| 摘要 |
PROBLEM TO BE SOLVED: To obtain an image signal having high S/N and to improve the diagnostic performance by obtaining an optimum value from correlation between the thickness of a photoconductive layer and applied voltage, etc. SOLUTION: Charge in accordance with the intensity of X-ray energy is generated inside the photoconductive layer 57 by an X-ray made incident on the layer 57, and is stored at both poles 42 and 46 of a capacitor 24. The charge stored in the capacitor 24 is guided to a horizontal scanning part by turning on a TFT 26. The voltage E applied on an image pickup panel from a power source part 28 and the thickness L of the layer 57 are selected to satisfy an expression: (ρ×W/Eg)×(μ×τ×E/L)=4×10<4> to 5×10<7> . In the expression,ρis X-ray absorptivity, W is the average energy (eV) of an absorbed light beam, Eg is the band gap (eV) of photoconductive substance,μ×τis the product of the mobility of the charge and the life and is a larger one (cm<2>×V<-1> ) between an electron and a hole, E is the intensity (V×cm<-1> ) of electric field impressed on the photoconductive layer, and L is the thickness (cm) of the photoconductive layer.
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