We are investigating the performance of a digital photoelectronic imaging system assembled in our laboratory. The primary radiological image is converted to a visible image by a Gd2O2S:Tb fluorescent screen optically coupled to a microchannel plate intensified CCD camera. The imaging system includes a motorized zoom lens, with a nominal zoom range of 6, for changing the imaging field size from 12.0 × 10.7 mm2 to 63 × 56 mm2. Video images are digitized by a real-time frame grabber, integrated with a personal computer for image processing and analysis by using specially developed computer software. The Modulation Transfer Functions of the system have been determined for various zoom factors. A spatial resolution limit of 7.5 lp/mm and of 2.5 lp/mm has been obtained for the maximum and the minimum optical zoom factor, respectively. For large zoom factors the resolution limit is due to the intrinsic resolution of the fluorescent screen.
Real-time digital radiographic system with continuously variable magnification using an intensified CCD camera and a fluorescent screen
GAMBACCINI, Mauro;TAIBI, Angelo;MARZIANI, Michele;
1994
Abstract
We are investigating the performance of a digital photoelectronic imaging system assembled in our laboratory. The primary radiological image is converted to a visible image by a Gd2O2S:Tb fluorescent screen optically coupled to a microchannel plate intensified CCD camera. The imaging system includes a motorized zoom lens, with a nominal zoom range of 6, for changing the imaging field size from 12.0 × 10.7 mm2 to 63 × 56 mm2. Video images are digitized by a real-time frame grabber, integrated with a personal computer for image processing and analysis by using specially developed computer software. The Modulation Transfer Functions of the system have been determined for various zoom factors. A spatial resolution limit of 7.5 lp/mm and of 2.5 lp/mm has been obtained for the maximum and the minimum optical zoom factor, respectively. For large zoom factors the resolution limit is due to the intrinsic resolution of the fluorescent screen.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
