Lakhasly

We conducted a preliminary evaluation of a digital fluoroscopy sys tern for general applications, including gastrointestinal imaging, ye nography, rnyelography, and genitourinary fluoroscopy.The installation is designed primarily for digital fluoroscopy and radiogra phy of the gastrointestinal tract but is also being eva!uated for a variety of fluoro scopic procedures, including venography, mye!ography, arthrography, and genito urinary procedures.U INTRODUCTION The development of digital equivalents of conventional radiography and fluoros copy is critical if digital image acquisition and management are to be extended be yond the current digital imaging modalities (computed tomography, magnetic res onance imaging, nuclear medicine, ultrasound, and digital angiography) (1-4).The image intensifier selected for our installation has a 33-cm (13-inch) nominal field size with an electronic zoom feature that provides additional field sizes of 23 cm (9 inches) and 17 cm (7 inches).In this article, we describe the system, its operation, and its parameters and dis play conventional images paired with digital images obtained in various clinical app!ications.?????

We conducted a preliminary evaluation of a digital fluoroscopy sys
tern for general applications, including gastrointestinal imaging, ye
nography, rnyelography, and genitourinary fluoroscopy. We describe
the system, present examples of images obtained in a variety of app!i
cations, and assess the performance of the system.
U INTRODUCTION
The development of digital equivalents of conventional radiography and fluoros
copy is critical if digital image acquisition and management are to be extended be
yond the current digital imaging modalities (computed tomography, magnetic res
onance imaging, nuclear medicine, ultrasound, and digital angiography) (1-4).
For the past 12 months, we have been evaluating a digital fluoroscopy system. The
system is based on conventional image intensifier technology and incorporates a
microprocessor-controlled, general-purpose fluoroscopy unit. The digital images
can either be transferred to an image management system or converted to hard
copy with a laser film recorder. The fluoroscopy room is a!so equipped with a
conventional spot film system and an overhead x-ray tube for conventional radiog
raphy. The installation is designed primarily for digital fluoroscopy and radiogra
phy of the gastrointestinal tract but is also being eva!uated for a variety of fluoro
scopic procedures, including venography, mye!ography, arthrography, and genito
urinary procedures.
In this article, we describe the system, its operation, and its parameters and dis
play conventional images paired with digital images obtained in various clinical
app!ications. Our preliminary assessment of the system, as well as suggestions for
improvement, are summarized
SYSTEM DESCRIPTION
The Sireskop 5 (Siemens Medical Systems, Iselin, N) is a microprocessor-controlled, general-purpose fluoroscopy unit. The image intensifier selected for our installation has a
33-cm (13-inch) nominal field size with an electronic zoom feature that provides additional field sizes of 23 cm (9 inches) and 17 cm (7 inches). The resolution of the image intensifier operating at the 17-cm field size is 1.4 line pairs per millimeter (Ip/mm), as determined from line pair phantom measure-
ments.
The analog output of the image intensifier is converted to a 1,024 X 1,024 X 8-bit image with the use of a video digitizer (model
DS1000; Siemens). The digitizer provides two 1,024 X 1,024 X 10-bit semiconductor memories and two analog video outputs, features that allow simultaneous display of two images on the dual video display of the sys-tem. A Winchester disk drive in the video digitizer provides for storage of up to 100, 1,024 X 1,024 X 8-bit images. Other features of the system include digital spot re-cording, last image hold, image subtraction, window and level adjustment, video edge en-hancement, and character generation.
The video digitizer has a standard interface
(DR11W) for transferring images to an image management network. In our depart-ment, network acquisition nodes are con-
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structed with microcomputers (model
68010; Motorola, Austin, TX) operating under the UNIX V system (AT&T Technologies Morristown, N).
• SYSTEM OPERATION
The digital image acquisition system can be operated in two modes. In the fluoroscopic mode, the fluoroscopic image is observed on one of the two trolley-mounted monitors in the examination room. When the operator terminates a fluoroscopic exposure, the last-image-hold feature of the digitizer averages the last 10 video frames and displays the resulting image on the second monitor. This image can then be stored on the hard disk at 1,024 X 1,024 X 8 bits.
In the digital radiographic mode, digital images are generated by digitizing the output of a progressive scan video circuit. The 1,024 X 1,024 X 8-bit images are stored on the hard disk of the video digitizer. The digital image may be processed with a real-time video unsharp-masking feature for edge en-hancement. The processed image can be displayed and digitized for storage. Serial digital images can be obtained at a rate of one image every 1.5 seconds.
In the digital radiographic mode, the colli-mation system automatically limits exposure to correspond to the area displayed fluoro-scopically. An automatic exposure timer is used in the radiographic mode. Technical factors for radiographic exposures may be selected at either the generator console or the operator's tower in the examination room.