Phase-contrast x-ray tomography of neuronal tissue at laboratory sources with submicron resolution

Abstract

Recently, progress has been achieved in implementing phase contrast tomography of soft biological tissues at laboratory sources.1-4 This opens up novel opportunities for three-dimensional (3d) histology based on x-ray computed tomography (μ- and nanoCT) in direct vicinity of hospitals and biomedical research institutions. Combining novel x-ray generation and detection techniques with suitable phase reconstruction algorithms, 3d histology can be obtained even of unstained tissue of the central nervous system, as shown for example for biopsies and autopsies of human cerebellum.5, 6 Depending on the setups, in particular source, detector, and geometric parameters, laboratory-based tomography can be implemented at very different sizes and length scales. In the present work, we investigate to which extent 3d histology of neuronal tissue can take advantage of cone-beam geometry at high magnification M using a nanofocus x-ray source (Excillum AB) with a minimum spot size of 300 nm, in combination with a single-photon counting camera. Tightly approaching the source spot with the biopsy punch, we achieve high M of ≈ 101-102, high flux density and can exploit the superior efficiency of this detector technology. Results are compared with those obtained at a microfocus rotating-anode x-ray tomography setup equipped with a high resolution detector, i.e. an low-M geometry.