Evaluation of an amorphous selenium array for industrial x-ray imaging
The large market for digital x-ray imaging in medicine has driven the development of flat panel imaging devices. We evaluated one such device using the higher energy x-rays typical of industrial applications. This imager is a 360 x 430-mm array employing amorphous selenium (amSe). The defining characteristic of this technology is that electrons produced by radiation interaction in the Se are directly collected and processed. There is no intermediate scintillation or other conversion process. We compare performance to existing LLNL technology. We found: · Modulation transfer function remains high as spatial frequencies approach the limit imposed by the 139 mm pixel size. · Increasing x-ray energy degrades spatial resolution performance somewhat, but the amSe imager performs well in spectra as energetic as 450-kV applied potential. · The MTF of this amSe imager is drops rapidly with frequency between 0.0 and 0.1 mm-1 for the heavily-filtered spectra used in this study. Secondary radiation transport in material behind the Se is a significant contributor to this attribute. · Required exposure for the spectra tested ranges from 10 to 100 mRoentgen. This is 15 to 100 times less than LLNL's home-built system employing scintillating glass and a CCD camera. Cycle time for CT applications will be dominated by read and refresh time of nearly 1 minute. This will allow for great flexibility in utilizing microfocus (low power) sources or large souce-to-detector distances. · Except for issues of peripheral electronics, which we did not address, Monte Carlo simulations suggest that this amSe imager could offer attractive performance at x-ray energies of 3 MeV or more.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE Office of Defense Programs (DP)
- DOE Contract Number:
- W-7405-Eng-48
- OSTI ID:
- 7278
- Report Number(s):
- UCRL-ID-132315; YN0100000; ON: DE00007278
- Country of Publication:
- United States
- Language:
- English
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