TIME-LAPSE MICRO-TOMOGRAPHY ANALYSIS OF THE DEFORMATION RESPONSE OF A GELLAN-GUM-BASED SCAFFOLD

摘要

The presented work is aimed at a demonstration of modern radiological methods for an investigation of the deformation behaviour of bone scaffolds. Bone scaffold is an artificial structure used for the repairs of trabecular bones damaged by injuries or degenerative diseases. In bone-tissue engineering a proper description of its deformation behaviour is one of the most important characteristics for an assessment of the biocompatibility and bone-integration characteristics of the proposed structure intended to be used as a bone scaffold. According to recent studies bioactive-glass-reinforced gellan-gum (GG-BAG) is a promising material for bone-scaffold production. However, its low specific stiffness and simultaneous low attenuation to X-rays makes both the mechanical and imaging parts of the deformation experiments difficult. As a result a state-of-the-art experimental setup composed of high-precision micro-loading apparatus designed for the X-ray observation of deformation processes and an advanced radiographical device is required for such experiments. Furthermore, the radiographical device has to utilize highly sensitive detectors and corresponding radiation sources with appropriate beam characteristics that provide a high signal-to-noise ratio (SNR) during all the measurements. High-resolution time-lapse micro-focus X-ray computed tomography (micro CT) under loading in three different imaging modes was performed to obtain a precise structural and mechanical description of the observed deforming GG-BAG scaffolds. The digital volumetric correlation (DVC) method was applied on reconstructed data from micro CT measurements to evaluate not only the effective mechanical characteristics but also to enable a detailed inspection of the specimens' internal structure, particularly the deformation modes of the individual struts and joints. The calculated volumetric strain fields demonstrate the suitability of such experimental methodology and devices for the assessment of both the microscopic and macroscopic characteristics of the investigated complex GG-BAG microarchitectures.