2. マルチフォーマットカメラの MTF(3. 解像特性, ディジタルラジオグラフィの画像評価)

概要

論文の詳細を見る
Multi-format camera or laser printer is important device of digital radiography. We have investigated the characteristics of the resolution for multi-format camera. It is said that the diameter and the luminance distribution of electron beam spot of the cathode ray tube (CRT) are the fluctuating factors which depend upon cathode current. In this study, we have taken a photograph of slit image which is one pixel, and after generating the luminance distribution curve of that photograph. We assessed the characteristics of the spatial resolution by using modulation transfer function (MTF). Results are as follows : 1) The brightness of CRT is controlled with cathode voltage and current. Deterioration of the resolution of CRT was caused by the expansion of the diameter of electron beam spot, which is induced by increment of the cathode current. 2) The contrast is adjusted with amplification of image signals. The maximum value of line spread function (LSF) is variable with ajustment of the contrast, however the diameter of electron beam spot is constant. The MTF was improved with increment of amplification of the image signals. But, this tendencies did not observed in CRT with low resolution. 3) The spatial resolution was inconstant on the locations of the CRT. Especially it was remarkably decreased in the peripheral area of the CRT.
公益社団法人日本放射線技術学会の論文
1991-06-01