Convert a 3D .obj mesh (from blender) into a 3D-CT .nii image with its materials.

I’ve tried converting my blender mesh to voxel by taking the materials into account for each voxel (for organic material, I want to set the voxel value to 0.3, for example), but it doesn’t work well. So I’m wondering if I export my blender object as an .obj file, then if I use VTK for that, will that be a good solution?