Porosity is an important factor to consider in a large variety of materials. Porosity can be visualized in bone or 3D synthetic biomaterials by microcomputed tomography (microCT). Blocks of porous poly(2-hydroxyethyl methacrylate) were prepared with polystyrene beads of different diameter (500, 850, 1160 and 1560 μm) and analysed by microCT. On each 2D binarized microCT section, pixels of the pores which belong to the same image column received the same pseudo-colour according to a look up table. The same colour was applied on the same column of a frontal plane image which was constructed line by line from all images of the microCT stack. The fractal dimension Df of the frontal plane image was measured as well as the descriptors of the 3D models (porosity, 3D fractal dimension D3D, thickness, density and separation of material walls. Porosity, thickness Df and D3D increased with the size of the porogen beads. A linear correlation was observed between Df and D3D. This method provides quantitative and qualitative analysis of porosity on a single frontal plane image of a porous object.Lay Description
Porous materials exist in every scientific domain from geology to biomedicine. The measurement of the amount of pores within a material is termed “porosity”. However, porosity may also have characteristics such as the regularity of distribution of the pores within the material. Porosity can be visualized and measured by microcomputed tomography but special algorithms need to be developed to appreciate the regularity of distribution of the pores. We present here a new algorithm allowing the visualization of the pores contained in a series of porous polymer blocks on a frontal plane. The fractal dimensions are used to characterize the regularity of the distribution. The method can be transposed to more complex objects such as bone.