High resolution X-ray micro-CT imaging of fibrin scaffold using large area single photon counting detector

Abstract

This paper deals with the high resolution X-ray micro-computed tomographical (micro-CT) visualization of a fibrin scaffold intended to be used during medical repairs of various types of human tissue. Due to the cellular nature of scaffolds, it is important to inspect their microstructure in high detail on a volumetric basis. In this work, we demonstrate the micro-CT measurement of a fibrin-based bone scaffold performed using a proprietarily developed tomographical scanner equipped with a large-area imaging device (LAD) composed of 10× 10 Timepix silicon pixel detectors without any gaps between the individual tiles. The fibrin scaffolds are based on organic materials, which may be reinforced by various additives to improve their mechanical characteristics, and their dimensions are generally very small (i.e. micrometer to millimeter scale). As the organic material used in fibrin scaffolds exhibits very low X-ray attenuation, low-energy X-ray radiation is desirable to achieve sufficient contrast in the projections. Moreover, a high resolution is needed to visualize the fine features in the scaffolds. Here, conventional scintillation detectors suffer two problems that make the aforementioned LAD superior for the imaging of the investigated scaffolds: a wide point-spread function and low sensitivity at low energies. Despite the high LAD sensitivity to low-energy photons, it was necessary to apply several correction procedures to achieve the highest possible resolution. Here, a computational procedure was developed to compensate for the drift of the tube's focal spot, geometrical imperfections of the LAD detector assembly, and the effects of its border pixels with different responses and sizes. We demonstrate the results on the final reconstructed images based on uncorrected and corrected projections, where we achieved a 1 μm voxel size.

Time-lapse micro-CT analysis of fatigue microcrack propagation in cortical bone

“…Moreover, measurement in the nano-focus mode only allows for the reaching of rather low power at the target, thus resulting in considerably long scanning times. Changes in the spot position in the high-magnification scanning strongly affects the sharpness of the resulting reconstructed 3D volume [11,12]. To reduce these effects, a set of 20 sectional measurements was performed in each CT scan.…”

Application of 2 × 5 MPX3 camera with monolithic sensor for phase contrast imaging and computed tomography

“…It was already demonstrated in [1] that a large-area semiconductor pixelated detector [2] composed of 10 × 10 edgeless Timepix chips may be very useful for high-resolution and material-sensitive tomographic imaging of Carbon Fibre Reinforced Plastic (CFRP) composites, although X-ray images from this detector are often influenced by the edges of the sensors [3] and have to be corrected [4]. It was also shown in [5] that the phase contrast effect occurring on the crack faces may help to identify delamination due to its sharp edges utilizing various techniques.…”