US3859529A - Ionography imaging chamber - Google Patents

Ionography imaging chamber Download PDF

Info

Publication number
US3859529A
US3859529A US388212A US38821273A US3859529A US 3859529 A US3859529 A US 3859529A US 388212 A US388212 A US 388212A US 38821273 A US38821273 A US 38821273A US 3859529 A US3859529 A US 3859529A
Authority
US
United States
Prior art keywords
electrodes
gap
electrode
center
electrostatic
Prior art date
Legal status (The legal status 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 status listed.)
Expired - Lifetime
Application number
US388212A
Other languages
English (en)
Inventor
Andrew P Proudian
Teodoro Azzarelli
Murray Samuel Welkowsky
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ELSCINT IMAGING Inc
Elscint Ltd
Elscint Inc
Original Assignee
Xonics Inc
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 Xonics Inc filed Critical Xonics Inc
Priority to US388212A priority Critical patent/US3859529A/en
Priority to FR7346554A priority patent/FR2212563B1/fr
Priority to NL7317770A priority patent/NL7317770A/xx
Priority to JP48144801A priority patent/JPS49102286A/ja
Priority to CA189,085A priority patent/CA999042A/en
Priority to DE2365189A priority patent/DE2365189C2/de
Priority to IT54693/73A priority patent/IT1008637B/it
Priority to GB12274A priority patent/GB1419039A/en
Application granted granted Critical
Publication of US3859529A publication Critical patent/US3859529A/en
Assigned to ELSCINT IMAGING, INC., ELSCINT, LIMITED, ELSCINT, INC. reassignment ELSCINT IMAGING, INC. ASSIGNORS DO HEREBY QUITCLAIM, ASSIGN AND TRANSFER THEIR ENTIRE RIGHTS, TITLE AND INTEREST THEY MAY HAVE IN SAID INVENTIN TO ASSIGNEES Assignors: XONICS MEDICAL SYSTEMS, INC., XONICS, INC.
Assigned to XONICS INC., A CA. CORP. reassignment XONICS INC., A CA. CORP. RELEASED BY SECURED PARTY (SEE DOCUMENT FOR DETAILS). Assignors: FIRST CHICAGO INVESTMENT CORPORATION, AS AGENT
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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
    • G03G15/0545—Ionography, i.e. X-rays induced liquid or gas discharge

Definitions

  • the gas in the interelectrode gap plays two essential roles, namely, first as a maxima l ffi em b9 ofXjaysr tdicr.tqa h high sensitivity of the imaging technique, and second, as a means of stopping the primary electrons and creating secondaries in as short a distance from their point of creation as possible, in order to preserve the resolution of the imaging system.
  • the gas selected is a high Z gas, such as Krypton or Xenon, contained in the interelectrode gap at high pressure, typically twenty atmospheres or more.
  • the manimum gas pressure in the gap is limited essentially by the increasing difficulty of containing the gas within a chamber with X-ray transparent walls, as
  • FIG. 1 shows the increasing degradation of resolution with deviation of the xrays away from normal incidence.
  • X-rays incident along the central ray line AA create photoelectrons along the line AA which are multiplied in the gas (by the creation of secondaries) and are accelerated by the electric field E which is normal to the anode and cathode, and thus parallel to the line AA.
  • the electrons are collected at the receptor in a spot around the point A, whose width is small and determined by the range of the primary photoelectrons and by diffusion of the secondaries.
  • the effective spot diameter due to those effects will be less than 0.1 mm.
  • the charge distributioncollected around the point A will have a maximum at A, and fall off with distance away from the point, as depicted schematically in FIG. 2.
  • the fundamental source of geometric unsharpness in the electrostatic latent image formed on the receptor is the lack of coincidence between the line along which incident X-rays create photoelectrons, and the field lines which accelerate those electrons to the receptor. Since the electron creation paths are portions of straight lines or rays all pointing to a common center, viz. the X-ray source, then to avoid geometric unsharpness the electric field lines in the gas gap should also be portions of rays pointing to the same center. More precisely, this means that the equipotential surfaces of the electrostatic potential in the gas gap must be portions of concentric spheres centered at the X-ray source.
  • a flat parallel electrode image chamber has the advantage of ease of mounting of the dielectric receptor and more generally of practicality but suffers from geometric unsharpness.
  • a chamber with spherical electrodes overcomes the problem of geometric unsharpness but is difficult to implement in a practical system. It is desirable in some applications to make the imaging chamber electrodes cylindrical, because of added mechanical strength of such a configuration and for ease in applying the receptor to the electrode surface.
  • a cylindrically curved surface is topologically equivalent to a flat surface so that no stretching of a flat receptor is required, while the curvature allows a roll fed receptor to be pulled into contact with the curved surface more readily than with a flat surface.
  • the electrode surfaces at the gap in the cylindrical configuration usually will be portions of coaxial cylinders, with their common axis passing through the X-ray source.
  • the equipotential surfaces in the gas gap of an imaging chamber with coaxial cylindrical electrodes are also portions of coaxial cylinders, and therefore a geometric unsharpness problem similar to the one existing for flat parallel electrodes will also exist for the cylindrical electrode case. Accordingly, it is an object of the present invention to provide a means of overcoming the problem of geometric unsharpness due to oblique X-ray incidence while at the same time retaining a flat or cylindrical surface for mounting the latent image dielectric receptor.
  • the present invention uses an imaging chamber with physically flat or cylindrical electrical conductor electrodes which provide an electric field in the gap between the electrodes corresponding to that of concentric spherical electrodes. This is accomplished in one flat electrode embodiment by using low conductivity electrodes with radially varying resistance and maintaining an appropriate potential difference between the center and outer edge of those electrodes at each electrode surface. In the corresponding cylindrical electrode embodiment, the resistance is varied axially along the gap, with a potential between the center and opposite curved edges.
  • each electrode is varied from a central zone to the edge of the electrode, as by varying the thickness of the electrode and/or by varying the conductivity of the electrode material.
  • each electrode is formed as a plurality of concentric rings or parallel strips of different conductivities.
  • dielectric sheets are placed over metal electrodes, with the dielectric constant varied from the central zone to the edge.
  • FIG. 1 is a diagram illustrating operation of an imaging chamber with plane parallel electrodes
  • FIG. 2 is a diagram illustrating the charge distribution for the configuration of FIG. I;
  • FIG. 3 is a diagram similar to that of FIG. I illustrating concentric spherical electrodes
  • FIG. 4 is a diagrammatic illustration of an x-ray system with an imaging chamber incorporating the presently preferred embodiment of the invention
  • FIG. 5 is an enlarged view of the imaging chamber of FIG. 4;
  • FIG. 6 is a schematic of the equivalent circuit diagram of the imaging chamber of FIG. 5;
  • FIG. 7 is a perspective view looking down on a cylindrical cathode, illustrating an alternative embodiment of the invention.
  • FIG. 8 is a view similar to that of FIG. 5 showing an alternative embodiment
  • FIG. 9 is a view similar to that of FIG. 7 showing the alternative embodiment of FIG. 8 applied to a cylindrical electrode, and
  • FIG. 10 is a view similar to that of FIGS. 5 and 8 showing another alternative embodiment.
  • the system as illustrated in FIG. 4 includes an X-ray source 10 positioned for directing radiation to an 0bject 11 which may rest on a table 12.
  • An imaging chamber 13 carrying the sheet receptor 14 may be positioned below the table, with X-rays from the source 10 passing through the object 11 and into the gas filled gap 15 of the imaging chamber I3.
  • the design of the imaging chamber itself is not a feature of the present invention and various of the presently known imaging chambers may be utilized, including that illustrated in the aforementioned copending application.
  • the imaging chamber may comprise a housing 20 with a high resistance cathode 21 carried therein on an insulating sheet 22.
  • the housing cover 23 may serve as the electrical ground, with the center 25 of the high resistance anode 24 connected to the cover through a fine conducting (e.g., aluminum) wire or thin strip 26.
  • the anode is otherwise attached to the housing cover by a thin adhesive insulator 27, so that it is in electrical contact with the cover only through the strip or wire 26.
  • Conductive strips 28 and 29 are attached to the outer edges of the anode and the cathode, respectively, so as to make good electrical contact all around the edges of the electrodes.
  • the outer edge of the anode is electrically connected via the strip 28 to the center 30 of the cathode, through a variable resistance 31.
  • the outer edge of the cathode is connected via the strip 29 to a power supply 32.
  • the other terminal of the power source 32 is grounded or equivalently connected to the housing cover 23.
  • the electrical circuit formed by the above arrangement is shown schematically in FIG. 6.
  • the chamber may also include means (not shown) for introducing a gas under pressure into the gap.
  • the imaging chamber of FIG. 4 is utilized in the same manner as in the prior art devices described in the aforementioned copending application, and differs from the prior art devices in the electrode construction.
  • 0' (r) is the derivative of the potential 0 (r) with respect to r
  • I is a constant which is equal to the current flowing across any closed contour on the disk.
  • trodes which can support a potential difference be I from 2 10-1" ohm (l r /D
  • V 10,000 volts
  • I l milliampere
  • the 'total power dissipated, as computed from Eq. (4), is around 5 watts, which over a typical exposure time of 1/10 secondrepresents anegligible amount of heating.
  • a conductor electrode of uniform thickness and variable conductivity material may be used.
  • the conductivity must range cm at r, to 5X10 ohm cm
  • chalcogenide glasses e.g. A5 Se andcarbon impregnated plastics (e.g., thermosetting epoxy resin with'acetylene black), the latter being preferable. for ease of tailoring and forming, and weak temperature dependence of the conductivity.
  • These materials can be cast in molds or machined to thedesired thickness, and their conductivity can be varied from center to edge by variation of their composition (e.g., by varying the conductivity and/or loading of the carbon black filler in the material). If conductors ofnonuniformthickness are used, the insulating substrate to which they are attached would be given a reverse curvature to insure thatthe gap side of the electrode be flat, though small deviations from flatness are not serious. .
  • the variation of thickness and/or conductivity along the electrodes would be very nearly the same for the anode and the cathode, since the potentials along the -two electrodes have the same form, and differ only by the substitution of the length (D+d) for the length D between Eqs. (I) and ('2).
  • the potential change between the center and the periphery of let us say the anode is approximately 5000 volts, and the total resistance R between the anode center and periphery is approximately megohms.
  • the periphery of the anode would then be connected to the center of the cathode through an additional 5 megohm resistor (the variable resistance 31 of FIG. 6), and the applied potential V required between the cathode periphery and the anode center to produce a gap voltage of 10,000 volts at the gap center is 15,000 volts.
  • d is the gap width
  • D is the sum of D d
  • Z is the axial coordinate of the point p, that is, the coordinate measured along the cylinder axis from the center or middle of the cylindrical cap which forms the electrode, corresponding to r or Eq. 1 and 2.
  • S is the arc length of the cylindrical section constituting the electrodes
  • the thickness t and conductivity 0' of the electrodes are functions only i of the axial coordinate Z.
  • the required values of the electrode thicknesses, material conductivities, and the resultant current and power dissipation values are of the same magnitude as the case of flat electrodes.
  • the electrical connections with thecylindrical electrodes are basically the same as the case of flat electrodes: the central disk of perfect conductor of each electrode is replaced by a central arcuate strip (30' in FIG. 7) of perfect conduction a few centimeters in width, and the two arcuate edges (29' in FIG. 7) of the electrode are connected electrically to each other.
  • the arcuate edges of the anode are connected through the variable resistance 31 to the central arcuate strip on the cathode 21.
  • the arcuate edges of the cathode 21 are connected through the power supply 32 to the central strip of the anode 24.
  • D may be in the order of 2 meters,,so that the edge of a 12 inch wide electrode will be about a millimeter out of plane.
  • substantially planar is intended to cover such a structure, referring to both the flat and cylindrical embodiments.
  • the central zone with uniform high conductivity per unit area is preferred by not essential.
  • This zone is the disk in the flat electrode embodiment and the strip in the cylindrical electrode embodiment.
  • the problem due to the oblique path of the X-rays is minimal or nonexistent in the central zone.
  • This zone of high conductivity provides a good surface for electrical wire connection and also simplifies the electrode manufacturing process.
  • An approximation of the desired ideal concentric spherical potential variation can be achieved by means other than continuous variation of the conductivity and/or thickness of the electrodes.
  • a plurality of concentric annular rings, each of constant conductivity can be used to form an electrode, with the conductivity of each ring from the center to the edge being selected at a value such that the potential variation along the radial coordinate will approximate in a stair-step fashion, the desired ideal potential variation.
  • FIG. 8 A pair of electrodes 21, 24 incorporating this construction is shown in FIG. 8, with elements corresponding to those of FIG. 5 having the same reference numerals.
  • a plurality of concentric rings 40-45 are positioned about the conductive center 25, extending to the conductive edge 28.
  • a similar construction is provided for the electrode 21, with concentric rings 46-51.
  • Each of the rings 40-5l will be of low conductivity material, as used in the embodiment illustrated in FIG. 5.
  • Each ring will have a uniform conductivity, but the conductivity will vary from ring to ring. to approximate the desired relationship discussed above. In the embodiment illustrated in FIG. 8, only six rings are shown for purposes of clarity.
  • a typical imaging chamber might utilize I5 rings each inch wide.
  • FIG. 8 The approximation configuration of FIG. 8 is suitable for use with the cylindrical electrode configuration of FIG. 7, and a corresponding structure is shown in FIG. 9.
  • strips 46' 51' are provided between the center 30' and edges 29'.
  • Each of the strips 46 51' is of constant conductivity, with the conductivity of adjacent strips chosen to provide the stair-step approximation to the desired ideal potential variation.
  • the desired electric field is accomplished by utilizing metal electrodes, typically aluminum or beryllium, with dielectric sheets of uniform thickness at each electrode surface with each sheet comprising at least two different dielectric materials.
  • metal electrodes typically aluminum or beryllium
  • dielectric sheets of uniform thickness at each electrode surface with each sheet comprising at least two different dielectric materials.
  • FIG. 10 One such configuration is illustrated in FIG. 10 with elements corresponding to those of FIG. 5 identified by the same reference numerals.
  • the dielectric embodiment is also applicable to the cylindrical configuration of FIG. 7.
  • a dielectric sheet 60 is carried on the electrode 24a and another dielectric sheet 61 is carried on the electrode 21a.
  • the desired variation of electrostatic potential along the bounding surfaces S and S of the gas gap can be achieved by the use of the composite dielectric sheets 60, 61 between the plane electrodes 24a, 21a and the gas gap surfaces 8,, S
  • the dielectric sheet consists of improvement comprising:.
  • Thedielectric sheet 6-l similarly-consists of a pair of dielectric inserts 61a, 61b of -variab le, thickness and of uniform but unequal dielectric constants 62 ,2
  • Dielectric sheet 60 has thickness T with layers 60a,60b of thickness 2 t respectively.
  • Dielectric sheet 61 has thickness T with layers 61a, 61b of thickness t respectively.
  • the iridividual thicknesses t t a'nd't are functions of r,
  • each composite dielectric sheet consists in one embodiment of an inner layer (i.e.-,-adjjacent to the electrode) of relatively higher dielectric' constant e, of maximum thicknesst (0) at the center, tapering down to a minimum thicknesst (p max) at the edge of the field of view, and
  • the desired v achieved by means of a ,s'ingleflay'e'r'inthe dielectric sheet with a variable dielectricconstantLTheoperation of the embodiment with the dielectric sheets is similar to that of the embodiment withthelowlconductivity electrodes," except-that the effectiveisurface charge generated by the current flowing in theconductor, is re-; placed by static-polarizationcharge,
  • first and second substantially planar electrodes means for mounting said electrodes in the chamber in spaced relation defining a gap therebetween; means for connecting a power supply across said electrodes;
  • electrostatic potentials corresponding to the electrostatic potentials for concentric spherijcal metal electrodes so that, the. electric field lines I-i in said gap converge substantially to a'point.
  • each of said first and second electrodes comprising a plurality of sections of low conductivity material, with each section of different and substantially uniform conductivity, with said means for connecting including circuit means for connecting the power supply to the center of said first electrode and to opposite edges of said second electrode, and
  • said means for maintaining including aresismeans for maintaining along the gap surfacesof said:
  • each of said sheets comprises a first layer of a first dielectric conimaging chamber for an X-ray system, the
  • one of said layers having a maximum thickness at the center thereof and tapering to a minimum thickness at the edges thereof, and with the other of said layers having a complementary thickness.
  • first and second substantially planar electrodes of low conductivity material means for mounting said electrodes in the chamber in spaced relation defining a gap there between;
  • each of said electrodes varying from a central zone-to said edges such that the electrostatic potential at the gap surfaces of the electrodes is the same as the electrostatic potential for concentric spherical metal electrodes.
  • An imaging chamber as defined in claim 9 wherein the variation in conductivity per unit area is obtained byvarying the conductivity of the material of the electrode from the central zone to said edges.

Landscapes

  • Health & Medical Sciences (AREA)
  • Pathology (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Combination Of More Than One Step In Electrophotography (AREA)
  • Measurement Of Radiation (AREA)
  • Apparatus For Radiation Diagnosis (AREA)
  • X-Ray Techniques (AREA)
US388212A 1973-01-02 1973-08-14 Ionography imaging chamber Expired - Lifetime US3859529A (en)

Priority Applications (8)

Application Number Priority Date Filing Date Title
US388212A US3859529A (en) 1973-01-02 1973-08-14 Ionography imaging chamber
FR7346554A FR2212563B1 (enrdf_load_stackoverflow) 1973-01-02 1973-12-27
JP48144801A JPS49102286A (enrdf_load_stackoverflow) 1973-01-02 1973-12-28
CA189,085A CA999042A (en) 1973-01-02 1973-12-28 Ionography imaging chamber
NL7317770A NL7317770A (enrdf_load_stackoverflow) 1973-01-02 1973-12-28
DE2365189A DE2365189C2 (de) 1973-01-02 1973-12-29 Bildkammer für eine radiographische Einrichtung
IT54693/73A IT1008637B (it) 1973-01-02 1973-12-31 Camera di produzione di immagini per ionografia
GB12274A GB1419039A (en) 1973-01-02 1974-01-02 Imaging chamber fo x-ray systems

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US31999973A 1973-01-02 1973-01-02
US388212A US3859529A (en) 1973-01-02 1973-08-14 Ionography imaging chamber

Publications (1)

Publication Number Publication Date
US3859529A true US3859529A (en) 1975-01-07

Family

ID=26982247

Family Applications (1)

Application Number Title Priority Date Filing Date
US388212A Expired - Lifetime US3859529A (en) 1973-01-02 1973-08-14 Ionography imaging chamber

Country Status (8)

Country Link
US (1) US3859529A (enrdf_load_stackoverflow)
JP (1) JPS49102286A (enrdf_load_stackoverflow)
CA (1) CA999042A (enrdf_load_stackoverflow)
DE (1) DE2365189C2 (enrdf_load_stackoverflow)
FR (1) FR2212563B1 (enrdf_load_stackoverflow)
GB (1) GB1419039A (enrdf_load_stackoverflow)
IT (1) IT1008637B (enrdf_load_stackoverflow)
NL (1) NL7317770A (enrdf_load_stackoverflow)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3922547A (en) * 1974-12-06 1975-11-25 Xonics Inc Virtual electrode imaging chamber
US3927322A (en) * 1974-11-08 1975-12-16 Xonics Inc Electrode for electronradiography imaging chamber
US3961192A (en) * 1973-11-14 1976-06-01 Canon Kabushiki Kaisha Image formation method
US3963924A (en) * 1973-06-23 1976-06-15 National Research Development Corporation Method and apparatus for taking x-ray pictures
FR2300358A1 (fr) * 1975-02-07 1976-09-03 Philips Nv Dispositif de prise de radioscopies muni d'une chambre remplie d'un gaz
US4021668A (en) * 1975-03-26 1977-05-03 Agfa-Gevaert, A.G. Ionography imaging chamber
US4025789A (en) * 1973-11-14 1977-05-24 Canon Kabushiki Kaisha Image formation method
US4139768A (en) * 1976-07-28 1979-02-13 Agfa-Gevaert N.V. Imaging chamber with electrode structure
US4254033A (en) * 1977-12-07 1981-03-03 Agfa-Gevaert N.V. Method of recording X-ray images and imaging chamber suited therefor
WO1991005270A1 (en) * 1989-09-29 1991-04-18 Eastman Kodak Company Telecentric scanning for transparent storage phosphors

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2529037C3 (de) * 1975-06-28 1978-03-09 Philips Patentverwaltung Gmbh, 2000 Hamburg Elektroradiographische Vorrichtung
DE2737036C3 (de) * 1977-08-17 1981-04-30 Agfa-Gevaert Ag, 5090 Leverkusen Bildkammer zur Erzeugung elektronenradiografischer Abbildungen

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2606295A (en) * 1948-07-14 1952-08-05 Well Surveys Inc High-efficiency ionization chamber
US2692948A (en) * 1948-12-29 1954-10-26 Kurt S Lion Radiation responsive circuits
US3508477A (en) * 1967-12-06 1970-04-28 Columbia Broadcasting Syst Inc Apparatus for producing electrostatic images
US3710125A (en) * 1970-04-29 1973-01-09 Univ Northwestern Secondary emission enhancer for an x-ray image intensifier

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1063899B (de) * 1953-07-16 1959-08-20 Haloid Co Verfahren und Vorrichtung zur Erzeugung eines latenten elektrostatischen Bildes auf einer isolierenden Bildaufnahmeflaeche
FR1145166A (fr) * 1954-09-22 1957-10-23 Battelle Development Corp Procédé et appareil destinés à empêcher l'escamotage des bords d'une image xéroradiographique
BE792334A (fr) * 1972-01-12 1973-03-30 Xonics Inc Systeme radiographique a impression xerographique
DE2226130B2 (de) * 1972-05-29 1978-08-24 Siemens Ag, 1000 Berlin Und 8000 Muenchen Vorrichtung zur elektrofotografischen Aufnahme von Röntgenbildern

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2606295A (en) * 1948-07-14 1952-08-05 Well Surveys Inc High-efficiency ionization chamber
US2692948A (en) * 1948-12-29 1954-10-26 Kurt S Lion Radiation responsive circuits
US3508477A (en) * 1967-12-06 1970-04-28 Columbia Broadcasting Syst Inc Apparatus for producing electrostatic images
US3710125A (en) * 1970-04-29 1973-01-09 Univ Northwestern Secondary emission enhancer for an x-ray image intensifier

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3963924A (en) * 1973-06-23 1976-06-15 National Research Development Corporation Method and apparatus for taking x-ray pictures
US3961192A (en) * 1973-11-14 1976-06-01 Canon Kabushiki Kaisha Image formation method
US4025789A (en) * 1973-11-14 1977-05-24 Canon Kabushiki Kaisha Image formation method
US3927322A (en) * 1974-11-08 1975-12-16 Xonics Inc Electrode for electronradiography imaging chamber
US3922547A (en) * 1974-12-06 1975-11-25 Xonics Inc Virtual electrode imaging chamber
FR2300358A1 (fr) * 1975-02-07 1976-09-03 Philips Nv Dispositif de prise de radioscopies muni d'une chambre remplie d'un gaz
US4021668A (en) * 1975-03-26 1977-05-03 Agfa-Gevaert, A.G. Ionography imaging chamber
US4139768A (en) * 1976-07-28 1979-02-13 Agfa-Gevaert N.V. Imaging chamber with electrode structure
US4254033A (en) * 1977-12-07 1981-03-03 Agfa-Gevaert N.V. Method of recording X-ray images and imaging chamber suited therefor
WO1991005270A1 (en) * 1989-09-29 1991-04-18 Eastman Kodak Company Telecentric scanning for transparent storage phosphors

Also Published As

Publication number Publication date
NL7317770A (enrdf_load_stackoverflow) 1974-07-04
DE2365189C2 (de) 1982-08-26
CA999042A (en) 1976-10-26
FR2212563A1 (enrdf_load_stackoverflow) 1974-07-26
DE2365189A1 (de) 1974-07-11
JPS49102286A (enrdf_load_stackoverflow) 1974-09-27
FR2212563B1 (enrdf_load_stackoverflow) 1975-04-11
IT1008637B (it) 1976-11-30
GB1419039A (en) 1975-12-24

Similar Documents

Publication Publication Date Title
US3859529A (en) Ionography imaging chamber
US4047041A (en) X-ray detector array
GB1602757A (en) Radiation imaging and readout system and method utilizing a multilayered device having a photo conductive insulative layer
GB1409735A (en) Ionpermeable control member for an imaging system
US4686369A (en) Electric shielding for kinestatic charge detector
US3832546A (en) X-ray system with aligned source and slits
US2643343A (en) Balanced double ionization chamber X-ray monitor
CA1038441A (en) Process for forming developable electrostatic charge patterns and devices therefor
Ritz Design of free-air ionization chambers for the soft x-ray region (20–100 kv)
US2796527A (en) Device for automatically determining the optimum exposure time in radiography
US2651727A (en) X-ray tube
US3883740A (en) Ionography imaging chamber for variable distance X-ray source
US6198798B1 (en) Planispherical parallax-free X-ray imager based on the gas electron multiplier
US4218619A (en) Multi-copy ion-valve radiography
US3961192A (en) Image formation method
US3988584A (en) Arrangement for the electro-photographic taking of radioscopic pictures
US4095109A (en) Radiation detector for an automatic x-ray exposure timer
CA1124411A (en) Apparatus for ascertaining and/or regulating the amounts of radiation in the making of x-ray images
US4260887A (en) Electroradiographic recording device
US5526222A (en) Background recharging scorotron
Bouclier et al. Microstrip gas chambers on thin plastic supports
US4025789A (en) Image formation method
US3922547A (en) Virtual electrode imaging chamber
US4139768A (en) Imaging chamber with electrode structure
Garrett et al. A diagnostic X-ray exposure dose chamber

Legal Events

Date Code Title Description
AS Assignment

Owner name: ELSCINT, LIMITED, ILLINOIS

Free format text: ASSIGNORS DO HEREBY QUITCLAIM, ASSIGN AND TRANSFER THEIR ENTIRE RIGHTS, TITLE AND INTEREST THEY MAYHAVE IN SAID INVENTIN TO ASSIGNEES;ASSIGNORS:XONICS, INC.;XONICS MEDICAL SYSTEMS, INC.;REEL/FRAME:005029/0007

Effective date: 19880718

Owner name: ELSCINT, INC., MASSACHUSETTS

Free format text: ASSIGNORS DO HEREBY QUITCLAIM, ASSIGN AND TRANSFER THEIR ENTIRE RIGHTS, TITLE AND INTEREST THEY MAYHAVE IN SAID INVENTIN TO ASSIGNEES;ASSIGNORS:XONICS, INC.;XONICS MEDICAL SYSTEMS, INC.;REEL/FRAME:005029/0007

Effective date: 19880718

Owner name: ELSCINT IMAGING, INC., MASSACHUSETTS

Free format text: ASSIGNORS DO HEREBY QUITCLAIM, ASSIGN AND TRANSFER THEIR ENTIRE RIGHTS, TITLE AND INTEREST THEY MAYHAVE IN SAID INVENTIN TO ASSIGNEES;ASSIGNORS:XONICS, INC.;XONICS MEDICAL SYSTEMS, INC.;REEL/FRAME:005029/0007

Effective date: 19880718

AS Assignment

Owner name: XONICS INC., A CA. CORP., ILLINOIS

Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:FIRST CHICAGO INVESTMENT CORPORATION, AS AGENT;REEL/FRAME:005013/0715

Effective date: 19881207