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US 2011/0079729 A1Published application
Megavoltage imaging with a photoconductor based sensor
OwnerLarry Dean Partain, George Zentaiinventors
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Abstract
A photodetector for detecting megavoltage (MV) radiation comprises a semiconductor conversion layer having a first surface and a second surface disposed opposite the first surface, a first electrode coupled to the first surface, a second electrode coupled to the second surface, and a low density substrate including a detector array coupled to the second electrode opposite the semiconductor conversion layer. The photodetector includes a sufficient thickness of a high density material to create a sufficient number of photoelectrons from incident MV radiation, so that the photoelectrons can be received by the conversion layer and converted to a sufficient of recharge carriers for detection by the detector array.
Claims31
A photodetector comprising:
- a semiconductor conversion layer having a first surface and a second surface disposed opposite the first surface;
- a first electrode coupled to the first surface of the semiconductor conversion layer;
- a second electrode coupled to the second surface of the semiconductor conversion layer;
- a low density substrate coupled to the second electrode opposite the semiconductor conversion layer, the low density substrate including a detector array;
- a high density layer disposed over the first electrode opposite the semiconductor conversion layer;
- wherein the high density layer includes a thickness of a high density material to create a number of photoelectrons caused by mega-voltage x-ray photons incident upon the high density layer, the photoelectrons to be received by the semiconductor conversion layer;
- wherein the first electrode includes a thickness of another high density material to create a number of photoelectrons caused by mega-voltage x-ray photons incident upon the first electrode to be received by the semiconductor conversion layer;
- wherein the semiconductor conversion layer includes a thickness of a photo-conductive material to convert photoelectrons received from one of the high density layer and the first electrode to free charge carriers for detection by the detector array, wherein detected free charge carriers provide an image, and
- wherein the low density substrate has a density and thickness so that mega-voltage x-ray photons incident upon the low density substrate create no more than an insubstantial amount of photoelectrons to be converted by the semiconductor conversion layer.
6 more elements
A photodetector comprising:
- a semiconductor conversion layer having a first surface and a second surface disposed opposite the first surface, the semiconductor conversion layer comprising a thickness of between 20 and 20000 microns of one of mercuric iodide and lead iodide;
- a first electrode comprising a continuous upper conducting electrode of palladium or carbon coupled to the first surface of the semiconductor conversion layer;
- a second electrode comprising an upper pixilated electrode of indium tin oxide coupled to the second surface of the semiconductor conversion layer;
- a low density substrate coupled to the second electrode opposite the semiconductor conversion layer, the low density substrate comprising an unleaded glass plate having a detector array, the detector array including a plurality of amorphous silicon thin film transistor (TFT) pixilated electronic switches and amorphous silicon thin film transistor (TFT) pixilated electronic capacitors;
- a high density layer comprising a thickness of between 0.2 and 1.5 millimeters of lead or copper over the first electrode opposite the semiconductor conversion layer;
- and
- wherein the thickness of the semiconductor conversion layer is inversely proportional to the thickness of the high density layer.
4 more elements
A method comprising:
- absorbing megavoltage X-ray photons incident upon a high density layer;
- producing high energy photoelectrons from the megavoltage X-ray photons;
- generating free charged carriers in a photoconductive layer from the photoelectrons;
- and
- detecting the free charge carriers at a plurality of pixels on a low density substrate,
- wherein substantially all of the high energy photoelectrons are produced by the collision of the megavoltage X-ray photons and the high density layer, and no more than an insubstantial number of high energy photoelectrons are produced by the collision of the megavoltage X-ray photons and the low density layer.
3 more elements
Dependencies are inferred from the claim text.