Image reconstruction apparatus and image reconstruction method

An image reconstruction apparatus for generating a reconstruction image, comprising:

• a processor programmed to:
• generate a streak reduction image as an image obtained by reducing a streak-like artifact in the reconstruction image;
• acquire a first noise reduction ratio as a noise reduction ratio to be used for reducing a granular noise while retaining a structure boundary in the reconstruction image, and a second noise reduction ratio as a noise reduction ratio to be used for generating the streak reduction image;
• add an addition image to be generated based on the first noise reduction ratio and the second noise reduction ratio to the streak reduction image;
• generate a boundary retention image as an image obtained by reducing the granular noise while retaining the structure boundary in the reconstruction image;
• and
• calculate the first noise reduction ratio from noise amounts of both the reconstruction image and the boundary retention image, and the second noise reduction ratio from noise amounts of both the reconstruction image and the streak reduction image.

An image reconstruction method for generating a reconstruction image comprising:

• generating a streak reduction image as an image obtained by reducing a streak-like artifact in the reconstruction image;
• acquiring a first noise reduction ratio as a noise reduction ratio to be used for reducing a granular noise while retaining a structure boundary in the reconstruction image, and a second noise reduction ratio as a noise reduction ratio to be used for generating the streak reduction image;
• adding an addition image to be generated based on the first noise reduction ratio and the second noise reduction ratio to the streak reduction image;
• and
• generate the addition image by executing intensity modulation to a difference image between the streak reduction image and a smoothed image obtained by smoothing the streak reduction image by a magnification to be calculated based on the first noise reduction ratio and the second noise reduction ratio.