JP2014059168A - Radioactive ray irradiation condition determination method and radioactive ray irradiation condition determination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently perform an adjustment of an irradiation condition and an inspection of a radioactive ray by determining propriety of an irradiation condition more easily.SOLUTION: The method of determining the irradiation condition of the radioactive ray prior to a radioactive ray inspection is configured to include: a luminance detection step (S102) of detecting luminance of a digital transmission image obtained by irradiating an inspection object with a radioactive ray; a luminance/concentration conversion step (S104) of converting the detected luminance to concentration of the transmission image; and a determination step (S105) of determining whether a maximum value of the concentration and a minimum value of the concentration fall within a predetermined concentration range. Then, as a result of the determination, when at least one of the maximum value of the concentration and the minimum value thereof falls outside the concentration range, the irradiation condition can be changed.

Description

  The present invention relates to a radiation irradiation condition determination method and a radiation irradiation condition determination device for determining whether or not the irradiation condition is good when inspecting deterioration or damage of a welded part or the like by radiation irradiation.

  For members with welded parts, including gas turbine combustors and turbine blades, etc., in order to ensure quality, the welded parts are irradiated with radiation to ascertain the occurrence of welded construction defects and damage, The non-defective products and defective products are selected, and repairs are performed as necessary.

  In such a radiation inspection, radiation is irradiated from one side of the member, and a transmission image (inspection image) of the radiation is obtained by a film or an image sensor disposed on the other side of the member. This transmitted image appears in light and shade on a film or an image obtained by an image sensor. By evaluating this transmitted image, it is possible to grasp whether or not there is a construction failure or damage in the welded portion.

  Patent Document 1 discloses a configuration in which a radiographic inspection automatically inspects a welded portion based on a captured transmission image using an image processing technique.

Japanese Patent No. 4211092

By the way, even if a member is irradiated with radiation, the density of the obtained transmission image varies depending on the material and thickness of the member.
In the JIS standard, a density range of a transmission photograph (transmission image of a film) in such a radiation transmission test is defined (JIS Z 3106).

Therefore, prior to performing the radiological inspection, the member to be inspected is actually irradiated with radiation, and the density of the transmission image of the obtained film (the density of the darkest part and the thinnest part) is detected. It is confirmed whether the range is within the specified concentration range. When the density of the transmitted image is outside the specified density range, the radiation irradiation condition is changed, the radiation is irradiated again, and the confirmation of the density range of the transmitted image is repeated. Finally, the change of radiation irradiation conditions and the acquisition of a transmission image by radiation irradiation are repeated until the density of the transmission image falls within a prescribed density range.
Here, the irradiation conditions to be changed include the type of radiation source, the magnitude of the tube voltage, the magnitude of the tube current, and the irradiation time.

  A densitometer is used to detect the density of the transmission image of the film. For this reason, each time the radiation irradiation conditions are adjusted, the inspector must detect the density of the transmitted image with a densitometer before performing the radiation inspection, which is troublesome.

  Even in the technique described in Patent Document 1, there is no change in adjusting the irradiation conditions in the same manner as described above prior to the actual inspection. In the technique described in Patent Document 1, the shading is corrected by the shading morphology process, but this is for correcting the shading difference due to the difference in the amount of radiation irradiation for the transmission image obtained by the radiation irradiation. Depending on the material and thickness of the member, the irradiation conditions are not adjusted before the transmission image is taken.

  The present invention has been made in view of such circumstances, and it is easier to adjust irradiation conditions and to perform radiation inspection efficiently by determining whether irradiation conditions are possible or not. An object is to provide a determination method and a radiation irradiation condition determination apparatus.

In order to solve the above problems, the radiation irradiation condition determination method and the radiation irradiation condition determination apparatus of the present invention employ the following means.
That is, the radiation irradiation condition determination method of the present invention is a method for determining the irradiation condition of radiation prior to performing a radiation inspection, and the luminance of a digital transmission image obtained by irradiating the inspection object with radiation. A luminance detection step for detecting; a luminance / density conversion step for converting the detected luminance into a density of the transmission image based on a reference data table indicating a relationship between density and luminance; A determination step of determining whether or not the minimum density value is within a predetermined density range. The luminance described here indicates the level of brightness in the digital transmission image, and the density indicates the density when the transmission image is in a film state.
Thereby, it is possible to determine whether or not the density range of the transmission image is within the specified density range without measuring the density of the transmission image obtained by irradiating the inspection object with radiation.
In addition, since the conversion between luminance and density can be performed by referring to the standard data table, the standard data table may be generated once.
Here, the transmission image may be in the form of a film, or may be an image taken by a so-called digital imaging device equipped with an imaging device. In the case of a film state, the film is scanned and an image is taken into a computer device, whereby the transmission image is converted into a digital image data state. Thus, if the transmission image is in the state of image data, a series of processing can be automatically executed on the computer device.
Therefore, prior to performing the radiation examination, it is possible to easily and quickly determine whether the irradiation conditions are acceptable.

  Here, the reference data table includes, in a transmission image obtained by irradiating a test piece having different thicknesses in a plurality of stages in advance, the density of each area having a different density for each thickness of the test piece. Preferably, it is generated by measuring the luminance.

Further, when at least one of the maximum density value and the minimum density value obtained by converting from the luminance of the digital transmission image is outside the predetermined density range, the radiation irradiation condition for the inspection object Then, the luminance detection step, the luminance / density conversion step, and the determination step are repeated.
In this way, irradiation conditions that clear the specified concentration range can be obtained efficiently.

  The radiation irradiation condition determination apparatus according to the present invention is an irradiation condition determination apparatus that determines a radiation irradiation condition prior to performing a radiation inspection, and is a digital transmission image obtained by irradiating the inspection object with radiation. A luminance detection unit that detects the luminance of the transmission image, a data storage unit that stores a reference data table indicating the relationship between the luminance and density of the transmission image, and the detected luminance based on the reference data table. A luminance / density conversion unit for converting to a density; and a determination unit that determines whether or not the maximum density value and the minimum density value are within a predetermined density range. To do.

  It is possible to determine whether or not the density range of the transmission image is within a specified density range without measuring the density of the transmission image obtained by irradiating the inspection object with radiation using a densitometer. it can. Thereby, it is possible to efficiently set to appropriate irradiation conditions, and it is possible to perform a radiation examination more easily.

It is a figure which shows schematic structure of the irradiation condition determination apparatus of the radiation of this invention. It is a figure which shows the method of producing | generating the basic data table which shows the relationship between the brightness | luminance and density | concentration of a transmission image used with the irradiation condition determination method of the radiation of this invention, (a) is a cross section of the test piece from which thickness differs in several steps FIG. 4B shows an example of a transmission image when the test piece of FIG. It is a figure which shows an example of the relationship between the brightness | luminance and density | concentration of a transmitted image used with the irradiation condition determination method of the radiation of this invention. It is a figure which shows the flow of the irradiation condition determination method of the radiation | emission of this invention.

Hereinafter, an embodiment of a radiation irradiation condition determination method and a radiation irradiation condition determination apparatus according to the present invention will be described with reference to the drawings.
As shown in FIG. 1, a radiation inspection apparatus (irradiation condition determination apparatus) 10 includes a radiation irradiation unit 11 that irradiates an inspection target with radiation, and radiation irradiated from the radiation irradiation unit 11 passes through the inspection target. A transmission image acquisition unit 12 that acquires a transmission image obtained in step (b), and a density determination unit (a luminance detection unit, which determines whether the density of the transmission image acquired by the transmission image acquisition unit 12 is within a specified density range. (Luminance / density conversion unit, determination unit) 20 and an information output unit 30 such as a monitor and an indicator lamp for outputting information to the outside according to the determination result of the light / dark determination unit 20.

In such a radiation inspection apparatus 10, the radiation irradiation unit 11 irradiates the inspection object with radiation, and a transmission image is acquired by the transmission image acquisition unit 12.
Here, the radiation irradiation unit 11 can adjust the type of radiation source that emits radiation, the line voltage / line current for emitting radiation, and the radiation irradiation time.

  The transmission image acquisition unit 12 can be configured by a digital imaging device that captures a transmission image of radiation that has passed through the inspection object using an imaging device.

The radiation inspection apparatus 10 can output the transmission image obtained by the transmission image acquisition unit 12 as image data, or print it on a film or paper for printing. Furthermore, the radiation inspection apparatus 10 can further include a diagnosis unit that determines whether or not the welded portion of the inspection target has a construction defect or a defect based on the output image data.
In the present embodiment, it is assumed that the transmission image acquisition unit 12 captures a transmission image of radiation with an imaging element.

In such a radiation inspection apparatus 10, prior to performing the inspection by radiation irradiation, the light / dark determination unit 20 sets the irradiation conditions. The flow is shown below.
In order to set the irradiation condition in the light / dark determination unit 20, a reference data table that is a reference for setting (adjusting) the irradiation condition is generated in advance. For this, a test piece 100 as shown in FIG. The test piece 100 is made of, for example, metal, and has a plurality of thicknesses t1, t2,... With one surface 101 being stepped and the other surface 102 being flat.
Such a test piece 100 is irradiated with radiation by the radiation irradiation unit 11 in the same manner as the inspection object, and a transmission image thereof is acquired by the transmission image acquisition unit 12.

  As shown in FIG. 2B, the obtained transmission image 200 has different radiation transmission amounts in the respective areas A1, A2,... Corresponding to the thicknesses t1, t2,. The concentration is different.

The light / dark determination unit 20 detects the luminance of the obtained transmission image 200 from the respective digital transmission images of the areas A1, A2,... Corresponding to the thicknesses t1, t2,. At this time, the luminance in the area A0 without the test piece 100 is used as a reference.
In the transmission image 200, the density is measured by a densitometer in each of the areas A1, A2,... Corresponding to the thicknesses t1, t2,.

FIG. 3 shows an example of the relationship between density and luminance obtained in this way.
Then, a reference data table indicating the relationship between the density and luminance of the transmission image is generated from the obtained luminance and density detection values. The generated reference data table is stored in the data storage unit 21 (see FIG. 1) of the density determination unit 20.

  Thereafter, in order to set the irradiation condition for actually performing the radiological inspection of the inspection object, as shown in FIG. 4, first, the inspector irradiates the digital irradiation image with the radiation irradiation unit 11. Obtain (step S100). Basically, the main objective is to acquire a transmission image digitally from the beginning by capturing a transmission image with a digital imaging device. However, an analog imaging device is used, and the transmission image is not a digital film. In the analog state such as the above, data obtained by converting an analog transmission image into a digital transmission image by digital scanning or the like is acquired. Thereby, the transmission image acquisition unit 12 acquires data of the transmission image (step S101).

The obtained transmission image data is sent to the density determination unit 20. The density determination unit 20 measures the luminance of each part of the transmission image based on the transmission image data (step S102: luminance detection step).
Then, the maximum value and the minimum value of the brightness are extracted from the measured brightness of each part (step S103).

The density determination unit 20 converts the extracted maximum and minimum luminance values into densities based on the reference data table (step S104: luminance / density conversion step).

  It is determined whether or not the density of the portion with the maximum luminance and the density of the portion with the minimum luminance are in a predetermined density range determined in advance based on the JIS standard. (Step S105: Determination step).

  As a result of the determination, if both the density of the part with the highest brightness and the density of the part with the lowest brightness are within the specified density range, there is no need to change the irradiation conditions, so that The process proceeds to a defect evaluation process for determining whether or not there is a construction failure or defect in the welded part (step S106).

  As a result of the determination in step S105, if it is determined that at least one of the density of the portion with the highest luminance and the density of the portion with the lowest luminance is not within the specified density range, data is acquired in step S101. The fact that the density of the transmitted image is out of the specified range is displayed on the information output unit 30 by displaying character information or the like on the monitor, lighting the indicator lamp, or the like (step S107).

The inspector who sees the display in the information output unit 30 changes the radiation irradiation conditions (tube current, magnitude of tube voltage, irradiation time) in the radiation irradiation unit 11 based on the display (step S110).
At this time, if it is determined in step S105 that the density determination unit 20 is not within the specified concentration range, the tube current, the magnitude of the tube voltage, and the irradiation time are set to predetermined priorities each time it is determined. It is preferable to change the For example, when the density range of the transmission image is shifted in a direction darker than the standard, it is preferable to increase the tube voltage or tube current in the radiation irradiation unit 11 or lengthen the irradiation time.

After changing the irradiation condition, the inspector again irradiates radiation with the radiation irradiation unit 11 to capture a transmission image (step S100), and then returns to step S101 to transmit the captured transmission image data to the transmission image acquisition unit 12. Get in.
Thereafter, Steps S102 to S105 are repeated for the transmission image from which data is obtained, and the irradiation condition is changed until it falls within the specified density range in Step S105.

As described above, the relationship between the density and the luminance in the transmission image is grasped in advance using the test piece 100, and the maximum / minimum luminance of the obtained transmission image is detected in the density determination unit 20, and this maximum -From the minimum luminance, it was determined whether or not the transmitted image was within the specified density range.
Thereby, it is not necessary to manually measure the concentration, and the radiation inspection apparatus 10 can automatically determine whether the irradiation condition is acceptable.
Further, it is possible to shorten the transmission image density (luminance) detection time when setting the irradiation conditions. As a result, it is possible to efficiently set the radiation irradiation conditions and further perform the radiation inspection.
Further, as a result of the determination in step S105, the irradiation condition may be automatically changed and the irradiation condition may be set when it is determined that it is not within the prescribed concentration range.

In the above embodiment, the configuration of the radiation inspection apparatus 10 may be any configuration as long as it is within the scope of the present invention.
The transmission image acquisition unit 12 can also use a film to obtain a transmission image, and can output a transmission image printed on the film. In this case, in order for the light / dark determination unit 20 to perform the determination, the film needs to be digitally scanned and read and sent to the light / dark determination unit 20 in the state of digital image data.
In addition, for the radiation irradiation unit 11 and the transmission image acquisition unit 12 that perform imaging by irradiating the test piece 100 and the actual inspection object with radiation, the light / dark determination unit 20, the data storage unit 21, and the information output unit that perform light / dark determination It may be a separate body from 30. That is, in such a case, the density determination unit 20, the data storage unit 21, and the information output unit 30 constitute a transmission image density determination device or a radiation irradiation condition determination device obtained by irradiating radiation alone. can do.

10 Radiation inspection equipment (irradiation condition judgment equipment)
DESCRIPTION OF SYMBOLS 11 Radiation irradiation part 12 Transmission image acquisition part 20 Density determination part (luminance detection part, luminance / density conversion part, determination part)
21 Data storage unit 30 Information output unit 100 Test piece 101 One side 102 Other side 200 Transmission image

Claims (4)

A method for determining irradiation conditions prior to performing a radiation examination,
A luminance detection step for detecting the luminance of a transmission image obtained by irradiating the inspection object with radiation;
A luminance / density conversion step for converting the detected luminance into the density of the transmission image based on a reference data table indicating the relationship between the density and the luminance;
A determination step of determining whether the maximum value of the density and the minimum value of the density are within a predetermined density range;
A radiation irradiation condition determination method comprising:   In the reference data table, in the transmission image obtained by irradiating the test pieces with different thicknesses in a plurality of stages in advance, the density and brightness of each area having different densities for each thickness of the test piece. The radiation irradiation condition determination method according to claim 1, wherein the radiation irradiation condition determination method is a measurement method.   When at least one of the maximum density value and the minimum density value is outside the predetermined density range, after changing the irradiation condition of the radiation to the inspection object, the luminance detection step, 3. The radiation irradiation condition determination method according to claim 1, wherein the luminance / density conversion step and the determination step are repeated. An irradiation condition determination device that determines irradiation conditions of radiation prior to performing a radiation examination,
A luminance detector that detects the luminance of a transmission image obtained by irradiating the inspection object with radiation;
A data storage unit storing a reference data table indicating the relationship between the brightness and density of the transmission image;
A luminance / density conversion unit for converting the detected luminance into the density of the transmission image based on the reference data table;
A determination unit for determining whether the maximum value of the density and the minimum value of the density are within a predetermined density range;
A radiation irradiation condition determining apparatus comprising:

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