Browsing by Subject "Tomography, X-Ray Computed"
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Item 4D Study of Thoracic Cancer Radiation Treatment(2007-05-22) Huang, Tzung-Chi; Zhang, GeoffreyRespiratory motion causes an added uncertainty in the radiation treatment of thoracic malignancies due to an increase in the normal tissue irradiated and an uncertainty in the radiation coverage of the tumor. This results in a potential increase in complications from treatment and may be insufficient to ensure coverage of the tumor. Reduction of the volume of normal tissue irradiation while maintaining tumor coverage is used to accomplish this goal. The application of 4D CT imaging to radiotherapy treatment planning is an active area of research with the goal to reduce the required normal tissue irradiation and improve the tumor coverage. Deformable image registration holds the key to link the information of two images at various phases. The major purpose of this study is to develop and validate the optical flow method (OFM), a method of deformable image registration by which the image content properties are utilized to generate a displacement vector between each voxel in the reference image to the target image for registration. With OFM, we were able to develop and validate an automated method for intrathoracic motion estimation from breath-hold and 4-D computed tomography imaging; demonstrate the path integration of a four-dimensional dose distribution onto the 3-D anatomy; develop an automated target delineation technique; and to develop and implement a method to quantify tumor response and normal tissue damage by comparison of pre- and post-treatment and 18F-FDG-PET scans, all of which constitute meaningful applications and represent substantial progress in radiation treatment.Item Mechanical signals for compensatory lung growth assessed by high resolution computed tomography(2008-09-18) Ravikumar, Priya; Hsia, Connie C.W.This dissertation involves the use of high resolution computed tomography (HRCT) to understand the role of intra-thoracic mechanical force and its distribution in regenerative growth in dogs i.e. to quantify lobar lung volumes and density gradients in normal and post-pneumonectomy (following lung resection) lungs. HRCT was used to quantitatively assess regional distribution of lung volume and density gradients among lobes of the lung in order to follow the expansion of remaining lobes following lung resection with a high degree of anatomical precision, and to determine the relationships between lung expansion and alveolar tissue growth. I also extended this work by relating regional lung expansion and growth assessed by radiology to regional alveolar tissue growth assessed by detailed quantitative histology under light and electron microscopy. This study illustrates for the first time a powerful and novel use of in vivo imaging to quantify regional lung distortion and changes in local volume, lung compliance as well as soft tissue density. These changes can be followed non-invasively and serially in a wide range of clinical and investigational applications, such as a) assessing the extent and progression of regional heterogeneity in lung disease or injury; b) assessing local response to treatment or surgical intervention; or c) assessing normal or abnormal patterns of lung growth.