Development of a 3-D X-Ray Micro-tomography System and its Application to Trabecular Bone/Cement Interface

Abstract

In recent years,the interface analysis of micro-structure based objects is an important research in osteoporosis,vascular imaging since a 3-D X-ray micro-tomography system was developed. However,the micro-tomographic image shows the white-out appearance in case of imaging of similar density objects with low energy X-ray.Therefore these images must be analyzed about the interface between micro-sucture based objects for its application to biomechanical study. Many published studies suggested approximately assumed model of interface and predicted mechanical failure by means of Finite Element Method (FEM) but these FEM analysis has not used for modeling the real structure and interface between objects such as roughness,voids and pores of objects.We developed micro-tomography system and suggest the application of micro-tomographic image for predicting mechanical failure at the interface.The micro-tomography system consists of a 5µm micro-focus X-ray tube,a CMOS-based image sensor and a rotating sample holder controlled by a precision motor. CMOS image sensor has 62×62 mm2 sensing area and uses opticallenses system for increasing resolution.The sample which was manufactured by implanting cement in a pig hip bone was used and its fracture is considered to be an important cause of loosening of hip joint replacement in orthopedic implants. A Feldkamp’s cone-beam reconstruction algorithm on the equispatial detector case was used for bone/cement 3D volume data and the analysis of a trabecular bone/cement interface containing white-out appearance was performed by using multiple criterion segmentation of region and volume. Finally,the segmented data can be used for fracture prediction of FEM by determining node ofhexahedron meshing.In this paper,we present development of a 3-D cone beam micro-tomographic system with CMOS image sensor and its application to a complex structure of a trabecular bone and implanted cement for predicting the failure mechanism of orthopedic implants due to stress and pressure. We wi1l also show that how the segmented data is used as geometric input data of I-DEAS for FEM simulation.