Radiant energy – Source with recording detector – Including a light beam read-out
Reexamination Certificate
1999-01-20
2001-10-30
Hannaher, Constantine (Department: 2878)
Radiant energy
Source with recording detector
Including a light beam read-out
C250S585000, C250S338400
Reexamination Certificate
active
06310358
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to apparatus and methods for detecting ionizing radiation images and more specifically relates to apparatus and methods for digital detection of x-ray images.
BACKGROUND OF THE INVENTION
There are described in the patent literature numerous systems and methods for the recording of X-ray images. Conventional X-ray imaging systems use an X-ray sensitive phosphor screen and a photosensitive film to form visible analog representations of modulated X-ray patterns. The phosphor screen absorbs X-ray radiation and is stimulated to emit visible light. The visible light exposes photosensitive film to form a latent image of the X-ray pattern. The film is then chemically processed to transform the latent image into a visible analog representation of the X-ray pattern.
Recently, there have been proposed systems and methods for detection of X-ray images in which the X-ray image is directly recorded as readable electrical signals, thus obviating the need for film in the imaging process.
For example, U.S. Pat. No. 4,961,209 to Rowlands et al describes a method for employing a transparent sensor electrode positioned over a photoconductive layer and a pulsed laser that scans the photoconductive layer through the transparent sensor electrode.
U.S. Pat. No. 5,268,569 to Nelson et al. describes an imaging system having a photoconductive material which is capable of bearing a latent photostatic image, a plurality of elongate parallel strips adjacent the photoconductive material, and a pixel source of scanning radiation.
U.S. Pat. No. 5,652,430 to Lee describes a radiation detection panel for X-ray imaging systems which is made up of a matrix assembly of radiation detection sensors arrayed in rows and columns to record still or moving images.
Examples of commercially available systems in which X-ray images are directly recorded as readable electrical signals include the Direct Radiography line of detector arrays offered by Sterling Diagnostic Imaging (formerly DuPont) of Delaware, USA; the Pixium line of flat panel X-ray detectors for radiography offered by Trixell of Moirans, France; the Digital Imaging Center offered by Swissray Medical AG of Switzerland; and the Canon Digital Radiography System offered by the Canon Medical Division of Canon U.S.A.
In addition, digital mammographic x-ray systems are commercially available. For example, the Opdima system offered by Siemens Medical Systems, Inc. of New Jersey, USA.
SUMMARY OF THE INVENTION
The present invention seeks to provide an improved X-ray imaging system and method.
There is thus provided in accordance with a preferred embodiment of the present invention a radiation detection module including a generally uniform dielectric layer with generally opposite first and second surfaces, a conductive layer interfacing the first surface of the generally uniform dielectric layer, an ionizing radiation detection multi-layer structure including a photoelectric conversion layer which interfaces the second surface of the generally uniform dielectric layer; the conductive layer, the ionizing radiation detection multi-layer structure and the generally uniform dielectric layer being configured and arranged with respect to each other and being operative such that an imagewise ionizing radiation pattern impinging on the ionizing radiation detection multi-layer structure causes a corresponding charge pattern representing the imagewise ionizing radiation pattern to be generated at the interface between the generally uniform dielectric layer and the photoelectric conversion layer and also causes a readable imagewise replica of the charge pattern to be formed in the conductive layer.
Further in accordance with a preferred embodiment of the present invention, the photoelectric conversion layer of the ionizing radiation detection multi-layer structure converts radiation to charge carriers and the ionizing radiation detection multi-layer structure also includes a continuous electrode disposed over the photoelectric conversion layer.
Still further in accordance with a preferred embodiment of the present invention the ionizing radiation detection multi-layer structure includes a barrier or blocking layer disposed between said continuous electrode and said photoelectric layer.
Additionally in accordance with a preferred embodiment of the present invention the photoelectric conversion layer is selenium or a selenium alloy. Alternately, in accordance with a preferred embodiment of the present invention, the photoelectric conversion layer is lead oxide, thallium bromide, cadmium telluride, cadmium zinc telluride, cadmium sulfide or mercury iodide.
In yet further accordance with a preferred embodiment of the present invention, the ionizing radiation detection multi-layer structure also includes a scintillator which absorbs ionizing radiation and emits optical radiation and a continuous electrode which is generally transparent to optical radiation, disposed between the scintillator and the photoelectric conversion layer.
Still in further accordance with a preferred embodiment of the present invention, an optically transparent barrier layer is disposed between the continuous electrode and the photoelectric conversion layer.
Additionally in accordance with a preferred embodiment of the present invention, the scintillator is either cesium iodide or a doped version thereof.
Preferably, the photoelectric conversion layer is amorphous selenium, a selenium alloy or amorphous silicon. Alternately, the photoelectric conversion layer may be an organic photoconductor.
In further accordance with a preferred embodiment of the present invention, the radiation detection module includes an optical radiation source which scans at least part of the conductive layer. Furthermore, the conductive layer and the dielectric layer are preferably transparent to optical radiation.
Moreover, in accordance with a preferred embodiment of the present invention, the optical radiation source includes at least one source of optical radiation which impinges on but does not pass entirely through the photoelectric conversion layer.
In still further accordance with a preferred embodiment of the present invention, the optical radiation source also includes a second source of optical radiation, which generally passes through the photoelectric conversion layer.
Preferably the optical radiation source is a generally linear array of light emitting diodes that emits a generally elongate beam of optical radiation.
Furthermore, in accordance with a preferred embodiment of the present invention, the elongate beam of optical radiation has at least one well-defined edge.
Additionally, in accordance with a preferred embodiment of the present invention, readout electronics are coupled to the conductive layer to sense an electric current flowing therealong as the optical radiation source scans the conductive layer and as the optical radiation source is operative.
In accordance with a preferred embodiment of the present invention, the readout electronics are removably coupled to the conductive layer. Alternately, in accordance with a preferred embodiment of the present invention, the readout electronics may be permanently coupled to the conductive layer.
Preferably, the ionizing radiation is x-ray radiation.
There is also provided in accordance with a preferred embodiment of the present invention an addressable array of radiation detection elements including a multi-layer radiation sensor, a plurality of electronically addressable optically transparent conductive columns associated with the multi-layer radiation sensor, readout electronics coupled to the plurality of electronically addressable, optically transparent conductive columns and a scanning source of optical radiation, projecting an elongate beam that transverses the conductive columns. The elongate beam, which is generally wider than a single row, scans the optically transparent conductive columns to provide sequential addressing of each row of the array of radiation detection elements.
In further accordance with a p
Edge Medical Devices Ltd.
Hannaher Constantine
Israel Andrew
Pillsbury & Winthrop LLP
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