Image processing apparatus, image processing method, and storage medium for extracting an irradiation field of a radiograph
An image processing apparatus configured to extract an irradiation field from an image obtained through radiation imaging, comprises: an inference unit configured to obtain an irradiation field candidate in the image based on inference processing; a contour extracting unit configured to extract a contour of the irradiation field based on contour extraction processing performed on the irradiation field candidate; and a field extracting unit configured to extract the irradiation field based on the contour.
1. An image processing apparatus for processing an image obtained through radiation imaging, comprising:
at least one processor; and
at least one memory storing instructions that, when executed by the at least one processor, cause the at least one processor to function as:
a first obtaining unit configured to obtain an irradiation field candidate by inputting an image into a neural network learned using learning data which include information regarding an irradiation field in an image, the irradiation field candidate being a map regarding a pixel in the input image being the irradiation field or not being the irradiation field; and
a second obtaining unit configured to perform a determination regarding a contour of an irradiation field using a contour candidate of the irradiation field and the obtained irradiation field candidate and to obtain the irradiation field based on the determination, the contour candidate of the irradiation field being obtained using the obtained irradiation field candidate.
2. The image processing apparatus according to claim 1 , wherein the second obtaining unit is configured to (a) obtain a contour of the irradiation field using the obtained irradiation field candidate and (b) obtain the irradiation field using the obtained contour.
3. The image processing apparatus according to claim 1 , wherein the map indicates a probability of being the irradiation field or a probability of not being the irradiation field for a pixel of the image input into the neural network.
4. The image processing apparatus according to claim 1 , further comprising a preprocessing unit configured to perform, on an image, at least one preprocessing of grid removal processing, scattered ray reduction processing, noise reduction processing, logarithmic conversion processing, and normalization processing; wherein the first obtaining unit obtains the irradiation field candidate by inputting the image preprocessed by the preprocessing unit into the neural network.
5. The image processing apparatus according to claim 1 ,
wherein the second obtaining unit is configured to (a) obtain the contour candidate of the irradiation field using the obtained irradiation field candidate and information regarding a shape of a collimator, (b) perform the determination, (c) obtain the irradiation field using the contour of the irradiation field obtained based on the determination.
6. The image processing apparatus according to claim 5 ,
wherein the determination is regarding whether the contour candidate of the irradiation field is valid as a contour of the irradiation field using the contour candidate of the irradiation field and the obtained irradiation field candidate.
7. The image processing apparatus according to claim 1 ,
wherein the second obtaining unit is configured to (a) obtain a contour candidate of the irradiation field using the obtained irradiation field candidate and information regarding a shape of a collimator, (b) perform the determination, and
in a case where the contour candidate of the irradiation field is determined to be valid as the contour, (c) obtain the irradiation field using the contour candidate of the irradiation field as the contour.
8. The image processing apparatus according to claim 1 ,
wherein the second obtaining unit is configured to (a) obtain a contour candidate of the irradiation field using the obtained irradiation field candidate and information regarding a shape of a collimator, (b) perform the determination, and
in a case where the contour candidate is determined to be valid as the contour, (c) obtain the irradiation field using the contour candidate as the contour, and
in a case where the contour candidate is not determined to be valid as the contour, (d) obtain the irradiation field using another contour candidate of the irradiation field as the contour.
9. The image processing apparatus according to claim 1 ,
wherein the second obtaining unit is configured to (a) obtain a contour candidate of the irradiation field using the obtained irradiation field candidate and information regarding a shape of a collimator, (b) perform the determination to obtain a contour of the irradiation field based on a region of overlap between an irradiation field presumed from the contour candidate and an irradiation field presumed from the obtained irradiation field candidate, and (c) obtain the irradiation field using the contour.
10. The image processing apparatus according to claim 1 ,
wherein the second obtaining unit is configured to (a) obtain a contour candidate of the irradiation field using the obtained irradiation field candidate and information regarding a shape of a collimator, (b) perform the determination to obtain the irradiation field using, as a contour of the irradiation field, a region in which a ratio of overlap between an irradiation field presumed from the contour candidate and an irradiation field presumed from the obtained irradiation field candidate is greater than a threshold.
11. The image processing apparatus according to claim 1 , wherein the map is a map obtained by performing binary coded processing on a probability of being the irradiation field or not being the irradiation field for a pixel of the input two-dimensional image.
12. An image processing method for processing an image obtained through radiation imaging, comprising:
obtaining an irradiation field candidate by inputting an image into a neural network learned using learning data which include information regarding an irradiation field in an image, the irradiation field candidate being a map regarding a pixel in the input image being the irradiation field or not being the irradiation field;
performing a determination regarding a contour of an irradiation field using a contour candidate of the irradiation field and the obtained irradiation field candidate, the contour candidate of the irradiation field being obtained using the obtained irradiation field candidate; and
obtaining the irradiation field based on the determination.
13. A non-transitory computer-readable storage medium storing a program for causing a computer to execute the method according to claim 12 .