Flat-panel detector with avalanche gain
First Claim
Patent Images
1. A flat panel detector, comprising:
- a phosphor screen for receiving x-rays and converting the x-rays into optical photons;
an avalanche photoconductor for receiving the optical photons and converting the optical photons into electrical charges, the avalanche photoconductor having an avalanche gain programmable by changing an electric field applied across the avalanche photoconductor; and
an active matrix array for detecting the electrical charges.
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Abstract
The present invention is an indirect AMFPI wherein a phosphor such as a structured cesium iodide (CsI) is used to convert x-ray energy to optical photons or a charge, which is then detected by a two-dimensional array of either thin-film transistors (TFTs) such as an amorphous a-Se TFTs or a photodiode array. A scanning control circuit generates pulses to turn on the TFTs one row at a time, and thus the charge in the individual arrays is transferred from the TFT to one or more external charge-sensitive amplifiers. The charge-sensitive amplifiers are shared by all the pixels in the same column. The two-dimensional array can be read in real time.
125 Citations
17 Claims
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1. A flat panel detector, comprising:
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a phosphor screen for receiving x-rays and converting the x-rays into optical photons; an avalanche photoconductor for receiving the optical photons and converting the optical photons into electrical charges, the avalanche photoconductor having an avalanche gain programmable by changing an electric field applied across the avalanche photoconductor; and an active matrix array for detecting the electrical charges. - View Dependent Claims (2, 3, 4)
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5. A flat panel detector, comprising:
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a phosphor screen of structured cesium iodide (CsI) for converting x-rays into photon charges; an avalanche photoconductor layer of amorphous selenium (a-Se) for receiving the photon charges and converting the photon charges into electrical charges, the avalanche photoconductor having an avalanche gain programmable by changing an electric field applied across the avalanche photoconductor; and an active matrix of thin film transistors for detecting the electrical charges. - View Dependent Claims (6, 7, 8, 9, 10)
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11. A flat panel detector, comprising:
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a phosphor screen of structured cesium iodide (CsI) for converting x-rays into photon charges; an avalanche photoconductor layer of amorphous selenium (a-Se) for receiving the photon charges and converting the photon charges into electrical charges; and an active matrix of field emitters for detecting the electrical charges. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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Specification