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Biomedical subjects

R J Gonçalves

Publications and source records attributed to R J Gonçalves.

7 recordsLinked to original sources

Imaging transforms for visualizing surfaces and volumes.

Three-dimensional (3D) visualization in biomedical and other imaging areas is a rapidly emerging discipline. The major developments in this field are described in a unified and concise way. To this end, we introduce an operator notation to describe the basic imaging transforms commonly used in 3D visualization and to identify a comprehensive set of basic transforms. We also introduce several new basic transforms for filtering and interpolating scenes and structures and for rendering surfaces and volumes. We demonstrate not only how the existing visualization methodologies can be described concisely, but we also show how a great variety of new methodologies can be generated using both the existing imaging transforms and the new transforms introduced in this paper. A comprehensive evaluation method to compare objectively rendering methods used in visualization based on task-specific mathematical phantoms is described. We examine in detail separate transform sequences that are best suited for rendering robust and frail structures (ie, structures with well- and poorly defined boundaries).

Algorithms↗

Repair of postextraction sockets: influence of homogeneous bone implants preserved by formaldehyde. An experimental study in dogs.

Small bone sticks from a dog, fixed in formaldehyde from 1 to 4 weeks, were used as homoimplants in the left postextraction sockets of dogs, and the right sockets were allowed to heal as ungrafted controls. The animals were killed 5, 11, 22, and 60 days after implantation. No obvious differences were discovered, either clinically or radiographically, between the repair of the control sockets and that of the experimental sockets. However, appreciable histologic differences could be noted. The presence of the implant disturbed and retarded both the organization of the granulation tissue and the process of intra-alveolar ossification. The attempt to use homogeneous bone implants that had been preserved in formaldehyde in order to stimulate osteogenesis in the host produced unsatisfactory results, since it retarded the process of postextraction alveolar repair.

Alveolar Process↗