Radiation detecting device

1. A radiation detection device for a foreign substance inspection using a subtraction method, which detects radiation in a first energy range and radiation in a second energy range higher than the radiation in the first energy range that are transmitted through a specimen and incident from a radiation incident direction, comprising:

a first radiation detector that is positioned on the upstream side with respect to the radiation incident direction, and detects radiation in the first energy range and generates a first image corresponding to an image of the radiation;

a second radiation detector that is positioned on the downstream side with respect to the radiation incident direction, and detects radiation in the second energy range and generates a second image corresponding to an image of the radiation;

a first image processing section that applies image processing to the first image from the first radiation detector; and

a second image processing section that applies image processing to the second image from the second radiation detector, wherein

the first radiation detector includes a first pixel section that has a plurality of pixels arrayed along an image detection direction and acquires the first image based on the image of the radiation in the first energy range,

the second radiation detector includes a second pixel section that has a plurality of pixels arrayed along the image detection direction and acquires the second image based on the image of the radiation in the second energy range,

a first pixel width in the image detection direction of each of the plurality of pixels in the first pixel section is smaller than a second pixel width in the image detection direction of each of the plurality of pixels in the second pixel section, and

the first image processing section and the second image processing section carry out pixel change processing to make the number of pixels of the first image and the number of pixels of the second image equal to each other.

2. The radiation detection device according to claim 1 , wherein

the first image processing section and second image processing section applies pixel thinning-out processing to at least one of the number of pixels of the first image and the number of pixels of the second image.

3. The radiation detection device according to claim 2 , wherein

the thinning-out processing is simple thinning-out processing, averaging thinning-out processing, summing thinning-out processing, minimum filter thinning-out processing, or maximum filter thinning-out processing.

4. The radiation detection device according to claim 2 , wherein

in the thinning-out processing,

based on a ratio J to K of the number of pixels of the first image to the number of pixels of the second image, one correction pixel is generated from two pixels adjacent to each other of at least one of the pixels of the first image and the pixels of the second image so that the number of pixels of the first image becomes 1/J times and the number of pixels of the second image becomes 1/K times, and

a brightness value IL(y) of the correction pixel is set to satisfy the following equation:

IL ( y )= y ( a×L ( x )+β× L ( x+ 1))

based on signal values L(x) and L(x+1) of the two pixels before being corrected, pixel correction factors α and β, and a brightness adjustment factor γ.

5. The radiation detection device according to claim 1 , wherein t

the first image processing section and second image processing section apply pixel interpolation processing to at least one of the number of pixels of the first image and the number of pixels of the second image.

6. The radiation detection device according to claim 5 , wherein

the interpolation processing is simple interpolation processing, primary interpolation processing, secondary interpolation processing, spline interpolation processing, or Lagrange interpolation processing.

7. The radiation detection device according to claim 5 , wherein

in the interpolation processing,

based on the ratio J to K of the number of pixels of the first image to the number of pixels of the second image and a least common multiple L of J and K, interpolation pixels are interpolated for at least one of among the pixels of the first image and among the pixels of the second image so that the number of pixels of the first image becomes L/J times and the number of pixels of the second image becomes L/K times, and

a brightness value IH(y) of the interpolation pixel is set to satisfy the following equation:

IH ( y )=γ(α× H ( x )+β× H ( x+ 1))

based on signal values H(x) and H(x+1) of the pixels adjacent on both sides to the interpolation pixel, pixel correction factors α and β, and a brightness adjustment factor γ.

8. The radiation detection device according to claim 1 , wherein

the first radiation detector includes a first scintillator layer that extends along the image detection direction and converts an image of radiation in the first energy range into an optical image, and a first pixel section that acquires the first image based on the optical image converted by the first scintillator layer, and

the second radiation detector includes a second scintillator layer that extends along the image detection direction and converts an image of radiation in the second energy range into an optical image, and a second pixel section that acquires the second image based on the optical image converted by the second scintillator layer.

9. A system for acquiring a radiation image of an object, comprising:

a conveyor configured to convey the object in a conveying direction;

a first radiation detector arrayed a plurality of pixels along an image detection direction which intersects with the conveying direction and configured to detect radiation which are transmitted through the object and output first image data;

a second radiation detector arrayed a plurality of pixels along the image detection direction and configured to detect radiation which are transmitted through the first radiation detector and output second image data; and

an image processing device configured to generate a subtraction image on the basis of the first image data and the second image data; wherein

a first pixel width of each of the plurality of pixels in the first detector is smaller than a second pixel width of each of the plurality of pixels in the second pixel section, and

the image processing device carries out pixel change processing to make the number of pixels of the first image data and the number of pixels of the second image data equal to each other.

10. The system for acquiring a radiation image of an object according to claim 9 , wherein

the first radiation detector includes a first scintillator layer that extends along the image detection direction and is configured to convert an image of radiation in the first energy range into an optical image, and a first pixel section that is configured to acquire the first image based on the optical image converted by the first scintillator layer, and

the second radiation detector includes a second scintillator layer that extends along the image detection direction and is configured to convert an image of radiation in the second energy range into an optical image, and a second pixel section that is configured to acquire the second image based on the optical image converted by the second scintillator layer.

11. The system for acquiring a radiation image of an object according to claim 9 , wherein:

the pixel width is the width in an image detection direction.

12. The system for acquiring a radiation image of an object according to claim 9 , wherein:

the pixel width is the width in a direction orthogonal to the image detection direction.

13. A method of acquiring a radiation image of an object, comprising:

conveying the object in a conveying direction;

by a first radiation detector arrayed a plurality of pixels along an image detection direction which intersects with the conveying direction, detecting radiation which are transmitted through the object and outputting first image data;

by a second radiation detector arrayed a plurality of pixels along the image detection direction, detecting radiation which are transmitted through the first radiation detector and outputting second image data;

processing so as to make the number of pixels of the first image data and the number of pixels of the second image data equal to each other; and

generating a subtraction image on the basis the processed image data; wherein

a first pixel width of each of the plurality of pixels in the first detector is smaller than a second pixel width of each of the plurality of pixels in the second pixel section.

14. The method of acquiring a radiation image of an object, according to claim 13 , wherein

the first radiation detector includes a first scintillator layer that extends along the image detection direction and converts an image of radiation in the first energy range into an optical image, and a first pixel section that acquires the first image based on the optical image converted by the first scintillator layer, and

the second radiation detector includes a second scintillator layer that extends along the image detection direction and converts an image of radiation in the second energy range into an optical image, and a second pixel section that acquires the second image based on the optical image converted by the second scintillator layer.

15. The method of acquiring a radiation image of an object according to claim 13 , wherein:

the pixel width is the width in an image detection direction.

16. The method of acquiring a radiation image of an object according to claim 13 , wherein:

the pixel width is the width in a direction orthogonal to the image detection direction.