Reverse Engineering and Rapid Prototyping are extensively used technologies by both research and industrial community for rapid developments in various industrial as well as Bio-medical applications. Recent advances in computer technology and Biomedicines enabled Computer Aided Design (CAD) to find many novel applications in Bio-medical engineering and integration of CAD and Bio-medical technology is usually referred as Bio-CAD. The major objective of the current research work is to generate an efficient algorithm for generation of free form surface from non-invasive CT scan images. Minimally Invasive Spine Surgery (MISS) have enabled spinal surgeons to select patients and treat several spinal disorders like degenerative disc disease, herniated disc, fractures, tumors, infections, instability, deformity, etc. with less disruption of muscles, which enables patient towards faster recovery to normal functions, reduces operative blood loss. In this paper, it is proposed to extract point cloud data from stalk of non-invasive CT scan images by using Image Processing techniques and Reverse Engineering approach. This point cloud data is to be processed for noise reduction, point cloud data segmentation and CAD model generation. This image-based CAD modeling approach begins with the acquisition of CT scan in DICOM 3.0 format. The point cloud estimation is based on threshold techniques and edge detection method. This point cloud data is used for construction of 3D CAD model by fitting free form NURB surface between theses points and then fitting surface between these curve networks by swept blend technique. An efficient and robust algorithm has been developed for generation of curves from unorganized point cloud data.

This work deals with development of algorithm for physical replication of patient specific human bone and construction of corresponding implants/inserts RP models by using Reverse Engineering approach from non-invasive medical images for surgical purpose. In medical field, the volumetric data i.e. voxel and triangular facet based models are primarily used for bio-modelling and visualization, which requires huge memory space. On the other side, recent advances in Computer Aided Design (CAD) technology provides additional facilities/functions for design, prototyping and manufacturing of any object having freeform surfaces based on boundary representation techniques. This work presents a process to physical replication of 3D rapid prototyping (RP) physical models of human bone from various CAD modeling techniques developed by using 3D point cloud data which is obtained from noninvasive CT/MRI scans in DICOM 3.0 format. This point cloud data is used for construction of 3D CAD model by fitting B-spline curves through these points and then fitting surface between these curve networks by using swept blend techniques. This process also can be achieved by generating the triangular mesh directly from 3D point cloud data without developing any surface model using any commercial CAD software. The generated STL file from 3D point cloud data is used as a basic input for RP process. The Delaunay tetrahedralization approach is used to process the 3D point cloud data to obtain STL file. CT scan data of Metacarpus (human bone) is used as the case study for the generation of the 3D RP model. A 3D physical model of the human bone is generated on rapid prototyping machine and its virtual reality model is presented for visualization. The generated CAD model by different techniques is compared for the accuracy and reliability. The results of this research work are assessed for clinical reliability in replication of human bone in medical field.