| 摘要 |
PURPOSE: To control exposure by determining flowing current in the read-out amplifier of a read-out line, and using the same for the measurement of exposure or the correction of exposure during an X-ray exposure. CONSTITUTION: Prior to the execution of an X-ray exposure, an electric switch 13 is switched for a short time, so that the cathode of a photosensor element 11 becomes a ground potential. When the X-ray exposure is again conducted with a switch 13 successively, storage capacity 12 is discharged, and the common connection of the storage capacity 12 and the source of the switch 13 becomes more negative. After the completion of the exposure, the switch 13 is activated via a switch line 4, is read out via a read-out line 5, and is used to form an amplified 6 charge X-ray image. The charge is not used for exposure measurement during the exposure. Accordingly, a current flowing in a pair of electrodes 2 and the switch 13 is used for the exposure measurement during the exposure.
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