Patent ID: 7330578

Claim:
A computer implemented method for generating DRR (digitally reconstructed radiography) images, the method comprising: loading a volume rendering program into a graphics device, the volume rendering program representing a predetermined algorithm according to a non-linear attenuation mode; and in response to 3D scan data, invoking the graphics device to execute the volume rendering program to perform at least a portion of volume rendering operations on at least a portion of the 3D scan data, including modifying the 3D scan data according to the predetermined algorithm to compensate for a difference between a first attenuation of an object with respect to a second attenuation associating a known intensity of the object wherein the 3D scan data comprises a plurality of CT numbers representing an image intensity of corresponding 3D CT voxels, wherein each CT voxel represents a corresponding volume element of the object, and wherein each CT number represents an attenuated intensity of an X-ray CT beam that has been generated at a CT scan energy level and that has traversed the corresponding volume element of an anatomical region, wherein each CT voxel is disposed within one of a plurality of axial voxel slices, each axial voxel slice representing a corresponding axial slice of the object, wherein integrating the CT numbers comprises: performing a tri-linear interpolation for the CT voxels encountered by the ray; and for each voxel of interest, performing a one-dimensional polynomial interpolation over the voxel of interest and for voxels on each adjacent voxel slice.