Radiographic image detector

摘要

A flat panel detector (FPD) includes an imaging panel having pixels arranged in a matrix, a gate driver for turning thin film transistors (TFTs) of the pixels ON and OFF, a radiation detecting section for detecting the start of x-ray radiation from the x-ray source, and a controller. The controller controls the gate driver to turn the TFTs ON periodically to reset dark charges of the pixels. Before starting a charge accumulating operation for accumulating signal charges for imaging, the controller controls the gate driver to turn the TFTs OFF so that the radiation detecting section may detect the start of x-ray radiation on the basis of charge leaks from the pixels. When the start of x-ray radiation is detected, the controller starts the charge accumulating operation while keeping the TFTs in the OFF condition. Thereafter, the TFTs are turned ON to read out the accumulated signal charges.

主权项

1. A radiographic image detector comprising:
an imaging device configured to detect a radiographic image of a subject from radioactive rays that penetrate through the subject after being radiated from a radiation source, wherein said imaging device has an imaging area in which a plurality of pixels are arranged in a matrix to accumulate signal charges corresponding to incident amounts of the radioactive rays therein, and a plurality of scanning lines for driving said pixels and a plurality of signal lines for reading out the signal charges from said pixels to output the radiographic image are provided in correspondence with lines and columns of said pixels respectively; a driving device configured to output a drive signal to a respective scanning line to turn a single switching transistor, associated with a respective pixel of said plurality of pixels, ON and OFF, the source terminal of said single transistor connected to a respective signal line of said plurality of signal lines, said single switching transistor configured to execute sequentially a pixel resetting operation, a charge accumulating operation for accumulating the signal charge in said pixel, and a signal charge reading operation for reading out the accumulated signal charge from said pixel, wherein said single switching transistor is turned ON in said pixel resetting operation to read out a dark charge through said respective signal line, the dark charge being generated in said pixel regardless of the radioactive rays, said single switching transistor is turned OFF in said charge accumulating operation, and said single switching transistor is turned ON in said signal charge reading operation to read out the signal charge through said respective signal line; a radiation detecting device configured to perform a radiation detecting operation for detecting the start of radiation of the radioactive rays by monitoring a charge leak from said pixel to said respective signal line while said single switching transistor is OFF, the amount of charge leak corresponding to the dark charge and the signal charge accumulated in said pixel; and a control device configured to control said radiation detecting device and said driving device to start said radiation detecting operation by turning said single switching transistor OFF before starting said charge accumulating operation, and to start said charge accumulating operation while keeping said single switching transistor OFF after said radiation detecting device detects the start of radiation of the radioactive rays.