RADIOISOTOPES

Soft X-ray microscopy has been developed for high resolution imaging of hydrated biological specimens due to the availability of water window region. In particular, a projection type microscope has advantages in wide viewing area, easy zooming function and easy extensibility to CT. The blur of projection image due to the diffraction of X-rays, which eventually reduces spatial resolution, could be corrected by an iteration procedure, i.e., repetition of Fresnel and inverse Fresnel transformations. However, it was found that the correction is not sufficiently effective for all images, especially for images with low contrast. In this study, first, grayscale distribution of the projection images was analyzed to reveal the reason for the insufficient correction. The result showed that the insufficient correction is due to high background noises. Therefore, a noise removal method prior to the iteration procedure was applied and found to be effective. Thus, some chromosome images with magnification of 329 times or lower which had not been correctable solely by the iteration procedure became successfully correctable after noise removal in combination with our contrast enhancement method whose effect was evaluated as effective in the previous study.