Image fusion technique for head-neck CT and SPECT image registration

A SPECT-CT image fusion technique is developed to provide more precise anatomical location and extension of basal skull involvement of NPC detected by Tc-99m MDP bone scan, and a better treatment planning is achieved. In this technique, both SPECT images and head-neck CT images are appropriately separated to two sections, head slices of the images and neck slices of the images. A multimodality image registration procedure is used to individually align the head/neck section of SPECT images to the head/neck section of CT images respectively. The procedure requires: generation of simulated SPECT images using the bone component in CT images, and then aligning the measured SPECT images to the simulated ones that are based on CT images. In order to benefit from the advantages of CT and SPECT images, the two aligned images have fused together. The fused images allow users to precisely delineate the interests of region (ROIs) on SPECT images shown to have involvement of NPC. Moreover, the fused images are also useful for accurate therapeutic planning in radiation oncology and for consistent evaluation of the results between the pre- and post-treatments