There is growing interest in using low-energy flash x-ray sources in radiographic applications to provide high-contrast
images of low-density objects. Due to the low-energy nature of the detected photons, thin bright scintillators are desired.
In order to pursue an optimum radiographic system, experimental studies have been performed of the static imaging
properties of thin microcolumnar CsI using a Platts x-ray source. The Platts source is a nominally 300 keV endpoint rod
pinch diode x-ray source with a ~35 ns pulse time. The source was used to measure the imaging properties of
microcolumnar CsI with various thicknesses and backings. The experimental setup was modeled in GEANT4, and the
images were simulated to estimate system performance. Taking into account the source photon production, radiation
transport, and system optical performance, an accurate assessment of the detection system can be deduced.
We are investigating scintillator performance in radiographic imaging systems at x-ray endpoint energies of 0.4 and 2.3 MeV in single-pulse x-ray machines. The effect of scene magnification and geometric setup will be examined along with differences between the detector response of radiation and optical scatter. Previous discussion has reviewed energy absorption and efficiency of various imaging scintillators with a 2.3 MeV x-ray source. The focal point of our study is to characterize scintillator blur to refine system models. Typical detector geometries utilize thin tiled LYSO:Ce (cerium-doped lutetium yttrium orthosilicate) assembled in a composite mosaic. Properties of individual tiles are being studied to understand system resolution effects present in the experimental setup. Comparison of two different experiments with different geometric configurations is examined. Results are then compared to different scene magnifications generated in a Monte-Carlo simulation.
Electronic charge-coupled device (CCD) cameras equipped with image intensifiers are increasingly being used for radiographic applications. These systems may be used to replace film recording for static imaging, or at other times CCDs coupled with electro-optical shutters may be used for static or dynamic radiography. Image intensifiers provide precise shuttering and signal gain. We have developed a set of performance measures to calibrate systems, compare one system to another, and to predict experimental performance. The performance measures discussed in this paper are concerned with image quality parameters that relate to resolution and signal-to-noise ratio.