パワースペクトル法を用いた散乱線画像の評価

概要

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We evaluated the influence of scatter-rays on images using the power spectrum method and attempted to determine the best energy window for image acquisition. We acquired planar images of a phantom that had existing signals of known diameters, at different energy windows. We varied these according to the following two parameters:(1)width of the energy window and (2)level of the energy window. We then used ^<99m>Tc, ^<201>Tl, and ^<123>I as signal sources. We determined that the influence of scatter-rays on images decreased as Pr(n)on the same frequency that indicated each signal and the integral value of Pr(n)increased on frequency analysis. Results indicated that(1)with ^<99m>Tc and ^<123>I, depending on the width of the energy window, Pr(n)decreased, and with ^<201>Tl, Pr(n)varied less. (2)With ^<99m>Tc, ^<201>Tl, and ^<123>I, Pr(n)decreased at lower energy levels to photopeak.At upper energy levels, increases were noted with ^<99m>Tc and ^<201>Tl, whereas a decrease was noted with ^<123>I. From the standpoint of image quality, we consider that images acquired with an asymmetric energy window that included an upper rather than lower level to photopeak were less affected by scatter-rays on ^<99m>Tc and ^<201>Tl imaging and by a narrow energy window width on ^<123>I imaging.
公益社団法人日本放射線技術学会の論文
1998-08-20