Abstract: Provided are a method and apparatus for interpolating X-ray tomographic image data by using a machine learning model. A method of interpolating an X-ray tomographic image or X-ray tomographic composite image data includes obtaining a trained model parameter via machine learning that uses a sub-sampled sinogram for learning as an input and uses a full-sampled sinogram for learning as a ground truth; radiating X-rays onto an object at a plurality of preset angular locations via an X-ray source, and obtaining a sparsely-sampled sinogram including X-ray projection data obtained via X-rays detected at the plurality of preset angular locations; applying the trained model parameter to the sparsely-sampled sinogram by using the machine learning model; and generating a densely-sampled sinogram by estimating X-ray projection data not obtained with respect to the object on the sparsely-sampled sinogram.

Abstract: Provided are a method and apparatus for interpolating X-ray tomographic image data by using a machine learning model. A method of interpolating an X-ray tomographic image or X-ray tomographic composite image data includes obtaining a trained model parameter via machine learning that uses a sub-sampled sinogram for learning as an input and uses a full-sampled sinogram for learning as a ground truth; radiating X-rays onto an object at a plurality of preset angular locations via an X-ray source, and obtaining a sparsely-sampled sinogram including X-ray projection data obtained via X-rays detected at the plurality of preset angular locations; applying the trained model parameter to the sparsely-sampled sinogram by using the machine learning model; and generating a densely-sampled sinogram by estimating X-ray projection data not obtained with respect to the object on the sparsely-sampled sinogram.

Abstract: A method of reconstructing a tomography image of an object from a plurality of projection images generated by scanning the object in a plurality of projection directions includes: determining whether a truncated portion of the object exists in the plurality of projection images; reconstructing a first reconstruction image; calculating projection data for the first reconstruction image; and reconstructing a tomography image of the object by using the calculated projection data.

Abstract: A computed tomography apparatus includes an X-ray irradiation unit irradiating an X-ray to an object while rotating along a predetermined rotation path, a detector acquiring projection data by detecting an X-ray transmitted through the object, a filter unit located between the X-ray irradiation unit and the object and comprising a plurality of transmissive areas and a plurality of slightly transmissive areas that are arranged in a predetermined direction, and a control unit controlling a motion of the filter unit to allow a relative position of the plurality of transmissive areas with respect to the X-ray irradiation unit and a relative position of the plurality of slightly transmissive areas with respect to the X-ray irradiation unit to change while the X-ray irradiation unit rotates.

Abstract: A method of reconstructing a tomography image of an object from a plurality of projection images generated by scanning the object in a plurality of projection directions includes: determining whether a truncated portion of the object exists in the plurality of projection images; reconstructing a first reconstruction image; calculating projection data for the first reconstruction image; and reconstructing a tomography image of the object by using the calculated projection data.

Abstract: An avalanche photodiode capable of generating a minimal surface leakage current as well as achieving a uniform electrical field. The avalanche photodiode includes a semiconductor substrate provided with a lower electrode underneath it, an amplification layer producing pairs of electron-holes through ionized collision of carriers injected by an internal electrical field, and an absorption layer producing the carriers according to splitting of the pairs of electron-holes by the electrical field. The avalanche photodiode further includes a contact layer formed on the absorption layer, with a core section in the center of the contact layer and a guard section surrounding the core section spaced apart from each other, and at least one upper electrode with a core electrode formed on the core section and a guard electrode formed on the guard section. The upper electrode generates the internal electrical field together with the lower electrode.

Abstract: An avalanche photodiode capable of generating a minimal surface leakage current as well as achieving a uniform electrical field. The avalanche photodiode includes a semiconductor substrate provided with a lower electrode underneath it, an amplification layer producing pairs of electron-holes through ionized collision of carriers injected by an internal electrical field, and an absorption layer producing the carriers according to splitting of the pairs of electron-holes by the electrical field. The avalanche photodiode further includes a contact layer formed on the absorption layer, with a core section in the center of the contact layer and a guard section surrounding the core section spaced apart from each other, and at least one upper electrode with a core electrode formed on the core section and a guard electrode formed on the guard section. The upper electrode generates the internal electrical field together with the lower electrode.