Multi-element-amorphous-silicon-detector-array for real-time imaging and dosimetry of megavoltage photons and diagnostic X rays
AssigneesThe Regents of the University of Michigan, Xerox Corporation
InventorsLarry E. Antonuk, Robert A. Street
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Abstract
A multi-element-amorphous-silicon detector-array real-time imager and dosimeter for diagnostic or megavoltage X rays having megavoltage photons having a plurality of photodiodes made of hydrogenated amorphous silicon arrayed in columns and rows upon a glass substrate. Each photodiode is connected to a thin film field effect transistor also located upon the glass substrate. Upper and lower metal contacts are located below and above the photodiodes to provide the photodiodes with a reverse bias. The capacitance of each photodiode when multiplied by the resistance of the field effect transistor to which it is connected yields an RC time constant sufficiently small to allow real time imaging.
Claims24
A real-time imaging device, said device being for use with an incident radiation beam, said device comprising:
- conversion means for converting said radiation beam to visible light;
- signal detection means including an a--Si:H sensor having a predetermined capacitance for detecting the visible light and for storing a signal corresponding to the detected light;
- and
- switching means including a transistor having a predetermined resistance for reading out the signal stored by said signal detection means, wherein the capacitance of the a--Si:H sensor when multiplied by the resistance of the transistor yield an RC time constant which is less than 10 microseconds, thereby to permit real-time imaging of said radiation beam.
A real-time imaging device for storing and retrieving an imaging signal resulting from incident radiation bursts, comprising:
- a scintillation layer;
- an a--Si:H sensor having a first a--Si:H layer doped to a first conductivity type, a second a--Si:H layer doped to a second conductivity type, and an intrinsic a--Si:H layer sandwiched between said first and second a--Si:H layers;
- and
- a transistor having a predetermined resistance connected to a a--Si:H sensor for reading out the stored signal, wherein the capacitance of the a--Si:H sensor when multiplied by the resistance of the transistor yield an RC time constant less than 10 microseconds, thereby to permit real-time imaging of said incident radiation bursts.
A device for storing and retrieving an imaging signal obtained as a result of diagnostic X rays for purposes of realizing real-time images, comprising:
- an array having a plurality of sensors arranged in rows and columns;
- each sensor of said plurality of sensors being an a--Si:H sensor having a first a--Si:H layer doped to a first conductivity type, a second a--Si:H layer doped to a second conductivity type, and an intrinsic a--Si:H layer sandwiched between said first and second a--Si:H layers;
- an upper electrode layer transparent to visible light connected atop said first a--Si:H layer of each of said sensors;
- a lower electrode layer connected below said second a--Si:H layer of each of said sensors;
- and
- a plurality of thin film field effect transistors each having a predetermined resistance, each transistor of said plurality of transistors being connected to and paired with a sensor of said plurality of sensors for reading out an imaging signal stored in a respective sensor upon irradiation by said diagnostic x-rays, wherein the capacitance of each a--Si:H sensor of said plurality of sensors when multiplied by the resistance of each transistor to which each a--Si:H sensor is connected yields an RC time constant less than 10 microseconds, thereby to permit real-time imaging of said diagnostic x-rays.
A real-time imaging device having a plurality of arrays one stacked upon the other, with each array of said plurality of arrays having a plurality of sensors arranged in rows and columns, each sensor of each array comprising:
- a scintillation layer to convert incident radiation signals into visible light signal,
- an a--Si:H sensor, said a--Si:H sensor having a first a--Si:H layer doped to a first conductivity type, a second a--Si:H layer doped to a second conductivity type, and an intrinsic a--Si:H layer sandwiched between said first and second a--Si:H layers;
- a thin film field effect transistor connected to each a--Si:H sensor and formed upon a mutual substrate as said each a--Si:H sensor, for reading out a signal from said respective sensor, wherein a capacitance of each a--Si:H sensor of said plurality of sensors when multiplied by a resistance of each transistor to which each a--Si:H sensor is connected yields an RC time constant less than 10 microseconds, thereby to permit real-time imaging of said incident radiation signals.
Dependencies are inferred from the claim text.