Computed microtomography (μCT) with unmonochromatized synchrotron X-rays for cancerous human breast tissue and mouse vertebra

The use of X-ray computed microtomography (PCT) has increased in biomedical research and industrial applications. The inherited high quality of synchrotron radiation (SR) X-rays including high flux, collimation, and coherence, has been used recently to produce radiographic images with high spatial resolution and contrast. A simple and stable imaging system using an unmonochromatized SR source based on the principle of phase contrast X-ray imaging consists of a charge-coupled device (CCD) detector coupled with an optical lens system at the Pohang Light Source (PLS) 5C1 beamline. The spatial resolution of the imaging system was determined using the modulation transfer function (MTF), which was measured by step-by step calculations obtained from sharp edge images. Projection image data were obtained at 250 steps over 180 degrees of rotation with an acquisition time, depending on the imaged object materials, of 30 to 150 ms per projection image. The tomographic images were reconstructed using a simple filtered backprojection algorithm to reconstruct two-dimensional (2-D) images using projection data which may include characteristics of beam collimation and phase contrast. Although the use of a monochromatic X-ray beam has previously demonstrated to provide high resolution and enhanced contrast, our approach uses an unmonochromatized SR X-ray beam and shows similar image capability, without the needs for sophisticated X-ray optics, in an exposure time which is significantly less, by two orders of magnitude, than that for the monochromatic SR system. The current PLS 5C1 SR imaging system can produce projection images at a spatial resolution of 8.3 μm over a field of view of about 5 mm at an exposure time of 30 ms per projection image for 1.5 × optical magnification. This study presents the results of SR μCT images of cancerous human breast tissue containing microcalcifications, mouse lumbar vertebra, and mouse coccygeal vertebra. The unmonochromatized SR μCT imaging system provides an effective means of evaluating microstructures, not only in biomedical specimens but also in inorganic samples.