WO1994004963A1 - Element, dispositif et procede associe de prise d'une image radiographique latente - Google Patents

Element, dispositif et procede associe de prise d'une image radiographique latente Download PDF

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Publication number
WO1994004963A1
WO1994004963A1 PCT/US1992/006891 US9206891W WO9404963A1 WO 1994004963 A1 WO1994004963 A1 WO 1994004963A1 US 9206891 W US9206891 W US 9206891W WO 9404963 A1 WO9404963 A1 WO 9404963A1
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WO
WIPO (PCT)
Prior art keywords
layer
conductive
microplates
photoconductive
actinic
Prior art date
Application number
PCT/US1992/006891
Other languages
English (en)
Inventor
Denny Lap Yen Lee
Lothar Siegfried Jeromin
Original Assignee
E.I. Du Pont De Nemours And Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by E.I. Du Pont De Nemours And Company filed Critical E.I. Du Pont De Nemours And Company
Priority to PCT/US1992/006891 priority Critical patent/WO1994004963A1/fr
Publication of WO1994004963A1 publication Critical patent/WO1994004963A1/fr

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Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/054—Apparatus for electrographic processes using a charge pattern using X-rays, e.g. electroradiography
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/24—Measuring radiation intensity with semiconductor detectors
    • G01T1/246—Measuring radiation intensity with semiconductor detectors utilizing latent read-out, e.g. charge stored and read-out later

Definitions

  • the present invention relates to an element, a device and an associated method for capturing radiographic images. More particularly, the present invention uses a unique microcapacitor matrix structure to hold varying electrical charges representing a latent radiographic image.
  • SUBSTITUTE SHEET is thus greatly enhanced.
  • X-ray films are often coated on both sides with photosensitive emulsion and two screens are used to expose the film from both sides, further increasing the efficiency of the system and reducing the exposure time required to obtain a radiogram.
  • Radiograms have also been produced by capturing a latent radiographic image using a photoconductive plate in a xeroradiographic process.
  • a photoconductive plate sensitive to X-ray radiation comprising at least a photoconductive layer coated over a conductive backing layer is first charged by passing under a charging station typically comprising a corona wire. Positive or negative charge is uniformly deposited over the plate surface. The plate is next exposed to X-ray radiation. Depending on the intensity of the incident radiation, electron hole pairs generated by the X-ray radiation are separated by a field incident to the charge laid over the surface and as a result move along the field to recombine with the surface charge.
  • a latent image in the form of electrical charges of varying magnitude remain on the plate surface, representing a latent electrostatic radiogram.
  • This latent image may then be rendered visible by toning and preferably transferring onto a receiving surface for better viewing.
  • Xeroradiography a specific application of electroradiography offers high resolution and, because the photoconductive layer may be made fairly thick comparative to the the phosphor screens, results in good X-ray conversion efficiency. It is, however, limited by the same limitations found in xerography in general, i.e., dynamic range and the complexity of processing equipment. Furthermore, the image is not in a format that can readily provide a digital output.
  • SUBSTITUTE SHEET More recent developments include the use of an electrostatic image capture element to capture a latent X-ray image, the element comprising a photoconductive layer over an insulating layer on a conductive support, the photoconductive layer also covered by a dielectric layer, and the dielectric layer overcoated with a transparent electrode.
  • a biasing voltage is applied between the transparent electrode and the conductive support to charge the element which is a large parallel plate capacitor. While the bias voltage is applied, the element is exposed to image wise modulated X-ray radiation. Following exposure, the bias is removed and a latent image is preserved as a charge distribution trapped in the dielectric layer.
  • the latent image represented by local charge variations is a very small signal charge that must be extracted in the presence of random noise in the total capacitive charge in the full plate.
  • Signal to noise ratio is typically poor.
  • the transparent electrode is laid over the dielectric layer as a plurality of parallel narrow strips . In this manner the overall plate capacity is reduced and the signal extracted per picture element has a better signal to noise ratio.
  • Methods to readout the latent image include inter alia, scanning the length of the strip electrode with a laser beam while reading the charge flow across the electrode and the conductive plate.
  • an X-ray image capture element comprising a microcapacitor matrix structure that effectively retains charge while limiting the effects of dark current leakage during reading of the image.
  • an X-ray image capture element comprising: a first, electrically conductive, backing layer; a second, photoconductive layer responsive to both actinic and X-ray radiation extending substantially over said backing layer; a third, dielectric layer substantially transparent to both actinic and X-ray radiation, the dielectric layer having a front surface and a back surface extending substantially over and in contact with said photoconductive layer; and a plurality of discrete conductive microplates substantially transparent to both actinic and X-ray radiation, said microplates on said front surface, each of said microplates having dimensions coextensive with a minimum resolvable picture element .
  • the barrier layer may behave as a blocking diode blocking the flow of charges in one direction.
  • an X-ray image capture device comprising: (a) an element having: a first, electrically conductive, backing layer; a second, photoconductive layer responsive to both actinic and X-ray radiation extending substantially over said backing layer;
  • SUBSTITUTE SHEET a third, dielectric layer substantially transparent to both actinic and X-ray radiation, the dielectric layer having a front surface and a back surface extending substantially over and in contact with said photoconductive layer; and a plurality of discrete conductive microplates substantially transparent to both actinic and X-ray radiation, said microplates on said front surface, each of said microplates having dimensions coextensive with a minimum resolvable picture element;
  • conductive contacting means preferably resilient, for simultaneously contacting said plurality of microplates movable between a first position in contact with said microplates to a second position away from contact with said microplates;
  • Still another object of the present invention is to provide a method for capturing a radiogram on an X-ray image capture element comprising: a first, electrically conductive, backing layer; a second, photoconductive layer responsive to both actinic and X-ray radiation extending substantially over said backing layer; a third, dielectric layer substantially transparent to both actinic and X-ray radiation, the dielectric layer having a front surface and a back surface extending substantially over and in contact with said photoconductive layer; and
  • SUBSTITUTE SHEET a plurality of discrete conductive microplates substantially transparent to both actinic and X-ray radiation, said microplates on said front surface, each of said microplates having dimensions coextensive with a minimum resolvable picture element; the method comprising:
  • the method further comprises an additional step (e) after step (d) , the step (e) comprising exposing the element to uniform actinic radiation for a second time period.
  • Figure 1 shows a schematic cross sectional view of an X-ray capture element in accordance with the present invention.
  • Figure 2 shows a schematic cross sectional view of an alternate embodiment of an X-ray capture element in accordance with the present invention incorporating a charge barrier layer.
  • Figure 2a is a top view of the embodiment of the X- ray capture element shown in Figure 2.
  • Figure 3 shows a schematic cross sectional view of a device for capturing a latent X-ray image in accordance with the present invention.
  • SUBSTITUTE SHEET Figure 4 depicts a schematic representation of the device of Figure 3 in an enclosure to protect the device from exposure to actinic radiation.
  • Figure 5 shows in schematic representation an arrangement using the enclosure of Figure 4 for capturing a latent X-ray image.
  • Figure 6 represents an electrical equivalent of the element prior to exposure to x-ray radiation.
  • Figure 7 represents an electrical equivalent of the element just after exposure to x-ray radiation.
  • Figure 8 represents an electrical equivalent of the element just after exposure to x-ray radiation and removal of the conductive, resilient contacting layer.
  • Figure 9 represents an electrical equivalent of the element just after a uniform actinic exposure following exposure to x-ray radiation and removal of the bias source and of the conductive, resilient contacting layer.
  • Figure 10 is a schematic representation of a preferred arrangement of a resilient conductive contacting layer with pneumatic backing.
  • an X- ray image capture element 16 has a first conductive backing layer 12.
  • This conductive backing layer 12 is made of conductive material, and may be rigid or flexible, transparent or non transparent. Preferably it is a continuous layer made of a sufficiently thick and rigid conductive material to serve as support for the other layers that comprise the image capture element 16.
  • the photoconductive layer 8 preferably exhibits very high dark resistivity.
  • the photoconductive layer 8 may comprise amorphous selenium, lead oxide, cadmium sulfide, mercuric iodide or any other such material, including organic materials such as photoconductive polymers preferably loaded with X-ray absorbing compounds, which exhibit photoconductivity.
  • exhibiting photoconductivity means that upon exposure to actinic or X-ray radiation, the material exhibits reduced resistivity than in the absence of such exposure.
  • the reduced resistivity is in reality the effect of electron hole pairs generated in the material by the incident radiation.
  • the change in apparent resistivity is proportional to the intensity of the incident radiation.
  • actinic radiation again for purposes of describing the present invention, is meant ultraviolet (U.V.), infrared (I.R.) or visible but excludes X-ray and gamma radiation.
  • the photoconductive layer 8 should be chosen of sufficient thickness to absorb the incident X-ray radiation, or a substantial portion thereof, to provide high efficiency in radiation detection.
  • the specific type of material selected will further depend upon the desired charge retention time, and the desired simplicity of manufacture. Selenium is one preferred such material.
  • dielectric layer 6 Over the front surface of photoconductive layer 8 there is applied a dielectric layer 6.
  • the dielectric layer 6 must be transparent to both X-ray and actinic radiation and have sufficient thickness to prevent charge leakage. In the preferred embodiment of the present invention, the dielectric layer 6 should have a thickness greater than 100 Angstroms. Mylar® with a
  • SUBSTITUTE SHEET thickness of 50 ⁇ m may be used for layer 6, although thinner layers are suitable.
  • microplates As shown in Figures 1, 2 and 2a, over the dielectric layer 6 there is created a plurality of discrete minute conductive electrodes, 4a, 4b, 4c, etc., referred to herein as microplates .
  • the dimensions of the microplates define a smallest picture element (PIXEL) resolvable by this element 16.
  • PIXEL picture element
  • the electrodes 4a, 4b, 4c, etc. are substantially transparent to both actinic and X-ray radiation. They are deposited on the dielectric layer 6, typically, though not necessarily, using vapor or chemical deposition techniques, and can be made of a very thin film of metal such as gold, silver, aluminum, copper, chromium, titanium, platinum and the like.
  • the microplates 4a, 4b, 4c, etc. are made of transparent indium-tin oxide.
  • the microplates 4a, 4b, 4c, etc. are normally deposited as a continuous layer which is then etched to produce a plurality of individual discrete microplates having dimensions coextensive with the smallest resolvable picture element.
  • the microplates 4a, 4b, 4c, etc. may also be produced using laser ablation or photoetching.
  • the technology to produce such microplates is well known in the art and is not further discussed herein. A good description of photomicrofabrication techniques is given in imaging Processing _&. Material, chapter 18, entitled “Imaging for Microfabrication", P. 567 by J. M. Shaw of IBM Watson Research Center.
  • each one of the microplates 4a, 4b, 4c, etc., with the dielectric layer 6, the photoconductive layer 8, and the backing conductive layer 12 form two microcapacitors in series, a first microcapacitor being created between the microplate and the front surface of the photoconductive layer 8 and a
  • a charge barrier layer 10 is added on top of the conductive layer 12.
  • the base plate or layer 12 is made of an oxide forming metal such as aluminum, and the charge barrier layer 10 is provided by an aluminum oxide layer formed on the surface of the base plate or layer 12.
  • the subsequent coating thereon of a selenium photoconductive layer 8 produces a barrier layer 10 behaving as a blocking diode, inhibiting charge flow in one direction.
  • the charge barrier layer 10 may also be a simple insulating layer such as Polyethylene Terephthalate (Mylar®) , of dimensions comparable to the dielectric layer 6.
  • Mylar® Polyethylene Terephthalate
  • Dielectric layer 6 substantially transparent to both X-ray and actinic radiation and having sufficient thickness to prevent charge leakage, is placed over the front surface of photoconductive medium layer 8.
  • Transparent, discrete, microplates or electrodes 4a, 4b, 4c, etc., are formed over the dielectric layer 6 as before.
  • the entire element 16 can be made by depositing successive layers of conductor, insulator, photoconductor, insulator, and conductor upon a substrate. Assembly may be accomplished by vapor deposition, vacuum deposition, lamination, sputtering or any other known technique useful to deposit even thickness films.
  • the conductive backing layer 12, the charge barrier layer 10, the photoconductive layer 8 and the dielectric layer 6, are all continuous layers. However, it is still within the contemplation of the present invention to manufacture an
  • SUBSTITUTE SHEET element for X-ray capture as herein above structured, in which not only the transparent electrode layer has been etched to produce a plurality of microplates 4a, 4b, 4c, etc., but one or more of the underlying layers 6, 8, 10 and 12 may also be etched with substantially the same pattern as the electrode layer, to form a plurality of discrete dielectric portions, photoconductive portions, barrier layer portions or even conductive portions lying below the microplates 4a, 4b, 4c, etc., in registration therewith.
  • microplates 4a, 4b, 4c, etc. rather than etching a continuous layer to generate the microplates 4a, 4b, 4c, etc., direct deposition of the microplates 4a, 4b, 4c, etc., using masking techniques may be used, the method of manufacturing being one of choice depending on available resources and cost considerations, rather than an essential element or step of the present invention.
  • the element 16 of Figure 1 or 2 is preferably used in a device of the type shown in Figure 3 to capture a latent X-ray image in a manner somewhat similar to the use of traditional silver halide film in a screen containing cassette.
  • a device comprises in addition to an element for x-ray capture as described above, additional layers 2 and 20.
  • Layer 2 is a conductive contacting layer which, in order to assure good electrical contact is preferably a resilient conductive layer, such as conductive foam, conductive velvet or conductive rubber.
  • the use of the term resilient herein includes flexible layers.
  • Layer 2 is movable between two positions, a first position in contact with the microplates 4a, 4b, 4c, etc., and a second position, not shown in the Figures, away from the microplates 4a, 4b, 4c, etc.
  • This resilient layer 2 is preferably affixed onto a rigid supporting layer 20.
  • Layers 20 and 2 are substantially transparent to X-ray radiation.
  • An electrical bias source 30 is connected to the backing electrode 12 and the conductive resilient layer 2 to apply a DC bias voltage across the element 16.
  • the conductive layer 2 comprises a conductive membrane 62 mounted on a framework which allows the application of pressure from a back side of the membrane 62 by injection of a fluid medium, such as air.
  • Figure 10 shows such a possible structure which may be incorporated as an integral part of a cassette 22 shown in Figure 4 and discussed in detail below.
  • the structure comprises a supporting enclosure 60 which is preferably airtight, and which supports on its lower end the flexible conductive membrane 62.
  • the membrane 62 may be conductive rubber.
  • Contact means 72 are available to provide a path for connecting an external electrical bias source, i.e., source 30 which is not shown in Figure 10, to the membrane 62.
  • An orifice means 66 through a valve 68 allows one to supply the fluid medium to chamber 64 formed by the airtight enclosure 60 and the flexible membrane 62.
  • This structure results in a support for the membrane 62 that exhibits good and uniform flexibility and resiliency, assuring that each and everyone of the microplates 4a, 4b, 4c, etc., is contacted by the conductive layer 62.
  • the contacting layer 2 may comprise a layer of ionized gas contained in an enclosure covering the top surface of the element 16 to provide electrical contact between the microplates 4a, 4b, 4c, etc., and the bias source 30.
  • the ionization of the gas may be achieved using a two dimensional corona device which may be built within an enclosure which may also be built as an integral part of cassette 22.
  • the device described may include a cassette enclosure to shield the element 16 from exposure to
  • FIG. 4 shows such an arrangement in which a cassette-like enclosure 22 is used.
  • the cassette enclosure 22 is made of material which is opaque to ambient actinic radiation but transparent to X-rays. Since the ambient levels of gamma radiation are not usually high enough to present any exposure problems, it is not necessary that the material be opaque to gamma radiation. Similarly, in the absence of ambient IR radiation the enclosure need not be opaque thereto.
  • the enclosure 22 may include a hinge 24 hingedly connecting a top section 25 and a bottom section 27, allowing the cassette 22 to open and close at will.
  • a hinge 24 hingedly connecting a top section 25 and a bottom section 27, allowing the cassette 22 to open and close at will.
  • the cassette 22 further includes electrical connecting means 34 which permits one to connect power source 30 via wiring 26 and 28 to the conductive layer 2 and the conductive backing 12. Supporting layer 20 may also be conductive to facilitate the connection arrangement.
  • a switch 32 is optionally provided to permit applying and stopping the applying of a bias voltage to the cassette 22.
  • the element 16 is placed in the cassette 22 as shown in Figure 4, and the cassette 22 is placed in the path of information modulated X-ray radiation in a manner similar to the way a traditional cassette-photosensitive film combination is positioned.
  • This arrangement is schematically depicted in Figure 5 which shows a source of X-ray radiation 35, emitting a beam 36 of X-rays.
  • a target 38 i.e., a patient in the case of medical diagnostic imaging, is placed in the X-ray beam path. The emerging radiation through the patient is intensity modulated
  • SUBSTITUTE SHEET because of the different degree of X-ray absorption in the target 38.
  • the modulated X-ray radiation beam 36 is then intercepted by the cassette 22 containing element 16.
  • X-rays penetrate the enclosure 22 and are eventually absorbed by the photoconductive layer 8 altering its apparent resistivity in proportion to the radiation intensity along the X-ray paths therethrough. Viewed in a different way, the X-rays generate a flow of electron hole pairs, of which the electrons are accumulated in the interface between the photoconductive layer 8 and the dielectric layer 6.
  • Switch 32 is closed during the exposure step in synchronization therewith or prior thereto, applying a bias D.C. voltage to the element.
  • the X-ray flux is interrupted and X-rays no longer impinge on the element 16.
  • the application of the bias voltage is then, either simultaneously or soon thereafter removed from the element 16, such as, by opening the switch 32.
  • the layer 2 is moved away from contact with element 16 and the cassette 22 may then be opened.
  • the cassette 22 may be so arranged that moving layer 2 away from contact with element 16 results in the removal of the bias voltage in a manner similar to that obtained through the action of switch 32.
  • the element 16 can now be handled in the presence of actinic radiation without loss of the stored image information contained in it as a charge distribution in the microcapacitors in the dielectric layer 6.
  • the element 16 is intentionally exposed to a large dose of actinic radiation, as by a flash exposure, to eliminate the charges stored in the photoconductive layer 8, by momentarily rendering such photoconductive layer 8
  • SUBSTITUTE SHEET substantially conductive.
  • the layer 8 behaves as substantially conductive, because the abundant illumination produces an ample supply of electron hole pairs, in effect neutralizing any charges stored in the photoconductive layer 8.
  • Figure 6 which represents an equivalent electric circuit of the combination of the transparent electrode, the dielectric, the photoconductive and the backing conductive layers 4, 6, 8 and 10.
  • a variable resistance in dotted lines representing the effect of the electron hole pair generation in the photoconductive layer 8.
  • the microcapacitors When voltage supply 30 is connected across the element 16 as shown in Figure 6, in the absence of actinic or X-ray radiation, the microcapacitors are all charged uniformly, the charge being a function of the capacitance of each capacitor. In the present case where all capacitors have the same area plates, the capacitance will depend on the plate separation and dielectric constant of the material between the plates . In the described structure this will result in two different voltages appearing across the capacitors, one in the capacitors representing the photoconductor layer 8, the other in the dielectric layer 6. If, for instance, the applied voltage difference from the bias source 30 is 2000 volts, it could be distributed across the two capacitors as 1200 volts across the dielectric layer 6 and 800 volts across the photoconductor layer 8.
  • the optional charge barrier layer 10 acts to assure that there is no charge leakage to equalize the charges over long periods of time.
  • the conductive contacting resilient layer 2 After termination of the X-ray exposure, the conductive contacting resilient layer 2 is moved to a position away from the microplates 4a, 4b, etc., breaking contact therewith and removing the source 30 from the element 16.
  • Figure 8 shows the voltage distribution at this point . The charges having nowhere to go and remain fixed as they were at the end of the X- ray exposure time period. At this time the voltage source 30 may be completely removed from contact with the element 16 or the cassette 22.
  • each capacitor pair is still 2000 volts.
  • the charges in the dielectric portion of each capacitor are no longer uniform across the full surface of element 16, but vary, representing a latent radiographic image.
  • the flash exposure while preferably done using actinic radiation, can also be performed using additional, unmodulated X- ray radiation.

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  • Health & Medical Sciences (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Pathology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Molecular Biology (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Measurement Of Radiation (AREA)

Abstract

L'invention concerne un élément, un dispositif et un procédé associé de prise d'images radiographiques. Plus particulièrement, la présente invention utilise une structure spéciale de matrice de microcondensateurs pour conserver des charges électriques de grandeur variable représentant une image radiographique latente.
PCT/US1992/006891 1992-08-14 1992-08-14 Element, dispositif et procede associe de prise d'une image radiographique latente WO1994004963A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/US1992/006891 WO1994004963A1 (fr) 1992-08-14 1992-08-14 Element, dispositif et procede associe de prise d'une image radiographique latente

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1992/006891 WO1994004963A1 (fr) 1992-08-14 1992-08-14 Element, dispositif et procede associe de prise d'une image radiographique latente

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WO1994004963A1 true WO1994004963A1 (fr) 1994-03-03

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Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4268750A (en) * 1979-03-22 1981-05-19 The University Of Texas System Realtime radiation exposure monitor and control apparatus
DE3236137A1 (de) * 1982-09-29 1984-03-29 Siemens AG, 1000 Berlin und 8000 München Bildaufnahmeeinrichtung
EP0200300A1 (fr) * 1985-04-03 1986-11-05 Emil Kamienicki Lecture non destructive d'une image électrostatique latente formée sur matériau isolant
EP0252820A1 (fr) * 1986-07-08 1988-01-13 Thomson-Csf Détecteur d'image à photoconducteur à mémoire
US4778985A (en) * 1987-09-14 1988-10-18 Texas Medical Instruments, Inc. Imaging plate structure
EP0318807A1 (fr) * 1987-12-01 1989-06-07 Noranda Inc. Système de mesure de distribution de charge sur une surface photoréceptrice
DE3910462A1 (de) * 1988-04-01 1989-10-19 Hitachi Ltd Radiographische bildaufnahmevorrichtung
US5127038A (en) * 1991-06-28 1992-06-30 E. I. Du Pont De Nemours And Company Method for capturing and displaying a latent radiographic image
US5166524A (en) * 1991-06-28 1992-11-24 E. I. Du Pont De Nemours & Company Element, device and associated method for capturing a latent radiographic image
US5168160A (en) * 1991-06-28 1992-12-01 E. I. Du Pont De Nemours And Company Method and apparatus for acquiring an electrical signal representing a radiographic image

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4268750A (en) * 1979-03-22 1981-05-19 The University Of Texas System Realtime radiation exposure monitor and control apparatus
DE3236137A1 (de) * 1982-09-29 1984-03-29 Siemens AG, 1000 Berlin und 8000 München Bildaufnahmeeinrichtung
EP0200300A1 (fr) * 1985-04-03 1986-11-05 Emil Kamienicki Lecture non destructive d'une image électrostatique latente formée sur matériau isolant
EP0252820A1 (fr) * 1986-07-08 1988-01-13 Thomson-Csf Détecteur d'image à photoconducteur à mémoire
US4778985A (en) * 1987-09-14 1988-10-18 Texas Medical Instruments, Inc. Imaging plate structure
EP0318807A1 (fr) * 1987-12-01 1989-06-07 Noranda Inc. Système de mesure de distribution de charge sur une surface photoréceptrice
DE3910462A1 (de) * 1988-04-01 1989-10-19 Hitachi Ltd Radiographische bildaufnahmevorrichtung
US5127038A (en) * 1991-06-28 1992-06-30 E. I. Du Pont De Nemours And Company Method for capturing and displaying a latent radiographic image
US5166524A (en) * 1991-06-28 1992-11-24 E. I. Du Pont De Nemours & Company Element, device and associated method for capturing a latent radiographic image
US5168160A (en) * 1991-06-28 1992-12-01 E. I. Du Pont De Nemours And Company Method and apparatus for acquiring an electrical signal representing a radiographic image

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