Premium
A modified x‐ray image intensifier with continuously variable field of view: Resolution considerations
Author(s) -
Drangova M.,
Holdsworth D. W.,
Picot P. A.,
Schulenburg K.,
Fenster A.
Publication year - 1993
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.596951
Subject(s) - image intensifier , zoom , optical transfer function , optics , image resolution , detector , physics , resolution (logic) , field of view , x ray detector , image sensor , zoom lens , computer science , artificial intelligence , lens (geology)
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 f 0.1 (the frequency at which MTF=0.1) from 1.41 to 3.05 mm −1 , while optical zooming increased f 0.1 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.