Quantifying Changes in Nuclear Organization in Normal vs. Cancer Cells using X- ray Tomography

Soft X-ray tomography (SXT) is similar in concept to the well-established medical diagnostic technique, computed axial tomography (CAT), except SXT is capable of imaging with a spatial resolution of 50 nm, or better. With SXT we can examine whole, hydrated cells (between 10-15 μm thick), eliminating the need for time-consuming embedding and sectioning procedures. For SXT, cells are imaged using Xray energies between the K shell absorption edges of carbon (284 eV, λ=4.4 nm) and oxygen (543 eV, λ=2.3 nm). In this energy range, photons readily penetrate the aqueous environment while encountering significant absorption from carbonand nitrogen-containing organic material. Consequently organic material absorbs approximately an order of magnitude more strongly than water, producing a quantifiable natural contrast image of cellular structures[1]. SXT, like other tomography modalities, requires recording images from multiple different viewing angles. By collecting images from multiple angles through 360 degrees of rotation, SXT reconstructions yield information at isotropic resolution.