22 March 2007 Fiducial-less 2D-3D spine image registration using spine region segmented in CT image
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Abstract
The target pose (position and orientation) of a spinal lesion can be determined using image registration of a pair of two-dimensional (2D) x-ray projection images and a pre-treatment three-dimensional (3D) CT image. This is useful for detecting, tracking and correcting for patient movement during image-guided spinal radiotherapy and radiosurgery. We recently developed a fiducial-less 2D-3D spine image registration that localizes spinal targets by directly tracking adjacent skeletal structures and thereby eliminates the need for implanted fiducials. Experience has shown this method to be robust under a wide range of clinical circumstances. However, image artifacts in digitally reconstructed radiographs (DRRs) that can be introduced by breathing during CT scanning or by other surrounding structures such as ribs have the negative effects on image registration performance. Therefore, we present an approach to eliminate the image artifacts in DRRs for a more robust registration. The spinal structures in the CT volume are approximately segmented in a semi-automatic way and saved as a volume of interest (VOI). The DRRs are then generated within the spine VOI for two orthogonal projections. During radiation treatment delivery, two X-ray images are acquired simultaneously in near real time. Then each X-ray image is registered with the DRR image to obtain 2D local displacements of skeletal structures. The 3D tumor position is calculated from the 2D displacements by 2D-to-3D back-projection and geometric transformation. Experiments on clinical data were conducted to evaluate the performance of the improved registration. The results showed that spine segmentation substantially improves image registration performance.
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Dongshan Fu, Dongshan Fu, Hongwu Wang, Hongwu Wang, Calvin R. Maurer, Calvin R. Maurer, Gopinath Kuduvalli, Gopinath Kuduvalli, } "Fiducial-less 2D-3D spine image registration using spine region segmented in CT image", Proc. SPIE 6509, Medical Imaging 2007: Visualization and Image-Guided Procedures, 650935 (22 March 2007); doi: 10.1117/12.711627; https://doi.org/10.1117/12.711627
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