Masayuki Kunii

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Size and density measurements of objects undertaken using computed tomography (CT) are clinically significant for diagnosis. To evaluate the accuracy of these quantifications, we simulated three-dimensional (3D) CT image blurring; this involved the calculation of the convolution of the 3D object function with the measured 3D point spread function (PSF). We(More)
A method for verifying the point spread function (PSF) measured by computed tomography has been previously reported [Med. Phys. 33, 2757-2764 (2006)]; however, this additional PSF verification following measurement is laborious. In the present study, the previously described verification method was expanded to PSF determination. First, an image was obtained(More)
We propose a method to estimate the accuracy of the line spread function (LSF) in computed tomography (CT). When we assume an object for scanning has a shape and CT-value in the x-y scan-plane that are constant in the z-direction perpendicular to the scan-plane, blurring in the image of the object is predicted with calculation by the LSF measured in the(More)
New methods which reduce the unfavorable energy spread of output electrons from a single channel electron multiplier are presented. A modified output electrode produces a pronounced narrowing effect on the energy distribution without much affect on the gain. A simplified analysis of the field inside the channel shows that the fixed channel wall potential(More)
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