Radiant energy – Invisible radiant energy responsive electric signalling – Semiconductor system
Patent
1992-12-10
1995-01-17
Hannaher, Constantine
Radiant energy
Invisible radiant energy responsive electric signalling
Semiconductor system
250366, 250367, 250368, 25037009, G01T 120
Patent
active
053827988
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to ionizing radiation sensors, such as X or gamma ray sensors, used in industrial or medical radiographic imaging systems.
2. Description of the Related Art
A sensor of this kind, used for some years in intra-oral dental radiology in an apparatus that permits displaying in real time on a screen the radiographic data furnished and marketed under the designation Radiovisiographie.RTM., has been described notably in European Patent No. 0,129,451 and in U.S. Pat. No. 4,593,400 in the Applicant's name.
Schematically such a sensor comprises a charge transfer array device, also known as a charged-coupled device, (CCD), coupled to a scintillator element and a filter means to impede the passage of the X-rays not transformed by the scintillator element into rays of visible wavelength.
In the sensor in question this filter means is a screen formed by optic fibers provided with metal oxide particles intended to absorb the energy of the X-rays not transformed by the scintillator.
Although the data obtained with a sensor of this type are particularly reliable and workable without reservation by the practitioner, the fact remains that the thickness which must necessarily be given to the screen, for it to fully play its role of filter, constitutes a dimensional limitation affecting the size of the sensor to some extent.
This limitation is overcome with the sensor of the invention which makes use of a means ensuring not only a function of filtering but also of guiding the radiations, the latter function contributing in large measure, as will be understood on reading the description below, to the formation of high quality pictures.
SUMMARY OF THE INVENTION
More precisely, the sensor of the invention is characterized in that said filter means is formed by the combination of a non-optical element consisting of a group ("bundle") of tubular guides, wholly or partly of metal, and of the scintillator element, the latter being housed in said non-optical element.
A first remark must at once be emphasized: Contrary to the sensors of the prior art, the sensor of the invention does not comprise an optic fiber system, which makes it possible notably to greatly reduce the overall dimensions of the device, this being of great interest in some applications where the space usable for the examination is limited, for example, inside the buccal cavity.
It should be made clear also that the function of guiding the radiations may be considered to be secondary. It is not realized by a system of optic fibers, as has just been emphasized, nor by the scintillattor itself, as for example in EP-A-0,423,030, but by metal tubes.
Other important characteristics and advantages of the invention will appear in the description that follows of an example of realization of an X-ray sensor according to said invention, this description being accompanied by drawings which show respectively:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic sectional view showing the relative position of the various component parts of the sensor.
FIG. 2 is an enlarged schematic view of one of the tubular guides of the filter means and an illustration of the theoretical path of the various rays reaching the zones limited by this guide.
FIG. 3 is a schematic front elevation of the charge-coupled device of FIG. 1, illustrating the position of the pixels.
FIG. 4 is a schematic front elevation view of a 2:1 array of four tubular guides in a linear relationship with one pixel of the charge-coupled device of FIG. 3.
FIG. 5 is a schematic front elevation view of a 5:1 array of twenty-five tubular guides in a linear relationship with one pixel of the charge-coupled device of FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring more particularly to FIG. 1, there is shown at 1 the sensor which is formed by a casing 10 impermeable to liquids and gases, which contains a charge coupled device 20 (CCD) coupled to a microelectronic drive and output signal amplifier (30) of the charge-couple
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Glick Edward J.
Hannaher Constantine
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