiating an inspection target, an X-ray detection device for measuring a transmitted X-ray image of the inspection target, and an arithmetic processing of an output signal of the X-ray detection device. And a data processing device that obtains the image of the inspection target, and the data processing device corrects an afterimage of a transmission X-ray image generated by the X-ray detection device with respect to the measured output signal. Calculation processing for afterimage correction, calculation processing for system sensitivity correction for correcting changes in the sensitivity of the entire X-ray inspection apparatus depending on the measurement conditions of the image, and dependence on the distance that X-rays penetrate through the inspection target. An X-ray inspection apparatus, characterized in that a size dependence correction calculation process for correcting a change in X-ray energy distribution is executed. 2. The X-ray inspection apparatus according to claim 1, wherein the data processing device calculates an attenuation ratio (r) of an afterimage per measurement time of one transmission X-ray image, and the i-th (i:
The afterimage correction is performed by a calculation process of subtracting a value obtained by multiplying the output signal measured at (i-1) th by r from a value obtained by multiplying the output signal measured at (integer number) by (1 + r). An X-ray inspection apparatus characterized in that 3. The X-ray inspection apparatus according to claim 2,
The data processing device adds (i +
1) The value obtained by multiplying the output signal measured at the 1st time by a coefficient (w) is added, and the coefficient (w) is w = r ² or w = {r ² / (1-r ² )}. X characterized by being
Line inspection equipment. 4. The X-ray inspection apparatus according to claim 1, wherein the data processing device uses measurement conditions of the transmission X-ray image determined by operating conditions of the X-ray generation device and the X-ray detection device. , A system sensitivity correction amount for correcting the sensitivity of the entire X-ray inspection apparatus, and a logarithmic conversion of the output signal divided by the sensitivity correction amount, or a logarithmic conversion of the output signal. An X-ray inspection apparatus configured to perform the system sensitivity correction by a calculation process of subtracting the sensitivity correction amount. 5. The X-ray inspection apparatus according to claim 1, wherein the data processing apparatus indicates a size-dependent correction amount indicating a change in energy distribution of the X-ray depending on a distance at which the X-ray penetrates through the inspection object. And the logarithmically converted output signal is multiplied by the size-dependent correction amount to perform the size-dependent correction. 6. An X-ray generator that generates X-rays that irradiate an inspection target, an X-ray detection device that measures a transmitted X-ray image of the inspection target, and an arithmetic processing of output signals of the X-ray detection device. A data processing device for obtaining an image of the inspection object, wherein the data processing device is (1) one of the transmission X
The afterimage attenuation ratio (r) per measurement time of the line image was calculated, and the value obtained by multiplying the output signal measured at the i-th (i: integer) by (1 + r) was measured at the (i-1) -th time. A calculation process of performing afterimage correction by subtracting a value obtained by multiplying the output signal by r, and (2) a measurement condition of the transmission X-ray image determined by operating conditions of the X-ray generation device and the X-ray detection device. Is used to calculate the system sensitivity correction amount for correcting the sensitivity of the entire X-ray inspection apparatus, and the result of the arithmetic processing of (1) or the output signal divided by the sensitivity correction amount is logarithmically converted. , Or the above log-transformed (1)
Of the calculation process result or the logarithmically converted output signal by subtracting the logarithmically converted sensitivity correction amount to correct the change in the system sensitivity, and (3) depending on the distance that the X-ray penetrates through the inspection object. The size-dependent correction amount indicating the change in the energy distribution of the X-ray is calculated, and the logarithmically converted output signal or the result of the arithmetic processing of (2) is multiplied by the size-dependent correction amount to obtain the inspection target. X-ray inspection apparatus, characterized in that any one or more of the arithmetic processing for correcting the size dependency of the above X is performed. 7. The X-ray inspection apparatus according to claim 6,
The data processing device adds a value obtained by multiplying the (i + 1) th measured output signal by a coefficient (w) to the result of the arithmetic processing of (1), and the coefficient (w) is w =
An X-ray inspection apparatus characterized in that r ² or w = {r ² / (1-r ² )}. 8. The X-ray inspection apparatus according to claim 6, further comprising correction setting means for setting a correction item selected from the arithmetic processes of (1), (2) and (3). Characteristic X-ray inspection device. 9. The X-ray inspection apparatus according to claim 6, further comprising measurement mode setting means for setting a measurement mode for measuring the image of the inspection object. 10. An X-ray generator for generating X-rays for irradiating an inspection target, and an X for measuring a transmitted X-ray image of the inspection target.
It has a line detection device and a data processing device for calculating the output signal of the X-ray detection device to obtain an image of the inspection target, and the data processing device is (1) X without the inspection target. Calculation processing for performing offset correction for subtracting the offset image measured without irradiating X-rays from the air image measured by irradiating X-rays and the transmission X-ray image, respectively, and (2) generating the X-rays. Device and said X
The offset X-corrected transmission X-ray is calculated by calculating the system sensitivity correction amount for correcting the sensitivity of the entire X-ray inspection apparatus using the measurement conditions of the transmission X-ray image determined by the operating conditions of the X-ray detection apparatus. The pixel value of the image is compared with a saturation determination value obtained by multiplying the pixel value of the air image subjected to the offset correction processing by the sensitivity correction amount and a coefficient s (where 0 ≦ s ≦ 1) to perform the offset correction. A value obtained by multiplying the pixel value of the offset-corrected transmission X-ray image by the pixel value of the air image by the sensitivity correction amount when the pixel value of the processed transmission X-ray image is larger than the saturation determination value. And the calculation process for performing the saturation value restoration correction process,
(3) The attenuation ratio (r) of the afterimage per measurement time of one transmission X-ray image is calculated using the output signal that has been subjected to the saturation value restoration correction processing, and the i-th (i: integer) From the value obtained by multiplying the output signal measured at (1 + r) by (i
-1) The logarithm of the calculation process of subtracting a value obtained by multiplying the measured output signal by r to correct the afterimage, and (4) the result of the calculation process of (3) divided by the sensitivity correction amount. Arithmetic processing for conversion, or arithmetic processing for performing system sensitivity correction by subtracting the logarithmically converted sensitivity correction amount from the logarithmically converted operation result of (3), and (5) the operation obtained in (4) above. An arithmetic process of performing non-uniformity correction by subtracting the logarithmically converted air image from the transmission X-ray image that has been subjected to system sensitivity correction, and (6) Depends on the distance that the X-ray penetrates through the inspection target. A size-dependent correction amount indicating a change in the energy distribution of X-rays is calculated, and the calculation process of (5) is multiplied by the size-dependent correction amount to perform size-dependent correction. X-ray characterized by査 apparatus. 11. The X-ray inspection apparatus according to claim 10, wherein the data processing apparatus adds a coefficient (w) to the (i + 1) th measured output signal as a result of the arithmetic processing of (3). The values multiplied by are added, and the coefficient (w) becomes w =
An X-ray inspection apparatus characterized in that r ² or w = {r ² / (1-r ² )}. 12. The X-ray inspection apparatus according to claim 1, 6, or 10, wherein the X-ray generator has an X-ray tube, and the X-ray detector has an X-ray detector, An X-ray inspection apparatus comprising: a rotation drive device that rotates the X-ray tube and the X-ray detector around the inspection target.