Abstract
Recently, study on CAD system is addressed. The CAD system can assist to medical doctor for diagnosis in visual screening. Temporal subtraction method is the one of techniques for implementation of CAD. The temporal subtraction method, which enhances temporal changes such as new lesions, is useful for thoracic CT diagnostic imaging. To achieve a temporal subtraction method, image registration technique is required as essential procedure. If the image registration procedure is implemented insufficiently, subtraction artifacts are remained as the result of miss-registration on temporal subtraction image. Also, in the case of using thoracic MDCT, 3-dimensional image registration is applied for temporal subtraction method. However, because of the complication of temporal deformation on 3D region, large amount of calculation costs are required for the image registration between current image and previous one. In this study, to reduce computational time for temporal subtraction on thoracic MDCT, we have developed hierarchical 3D image registration method based on octree data structure. Some experimental results are shown with discussion.
