Continuous x-rays produced in light-ion atom collisions have been experimentally and theoretically studied. The experimental results for aluminum target bombarded with ∼1.5 MeV protons can be mainly explained by atomic bremsstrahlung (AB) of K-shell electrons. We measured the continuous x-ray spectra from a silver target and gold target bombarded with 1.5 MeV protons at the detection angle of 90°with respect to the beam direction to investigate AB of L-and M-shell electrons and found that the experimental production cross-sections of continuous x-rays are much smaller than the predictions based on the plane wave born approximation (PWBA) theory of AB. The discrepancy can be reduced by taking account of a screening effect previously introduced, but this does not resolve the problem completely. We applied the theory of AB based on the binary encounter approximation (BEA) and compared this with the experiment. It is shown by the BEA theory that, without consideration of the screening effect, the agreement between the theory and the experimental cross-sections of the Al target, Ag target and Au target can be systematically explained by the AB of K-, L-and M-electrons, respectively.
A rare case of operatively verified intracranial adenoid cystic carcinoma is reported. In this case, haematogeneous metastasis to the brain parenchyma was suspected. The computer tomography showed a large hypodense mass in the left frontal lobe. The lateral wall of the tumour was irregularly enhanced with contrast media.
We developed a micron-CT consisting of micro-beam system and X-ray CCD camera (Hamamatsu photonics C880OX), whose element size is 8umX8um and a total number of image elements 1000 X 1000 gives an image size of 8mm X 8mm. The sample is placed in a tube of a small diameter, which is rotated by a stepping motor. The transmission data through the sample are taken with characteristic Ti-K-X-rays (4.558 keV) produced by 3MeV proton and a particle micro-beams. After image reconstruction using an iteration method, 3D-images of small objects namely, hair and small ants were obtained with a spatial resolution of -5um. It is expected that our micron-CT can provide cross sectional images of in-vivo cellular samples with high resolution and can be applied to a wide range of research in biology and medicine.
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