JP2007121010A - X-ray inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray inspection device capable of using the whole light-receiving surface, and predicting its lifetime as accurately as possible. <P>SOLUTION: The device wherein an X-ray measuring optical system 13 comprising an X-ray source 11 and a flat panel X-ray detector 12 is arranged oppositely so as to sandwich a measuring object, is equipped with a cumulative incident X-ray dose estimation part 34 for estimating the cumulative incident X-ray dose into the flat panel X-ray detector 12 by measuring or calculating cumulatively an X-ray dose equivalent to the incident X-ray dose into the flat panel X-ray detector 12; and a lifetime determination part 35 for determining the lifetime of the flat panel X-ray detector by comparing a determination reference set beforehand with the estimated cumulative incident X-ray dose. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an X-ray inspection apparatus for performing fluoroscopic inspection or CT inspection of industrial products and the like, and more particularly to an X-ray inspection apparatus using a flat panel X-ray detector as an X-ray detector.

The flat panel X-ray detector has a feature that it is small and light and has a good resolution and contrast ratio of the X-ray image.
Therefore, in X-ray inspection apparatuses that perform fluoroscopic inspection of industrial products and the like, in recent years, a flat panel X-ray detector is disposed so as to face the X-ray source of the X-ray generator, and further, the X-ray source and the flat panel X-ray An X-ray inspection apparatus that measures a fluoroscopic X-ray image by placing a movable stage between a detector and placing an object to be measured on the stage is used.

  The light-receiving surface of the flat panel X-ray detector is designed to be as durable as possible with respect to incident X-rays because X-rays are constantly irradiated during measurement, but it gradually deteriorates. For this reason, each flat panel X-ray detector has a lifetime determined by the cumulative value of the incident X-ray dose, and is replaced when the lifetime is reached. In an X-ray inspection apparatus using a flat panel X-ray detector, the cumulative irradiation time from the X-ray source is simply assumed that the X-ray source used in the X-ray generator always outputs at the maximum output (100% output). Is monitored, and when the cumulative irradiation X-ray dose exceeds the value defined as the lifetime, it is urged to be replaced.

However, in practice, X-rays are not always emitted at the maximum output. Since flat panel X-ray detectors are expensive, there is a desire to predict the life as accurately as possible in advance and purchase it immediately before the life.
As a method for predicting the lifetime, for example, in an X-ray inspection apparatus (X-ray foreign object detection apparatus) using an X-ray detector using a scintillator and a line sensor (photodiode), the lifetime of the line sensor is predicted in advance. Therefore, by comparing the dark current of the photodiode at the position where X-rays are irradiated and the photodiode at the position where no X-rays are irradiated at all, the lifetime is determined when the difference exceeds a set value. In addition, it is disclosed that the life of a line sensor is predicted quantitatively (see Patent Document 1).
JP 2002-168806 A

  As described above, the flat panel X-ray detector is an expensive component, and the device manager determines the life as accurately as possible, and in some cases, wants to use it until it fails even after the life time has passed. Yes. When trying to use up to the end of its lifetime, it is always necessary to make the replacement part easy so that it can be replaced immediately in case of failure. It is desirable to always provide spare parts for replacement of one or more flat panel X-ray detectors as a countermeasure against failure, but it is difficult in terms of cost and purchases spare parts when the life is approaching to some extent. There is a request to do. In that case, it is desired to accurately estimate the lifetime of the flat panel X-ray detector in advance.

As in Patent Document 1, a portion where no X-ray is irradiated is formed on a part of the light-receiving surface of the flat panel X-ray detector, and the darkness between the portion irradiated with X-ray and the portion not irradiated with X-ray at all Although it is conceivable to compare currents, the life of a flat panel X-ray detector cannot always be predicted well with dark current.
In addition, in the X-ray foreign matter inspection apparatus for measuring using a line sensor, there is no problem in performing inspection even if a portion where the X-ray is not irradiated is formed on the sensor end, but X using a flat panel X-ray detector is used. In the X-ray inspection device, the measurement visual field depends on the light receiving surface of the flat panel X-ray detector, so there is a case where it is desired to widen the measurement visual field as much as possible. Usually, the flat panel X-ray detector detects the entire light receiving surface. It is desirable. Therefore, it is not preferable to form a dead space part where X-rays are not irradiated in part.

Therefore, the present invention predicts the life of a flat panel X-ray detector as accurately as possible in an X-ray inspection apparatus using a flat panel X-ray detector, and purchases a spare flat panel X-ray detector at an appropriate time. It is an object of the present invention to provide an X-ray inspection apparatus that can make a plan to do so.
In addition, the present invention can use the entire light receiving surface so as not to prevent the X-rays from being irradiated to the entire light receiving surface of the flat panel X-ray detector, and can further predict the lifetime. An object is to provide a line inspection apparatus.

  An X-ray inspection apparatus according to the present invention, which has been made to solve the above problems, is arranged so that an X-ray measurement optical system comprising an X-ray source and a flat panel X-ray detector faces each other with an object to be measured interposed therebetween. In an X-ray inspection apparatus that captures a fluoroscopic X-ray image of an object to be measured by an optical system, an X-ray dose equivalent to an X-ray dose incident on a flat panel X-ray detector is measured or calculated cumulatively to thereby calculate a flat panel X. Lifetime determination for determining the lifetime of a flat panel X-ray detector by comparing the cumulative incident Xray dose estimation unit for estimating the incident Xray dose to the line detector and the estimated cumulative Xray dose estimated in advance. And so on.

  According to the present invention, the cumulative incident dose estimation unit does not directly measure the cumulative incident X-ray dose of X-rays to the flat panel X-ray detector, but cumulatively measures or calculates the equivalent X-ray dose. To make an estimate. That is, the X-ray dose is measured at a position where the equivalent X-ray dose is irradiated, or the equivalent X-ray dose is calculated by theoretical calculation instead of the measurement. Therefore, X-ray irradiation to the flat panel X-ray detector is not hindered. The lifetime determination unit compares the cumulative incident X-ray dose obtained by the cumulative incident X-ray dose estimation unit with a predetermined criterion for determining the cumulative incident X-ray dose, and determines the lifetime of the X-ray flat panel detector.

  According to the present invention, the lifetime of the flat panel X-ray detector can be predicted in advance by monitoring the cumulative incident X-ray dose, so that a spare flat panel X-ray detector can be purchased at an appropriate time. Thus, a spare flat panel X-ray detector for replacement can be purchased at an appropriate time. And according to this invention, since all the light-receiving surfaces of a flat panel X-ray detector can be irradiated with an X-ray, the measurement by a detector without a dead space is attained.

(Means and effects for solving other problems)
In the above invention, the cumulative incident X-ray dose estimation unit may estimate the cumulative incident dose based on the X-ray dose measured by a dosimeter attached in the vicinity of the light receiving surface of the flat panel X-ray detector.
According to this, since the cumulative incident dose at the place can be measured by a dosimeter attached in the vicinity of the light receiving surface of the flat panel X-ray detector, the cumulative incident dose of the flat panel X-ray detector can be accurately estimated. be able to.

  In the above invention, the X-ray dose irradiated under the reference X-ray irradiation condition is measured by a dosimeter temporarily attached in the vicinity of the light receiving surface of the flat panel X-ray detector and stored as a reference dose rate. Or a reference dose rate storage area for storing the dose rate obtained by calculating the X-ray dose irradiated from the X-ray source to the flat panel X-ray detector under the reference X-ray irradiation condition as a reference dose rate. The cumulative incident X-ray dose estimation unit may estimate the cumulative incident X-ray dose based on the stored reference dose rate and the X-ray irradiation conditions during the subsequent X-ray irradiation.

According to this, the reference dose rate storage area stores the reference dose rate of the light receiving surface of the flat panel X-ray detector in advance.
Here, the reference dose rate refers to an incident X-ray dose (unit: R / min) per unit time on the light receiving surface of the flat panel X-ray detector under the reference X-ray irradiation conditions.
The reference X-ray irradiation condition is an X-ray irradiation condition determined so as to be a reference of the irradiation condition by the X-ray inspection apparatus. The tube voltage, the tube current, and the SID (Source to Image Distance) are flat from the focus of the X-ray source. It means an X-ray irradiation condition consisting of a combination of measurable values (preferably typical values) about the distance to the light receiving surface of the panel X-ray detector.

  The reference dose rate can be determined by either: One is a method by actual measurement. In other words, to obtain the reference dose rate, when a dosimeter is temporarily attached near the light receiving surface (preferably on the light receiving surface) of the flat panel X-ray detector and X-rays are irradiated under the reference X-ray irradiation conditions By measuring the X-ray dose, the dose per unit time (reference dose rate) at that time is obtained. After the reference dose rate is determined, the dosimeter is removed so that measurements can be made with a flat panel X-ray detector. According to this method, since it is only necessary to temporarily attach a dosimeter at the time of initial apparatus adjustment, it is possible to use one dosimeter for a plurality of X-ray apparatuses.

  The other is a theoretical calculation method. That is, the dose rate at the light receiving surface of the flat panel X-ray detector is proportional to the square of the tube voltage, proportional to the tube current, and inversely proportional to the square of the SID. In the X-ray generator, an inspection report is created at the time of inspection. In the inspection report or the like, the X-ray dose under the X-ray irradiation condition at the time of inspection of the X-ray generator is described. Therefore, the reference dose rate on the light receiving surface of the flat panel X-ray detector can be obtained by performing proportional calculation using the tube voltage, tube current, and SID as parameters based on the data of the inspection report. The reference X-ray irradiation conditions at this time may be the conditions at the time of collecting X-ray dose data in the examination report. According to this method, the reference dose rate can be obtained only by theoretical calculation based on the inspection result data of the X-ray generator without using a dosimeter.

After the reference dose rate is obtained by any of the above methods, when X-rays are irradiated under various X-ray irradiation conditions, comparison between the reference X-ray irradiation conditions and the X-ray irradiation conditions at that time (proportional The dose rate at the light receiving surface at that time can be obtained by calculation. Then, the incident X-ray dose at that time can be calculated based on the obtained dose rate, and the current increase is added to the cumulative incident X-ray dose over the irradiation time.
Thereafter, based on various X-ray irradiation conditions during X-ray irradiation, the incident X-ray dose can be obtained by proportional calculation, and this can be added to estimate the cumulative incident dose.

In the above invention, each X-ray irradiation condition is measured by measuring the X-ray dose irradiated under each X-ray irradiation condition by a dosimeter temporarily attached near the light receiving surface of the flat panel X-ray detector. A dose rate table storage area for storing the dose rate in association with each other, and the cumulative incident X-ray dose estimation unit estimates the cumulative incident X-ray dose based on the X-ray irradiation conditions and the dose rate table at the time of X-ray irradiation. It may be.
According to this, since the dose rate under each X-ray irradiation condition is tabulated, initially the effort of calculating the dose rate is increased, but after that, the incident X-ray dose is calculated by performing proportional calculation for each measurement. There is no need to do it.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment, It cannot be overemphasized that various aspects are included in the range which does not deviate from the meaning of this invention.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of an X-ray inspection apparatus according to an embodiment of the present invention. This X-ray inspection apparatus 1 includes an X-ray measurement optical system 13 composed of an X-ray generator 11 and a flat panel X-ray detector 12, a stage 14 on which a measurement object S is placed, and a stage 14 orthogonally crossed. Drive mechanism 16 for translational driving in the XYZ direction (stage surface is defined as XY plane) and rotational driving along the Z axis, and a position adjacent to the light receiving surface of flat panel X-ray detector 12 and receiving light It is comprised by the dosimeter 19 attached to the position irradiated with incident X-ray dose equivalent to a surface, and the control system 20 which controls the whole apparatus.

The control system 20 is constituted by a general-purpose computer device. The hardware of the control system 20 is further described. The CPU 21, a keyboard 22 and a mouse 23 as input devices, a display device 24 such as a liquid crystal panel, and a memory 25 are provided. It consists of.
Further, the functions processed by the CPU 21 will be described in blocks. The functions are divided into an X-ray image creation unit 31, an X-ray image display control unit 32, a drive signal generation unit 33, a cumulative incident X-ray estimation unit 34, and a life determination unit. .
Further, the memory 25 is provided with a life determination threshold value storage area 41 and a cumulative incident X-ray dose storage area 42.

  The X-ray generator 11 constituting the X-ray measurement optical system 13 includes an X-ray tube for fluoroscopic X-ray irradiation. The flat panel X-ray detector 12 detects X-rays transmitted through the object to be measured S and captures a fluoroscopic X-ray image so as to output it as a video signal.

The stage 14 can be rotated by a lower stage that can slide in a three-dimensional direction of an XY direction that is a direction in the stage surface and a Z direction that is perpendicular to the stage surface, and a rotation axis in the Z-axis direction with respect to the lower stage. The object to be measured S is placed on the upper stage.
The drive mechanism 16 is equipped with an XYZ direction triaxial drive motor and a rotational drive motor, and translates or rotationally moves the stage 14 based on a drive control signal for driving the stage from the CPU 21. . A drive control signal for manually moving the stage 14 is sent by performing an input operation using the keyboard 22 or the mouse 23.
The dosimeter 19 is fixed at a position in the vicinity of the flat panel X-ray detector 12 so as not to obstruct the light receiving surface (that is, the measurement visual field region) of the flat panel X-ray detector 12 so as not to disturb the fluoroscopic X-ray image measurement. The X-rays emitted from the X-ray generator 11 are measured. As the mounting position, a position where X-rays equivalent to the light receiving surface are irradiated is selected. From the dosimeter 19, the incident X-ray dose from moment to moment is output as a digital signal.

Next, each functional block of the CPU 21 will be described.
The X-ray image creation unit 31 performs control to convert the video signals of the fluoroscopic X-ray images sent from the X-ray detector 12 into digital images one after another and create frame image data.
The X-ray image display control unit 32 sequentially sends the generated frame image data to the display device 24 and performs control to display a fluoroscopic X-ray image on the monitor screen. The image displayed on the monitor screen is an image (usually a local image) used for X-ray measurement (observation).

  The drive signal generator 33 generates a drive signal for controlling the drive mechanism 16. The drive signal is generated by, for example, pressing an arrow key in the moving direction on the keyboard 22 or clicking operation specifying the moving direction of the mouse 23.

  The cumulative incident X-ray dose estimation unit 34 adds the data of the incident X-ray dose newly output from the dosimeter 19 this time to the accumulated incident X-ray dose data stored in the cumulative incident X-ray dose storage area 42 so far. By adding, it is updated to the latest cumulative incident X-ray dose, and the updated cumulative incident X-ray dose data is accumulated in the cumulative incident X-ray dose storage area 42.

  The lifetime determination unit 35 compares the updated cumulative incident X-ray dose data with the reference value (t) stored in the lifetime determination threshold storage area 41, and if it is less than the reference value (t), nothing is done. If the reference value (t) is not reached, it is determined that the flat panel X-ray detector 12 has reached the end of life, and a display notifying that it is time to replace is displayed on the monitor screen of the display device 24.

Next, the processing operation by the above apparatus will be described. FIG. 2 is a flowchart for explaining operations executed by the X-ray inspection apparatus 1.
When the X-ray inspection apparatus 1 is activated, the dosimeter 19 enters a measurement state. In this state, the incident X-ray dose irradiated from the X-ray generator 11 is measured (S101). This incident X-ray dose is equivalent to the incident X-ray dose to the flat panel X-ray detector 12.
Data of the cumulative incident X-ray dose irradiated so far is extracted from the cumulative incident X-ray dose storage area 42, the incident X-ray dose measured this time is added, and the latest cumulative incident X-ray dose at the present time is obtained and accumulated. Data in the incident X-ray dose storage area 42 is updated (S102).

  The latest cumulative incident X-ray dose is compared with the threshold value (t) stored in the lifetime determination threshold value storage area 41, and it is determined whether or not it is equal to or greater than the threshold value (S103). If it is less than the threshold value (t), it is determined that the flat panel X-ray detector 12 currently in use is not yet in service, and the process returns to S101 and the operation is repeated. On the other hand, when the threshold (t) or more is reached, it is determined that the life has expired, and a warning is given to the display device 24 that the flat panel X-ray detector 12 is in the replacement period (S104).

  With the above processing, since the cumulative incident X-ray dose equivalent to the cumulative incident X-ray dose of the flat panel X-ray detector 12 is actually measured, the replacement time can be accurately determined. Depending on the size of the object S to be measured, dimensions and / or dimensions that do not attenuate the X-rays irradiated to the light receiving surface of the dosimeter 19 while attenuating only the X-rays irradiated to the light receiving surface of the flat panel X-ray detector 12. A shape may be placed on the stage, but such cases are rare and can be ignored.

(Embodiment 2)
FIG. 3 is a block diagram showing a configuration of an X-ray inspection apparatus according to another embodiment of the present invention. In the figure, the same components as those in FIG.
In the X-ray inspection apparatus 2, the dosimeter 19 is not attached. Instead, the reference dose rate storage area 43 is provided in the memory 25, and the reference dose rate (A) is stored together with the reference X-ray irradiation conditions (tube voltage, tube current, SID).

  An X-ray irradiation condition monitoring unit 36 is added as a functional block of the CPU 21. The X-ray irradiation condition monitoring unit 36 monitors the tube voltage, tube current, SID, and irradiation time of the X-ray generation apparatus 11 that are X-ray irradiation conditions at the time of X-ray irradiation. Is not required).

  The dose rate is proportional to the square of the tube voltage, proportional to the tube current, and inversely proportional to the square of the SID. Therefore, the cumulative incident X-ray dose estimation unit 34 uses these monitored X-ray irradiation parameters, the reference X-ray irradiation conditions and the reference dose rate (A) stored in the reference dose rate storage area 43. Thus, the dose rate (B) under the X-ray irradiation conditions other than the reference X-ray irradiation conditions is obtained. The newly added incident X-ray dose is calculated by multiplying this dose rate (B) by the irradiation time under the current X-ray irradiation conditions.

  Then, as in the first embodiment described above, the lifetime determination is performed by adding the calculated incident X-ray dose to the cumulative value of the cumulative incident X-ray dose storage area 42 by executing the processing of the flowchart of FIG. Can do.

  Although the X-ray irradiation conditions are constant in one X-ray measurement, when changing the X-ray irradiation conditions during the measurement, it is considered that the measurement is different before and after the change. Accumulate.

(Embodiment 3)
FIG. 4 is a block diagram showing a configuration of an X-ray inspection apparatus according to another embodiment of the present invention. In FIG. 4, the same components as those in FIG.
In this X-ray inspection apparatus 3, a dose rate table storage area 44 is provided instead of the reference dose rate storage area 43 provided in the memory 25 of FIG. 3.
As shown in FIG. 5, the dose rate table storage area 44 stores measurable X-ray irradiation conditions and dose rates (B) under the conditions in a table format. As the dose rate (B) under each X irradiation condition, a value actually measured by a dosimeter temporarily attached at the time of apparatus inspection is used.

  In this embodiment, the cumulative incident X-ray dose estimation unit 34 performs the X-ray irradiation in the monitored parameters (tube voltage, tube current, SID) and the dose rate table storage area 44 corresponding thereto. Search for data that matches the monitored parameter among the conditions, and extract the dose rate (B) of the data. Then, the newly added incident X-ray dose is calculated by multiplying the extracted dose rate (B) by the irradiation time.

  Then, similarly to the above-described first and second embodiments, the lifetime is calculated by adding the calculated incident X-ray dose to the cumulative value in the cumulative incident X-ray storage area 42 by executing the processing of the flowchart of FIG. Judgment can be made.

  The present invention can be used in an X-ray inspection apparatus using a flat panel X-ray detector as a detector of an X-ray measurement optical system.

The block diagram which shows the structure of the X-ray inspection apparatus which is one Embodiment of this invention. The flowchart explaining the flow of the processing operation in this invention. The block diagram which shows the structure of the X-ray inspection apparatus which is other one Embodiment of this invention. The block diagram which shows the structure of the X-ray inspection apparatus which is other one Embodiment of this invention. The figure explaining an example of a dose rate table.

Explanation of symbols

1, 2, 3: X-ray inspection device 11: X-ray generator (X-ray source)
12: X-ray detector 13: X-ray measurement optical system 14: Stage 16: Drive mechanism 19: Dosimeter 20: Control system 21: CPU
22: Keyboard 23: Mouse 24: Display device 25: Memory 31: X-ray image creation unit 32: X-ray image display control unit 33: Drive signal generation unit 34: Cumulative incident X-ray dose estimation unit 35: Life determination unit 36: X Radiation irradiation condition monitor unit 41: Threshold value storage area for life determination 42: Cumulative incident X-dose storage area 43: Reference dose rate storage area 44: Dose rate table storage area

Claims (4)

An X-ray inspection apparatus in which an X-ray measurement optical system composed of an X-ray source and a flat panel X-ray detector is arranged to face each other with the object to be measured interposed therebetween, and a fluoroscopic X-ray image of the object to be measured is taken by the X-ray measurement optical system In
A cumulative incident X-ray dose estimation unit that estimates the cumulative incident X-ray dose to the flat panel X-ray detector by cumulatively measuring or calculating an X-ray dose equivalent to the incident X-ray dose to the flat panel X-ray detector; An X-ray inspection apparatus comprising: a life determination unit that determines the life of a flat panel X-ray detector by comparing a set determination criterion with an estimated accumulated incident X-ray dose. The cumulative incident X-ray dose estimation unit estimates a cumulative incident X-ray dose based on an X-ray dose measured by a dosimeter attached in the vicinity of a light receiving surface of a flat panel X-ray detector. Line inspection device. The X-ray dose irradiated under the reference X-ray irradiation conditions is measured by a dosimeter temporarily attached in the vicinity of the light receiving surface of the flat panel X-ray detector and stored as a reference dose rate, or the reference X A reference dose rate storage area for storing a dose rate obtained by calculating an X-ray dose irradiated from an X-ray source to a flat panel X-ray detector under a radiation exposure condition as a reference dose rate, and a cumulative incident X-ray dose The X-ray inspection apparatus according to claim 1, wherein the estimation unit estimates the cumulative incident X-ray dose based on the stored reference dose rate and the X-ray irradiation conditions during the subsequent X-ray irradiation. The X-ray dose irradiated under each X-ray irradiation condition is measured by a dosimeter temporarily installed in the vicinity of the light receiving surface of the flat panel X-ray detector, and each X-ray irradiation condition corresponds to the dose rate at that time. And a cumulative incident X-ray dose estimation unit for estimating a cumulative incident X-ray dose based on an X-ray irradiation condition at the time of X-ray irradiation and a dose rate table. The X-ray inspection apparatus according to 1.

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