Development of 3D micron-CT to observe the interior of cells with high space resolving power and high-speed photograph

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We developed "micron-CT", using micro-PIKE for in-vivo imaging. This system comprises an X-ray CCD camera with high resolution (pixel size : 8x8μm^2, number of pixels : 1000x1000) and an X-ray point source with a spot size of 1.5x1.5μm^2 which is generated by irradiation of a microbeam on a pure metal target. The sample is placed in a tube of a small diameter, and rotated by a stepping motor. The 3D images were reconstructed from the obtained projection data by using a cone-beam CT reconstruction algorithm. We applied this micron-CT to investigate the internal structure of small ant. Ti was used as an X-ray target considering detection. efficiency of the CCD camera. An ant after formalin-fixation was inserted into a micron tube. The 3D images of ant's head were obtained with 6 μm spatial resolution and the internal structure is clearly seen. Furthermore, we developed a method to measure an ant in-vivo. The ant was anaesthetized by chloroform and then it was inserted into the micron tube. The inside of the tube is kept in atmospheric pressure and enabled to measure in-vivo. There is a large difference on the images between the fixed ant and the living one. In the case of fixed ant, the brain shrank and something was washed out due to formalin-fixation. Because the CCD is sensitive to visible light, we also examined the capability of light micron-CT using visible red lights from an Al_2O_3(Cr) ruby scintillator and applied it to investigate a small red thick. Obscure images were obtained due to the dispersion of lights. The 3D micron-CT can provide cross sectional images of in-vivo samples with high spatial resolution and will be useful for biological studies.