Aim at traditional ray casting algorithm existing the problems that powerful computing capacity and slow rendering
velocity, an improved ray casting algorithm is presented in this paper. To reduce the number of voxels in reconstruction
process, the image segmentation is introduced to volume rendering. A segmentation algorithm based on multiple
structure elements is proposed to process ICT slice images original data field. The original voxels are divided into two
parts: the target voxel data set and the background voxel data set. Then, the target voxel data set is constructed as a new
data field, and using the ray casting algorithm to it. This reduces the number of voxels and accelerate the efficiency of ray
casting. The results of reconstruction show that this algorithm can greatly reduce reconstruction volume data and improve
the efficiency of ray casting.