Method and apparatus for acquiring an X-ray image using a thin film transistor array

A method for capturing a radiogram on an X-ray image capture element, comprising:

• a first, electrically conductive, backing layer;
• a second, photoconductive layer responsive to both actinic and X-ray radiation extending substantially over said backing layer;
• a third, dielectric layer substantially transparent to both actinic and X-ray radiation, the dielectric layer having a back surface extending substantially over and in contact with said photoconductive layer and a front surface;
• a plurality of discrete conductive outer microplates substantially transparent to both actinic and X-ray radiation, said microplates arranged on said front surface with a space between adjacent microplates, each of said microplates having dimensions coextensive with a minimum resolvable picture element, the microplates, dielectric layer, photoconductive layer and backing layer forming a plurality of microcapacitors;
• a first plurality of discrete conductive Xn address lines extending along the microplates;
• a second plurality of discrete conductive Yn sense lines extending along said microplates in a direction across said Xn address lines;
• and
• each microplate being connected to one adjacent of said plurality of said Xn and Yn lines via a transistor, the method comprising:
• (a) preventing actinic radiation from impinging on said element;
• (b) switching the pluralities of Xn and Yn lines to a first charging position and applying a bias voltage through the transistors simultaneously to all the microplates to develop an electric potential difference between said plurality of discrete conductive microplates and said backing layer;
• (c) impinging imagewise modulated X-ray radiation for a first time period onto the element;
• (d) after the first time period, stopping the applying of the bias voltage to trap in the microcapacitors electrical charges proportional to the intensity of the impinging radiation on the microplates;
• (e) switching the plurality of the Xn and Yn lines to a second readout position;
• (f) optionally exposing the element to uniform radiation for a second time period;
• (g) while exposing the element to actinic radiation, addressing one of said plurality of Xn lines with a trigger voltage to switch to a conductive state the transistors connecting the addressed Xn line to a subset of the microplates and to connect said subset of the microplates to the Yn lines;
• (h) sequentially detecting an output signal for each microplate connected to said plurality of Yn sense lines;
• and
• (i) repeating steps (g) and (h) for each of said plurality of Xn or Yn address lines until all signals from all microplates have been detected.