Distance‐preserving rigidity penalty on deformable image registration of multiple skeletal components in the neck. Issue 12 (14th November 2013)

• Record Type: Journal Article
• Authors: Kim, Jihun; Matuszak, Martha M.; Saitou, Kazuhiro; Balter, James M.
• Is Part Of: Medical physics. Volume 40:Issue 12(2013)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2013-11-14
• Subjects: Computed tomography -- Registration -- Interpolation; curve fitting; bone -- computerised tomography -- image registration -- medical image processing -- radiation therapy -- splines (mathematics) -- statistical analysis; rigidity penalty -- deformable image registration -- cervical vertebra -- head and neck; Computerised tomographs -- Biological material, e.g. blood, urine; Haemocytometers -- Digital computing or data processing equipment or methods, specially adapted for specific applications -- Image data processing or generation, in general; Medical imaging -- Image registration -- Computed tomography -- Cone beam computed tomography -- Dosimetry -- Tensor methods -- Cancer -- Surface measurements -- Tissues -- Radiation therapy; Medical physics -- Periodicals; Medical physics; Geneeskunde; Natuurkunde; Toepassingen; Biophysics; Periodicals; Periodicals; Electronic journals; 610.153
• DOI: 10.1118/1.4828783
• Languages: English
• ISSNs: 0094-2405

Abstract

Abstract : Purpose: : This study aims at developing and testing a novel rigidity penalty suitable for the deformable registration of tightly located skeletal components in the head and neck from planning computed tomography (CT) and daily cone‐beam CT (CBCT) scans of patients undergoing radiotherapy. Methods: : The proposed rigidity penalty is designed to preserve intervoxel distances within each bony structure. This penalty was tested in the intensity‐based B‐spline deformable registration of five cervical vertebral bodies (C1–C5). The displacement vector fields (DVFs) from the registrations were compared to the DVFs generated by using rigid body motions of the cervical vertebrae, measured by the surface registration of vertebrae delineated on CT and CBCT images. Twenty five pairs of planning CT (reference) and treatment CBCTs (target) from five patients were aligned without and with the penalty. An existing penalty based on the orthonormality of the deformation gradient tensor was also tested and the effects of the penalties compared. Results: : The mean magnitude of the maximum registration error with the proposed distance‐preserving penalty was (0.86, 1.12, 1.33) mm compared to (2.11, 2.49, 2.46) without penalty and (1.53, 1.64, 1.64) with the existing orthonormality‐based penalty. The improvement in the accuracy of the deformable image registration was also verified by comparing the Procrustes distance between the DVFs. With the proposed penalty, the average distance was 0.11 ( σ 0.03 mm) which is smaller than 0.53 (0.1 mm) without penalty and 0.28 (0.04 mm) with the orthonormality‐based penalty. Conclusions: : The accuracy of aligning multiple bony elements was improved by using the proposed distance‐preserving rigidity penalty. The voxel‐based statistical analysis of the registration error shows that the proposed penalty improved the integrity of the DVFs within the vertebral bodies.