A MODIFIED X-RAY IMAGE INTENSIFIER WITH CONTINUOUSLY VARIABLE FIELD-OF-VIEW - RESOLUTION CONSIDERATIONS

被引:4
作者
DRANGOVA, M [1 ]
HOLDSWORTH, DW [1 ]
PICOT, PA [1 ]
SCHULENBURG, K [1 ]
FENSTER, A [1 ]
机构
[1] UNIV WESTERN ONTARIO,DEPT MED BIOPHYS,LONDON N6A 3K7,ONTARIO,CANADA
关键词
X-RAY IMAGE INTENSIFIER; ELECTRONIC MAGNIFICATION; OPTICAL MAGNIFICATION; RESOLUTION GAIN;
D O I
10.1118/1.596951
中图分类号
R8 [特种医学]; R445 [影像诊断学];
学科分类号
1002 ; 100207 ; 1009 ;
摘要
A conventional x-ray image intensifier (XRII) has been modified to enable the field of view (FOV) to be varied continuously, by adjusting the potentials at the focusing electrodes. The benefit, to system resolution, from decreasing the FOV has been characterized by measuring the modulation transfer function (MTF) of the XRII coupled to a high-resolution photo-diode array (PDA), at a number of different FOVs achieved either by electronic or optical zooming. Electronic zooming of the XRII from FOV = 24 cm to FOV = 10 cm led to an increase in f0.1 (the frequency at which MTF = 0.1) from 1.41 to 3.05 mm-1, while optical zooming increased f0.1 from 1.41 mm-1 only to 1.88 mm-1. It is proposed that the advantage, with respect to resolution gain, of electronic zooming over optical zooming was realized only when the XRII limits system resolution. The MTF of the XRII coupled to a video camera, with lower resolving power than the PDA, was measured at different FOVs to show that using electronic zooming is only marginally beneficial when the optical detector and the XRII contribute equally to the resolution degradation. However, when a higher-resolution optical detector is used, electronic zooming always yields a greater gain in resolution.
引用
收藏
页码:1653 / 1660
页数:8
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