Patent US RE35798

A three-dimensional image processing apparatus includes a first three-dimensional memory for storing first voxel data representing a three-dimensional CT image, a level detector for comparing the first voxel data with CT values of an epidermis, a bone, and a blood vessel, second three-dimensional memories for storing second voxel data (binary) of the epidermis, the bone, and the blood vessel obtained by the level detector, a distance detector for detecting distances between a predetermined projection plane in a three-dimensional space and the second voxel data, a minimum detector for detecting a distance between the projection plane and one of the second voxel data of the epidermis, bone, and blood vessel, which is closest to the projection plane, and a surface image generating circuit for shading minimum values of pixels in the projection plane to generate a surface image. The projection plane in the three-dimensional space is partially moved into a memory space in the second voxel data, thereby simulating a surface image obtained when a three-dimensional CT image is cut.