Radiant energy – Invisible radiant energy responsive electric signalling – With or including a luminophor
Reexamination Certificate
2000-02-11
2002-10-29
Mai, Huy (Department: 2873)
Radiant energy
Invisible radiant energy responsive electric signalling
With or including a luminophor
C250S487100, C378S098300
Reexamination Certificate
active
06472665
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a radiation image detector and a radiation image forming system which are used for X-ray mammography and for radiographing the chest and appendicular skeletons.
As s system used for radiographing an X-ray image for medical diagnosis, there has generally been used an image forming system wherein a silver halide photographic film is superposed closely on an X-ray intensifying screen and is exposed to an X-ray image to be developed, fixed, washed with water and dried by an automatic processor.
In the case of diagnoses by X-ray images for medical use and of non-destructive inspections, the so-called X-ray films employing a silver halide emulsion have widely been used. For diagnoses by images for medical use, in particular, a screen film system wherein an intensifying screen and an X-ray film are combined has been used for 100 years.
These image information are the so-called analog image information which make it impossible to conduct free image processing and instant electric transmission which can be conducted for digital image information which have recently been developed.
As one of digital technologies for X-ray images, computed radiography (CR) is currently accepted in the field of medical service. However, its sharpness is not enough, its spatial resolution is insufficient and it is unable to reach the level of image quality of the screen/film system. As a technology of digital X-ray image which is further new, there has been developed a flat panel X-ray detection device (FPD) employing a thin film transistor (TFT) which is described, for example, in John ROWLANDS' thesis “Amorphous Semiconductor Usher in Digital X-ray Imaging” on page 24 of Nov. issue of the magazine “Physics Today” in 1997, or in L. E. ANTONUK's thesis “Development of a High Resolution, Active Matrix, Flat-Panel Imager with Enhanced Fill Factor” on page 2 of Volume 32 of the magazine “SPIE” in 1997.
This has special features that a device is smaller and image quality is more excellent, compared with CR. However, on the other hand, it has a defect that resolution of images is as low as about 3-4 lp/mm, due to the restriction of a size of an image element owned by TFT. Further, as another X-ray digital technology, there is known a method to use an X-ray scintillator and a small number of CCDs. However, a radiation image detector employing a small number of CCDs has a weak point that it is large in size and heavy in weight.
SUMMARY OF THE INVENTION
The invention has been achieved in view of the actual circumstances stated above, and its first object is to provide a radiation image detector and a radiation image forming system wherein spatial resolution is high, image quality is high, and a thickness is small and weight is light. Further, the second object of the invention is to provide a radiation image pickup apparatus wherein it is possible to obtain an image which is free from optical distortion caused by positional deviation and/or change in size for an effective image area caused by change of ambient circumstances, mainly by change of temperature, and to process a large quantity of data rapidly.
To solve the problems stated above and to attain the objects, the invention is structured as follows.
(1-1) A radiation image detecting device, comprises: a scintillator to emit light in accordance with an intensity of radiation energy when being irradiated with radiation;
a lens array in which a plurality of lens units are arranged in a form of an array, wherein the light emitted from the scintillator passes through the lens array;
a lattice to partition the lens array, wherein the plurality of lens units are arranged on the lattice; and
a plurality of area sensors corresponding to the plurality of lens units of the lens array, the plurality of area sensors receiving the light having passed through the plurality of lens units and converting the light into electric signals,
wherein the scintillator, the lens array and the plurality of area sensors are arranged in that order.
(1-2) The radiation image detecting device of (1-1), wherein the lattice has a opaque member.
(1-3) The radiation image detecting device of (1-2), wherein a transmissivity of light having a wavelength of 400 nm to 700 nm for the lattice in not larger than 10%.
(1-4) The radiation image detecting device of (1-1), wherein the scintillator emits visible light in accordance with an intensity of radiation energy.
(1-5) The radiation image detecting device of (1-4), wherein the scintillator contains gadolium oxysulfide (Gd
2
O
2
S:Tb) or cesium iodide (CsI:Tl).
(1-6) The radiation image detecting device of (1-1), wherein each lens unit in the lens array comprises plural different lenses.
(1-7) The radiation image detecting device of (1-6), wherein a magnification of the each lens unit is 1/1.5 to 1/20.
(1-8) The radiation image detecting device of (1-6), wherein an effective F-number of the each lens unit is not larger than 8.
(1-9) The radiation image detecting device of (1-6), wherein a difference of MTF between a center and a periphery on an forming plane by the each lens unit is not larger than 30%.
(1-10) The radiation image detecting device of (1-6), wherein a half field angle of the each lens unit is not more than 35°.
(1-11) The radiation image detecting device of (1-6), wherein the each lens unit comprises a focus point adjusting device.
(1-12) The radiation image detecting device of (1-6), wherein the each lens unit contains Pb by 0.47 wt % or more and less than 69 wt % of a total weight of glass components of the each lens unit.
(1-13) The radiation image detecting device of (1-6), wherein the each lens unit contains PbO by 0.5 wt % or more and less than 75 wt % of a total weight of glass components of the each lens unit.
(1-14) The radiation image detecting device of (1-1), wherein the area sensors comprises a solid-state image acquiring unit such as a CCD or a CMOS sensor.
(1-15) The radiation image detecting device of (1-1), further comprising a transparent member provided between the scintillator and the lens array.
(1-16) The radiation image detecting device of (1-15), wherein the transparent member comprises a glass and the transparent member contains Pb by 0.47 wt % or more and less than 69 wt % of a total weight of glass components of the transparent member.
(1-17) A radiation image detecting device, comprises:
a scintillator to emit light in accordance with an intensity of radiation energy when being irradiated with radiation;
a lens array comprising a plurality of lens unit, wherein the light emitted from the scintillator passes through the lens array; and
a plurality of area sensors corresponding to the plurality of lens unit of the lens array, the plurality of area sensors receiving the light having passed through the plurality of lens units and converting the light into electric signals,
wherein the scintillator, the lens array and the area sensors are arranged in this order and a focus length f (mm) of each lens unit satisfies the following formula:
2
<f
<20.
(1-18) A radiation image detecting apparatus, comprises:
a scintillator to emit light in accordance with an intensity of radiation energy when being irradiated with radiation;
a transparent member, wherein the light emitted from the scintillator passes through the transparent member;
a lens array comprising a plurality of lens units, wherein the light having passed through the transparent member further passes through the lens array; and
a plurality of area sensors corresponding to the plurality of lens units of the lens array, the plurality of area sensors receiving the light having passed through the lens arrays and converting the light into electric signals,
wherein the scintillator, the transparent member, the lens array and the plurality of area sensors are arranged in that order.
Here, it may be preferable that the apparatus described in (1-17) or (1-18) is used in combination with at least one of the structures of (1-1) to (1-16).
(1-19) A radiation image detecting apparatus, comprises
Ishisaka Akira
Ohara Hiromu
Cantor & Colburn LLP
Konica Corporation
Mai Huy
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