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Digital
Radiography Instruments
Digital radiography
detectors developed at RMD span a wide range of capabilities,
including high resolution and high efficiency for digital
mammography, and ultra-high-speed X-ray imaging for ballistic
impact studies. They include advanced photodetectors such
as a large-area CCD with 28 million pixels, a 1000 frames
per second imaging detector, and an ultra-high-speed detector
capable of acquiring 150,000 frames per second. Specialized
scintillators developed at RMD are an integral part of these
devices, making them unique in many respects. A novel electron-multiplying
CCD (EMCCD) detector developed for radionuclide imaging is
shown here.
We recently developed
an EMCCD based detector for use in X-ray radiography and radionuclide
imaging. The detector uses a thermoelectrically cooled, back-illuminated
sensor with a fiberoptic window. A 3:1 and a 6:1 fiberoptic
taper can be externally attached to the system to enhance
the imaging area. This system has been used for low dose small
animal CT scanning, and for detecting individual gray interactions
for single photon emission computed tomography (SPECT). An
image of juvenile mouse kidneys obtained by operating this
system in a photon counting mode shows excellent spatial resolution
(fig.1). The data were acquired using a 99mTc source and a
0.5 mm pin hole collimator.
For time resolved
X-ray crystallography, the same detector has been operated
at frame rates as high as 500 fps. A time resolved image of
an embedded insect flight muscle using small angle X-ray Scattering
(SAXS) technique was acquired at the Advanced Photon Source
at the Argonne National Laboratory Synchrotron (fig. 2).
For high speed
applications such as hypervelocity projectile imaging, RMD
has developed special phosphors that provide very bright emissions
along with sub microsecond decay times. The imaging detector
consists of a high speed CCD camera coupled to this special
scintillator and a portable pulsed X-ray generator. This is
the most cost effective system available in the market. An
X-ray image of an AR-15 bullet traveling at the speed of ~3,500
feet/sec is shown as it pierces an apple (fig. 3).
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