Dr. Gianluca Tozzi of University of Portsmouth discusses his research and X-ray tomography applications
Dr. Gianluca Tozzi is a Reader in Bioengineering at the School of Mechanical and Design Engineering and director of the ZEISS Global Centre at the University of Portsmouth, England. He took some time to share some of his work and research goals and use of x-ray tomography with us.
What are the big issues in your research area?
My research is devoted to push the understanding of structure/function of biological tissues and biomaterials, mainly in the musculoskeletal domain. This is fundamental to design novel treatments and biomaterials for pathological conditions and trauma. To achieve this goal, I am using a combination of high-resolution X-ray Computed Tomography (XCT), in situ mechanical testing and digital volume correlation (DVC). The integration of those investigative tools provides a comprehensive analysis of the mechanical performance of such materials, where microdamage initiation and progression can be tracked to understand overall failure mechanisms.
Reconstruction of bovine proximal epiphyseal growth plate. Acquired with ZEISS Xradia Versa 520 X-ray microscope, 10 µm voxel size.
What do you think are your most significant research accomplishments?
The combined use of X-ray computed tomography based mechanics and DVC has notably extended knowledge in the field of biological tissue and biomaterial interaction. For example, we were the first group to experimentally evaluate the local mechanics (in terms of strain distribution) of newly formed bone tissue promoted in vivo by the action of different osteoregenerative biomaterials (read the paper). This is fundamental to establish whether novel treatments are able to promote mechanically competent bone-biomaterial constructs and encourage bone formation quality, which can be compared to the native tissue they are meant to replace. In order to carry out such investigation we used both synchrotron (Diamond Light Source) and lab synchrotron-like (ZEISS Xradia Versa 510 X-ray microscope) XCT.
3D full-field maximum shear strain distribution (γmax) at failure for bone-biomaterial systems produced in vivo after the implantation of graft materials in a critical-sized defect ovine model. Bone-biomaterial interface is indicated by a dotted line and microcracks with arrows. TB: Trabecular bone; NFB: newly formed bone; BG: bone graft material.
X-ray computed tomogram (taken with ZEISS Xradia Versa 520, 11 µm voxel size) reconstruction of rat calvaria critical-sized defect model. Preliminary in vivo results showed the osseointegration of new bone tissue with the Mg-based fibers (purple).
If you had unlimited resources, what would you do with them?
The area of X-ray tomography imaging is constantly trying to include new capabilities and modal analysis to extend the investigation of biological tissues and biomaterials. In this sense, the possibility to better resolve tissues (i.e. soft tissues), characterise their ultrastructural properties and push the analysis towards more physiological regime will surely provide a more comprehensive picture of processes associated to disease and trauma; but also to assess the functional properties of biomaterials (i.e. osteoregenerative) and guide their future developmental stages.
Multiscale X-ray imaging and strain mapping of cortical bone. X-ray computed tomography (ZEISS Versa 510 X-ray microscope) was first performed on cylindrical cortical bone samples at (a) 5 µm voxel size followed by a zoom-in (Scout and Zoom software) in an internal region at (b) 2 µm voxel size, allowing a better visualisation of vasculature and osteocyte lacunae. (c) Residual strains after cyclic loading were mapped around vasculature to assess correlations between porosity and local strain concentrations.
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