Radiant energy – Invisible radiant energy responsive electric signalling – With or including a luminophor
Reexamination Certificate
2000-11-22
2002-11-05
Hannaher, Constantine (Department: 2878)
Radiant energy
Invisible radiant energy responsive electric signalling
With or including a luminophor
C250S370110
Reexamination Certificate
active
06476394
ABSTRACT:
This invention relates to a radiation image capturing apparatus for use in X-ray mammography, the radiographing of a chest or bones of limbs, etc., for example.
For a system for use in radiography for medical diagnosis, an image forming system, in which a silver halide photographic film is brought in close contact with a fluorescent intensifying screen, exposed to an X-ray image, developed by an automatic developing apparatus, fixed, rinsed, and dried, has been heretofore used generally.
In such an X-ray image diagnosis for medical use or a non-destructive inspection, what is called an X-ray film using a silver halide emulsion has been broadly used. Especially in image diagnosis for medical use, a screen film system having a intensifying screen and an X-ray film in combination has been used for about one hundred years.
Such image information is what is called analogue image information, therefore it is not possible to make such arbitrary image processing or instantaneous electrical transmission as has been done in digital image information processing which has been continuously developed in recent years.
Computed radiography (CR) as a digital technology for an X-ray image is now accepted in medical fields. However, its image sharpness is insufficient and spatial resolution is also insufficient, therefore, it has not attained an image quality level of the screen film system. Further, as a new digital X-ray imaging system, it has been developed a flat-panel X-ray detecting device (FPD) using thin film transistors (TFT) described in, for example, John Rowlands: “Amorphous Semiconductors Usher in Digital X-ray Imaging” Physics Today, November 1997, p. 24, L. E. Antonuk: “Development of a High Resolution, Active Matrix, Flat-Panel Imager with Enhanced Fill Factor”, SPIE, vol. 3032, p. 2, (1997), etc.
This has the advantage that its apparatus is made more small-sized than CR and its image quality is excellent. However, on the other hand, it has the defects that an enormous expense and a long period is necessary in newly developing an FPD using thin film transistors (TFT), and that, from the viewpoint of the manufacturing technology and the S/N ratio of the image obtained, it is difficult to make the pixel size small, which makes the resolution of the image low as 3-4 lp/mm or so.
If a radiation image can be obtained by using a number of low-priced area sensors such as CCD or CMOS sensors, the reliability as a sensor is high, the manufacturing cost can be reduced, and resolution of the image can be easily raised.
Incidentally, in order to obtain an image by an FPD, it is necessary such correction of the signal value as is represented by offset correction and gain correction; first, the signal value of each pixel when it is not exposed to a radiation and the signal value when it is exposed to a uniform radiation which has not been transmitted through the object of radiographing are obtained, to obtain image data for correction (correction data). This operation is generally called calibration. In an FPD using a number of area sensors, it is necessary to combine images which have been obtained by the respective area sensors; therefore, on top of the above-described correction of the signal value, geometrical corrections such as parallel shift, rotation, and a correction of distortion become necessary. For these geometrical corrections, it is necessary that the condition of the mounting of each area sensor and the lens unit can cope with the variation with the passage of time and the variation owing to environmental temperature, vibration, impact, etc; therefore, they are more complex than a mere correction of a signal value, and in most cases, because an error in the corrections makes a great hindrance in diagnosis, the corrections must be carried out more reliably than the correction of a signal value. Further, in order to carry out the combination of images in the case where a number of area sensors are used precisely in a practically short time, it has been necessary to grasp the positional relation of the sensors precisely.
SUMMARY OF INVENTION
This invention has been done in view of the above-described actual circumstances, and it is an object of the invention to provide a radiation image capturing apparatus which has a high reliability by calibration, and is capable of being subjected to the reduction of manufacturing cost, raising the resolution of the image easily, and being made flat-shaped and of light weight.
In order to solve the above-described problems and accomplish the object, this invention has any one of the structures described below.
(1) A radiation image capturing apparatus provided with a radiation image detector having a structure in which a scintillator, a lens unit array, and area sensors corresponding to each lens unit of the lens unit array are arranged in this order, further comprising a calibration practicing means for obtaining image data for correction by automatically carrying out calibration after a certain time from the turning-on of the electric power source, and a memory means for memorizing image data for correction obtained by calibration.
According to the invention described in this paragraph (1), image data for correction can be obtained by automatically carrying out calibration after a certain time from the turning-on of the electric power source; therefore, the apparatus has a high reliability and the resolution of the image can be easily raised.
(2) A radiation image capturing apparatus provided with a radiation image detector having a structure in which a scintillator, a lens unit array, and area sensors corresponding to each lens unit of the lens unit array are arranged in this order, further comprising a calibration practicing means for obtaining image data for correction by automatically carrying out calibration after passage of a certain time from the former calibration while the electric power source is kept turned on, and a memory means for memorizing image data for correction obtained by calibration.
According to the invention described in this paragraph (2), calibration can be automatically carried out when a certain set time has passed with the timer counting from the former calibration while the electric power source is kept turned on; therefore, the apparatus has a high reliability and the resolution of the image can be easily raised.
(3) A radiation image capturing apparatus provided with a radiation image detector having a structure in which a scintillator, a lens unit array, and area sensors corresponding to each lens unit of the lens unit array are arranged in this order and comprising a means for counting the cumulative number of times of image capturing, further comprising a calibration practicing means for obtaining image data for correction by automatically carrying out calibration when the number of times of image capturing from the former calibration has reached a specified number of times, and a memory means for memorizing image data for correction obtained by calibration.
According to the invention described in this paragraph (3), calibration can be automatically carried out when the number of times of image capturing from the former calibration has reached the specified number of times with a counter counting the number of times of image capturing; therefore, the apparatus has a high reliability and the resolution of the image can be easily raised.
(4) A radiation image capturing apparatus provided with a radiation image detector having a structure in which a scintillator, a lens unit array, and area sensors corresponding to each lens unit of the lens unit array are arranged in this order, further comprising a calibration specifying means for specifying the method and/or the timing of calibration.
According to the invention described in this paragraph (4), the method and/or the timing of calibration can be specified and an operator can arbitrarily vary the method and/or the timing of calibration in accordance with, for example, the operational condition of the radiation image capturing apparatus.
(5) A radiation image
Amitani Kouji
Ishisaka Akira
Kawano Tsutomu
Yonekawa Hisashi
Cantor & Colburn LLP
Hannaher Constantine
Konica Corporation
LandOfFree
Radiation image capturing apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Radiation image capturing apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Radiation image capturing apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2933165