Application of a-Si:H radiation detectors in medical imaging

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Monte Carlo simulations of a proposed a-Si:H-based current-integrating gamma camera were performed. The analysis showed that the intrinsic resolution of such a camera was 1 {approximately} 2.5 mm, which is somewhat better than that of a conventional gamma camera, and that the greater blurring, due to the detection of scattered {gamma}-rays, could be reduced considerably by image restoration techniques. This proposed gamma camera would be useful for imaging shallow organs such as the thyroid. Prototype charge-storage a-Si:H pixel detectors for such a camera were designed, constructed and tested. The detectors could store signal charge as long as 5 min at ... continued below

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188 p.

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Lee, Hyoung-Koo June 1, 1995.

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Description

Monte Carlo simulations of a proposed a-Si:H-based current-integrating gamma camera were performed. The analysis showed that the intrinsic resolution of such a camera was 1 {approximately} 2.5 mm, which is somewhat better than that of a conventional gamma camera, and that the greater blurring, due to the detection of scattered {gamma}-rays, could be reduced considerably by image restoration techniques. This proposed gamma camera would be useful for imaging shallow organs such as the thyroid. Prototype charge-storage a-Si:H pixel detectors for such a camera were designed, constructed and tested. The detectors could store signal charge as long as 5 min at {minus}26C. The thermal generation current in reverse biased a-Si:H p-i-n photodetectors was investigated, and the Poole-Frenkel effect was found to be the most significant source of the thermal generation current. Based on the Poole-Frenkel effect, voltage- and time-dependent thermal generation current was modeled. Using the model, the operating conditions of the proposed a-Si:H gamma camera, such as the operating temperature, the operating bias and the {gamma}-scan period, could be predicted. The transient photoconductive gain mechanism in various a-Si:H devices was investigated for applications in digital radiography. Using the a-Si:H photoconductors in n-i-n configuration in pixel arrays, enhancement in signal collection (more than 200 times higher signal level) can be achieved in digital radiography, compared to the ordinary p-i-n type a-Si:H x-ray imaging arrays.

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188 p.

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INIS; OSTI as DE95014877

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  • Other Information: TH: Thesis (Ph.D.)

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  • Other: DE95014877
  • Report No.: LBL--37385
  • Grant Number: AC03-76SF00098
  • Office of Scientific & Technical Information Report Number: 100242
  • Archival Resource Key: ark:/67531/metadc626656

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  • June 1, 1995

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  • June 16, 2015, 7:43 a.m.

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  • April 4, 2016, 9:03 p.m.

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Lee, Hyoung-Koo. Application of a-Si:H radiation detectors in medical imaging, thesis or dissertation, June 1, 1995; California. (digital.library.unt.edu/ark:/67531/metadc626656/: accessed August 17, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.