Quantum noise in digital x-ray image detectors with optically coupled scintillators
- Henry Ford Health System, Detroit, MI (United States)
- Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering
Digital x-ray imaging detectors designed to soft x-ray (1 to 50 keV) are significant for medical mammography, dental radiography, microradiography, and microtomography. Detector designs involve either direct absorption of x-rays in solid state devices or thin scintillator screens optically coupled to solid state sensors. Well designed scintillator systems produce 10 or more electrons per detected x-ray and, used with charge coupled devices (CCD), detect 100,000 x-rays per pixel before saturation. However, if the scintillator is directly coupled to the detector, radiation can penetrate to the semiconductor detector with a small number of events producing large charge and noise. The authors have investigated the degradation of image noise by these direct absorption events using numerical models for a laboratory detector system consisting of a 60 {micro}m CsI scintillator optically coupled to a scientific CCD. Monte Carlo methods were used to estimate the charge deposition signal and noise for both the CsI and the semiconductor. Without a fiber optic coupler, direct absorptions dominate the signal and increase the signal variance by a factor of about 30 at energies above 10 keV. With a 3 mm fiber optic coupler, no significant degradation is observed for input energies below 45 keV.
- OSTI ID:
- 379772
- Report Number(s):
- CONF-951073-; ISSN 0018-9499; TRN: 96:025278
- Journal Information:
- IEEE Transactions on Nuclear Science, Vol. 43, Issue 4Pt1; Conference: IEEE nuclear science symposium and medical imaging conference, San Francisco, CA (United States), 21-28 Oct 1995; Other Information: PBD: Aug 1996
- Country of Publication:
- United States
- Language:
- English
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