Radiant energy – Source with recording detector
Reexamination Certificate
2000-08-30
2003-06-03
Hannaher, Constatine (Department: 2878)
Radiant energy
Source with recording detector
C250S311000
Reexamination Certificate
active
06573525
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method and apparatus for recording and reading out images, wherein an image is recorded by use of an anisotropic fluorescent material screen.
2. Description of the Related Art
Apparatuses utilizing two-dimensional image read-out means, e.g. facsimile apparatuses, copying machines, and radiation image sensors, have heretofore been known.
For example, in the fields of medical radiation image sensors, and the like, methods and apparatuses for recording and reading out radiation image information, wherein two-dimensional image read-out means is utilized, have heretofore been proposed. With the proposed methods and apparatuses for recording and reading out radiation image information, such that a radiation dose delivered to an object during a medical radiation image recording operation may be kept small, and such that the image quality of an image and its capability of serving as an effective tool in, particularly, the efficient and accurate diagnosis of an illness may be enhanced, a solid-state radiation detector (an electrostatic recording material), which is provided with a photo-conductive material (layer) sensitive to radiation, e.g. X-rays, such as a selenium plate, is employed as the two-dimensional image read-out means. The solid-state radiation detector is exposed to radiation, such as X-rays, carrying radiation image information, and electric charges in an amount proportional to the radiation dose delivered to the solid-state radiation detector are accumulated as latent image charges at a charge accumulating section in the solid-state radiation detector. In this manner, the radiation image information is recorded as an electrostatic latent image at the charge accumulating section. Thereafter, the solid-state radiation detector, in which the radiation image information has been recorded, is scanned with a laser beam or a light beam radiated out from a line light source, and the radiation image information is thereby read out from the solid-state radiation detector.
As the solid-state radiation detectors utilized as the two-dimensional image read-out means in the aforesaid methods and apparatuses for recording and reading out radiation image information, various types of solid-state radiation detectors have heretofore been proposed. For example, from the aspect of a charge forming process for generating the latent image charges, which carry image information, in the solid-state radiation detector, the solid-state radiation detectors may be classified into photo conversion types of solid-state radiation detectors, direct conversion types of solid-state radiation detectors, and improved direct conversion types of solid-state radiation detectors which belong to the category of the direct conversion types of solid-state radiation detectors and in which the latent image charges are read out through scanning with reading light. Also, from the aspect of a charge reading process for acquiring an image signal proportional to the amount of the latent image charges accumulated at the charge accumulating section, the solid-state radiation detectors may be classified into thin-film transistor (TFT) reading types of solid-state radiation detectors and photo reading types of solid-state radiation detectors.
With the TFT reading types of solid-state radiation detectors, TFT's are operated successively in order to convert the latent image charges, which are accumulated at the charge accumulating sections, into a radiation image signal, and the radiation image signal is fed out. With the photo reading types of solid-state radiation detectors, a reading electromagnetic wave (ordinarily, visible light is employed as the reading electromagnetic wave) is irradiated to the solid-state radiation detectors in order to convert the latent image charges, which are accumulated at the charge accumulating section, into an image signal, and the image signal is fed out.
With the photo conversion types of solid-state radiation detectors, radiation is converted into light, and thereafter electric charges are generated with the light. For example, the photo conversion types of solid-state radiation detectors comprise two-dimensional image read-out means (i.e., solid-state radiation detecting means) and a fluorescent material (i.e., a scintillator) overlaid upon the two-dimensional image read-out means. The two-dimensional image read-out means comprises an insulating substrate and a plurality of photoelectric conversion devices (each having a charge accumulating section for accumulating electric charges to be detected), which are arrayed in a two-dimensional pattern on the insulating substrate. When the fluorescent material is exposed to radiation carrying image information, the fluorescent material produces visible light carrying the image information. The photo conversion types of solid-state radiation detectors are described in, for example, Japanese Unexamined Patent Publication Nos. 59(1984)-211263 and 2(1990)-164067, PCT International Publication No. WO92/06501, and “Signal, Noise, and Read Out Considerations in the Development of Amorphous Silicon Photodiode Arrays for Radiotherapy and Diagnostic X-ray Imaging,” L. E. Antonuk et al., University of Michigan, R. A. Street Xerox, PARC, SPIE Vol. 1443, Medical Imaging V; Image Physics (1991), pp. 108-119. The two-dimensional image read-out means employed in the photo conversion types of solid-state radiation detectors utilizes the TFT reading type of solid-state radiation detecting means. The two-dimensional image read-out means detects the fluorescence produced by the fluorescent material and accumulates the latent image charges, which carry the image information, at the charge accumulating sections of the photoelectric conversion devices. Also, the TFT's, each of which is connected to one of the photoelectric conversion devices, are operated successively, the latent image charges accumulated at the charge accumulating sections are thereby converted into a radiation image signal, and the radiation image signal is fed out.
With the direct conversion types of solid-state radiation detectors, radiation is irradiated to a photo-conductive layer, and electric charges are generated directly in the photo-conductive layer. For example, the direct conversion types of solid-state radiation detectors comprise a photo-conductive layer, which exhibits electrical conductivity when it is exposed to recording radiation, and two-dimensional image read-out means. The two-dimensional image read-out means is constituted of a plurality of charge collecting electrodes, which are arrayed in two-dimensional directions and collect electric charges generated in the photo-conductive layer, and capacitors, each of which acts as a charge accumulating section and is connected to one of the charge collecting electrodes. The electric charges having been collected by each of the charge collecting electrodes are accumulated at the corresponding capacitor as the latent image charges carrying the image information. The direct conversion types of solid-state radiation detectors are described in, for example, (i) “Material Parameters in Thick Hydrogenated Amorphous Silicon Radiation Detectors,” Lawrence Berkeley Laboratory, University of California, Berkeley, Calif. 94720 Xerox Parc. Palo Alto. Calif. 94304; (ii) “Metal/Amorphous Silicon Multilayer Radiation Detectors, IEE TRANSACTIONS ON NUCLEAR SCIENCE, Vol. 36, No. 2, April 1989; and (iii) Japanese Unexamined Patent Publication No. 1(1989)-216290. As in the photo conversion types of solid-state radiation detectors, the two-dimensional image read-out means employed in the direct conversion types of solid-state radiation detectors utilizes the TFT reading technique. Specifically, the TFT's are operated successively, the latent image charges having been accumulated at the capacitors are thereby converted into a radiation image signal, and the radiation image signal is fed out.
The improved direct conversion types of solid-state radiation detectors
Fuji Photo Film Co. , Ltd.
Gabor Otilia
Hannaher Constatine
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