Design and analysis of a system for 3D fabrication of synthetic anatomical structures

Abstract

This dissertation is the reading and display ofDICOM medical images (Digital Imaging and Communication in Medicine) and production ofmodel artifacts of anatomical organs using Rapid Prototyping An algorithm to read these DICOM medical images was developed. It also displays pixel information ofthe image. When the DICOM image has been read and displayed, the information required to produce the anatomical artifact is extracted. These 2D slice images, MRI (Magnetic Resonance Imaging) and CT Scan (Computer Tomography) images are written to 3D file in SLC (Slice files) and STL (Stereolithography File Format) format. A 3D softcopy ofthe anatomical structure is created. At this stage, the clinician or surgeon can make any changes or require additional information to be added to the anatomical structure. With the 3D model available in STL format, a physical artifact is produced using Rapid Prototyping. The external edge ofthe anatomical structure can be produced using Rapid Prototyping as well as the outer rim with the internal structures. To produce the external surface ofthe structure, an outer rim edge detection algorithm has been developed. This will only extract the external surface ofthe structure. In addition to the softcopy ofthe structure, multiple organs can be displayed on the same image and this will give a representation ofthe interaction ofneighboring organs and structures. This is useful as both the normal anatomy as well as the infiltration ofthe abnormal pathology can be viewed simultaneously. One of the major limitations ofdisplaying the information in a 3D image is that the files are very large. Since 3D STL files use triangles to display the outer surface ofa structure, a method to reduce the file size and still keep the image information was developed. The triangle reduction method is a method to display the 3D information and to decrease the STL file size depending on the complexity ofthe outer surface ofthe structure. To ensure that the anatomical model s represented as in the DlCOM files, an Interpolation Algorithm was developed to reconstruct the outer ofthe model from 2D MRI or CT-Scan images. A word about computer models: Some of the programs and presentations are based on the real world. They model the real world and anatomical structures. It is very important to note that the models are created with software. Obviously a model is useful if it resembles reality closely, but it is only a prediction about the model itself. Models are useful because they help to explain why certain things happen and how interaction takes place. Models provide suggestions for how structures might look. Computer models provide answers very quickly. These are computer models representing the real structure. (Czes Kosniowski, 1983)