JP2011177469A - Radiation image reading device, radiographic system, and radiation image reading method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To more simply and precisely conduct an offset correction process. <P>SOLUTION: The radiation image reading device 18 includes an offset image memory part 38 to store offset images obtained by a radiation detection device 24 at non-exposure time before and after exposure of radiation 14 to the radiation detection device 24 through an examinee 12, a correction image selection part 40 to select either of the offset image before exposure and the offset image after exposure stored in the offset image memory part 38 to be a correction image, and an image processing part 32 to obtain a radiation image obtained by the radiation detection device 24 at exposure time of the radiation 14, and conduct the offset correction process to the radiation image using the correction image selected by the correction image selection part 40. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a radiation image reading apparatus and a radiation image reading method for acquiring the radiation image from the radiation detection apparatus after the radiation exposed to the radiation detection apparatus through the subject is converted into a radiation image by the radiation detection apparatus. And a radiation imaging system including the radiation source for exposing the radiation to the subject, the radiation detection device, and the radiation image reading device.

  Conventionally, the radiation exposed to the radiation detection device through the subject is converted into a radiation image by the radiation detection device, and then the radiation image is read from the radiation detection device, and then offset from the radiation image. It is known that an offset component (for example, dark current) due to the characteristics of the radiation detection device included in the radiation image is removed by performing correction processing (see Patent Documents 1 to 3).

  Here, the offset correction processing refers to acquiring an image at the time of non-exposure when radiation is not exposed to the radiation detection apparatus as an offset image from the radiation detection apparatus, and using the offset image as a correction image and the radiation image. The offset component included in the radiographic image is removed by performing a subtraction process between the two.

JP-A-2005-283422 JP 2006-75359 A JP 2009-1000084

  However, in a radiography system including a radiation detection apparatus, when performing multiple imaging, an offset image is acquired from the radiation detection apparatus during a non-exposure time period between the previous imaging and the current imaging of the subject. Even so, there is a possibility that an afterimage of the radiation image in the previous imaging may remain in the offset image. Further, in the case where a plurality of imaging devices are arranged in an imaging room to which the radiation imaging system is applied, if another imaging is performed by another imaging device at the time of obtaining an offset image, the other imaging device There is a possibility that an image related to radiation from the image will appear in the offset image. Therefore, even if an offset correction process is performed using such an offset image, the offset component in the radiation image cannot be reliably removed.

  Accordingly, an image for correction is selected from a plurality of offset images based on the level of the afterimage, or the presence or absence of radiation exposure is detected as in the technique of Patent Document 1, and offset correction is performed only during non-exposure. Although processing may be considered, control and processing of the entire system may be complicated.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a radiation image reading apparatus, a radiation imaging system, and a radiation image reading method capable of performing offset correction processing more easily and accurately. And

The present invention is a radiological image reading apparatus that acquires the radiation image from the radiation detection apparatus after the radiation exposed to the radiation detection apparatus through the subject is converted into a radiation image by the radiation detection apparatus,
An offset image storage unit that stores an offset image obtained by the radiation detection device at the time of non-exposure before and after exposure of the radiation to the radiation detection device via the subject;
A correction image selection unit that selects any one of the offset image before exposure and the offset image after exposure stored in the offset image storage unit as a correction image;
An image processing unit that acquires the radiation image obtained by the radiation detection apparatus during the radiation exposure and performs an offset correction process on the radiation image using the correction image selected by the correction image selection unit It is characterized by having.

The present invention also provides a radiation source for exposing a subject to radiation, a radiation detection device for converting the radiation transmitted through the subject into a radiation image, and a radiation image reading device for acquiring the radiation image from the radiation detection device. A radiography system comprising:
The radiological image reader is
An offset image storage unit that stores an offset image obtained by the radiation detection device at the time of non-exposure before and after exposure of the radiation from the radiation source to the radiation detection device via the subject;
A correction image selection unit that selects any one of the offset image before exposure and the offset image after exposure stored in the offset image storage unit as a correction image;
An image processing unit that acquires the radiation image obtained by the radiation detection apparatus during the radiation exposure and performs an offset correction process on the radiation image using the correction image selected by the correction image selection unit It is characterized by having.

Furthermore, the present invention is a radiation image reading method for acquiring the radiation image from the radiation detection device after the radiation exposed to the radiation detection device through the subject is converted into a radiation image by the radiation detection device. ,
At the time of non-exposure before and after exposure of the radiation to the radiation detection device via the subject, the offset image obtained by the radiation detection device is stored in an offset image storage unit,
The offset image before exposure and the offset image after exposure stored in the offset image storage unit are selected as a correction image by the correction image selection unit,
After obtaining the radiation image obtained by the radiation detection apparatus at the time of the radiation exposure, an offset correction process is performed on the radiation image using the correction image by an image processing unit.

  According to these inventions, each offset image at the time of non-exposure before and after radiation exposure (before and after imaging) is acquired, and one of the offset images is used for offset correction processing. Select as a correction image. As a result, it is possible to reduce (halve) the risk of an afterimage remaining in the correction image and the risk that an image related to the exposed radiation appears in the correction image, and a highly accurate offset correction process is possible. It becomes.

  Therefore, according to the present invention, an offset correction process can be performed more easily and accurately by selecting one of the offset images at the time of non-exposure before and after the radiation exposure. It becomes possible.

  Here, the radiation image reading device further includes an offset image reading unit that reads the offset image from the radiation detection device at predetermined time intervals and sequentially stores the offset image in the offset image storage unit, and the correction image selection unit includes: Then, one of the plurality of offset images stored in the offset image reading unit is selected as the correction image.

  As described above, since the offset image is periodically acquired, and one offset image most suitable for the offset correction processing is selected as the correction image from the plurality of acquired offset images, the correction image The risk that an afterimage remains in the image and the risk that an image related to the exposed radiation appears in the correction image can be further reduced. Further, since the offset images are periodically acquired, there is no need to forcibly acquire the offset images immediately before and after the photographing, and the offset image acquisition process can be easily performed. Furthermore, since each offset image is sequentially stored in the offset image storage unit, it is possible to perform an offset correction process on the radiographic image after a considerable time has passed since the imaging.

  In this case, the correction image selection unit includes the offset image having the lowest pixel average value among the offset images, the pixel average value having the smallest difference from the pixel average value or the pixel intermediate value for all offset images, or An offset image having a pixel intermediate value, or an offset image having a pixel value having the smallest difference from the pixel average value or pixel intermediate value for each pixel of all offset images may be selected as the correction image.

  As described above, since the correction image is selected from a plurality of the offset images according to a statistical method, the correction image can be accurately and efficiently determined.

  According to the present invention, it is possible to perform offset correction processing more easily and accurately by selecting one of the offset images during non-exposure before and after radiation exposure. Become.

It is a block diagram of the radiography system concerning this embodiment. It is a flowchart which shows selection of the image for correction | amendment in the radiography system of FIG. 2 is a flowchart showing imaging for a subject in the radiation imaging system of FIG. 1. 4A and 4B are explanatory diagrams illustrating selection of a correction image. It is explanatory drawing which shows selection of the image for a correction | amendment. It is explanatory drawing which shows selection of the image for a correction | amendment. It is explanatory drawing which shows selection of the image for a correction | amendment.

  A preferred embodiment of the radiation image reading apparatus and the radiation imaging system according to the present invention will be described with reference to FIGS. 1 to 7 in relation to a radiation image reading method.

  A radiation imaging system 10 according to the present embodiment includes an imaging device 16 that irradiates a subject 12 with radiation 14 and performs imaging on the subject 12, and a console (radiation image reading device) 18 that controls imaging on the imaging device 16. And have.

  The imaging device 16 is disposed in a radiographing room or the like of a hospital (not shown) and houses a radiation source 20 that outputs radiation 14 according to predetermined imaging conditions and a radiation detector 22 that converts the radiation 14 that has passed through the subject 12 into a radiographic image. And a radiation detection device 24.

  On the other hand, the console 18 is arranged outside the imaging room, and stores an imaging condition storage for storing imaging conditions input by operating the operation unit 26 such as a keyboard and a mouse operated by a doctor or a technician, and the operation unit 26 by a doctor or a technician. Unit 28, control unit 30 that controls the imaging device 16, image processing unit 32 that reads a radiation image from the radiation detection device 24, performs predetermined image processing on the read radiation image, and a radiographic image after image processing Is stored, and a display unit 34 that displays the radiographic image after image processing is included.

  In addition, the console 18 switches the switch 36 for switching the output destination of the image (radiation image, offset image) read from the radiation detection device 24 according to the control from the control unit 30, and before and after the exposure of the radiation 14 to the subject 12 (imaging). The offset image storage unit 38 that stores the offset image read in the time zone during the non-exposure time (before and after), and one offset image among the plurality of offset images stored in the offset image storage unit 38 32, a correction image selection unit 40 that selects an image for correction that is optimal for the offset correction processing for the radiation image 32, and a correction image storage unit 42 that stores the correction image.

  The configuration of the radiation imaging system 10 is generally as described above. Next, some of the components will be described in more detail.

  In the imaging device 16, the radiation source 20 is a known thermal electron emission type or field emission type radiation source. The radiation detector 22 is a direct conversion type radiation detector that directly converts the radiation 14 that has passed through the subject 12 into an electrical signal, or the radiation detector 22 that has passed through the subject 12 is temporarily converted into visible light, and then converted. It is an indirect conversion type radiation detector that converts visible light into an electrical signal.

  On the other hand, in the console 18, the imaging condition storage unit 28 stores imaging conditions such as the tube current, tube voltage, and exposure time of the radiation source 20 according to the imaging region of the subject 12.

  The control unit 30 controls the photographing device 16 to photograph the subject 12 and controls the changeover switch 36 so that the image output destination of the changeover switch 36 is the image processing unit 32 during photographing. Therefore, the image processing unit 32 can read out the electrical signal as a radiation image from the radiation detector 22 via the changeover switch 36.

  The correction image selection unit 40 periodically requests the control unit 30 to acquire an offset image at a predetermined time interval (for example, every 10 minutes). Since the control unit 30 also controls the imaging device 16, every time there is an offset image acquisition request from the correction image selection unit 40, the acquisition request time point is not in the exposure time zone of the radiation 14. It is determined whether or not it is an exposure time zone. If it is a non-exposure time zone, the output destination of the image in the changeover switch 36 is switched to the offset image storage unit 38 and the offset to the radiation detection device 24 is set. Instructs the image output. Thereby, offset images can be sequentially stored in the offset image storage unit 38 from the radiation detection device 24 via the changeover switch 36.

  Further, the correction image selection unit 40 selects one offset image as a correction image optimal for the offset correction processing in the image processing unit 32 from the plurality of offset images stored in the offset image storage unit 38, It is stored in the correction image storage unit 42. In this case, the correction image storage unit 42 selects one offset image as a correction image according to the statistical methods (1) to (5) below.

  (1) The correction image selection unit 40 calculates the pixel average value of each offset image for all the offset images stored in the offset image storage unit 38, and determines the offset image having the lowest pixel average value as the correction image. Choose as.

  (2) The correction image selection unit 40 calculates a pixel average value for all pixels of all offset images stored in the offset image storage unit 38 and a pixel average value of each offset image, and the all pixels An offset image having a pixel average value closest to the pixel average value for is selected as a correction image.

  (3) The correction image selection unit 40 calculates a pixel intermediate value for all pixels of all offset images stored in the offset image storage unit 38 and a pixel intermediate value of each offset image. An offset image having a pixel intermediate value closest to the pixel intermediate value is selected as a correction image.

  (4) The correction image selection unit 40 calculates a pixel average value for the same pixel in all the offset images stored in the offset image storage unit 38, and calculates the pixel average value in addition to each offset image. This is also performed for all the pixels. Then, the correction image selection unit 40 takes the difference between the calculated pixel average value of each pixel and the pixel value of the corresponding pixel of each offset image, and the offset having the largest number of pixels with the smallest difference. The image is selected as a correction image.

  (5) The correction image selection unit 40 calculates a pixel intermediate value for the same pixel in all the offset images stored in the offset image storage unit 38, and calculates the pixel intermediate value in addition to each offset image. This is also performed for all the pixels. Then, the correction image selection unit 40 takes the difference between the calculated pixel intermediate value of each pixel and the pixel value of the corresponding pixel of each offset image, and the offset having the largest number of pixels with the smallest difference. The image is selected as a correction image.

  An offset component (for example, dark current) resulting from the characteristics of the radiation detector 22 is superimposed on the plurality of offset images stored in the offset image storage unit 38. In addition to the offset component, the offset image If the afterimage of the radiographic image obtained by imaging before acquiring the image remains, or if another imaging device in the imaging room is imaging at the time of acquiring the offset image, the radiation of the imaging device There may be an image of the radiation exposed from the source.

  Therefore, the correction image selection unit 40 includes an offset component from among a plurality of offset images by the statistical method shown in the above-described (1) to (5), and the influence of the afterimage and the image described above. The smallest offset image is selected as a correction image optimal for the offset correction process in the image processing unit 32.

  The image processing unit 32 reads the correction image stored in the correction image storage unit 42, and performs an offset correction process (subtraction process between the radiation image and the correction image) on the radiographic image using the read correction image. Then, an offset component is removed from the radiation image. Therefore, a radiographic image subjected to offset correction processing and other image processing (for example, gain correction processing) is stored in the image storage unit 44 or displayed on the display unit 34.

  The configuration of the radiation imaging system 10 according to the present embodiment is as described above. Next, the operation (radiation image reading method) of the radiation imaging system 10 will be described with reference to the flowcharts of FIGS. .

  Here, first, the offset image acquisition and correction image selection processing performed during the time period when radiation 14 is not exposed will be described with reference to FIG. The imaging for the subject 12 and the offset correction processing for the radiation image on the console 18 will be described with reference to FIG.

  In step S <b> 1 of FIG. 2, the correction image selection unit 40 (see FIG. 1) requests the control unit 30 to acquire an offset image. When there is an offset image acquisition request from the correction image selection unit 40, the control unit 30 determines whether or not the radiation 14 is currently being exposed, and is not a time zone for exposure of the radiation 14. In the exposure time zone, the image output destination in the changeover switch 36 is switched to the offset image storage unit 38 and the radiation detection device 24 is instructed to output an offset image. Thereby, the changeover switch 36 switches the image output destination from the image processing unit 32 to the offset image storage unit 38, while the radiation detection device 24 converts the electrical signal of the radiation detector 22 including the offset component into the offset image. As described above, the offset image is stored in the offset image storage unit 38 via the changeover switch 36 (step S2).

  Note that the above description of steps S1 and S2 is a description of the case where one offset image is acquired. When a plurality of offset images are to be acquired, as shown by a two-dot chain line in FIG. What is necessary is just to repeat the process of step S1, S2 regularly at a time interval. In this embodiment, the correction image selection unit 40 omits the offset image acquisition request (step S1) from the control unit 30, and the control unit 30 periodically detects radiation as indicated by the broken line in FIG. The apparatus 24 may be instructed to output an offset image.

  In step S3 after the offset image is stored in the offset image storage unit 38 in this way, the correction image selection unit 40 performs the offset image storage unit according to the statistical methods (1) to (5) described above. One offset image is selected from among a plurality of offset images stored in 38 as a correction image optimal for the offset correction processing. The correction image selection unit 40 stores the selected correction image in the correction image storage unit 42 (step S4). As a result, the image processing unit 32 can perform the offset correction process on the radiation image.

  Next, imaging with respect to the subject 12 and offset correction processing with respect to the radiation image will be described with reference to FIG.

  In step S <b> 11, the doctor or engineer operates the operation unit 26 (see FIG. 1) to input imaging conditions such as tube current, tube voltage, and exposure time according to the imaging region of the subject 12. The input shooting conditions are stored in the shooting condition storage unit 28.

  In the next step S <b> 12, the doctor or engineer positions the imaging region of the subject 12 on the radiation source 20 side of the radiation detection device 24, and directs the radiation source 20 toward the imaging region and the radiation detection device 24. Make preparations.

  In this way, when the doctor or engineer operates the operation unit 26 after the preparation for photographing the subject 12 is completed, the operation unit 26 functions as an exposure switch and instructs the control unit 30 to photograph the subject 12. .

  In step S13, the control unit 30 reads the shooting conditions from the shooting condition storage unit 28, and controls the shooting device 16 according to the read shooting conditions. That is, the control unit 30 controls the radiation detection device 24 so that the radiation detector 22 can detect the radiation 14 and then controls the radiation source 20 to emit the radiation 14. Further, the control unit 30 controls the changeover switch 36 to switch the image output destination of the changeover switch 36 to the image processing unit 32.

  The radiation 14 exposed from the radiation source 20 is exposed to the subject 12, and the radiation 14 transmitted through the subject 12 is guided to the radiation detector 22. The radiation detector 22 converts the radiation 14 into an electrical signal, and outputs the converted electrical signal as a radiation image to the image processing unit 32 via the changeover switch 36 (step S14).

  In step S15, when the radiation image is input, the image processing unit 32 reads the correction image from the correction image storage unit 42, and performs a subtraction process between the read correction image and the radiation image. An offset correction process for removing an offset component included in the radiation image is performed. As described above, the correction image is an offset image that is optimal for the offset correction process and includes only an offset component that does not include an afterimage or an image related to radiation emitted from another imaging apparatus. An offset component can be effectively removed by performing an offset correction process on the radiographic image using a commercial image.

  In the next step S16, the image processing unit 32 performs image processing (for example, gain correction processing) other than the offset correction processing on the radiographic image after the offset correction processing. The radiographic image after the image processing is stored in the image storage unit 44 or displayed on the display unit 34 (step S17).

  4A to 7 are explanatory diagrams illustrating the offset image and the radiographic image (captured image) stored in the offset image storage unit 38 in time series based on the acquisition time point.

  FIG. 4A illustrates a case where offset images A and B are acquired at the time of non-exposure before and after imaging, based on the captured image in which the image 52 of the imaging region is reflected. In this case, since the image 50a indicating the afterimage or the image related to the radiation from the other imaging apparatus is reflected in the offset image A before imaging, the correction image selecting unit 40 does not include the image 50a in the offset. Image B is selected as a correction image.

  In FIG. 4B, contrary to the case of FIG. 4A, the image 50 b is reflected in the offset image B after shooting. Therefore, the correction image selecting unit 40 corrects the offset image A in which the image 50 b is not reflected. Select as an image. Note that the image 50b is assumed to be an image related to the remaining radiation image from the imaging or radiation from another imaging apparatus.

  FIG. 5 illustrates acquisition of an offset image and a captured image from the start of daily use of the radiation imaging system 10. In this case, the offset image C is acquired at the start of use (when the radiation detection device 24 is turned on), and then the captured image of the chest, the captured image of the hand, the offset image D, the captured image of the knee, and the offset Image E is acquired in order. Note that an image 52 indicating the chest is reflected in the captured image of the chest, an image 54 indicating the hand is reflected in the captured image of the hand, and an image 56 indicating the knee is included in the captured image of the knee. Is reflected.

  In the example of FIG. 5, the correction image selection unit 40 is an image of the afterimage of the image 56 or the image related to the radiation from another imaging device among the offset images C, D, and E stored in the offset image storage unit 38. An offset image D excluding the offset image E reflected as 50e and the offset image C at the start of use is selected as a correction image. That is, in the radiation detection device 24, a temperature drift occurs with the passage of time, so that the correction image selection unit 40 is not the offset image C immediately after the start of use, but a certain amount of time has passed and the temperature drift is caused by the temperature drift. An offset image D that is assumed to contain an offset component is selected as a correction image.

  In the example of FIG. 5, it goes without saying that the offset image C in which the image 50e is not reflected may be selected as the correction image.

  FIG. 6 illustrates a case where a plurality of offset images F1 to Fn are acquired before shooting and a single offset image Fn + 1 is acquired after shooting. FIG. 7 illustrates a case where one offset image G1 is acquired before shooting and a plurality of offset images G2 to Gn are acquired after shooting.

  In the example of FIGS. 6 and 7, the correction image selection unit 40 does not include the afterimage or the image related to the radiation from another imaging apparatus as the images 50f and 50g, and is the closest to the captured image. The offset images Fn and G2 are selected as correction images, respectively.

  In the examples of FIGS. 6 and 7, it is needless to say that the offset image Fn + 1 and the offset image Gn in which the images 50f and 50g are not reflected may be selected as the correction image.

  As described above, in the examples of FIGS. 4A to 7, the correction image selection unit 40 selects one offset image that is optimal for the offset correction processing for the radiation image in the image processing unit 32 as the correction image.

  As described above, according to the radiation imaging system 10, the console 18, and the radiation image reading method according to the present embodiment, each offset image is acquired at the time of non-exposure before and after the radiation 14 is exposed (before and after the imaging). Then, one of the offset images is selected as a correction image for offset correction processing. As a result, it is possible to reduce (halve) the risk that an afterimage remains in the correction image and the risk that an image related to the exposed radiation appears in the correction image, and a highly accurate offset correction process is possible. .

  Therefore, according to the present embodiment, the offset correction process is performed more easily and accurately by selecting one of the offset images at the time of non-exposure before and after the exposure of the radiation 14. It becomes possible.

  In the present embodiment, an offset image is periodically acquired, and one offset image optimal for the offset correction processing is selected as a correction image from the plurality of acquired offset images. The risk that an afterimage remains and the risk that an image related to the exposed radiation appears in the correction image can be further reduced. Further, since the offset images are periodically acquired, there is no need to forcibly acquire the offset images immediately before and after the photographing, and the offset image acquisition process can be easily performed. Furthermore, since each offset image is sequentially stored in the offset image storage unit 38, it is possible to perform an offset correction process on the radiation image after a considerable time has elapsed since the imaging.

  Furthermore, since a correction image is selected from a plurality of offset images according to the statistical methods shown in (1) to (5) described above, the correction image can be determined accurately and efficiently.

  Note that the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 ... Radiation imaging system 12 ... Subject 14 ... Radiation 16 ... Imaging device 18 ... Console 20 ... Radiation source 22 ... Radiation detector 24 ... Radiation detection device 30 ... Control part 32 ... Image processing part 34 ... Display part 36 ... Changeover switch 38 ... offset image storage unit 40 ... correction image selection unit 42 ... correction image storage units 50a to 50g ... afterimages 52 to 56 ... image

Claims (5)

In the radiation image reading apparatus for acquiring the radiation image from the radiation detection apparatus after converting the radiation exposed to the radiation detection apparatus through the subject into a radiation image by the radiation detection apparatus,
An offset image storage unit that stores an offset image obtained by the radiation detection device at the time of non-exposure before and after exposure of the radiation to the radiation detection device via the subject;
A correction image selection unit that selects any one of the offset image before exposure and the offset image after exposure stored in the offset image storage unit as a correction image;
An image processing unit that acquires the radiation image obtained by the radiation detection apparatus during the radiation exposure and performs an offset correction process on the radiation image using the correction image selected by the correction image selection unit When,
A radiation image reading apparatus comprising: The apparatus of claim 1.
An offset image reading unit that reads the offset image from the radiation detection device at predetermined time intervals and sequentially stores the offset image in the offset image storage unit;
The radiographic image reading apparatus, wherein the correction image selection unit selects any one of the offset images stored in the offset image reading unit as the correction image. The apparatus of claim 2.
The correction image selection unit includes the offset image having the lowest pixel average value among the offset images, the pixel average value or the pixel intermediate value having the smallest difference from the pixel average value or the pixel intermediate value for all offset images. Or an offset image having a pixel value with the smallest difference from the pixel average value or the pixel intermediate value for each pixel of all offset images as the correction image. Reader. A radiation imaging system comprising: a radiation source that irradiates a subject with radiation; a radiation detection device that converts the radiation transmitted through the subject into a radiation image; and a radiation image reading device that acquires the radiation image from the radiation detection device. In
The radiological image reader is
An offset image storage unit that stores an offset image obtained by the radiation detection device at the time of non-exposure before and after exposure of the radiation from the radiation source to the radiation detection device via the subject;
A correction image selection unit that selects any one of the offset image before exposure and the offset image after exposure stored in the offset image storage unit as a correction image;
An image processing unit that acquires the radiation image obtained by the radiation detection apparatus during the radiation exposure and performs an offset correction process on the radiation image using the correction image selected by the correction image selection unit When,
A radiation imaging system comprising: In the radiation image reading method for acquiring the radiation image from the radiation detection device after converting the radiation exposed to the radiation detection device through the subject into a radiation image by the radiation detection device,
At the time of non-exposure before and after exposure of the radiation to the radiation detection device via the subject, the offset image obtained by the radiation detection device is stored in an offset image storage unit,
The offset image before exposure and the offset image after exposure stored in the offset image storage unit are selected as a correction image by the correction image selection unit,
Radiation image reading characterized in that after the radiation image obtained by the radiation detection device at the time of the radiation exposure is acquired, an offset correction process is performed on the radiation image using the correction image by an image processing unit. Method.

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