US20070009081A1 - Computed tomography system for imaging of human and small animal - Google Patents
Computed tomography system for imaging of human and small animal Download PDFInfo
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- US20070009081A1 US20070009081A1 US11/441,281 US44128106A US2007009081A1 US 20070009081 A1 US20070009081 A1 US 20070009081A1 US 44128106 A US44128106 A US 44128106A US 2007009081 A1 US2007009081 A1 US 2007009081A1
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment
- A61B6/02—Devices for diagnosis sequentially in different planes; Stereoscopic radiation diagnosis
- A61B6/03—Computerised tomographs
- A61B6/032—Transmission computed tomography [CT]
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment
- A61B6/40—Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment with arrangements for generating radiation specially adapted for radiation diagnosis
- A61B6/4021—Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment with arrangements for generating radiation specially adapted for radiation diagnosis involving movement of the focal spot
- A61B6/4028—Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment with arrangements for generating radiation specially adapted for radiation diagnosis involving movement of the focal spot resulting in acquisition of views from substantially different positions, e.g. EBCT
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment
- A61B6/50—Clinical applications
- A61B6/508—Clinical applications for non-human patients
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y10/00—Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
- G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
- G01N23/04—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material
- G01N23/046—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material using tomography, e.g. computed tomography [CT]
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J35/00—X-ray tubes
- H01J35/02—Details
- H01J35/04—Electrodes ; Mutual position thereof; Constructional adaptations therefor
- H01J35/06—Cathodes
- H01J35/065—Field emission, photo emission or secondary emission cathodes
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment
- A61B6/54—Control of apparatus or devices for radiation diagnosis
- A61B6/541—Control of apparatus or devices for radiation diagnosis involving acquisition triggered by a physiological signal
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2223/00—Investigating materials by wave or particle radiation
- G01N2223/30—Accessories, mechanical or electrical features
- G01N2223/316—Accessories, mechanical or electrical features collimators
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2223/00—Investigating materials by wave or particle radiation
- G01N2223/40—Imaging
- G01N2223/419—Imaging computed tomograph
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2223/00—Investigating materials by wave or particle radiation
- G01N2223/60—Specific applications or type of materials
- G01N2223/612—Specific applications or type of materials biological material
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2201/00—Electrodes common to discharge tubes
- H01J2201/30—Cold cathodes
- H01J2201/304—Field emission cathodes
- H01J2201/30446—Field emission cathodes characterised by the emitter material
- H01J2201/30453—Carbon types
- H01J2201/30469—Carbon nanotubes (CNTs)
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2235/00—X-ray tubes
- H01J2235/06—Cathode assembly
- H01J2235/068—Multi-cathode assembly
Definitions
- the present subject matter relates generally to field emission cathodes for x-ray radiation sources. More particularly, the present subject matter relates to carbon nanotube field emission cathodes and methods of manufacture and operation of such cathodes in linear or area x-ray radiation sources with individually addressable multi-beam x-rays suitable for use in diagnostic, imaging, and inspection applications.
- Computed tomography (CT) technology is widely used for medical, industrial and security imaging purposes.
- CT Computed tomography
- a three-dimensional (3-D) object is illuminated to form a two-dimensional (2-D) image.
- 2-D two-dimensional
- This limitation can be overcome in computed tomography systems by obtaining projection images of the object in different directions.
- the object is stationary while a single x-ray source rotates around the object and produces the images at different rotation angles. The collection of the projected images can then be used to reconstruct a three-dimensional image of the object.
- An electron-beam computed tomography (EBCT) system can address this problem.
- EBCT electron-beam computed tomography
- electrons produced by the cathode are scanned across the surface of the anode located in the gantry, which consists of a metal ring or multiple rings. The scanning is accomplished by electrical and magnetic fields.
- the machine is expensive and takes significantly larger space than a regular computed tomography system.
- it is highly desirable to have a small stationary x-ray source computed tomography system that is potentially more transportable and cost effective.
- the x-ray source is stationary and the object is rotated to collect the projection images.
- the x-ray source typically produces a fan beam onto the object.
- a cone beam and two-dimensional detector are used to record the images. The object is rotated and an image is collected at every rotation angle.
- An example of the two-dimensional area detector consists of a scintillation crystal that converts the x-ray photon to visible light, and a charge-coupled-detector (CCD) camera positioned behind the crystal that captures the image.
- CCD charge-coupled-detector
- a monochromatic x-ray From the point of view of image quality, it is preferred to use a monochromatic x-ray. This is because computed tomography measures, essentially, the linear absorption coefficient, which depends on the energy of the incident x-ray photon. However, in most computed tomography systems, with the exception of a synchrotron radiation source, continuous-energy x-ray rather than monochromatic x-ray is used so as to increase the x-ray intensity, and thus reduce the data collection time. In many computed tomography systems, the x-ray source is often placed far away from the object to minimize the non-even spatial distribution of the x-ray radiation from the single x-ray source and the divergence of the x-ray beam. As a result, only a small fraction of the produced x-ray photons are used for imaging.
- An exemplary embodiment of a computed tomography device comprises an x-ray source, and an x-ray detecting unit.
- the x-ray source comprises a cathode with a plurality of individually programmable electron emitting units that each emit an electron upon an application of an electric field, an anode target that emits an x-ray upon impact by the emitted electron, and a collimator.
- An exemplary method to operate a computed tomography device including an x-ray source, the x-ray source comprising a cathode with a plurality of individually programmable electron emitting units that each emit an electron upon an application of an electric field, an anode target that emits an x-ray upon impact by the emitted electron, a collimator, and an x-ray detecting unit, comprises applying the electric field to at least a first of the plurality of individually programmable electron emitting units to cause the emission of an electron, focusing the emitted electron at one of a plurality of focal points on the anode target, impacting the anode target with the emitted electron to form an emitted x-ray radiation, collimating the emitted x-ray radiation, passing the collimated x-ray radiation through an object, detecting the x-ray radiation with the x-ray detecting unit, and recording the detected x-ray radiation.
- FIG. 1 shows a schematic representation of an exemplary x-ray radiation source.
- FIG. 2 shows current density as a function of voltage for carbon nanotube cathodes having a gap distance between 62 ⁇ m and 280 ⁇ m.
- FIG. 3 shows a schematic representation of an exemplary embodiment of a collimated monochromatic x-ray radiation source.
- FIG. 4 shows a schematic representation of an exemplary embodiment of a linear x-ray radiation source with a fan-beam.
- FIG. 5 shows a schematic representation of an exemplary embodiment of an arch x-ray radiation source with a cone-beam.
- FIG. 6 shows a schematic representation of an exemplary embodiment of an area x-ray radiation source with a pencil-beam.
- FIG. 7 shows a schematic representation of an exemplary embodiment of a CT system with a linear x-ray radiation source rotated about a stationary stage.
- FIG. 8 shows a schematic representation of an exemplary embodiment of a CT system with a circular x-ray radiation source positioned about a stationary stage.
- FIG. 9 shows a schematic representation of an exemplary embodiment of an x-ray radiation source that can be operated in a computed tomography mode and a single projection mode
- FIG. 10 shows a schematic representation of an exemplary embodiment of a CT system with a ring target, the electron beam strikes the target by reorienting the electron beam source and/or by steering the electron beam.
- U.S. Pat. No. 6,553,096 discloses an x-ray generating device incorporating a nanostructure-containing material.
- U.S. Pat. No. 6,876,724 discloses a structure to generate x-rays having a plurality of stationary and individually electrically addressable field emissive electron sources with a substrate composed of a field emissive material, such as carbon nanotubes, that can be electrically switched at a predetermined frequency to field emits electrons in a programmable sequence.
- FIG. 1 shows a schematic representation of an exemplary x-ray radiation source 100 .
- the x-ray source 100 includes a cathode 102 with a plurality of individually programmable electron emitting units 104 that each emit an electron 106 upon an application of an electric field (E), an anode target 108 that emits an x-ray 110 upon impact by the emitted electron 106 , and a collimator 112 .
- E electric field
- the electron emitting unit 104 includes an electron field emitting material.
- the electron field emitting material can include a nanostructured material.
- the electron field emitting material includes a plurality of nanotubes or a plurality of nanowires.
- the nanotubes can include inorganic materials.
- the nanowires can include at least one field emitting material selected from the group consisting of carbon, boron, nitrogen, sulfur, and tungsten.
- the nanowires can included at least one field emitting material selected from the group consisting of silicon, germanium, carbon, oxygen, indium, cadmium, gallium, oxide, nitrides, silicides and boride.
- the nanowires can be fabricated by a variety of techniques including chemical vapor deposition, solution synthesis, and laser ablation.
- chemical vapor deposition vapor deposition
- solution synthesis vapor synthesis
- laser ablation a variety of techniques including laser ablation.
- J. Hu, et al. “Chemistry and Physics in One Dimension: Synthesis and Properties of Nanowires and Nanotubes”, Accounts of Chemical Research, Vol. 32, pages 435-445, 1999, the entire content of which is incorporated herein by reference, describes some of these fabrication methods.
- the cathode 102 can include one or more individually programmable and/or addressable electron emitting units 104 arranged on a support structure 114 .
- the electron emitting unit 104 is one or more electron emitting pixels.
- the electron emitting pixels can be any suitable electron source.
- the electron emitting pixels are electron field emission sources, such as electron field emitting materials including a plurality of single-wall carbon nanotubes (SWNT), a plurality of multi-wall carbon nanotubes (MWNT), a plurality of double-wall carbon nanotubes (DWNT), or a mixture thereof.
- suitable electron field emission sources include the carbon nanotube based electron field emission sources disclosed in U.S. Pat. No. 6,630,772 to Bower et al.
- the electron emitting pixels can be controlled individually, e.g., each electron emitting pixel can be individual electrically addressed and a controller can supply an electronic field to the electron emitting pixel in any desired manner, such as individually, as a group or plurality, in a specified sequence or pattern, or randomly.
- a suitable method of individual control is disclosed in U.S. Pat. No. 6,876,724, the entire contents of which is hereby incorporated by reference.
- 6,876,724 discloses individual control by electrically switching the field emissive electron sources at a predetermined frequency to field emit electrons in a programmable sequence toward an incidence point on a target and to thereby generate x-rays corresponding in frequency and in position to that of the field emissive electron source.
- Other suitable methods of control are disclosed in U.S. Pat. No. 6,553,096 and in U.S. Pat. No. 6,850,595, the entire content of each is hereby incorporated by reference.
- Other examples of individual control are disclosed in Brodie and C. A. Spindt, “Vacuum Microelectronics,” Advances in Electronics and Electron Physics, vol. 83, p. 1-106 (1992).
- the x-ray source can further comprise a gate electrode.
- the exemplary embodiment of an x-ray source 100 shown in FIG. 1 includes a gate electrode 116 located between the cathode 102 and the anode target 108 .
- the gate electrode 116 can extract the emitted electron 106 from one or more of the plurality of individually programmable electron emitting units 104 when the electrical field is applied between the gate electrode 116 and the one or more individually programmable electron emitting units 104 .
- the electrical field can be applied such that the gate electrode 116 is at a positive potential with respect to the one or more of the plurality of individually programmable electron emitting units 104 .
- the field strength of the electrical field can be from 0.1 Volt/ ⁇ m (V/ ⁇ m) to 100 V/ ⁇ m, preferably from 0.5 V/ ⁇ m to 20 V/ ⁇ m.
- At least one of the plurality of individually programmable electron emitting units has an emission threshold of less than 3 V/ ⁇ m for greater than 0.01 mA/cm 2 current density, preferably greater than 0.1 mA/cm 2 current density, and emits 0.1-100 mA total current.
- the emission current is approximately less than or equal to 100 ⁇ A per nanotube at an electrical field of less than 100 V/ ⁇ m.
- FIG. 2 shows current density (A/cm 2 ) as a function of voltage for carbon nanotube cathodes having a gap distance between 62 ⁇ m and 280 ⁇ m. As the gap distance decreases, the current density also decreases.
- Table 1 summarizes values of current density for a given electrical field. The values in FIG. 2 and Table 1 are merely examples, and values may vary significantly, depending on the sample preparation and how the measurement is performed. TABLE 1 Emission Characteristics for the Cathode Current Density (mA/cm 2 ) Electrical Field (V/ ⁇ m) 1 2 10 2.5 100 4 700 5.3
- the emission current-voltage (1-V) characteristics of the single-wall carbon nanotube film shown in FIG. 2 and Table 1 were measured using a hemispherical current collector with a 1 millimeter (mm) diameter (anode) at 5 ⁇ 10 ⁇ 8 Torr base pressure and different anode-cathode gap distances.
- the carbon nanotube film exhibits the classic Fowler-Nordheim behavior with a threshold field of 2 V/ ⁇ m for 1 mA/cm 2 current density.
- the effective emission area was calculated using a previously described method as disclosed in W. Zhu, C. Bower, O. Zhou, G. P. Kochanski, and S. Jin, Appl. Phys. Left., vol. 75, p. 873, (1999), the entire contents of which are herein incorporated by reference.
- the corresponding electric fields for various electron current densities are listed in Table 1. Emission current density over 1 A/cm 2 was readily achieved.
- the emission material was purified single-wall carbon nanotube (SWNT) bundles that were produced by the laser ablation method, as disclosed in O. Zhou, H. Shimoda, B. Gao, S. J. Oh, L. Fleming, and G. Z. Yue, “Materials Science of Carbon Nanotubes: Fabrication, Integration, and Properties of Macroscopic Structures of Carbon Nanotubes”, Acc. Chem. Res, vol. 35 p. 1045-1053 (2002), the entire contents of which are herein incorporated by reference.
- the emission material contains approximately 95-wt. % SWNT bundles with an average SWNT diameter of 1.4 nanometers (nm) and a bundle diameter of approximately 50 nm.
- Uniform SWNT film were coated on a flat metal disc by electrophoretic deposition, substantially similar to that disclosed in U.S. patent application Ser. No. 09/996,695, the entire contents of which are herein incorporated by reference.
- an iron inter-layer was first deposited on the substrate surface by either thermal evaporation or electrochemical plating before nanotube deposition, substantially similar to that disclosed in U.S. Pat. No. 6,277,318, the entire contents of which are herein incorporated by reference.
- the thickness and packing density of the nanotube film were controlled by the current, deposition time and the concentration of the nanotube suspension.
- the films were vacuum annealed at 800° C. before use.
- An exemplary embodiment of a computed tomography device also includes an x-ray detecting unit 118 .
- Any x-ray detecting unit can be used.
- the x-ray detecting unit can include an x-ray scintillation material and a digital imaging acquisition device.
- a suitable digital imaging acquisition device includes a charge-coupled-device (CCD) or a solid state based or gaseous based imaging device.
- the computed tomography device can have a control system between the x-ray detecting unit and a controller, a storage device, or a combined controller/storage device 120 for data collection, storage and reconstruction.
- the digital imaging acquisition device digitally records the x-ray intensity of the x-ray radiation.
- each beam of x-ray radiation can pass through, e.g, transmission x-ray source, or can reflect from, e.g., reflection x-ray source, a portion of the object.
- the x-ray radiation is then detected by the corresponding x-ray detecting unit.
- FIG. 3 is a schematic representation of an exemplary embodiment of a collimated monochromatic x-ray radiation source 300 .
- the collimated monochromatic x-ray radiation source 300 includes an x-ray source 302 and an x-ray detecting unit 304 , both of which can be substantially similar to that described herein with respect to FIG. 1 .
- the collimated monochromatic x-ray radiation source 300 includes a monochromator 306 placed in a path of the emitted x-ray 308 after the collimator 310 .
- An example of a suitable monochromator includes a crystal that selects an x-ray photon with a certain energy. Examples of suitable crystals include a single crystal of graphite or silicon (Si).
- the energy of the outgoing x-ray beam is selected by the diffraction conditions.
- a particular diffraction angle is chosen to produce a diffracted beam with a predetermined energy.
- monochromatic x-ray beams with different energies can be selected.
- An exemplary embodiment of a computed tomography system can have an x-ray source having any suitable geometry for directing a desired form of an x-ray beam toward an object of interest, such as medical applications for a patient or an animal and industrial and inspection applications such as for a structure or a container.
- an x-ray source can be a linear, an arched, and/or an area x-ray source.
- FIG. 4 is a schematic representation of an exemplary embodiment of a computed tomography device.
- the computed tomography device 400 comprises a linear scanning x-ray source 402 , an object support stage 404 , and a detector 406 .
- the linear scanning x-ray source 402 comprises a cathode 408 and an anode target 410 and a collimator 412 .
- the cathode 408 includes an array of individually programmable electron emitting units 414 arranged on a support structure 416 .
- a suitable arrangement of the plurality of individually programmable electron emitting units 414 includes arrangement linearly on an axis in a plane. Each individually programmable electron emitting unit is focused at one of a plurality of focal spots on the anode target 410 .
- the linear scanning x-ray source can have either transmission geometry or reflection geometry.
- the anode is a metal film which can be either free-standing or deposited on a low-atomic number material, such as carbon.
- the anode is at a higher electrical potential with the cathode. In one particular example, the anode is electrically grounded. A negative potential is applied to the cathode.
- a gate electrode can be included in the x-ray source and can be at a positive potential with respect to the cathode to extract the electrons from the cathode.
- all of the programmable electron emitting units are at the same potential.
- Each programmable electron emitting unit has a corresponding gate electrode. Electrons are extracted from a particular programmable electron emitting unit when the electrical field established between said unit and the corresponding gate exceeds a critical value (for example 3V/ ⁇ m or less).
- the distance between the anode and the cathode is such that the electrical field due to the anode voltage is sufficient to extract the filed-emitting electrons from the cathode.
- a reverse bias voltage is applied on the gate electrode to suppress electron emission from certain emitting units. This reverse bias voltage is scanned across the gate electrode to suppress a first group of electron filed emitting units and/or to activate a second group of programmable electron emitting units.
- Each individually programmable electron emitting unit comprises a layer of electron field emitting material.
- Individual or groups of electron field emitting material in the layer can form an array or matrix or pattern of electron emitting pixels.
- the electron field emitting material is a layer of carbon nanotubes, but any suitable field emitting material can be used including nanostructured material and nanotubes and nanowires as substantially described herein with respect to FIGS. 1 and 3 .
- a layer of carbon nanotubes e.g., single-walled nanotubes, multi-walled nanotubes, double-walled nanotubes, or mixtures thereof.
- the field emitters can also be lithographically formed Spindt-type tips.
- electrons 420 are emitted from the each of the electron emitting units 414 .
- the field emission of electrons from the array of electron emitting units can be from a single pixel, a group of pixels, either randomly arranged or in a pattern, or all the pixels, as determined by the controlled application of the applied potential.
- a bias potential applied between the gate and the cathode extracts electrons.
- a large, e.g. on the order of 10 to 200 KV/cm or greater, electrical voltage is further established between the gate and the anode to accelerate the emitted electrons to the desired energy level.
- the emitted electrons from the electron emitting units are accelerated and impinge on the anode target 410 , for example, each at a corresponding x-ray emitting pixel.
- An example of an x-ray emitting pixel includes a thin layer of metal target material, such as copper (Cu) and tungsten (W), a heat dissipating target supporting material.
- X-ray radiation 422 is emitted from the anode when it is bombarded by the electrons, e.g., the anode is a target for the accelerated electrons.
- the emitted x-ray radiation passes through the collimator 412 and optionally a monochromator (not shown in FIG. 4 ).
- the collimator 412 enables each x-ray emitting pixel to generate a particular geometry of x-ray radiation 422 , such as an uniform fan beam geometry.
- a particular geometry of x-ray radiation 422 such as an uniform fan beam geometry.
- any suitable geometry of x-ray radiation 420 can be formed, including a pencil beam geometry or a cone beam geometry.
- the computed tomography device 400 has an x-ray detector 406 .
- An exemplary x-ray detector 406 comprises a plurality of x-ray detecting units 424 .
- Each x-ray detecting unit 424 includes x-ray scintillation materials and a digital imaging acquisition device, such as a charge-coupled-device (CCD) or a solid state based or gaseous based imaging device.
- the digital imaging acquisition device digitally records the x-ray intensity of the x-ray radiation 422 .
- each beam of x-ray radiation 422 can pass through, e.g, transmission x-ray source, or can reflect from, e.g., reflection x-ray source, a portion of the object 426 .
- the x-ray radiation 422 is then detected by the corresponding x-ray detecting unit 424 .
- the x-ray detector includes a two-dimensional matrix of x-ray detecting units.
- the detection scheme depends on the type of x-ray beams generated by the linear x-ray source.
- an x-ray beam with fan-beam geometry is produced from each focal spot on the anode.
- the fan beam illuminates a slice of the object 426 .
- the illuminated area is defined by the geometry of the collimator used.
- the intensity of the x-ray beam from a particular focal spot passing through the object is measured by a pre-selected set of x-ray detection units on the x-ray detector.
- Each focal spot is associated with a set of x-ray detection units on the x-ray detector.
- the electron emitting units are activated one by one to produce an x-ray beam from the anode that is moving through the focal spots sequentially.
- the corresponding x-ray detection unit on the x-ray detector is also switched on to record the image from a particular x-ray beam, e.g., switched on sequentially or one-by-one.
- all the electron emitting units are turned on at the same time.
- the x-ray detecting units are also switched on at the same time to collect and/or record the images of the object.
- the collimators are designed such that x-ray radiation with cone-beam geometry is generated from each focal spot.
- the electron emitting units are activated sequentially or one-by-one.
- a particular unit is turned on, a cone-beam x-ray is generated from the corresponding focal spot on the anode.
- the x-ray beam illuminates the entire object 426 .
- the image of the object formed by this particular x-ray beam is collected and/or recorded by the entire x-ray detector.
- the image is then stored in, for example, a computer.
- the next electron emitting unit in the sequence is then switched on to generate another image of the entire object, from a different projection angle.
- the process repeats for all, or a subset of all, the emitting units in the x-ray source.
- FIG. 5 shows a schematic representation of an exemplary embodiment of a computed tomography device 500 with a linear scanning x-ray source 502 arranged as an arch x-ray source.
- the x-ray source 502 generates a particular geometry of x-ray radiation 504 , such as a cone beam geometry.
- any suitable geometry of x-ray radiation 504 can be formed by selection of a suitable collimator, including a pencil beam geometry or a fan beam geometry.
- the computed tomography device 500 includes a linear scanning x-ray source 502 , an object rotation stage 506 , and a detector 508 .
- the linear scanning x-ray source 502 includes a series of cathodes 510 and corresponding anode targets 512 lining the arched-shaped support structure 514 .
- the x-ray source 502 and x-ray detecting unit 508 can be substantially similar to that described herein with respect to the x-ray source and x-ray detecting unit of FIGS. 1 and 3 .
- the arched-shaped support structure 514 is constructed such that each focal spot on the anode is at an equal distance from the center of an object rotation stage, e.g., from a center of rotation of an object stage or from a central rotation axis of the object stage. Further, in a preferred case, the two-dimensional detector has a curved surface so that each detecting unit is also equidistant to the object.
- the computed tomography device 500 in FIG. 5 has an x-ray detector 508 .
- the x-ray detecting unit can be of any suitable type and/or any suitable arrangement, based on the geometric form of the x-ray radiation generated by the x-ray source. Similar to the geometry described above, the preferred geometry of the detector surface is a curved one so that each detecting unit is equidistance to the object.
- An exemplary x-ray detector 508 comprises a plurality of x-ray detecting units 516 .
- Each x-ray detecting unit 516 includes x-ray scintillation materials and a digital imaging acquisition device, such as a charge-coupled-device (CCD) or a solid state based or gaseous based imaging device.
- the digital imaging acquisition device digitally records the x-ray intensity of the x-ray radiation 504 .
- each beam of x-ray radiation 504 can pass through, e.g, transmission x-ray source, or can reflect from, e.g., reflection x-ray source, a portion of the object 518 .
- the x-ray radiation 504 is then detected by the corresponding x-ray detecting unit 516 .
- FIG. 6 shows a schematic representation of an exemplary embodiment of a computed tomography device 600 .
- the computed tomography device 600 includes an area scanning x-ray source 602 , an object rotation stage 604 , and a detector 606 .
- the linear scanning x-ray source 602 includes a series of cathodes 608 and corresponding anode targets 610 lining the planar-shaped support structure 612 .
- the x-ray source 602 and x-ray detecting unit 606 can be substantially similar to that described herein with respect to FIGS. 1 and 3 .
- the computed tomography device 600 has an area linear scanning x-ray source 602 arranged as a planar x-ray source generating a particular geometry of x-ray radiation 614 , such as a pencil beam geometry.
- a particular geometry of x-ray radiation 614 can be formed by selection of a suitable collimator, including a cone beam geometry or a fan beam geometry.
- the individually programmable electron emitting units of the cathode are arranged over an area of the planar-shaped support structure and each individually programmable electron emitting unit is focused at one of a plurality of focal spots on the anode target 610 .
- the computed tomography device 600 in FIG. 6 has an x-ray detector 606 .
- the x-ray detecting unit can be of any suitable type and/or any suitable arrangement, based on the geometric form of the x-ray radiation generated by the x-ray source.
- An exemplary x-ray detector 606 comprises a plurality of x-ray detecting units 616 .
- Each x-ray detecting unit 616 includes x-ray scintillation materials and a digital imaging acquisition device, such as a charge-coupled-device (CCD) or a solid state based or gaseous based imaging device.
- CCD charge-coupled-device
- the x-ray detecting units can be suitably arranged, such as in a matrix or an array.
- the digital imaging acquisition device digitally records the x-ray intensity of the x-ray radiation 614 .
- each beam of x-ray radiation 614 can pass through, e.g, transmission x-ray source, or can reflect from, e.g., reflection x-ray source, a portion of the object 618 .
- the x-ray radiation 614 is then detected by the corresponding x-ray detecting unit 616 .
- a method to operate a computed tomography device includes applying an electric field to at least a first of a plurality of individually programmable electron emitting units. Applying the electric field causes the emission of an electron.
- the emitted electron is focused at one of a plurality of focal points on an anode target.
- the emitted electron impacts the anode target to form an emitted x-ray radiation, which is collimated to a geometry, such as a cone beam geometry, a pencil beam geometry, or a fan beam geometry, and passed through an object.
- the x-ray radiation is then detected by an x-ray detecting unit and recorded.
- the method can be repeated to produce multiple detected x-ray radiation images without rotating the object positioned on the object stage.
- each of the plurality of individually programmable electron emitting units of the x-ray source can be operated in a particular sequence or operated as a group in a particular pattern to produce an emitted x-ray that illuminates the object in the computed tomography device from a different angle, plane, or other orientation. Accordingly, by repeating the steps of applying, focusing, impacting, collimating, passing, detecting, and recording with respect to a particular sequence or grouping of individually programmable electron emitting units, multiple detected x-ray radiation images can be produced.
- the electric field is applied to at least a second individually programmable electron emitting unit. Further, the emitted electrons are focused on a second of the plurality of focal points on the anode target when the step of focusing is repeated.
- the step of collimating can produce an x-ray radiation beam of a particular geometry.
- the collimator can be selected such that the emitted x-ray radiation is collimated to produce a fan beam geometry of x-ray radiation, a pencil beam geometry of x-ray radiation, or a cone beam geometry of x-ray radiation.
- Each of these x-ray radiation beam geometries has an associated imaging technique, such as a magnified stereo projection image, a parallel projection image, or projection images from different viewing angles for reconstruction of three-dimensional images.
- an electric field is applied between the cathode and a gate electrode.
- the gate electrode is at a positive potential with respect to the individually programmable electron emitting units of the cathode.
- An exemplary field strength of the electric field is from 0.1 V/ ⁇ m to 100 V/ ⁇ m, preferably from 0.5 V/ ⁇ m to 20 V/ ⁇ m. The application of the electric field accelerates the emitted electrons to a given energy.
- the electric field is established between the gate electrode and at least two of the plurality of individual programmable electron emitting unit sequentially.
- the electric field is established one individually programmable electron emitting unit or a group of individually programmable electron emitting units at a given time, from a first location on the cathode to a second location on the cathode.
- the applied electrical field has a predetermined frequency and pulse width.
- the frequency determines how many times per second the electrical field is switched on. There is a no limitation on the frequency. For example, the frequency can be in the range of 0.01-10 6 Hz.
- the pulse width determines the dwell time when the field is switched on. Again there is no limitation on the dwell time. For example, it can be in the range of one micro-second to one minute.
- an electrical field is established between the gate electrode and at least two of the plurality of individually programmable electron emitting units.
- the electrical field is established sequentially, one individually programmable electron emitting unit at a given time or a group of individually programmable electron emitting units, from a first location on the cathode to a second location on cathode at a given sweep rate.
- the sweep rate can be in the range of 0.01 Hz to 10 6 Hz.
- the frequency and pulse width of the electrical field applied to the gate electrode is synchronized with the data collection time of the x-ray detector.
- the x-ray radiation is generated only when the x-ray detector is collecting data. Synchronization of x-ray generation and data collection can significantly reduce the amount of unnecessary radiation dosage the object receives during imaging.
- the frequency and the pulse width of the electrical field applied to the gate electrode and thus the frequency and the pulse width of the x-ray produced are synchronized with either a physiological signal, an internal signal from the object, or an external signal source.
- the frequency and the pulse width of the x-ray generated can be gated by the cardiac or respiratory signals to obtain clear images of moving object.
- an x-ray radiation having a cone beam geometry originates from different focal points impinging on the object from different angles.
- the corresponding two-dimensional projection images are different. This is because the x-ray beams originate from different points in space and have different projection angles.
- internal structure of the object can be obtained.
- multiple two-dimensional images are acquired in short time without rotating the object. This greatly increases the image acquisition speed.
- a pulsed electrical field between the gate and the cathode is swept through the emitting pixels at a given speed.
- the field is set at a value such that each pixel will emit a certain current for a given duration and in a given sequence, which is determined by the pulse width of the sweeping field.
- the voltage between the anode and the gate remains at a constant value.
- the pulse-width, frequency and sweep rate of the electrical field on the gate are synchronized with the electronics that control the detector such that the images collected are in registry with the positions of the focal points.
- a controller can synchronize the electric field and the detector.
- the x-ray radiation from the x-ray source illuminates an object which is supported on the object support stage.
- the object support stage of an exemplary computed tomography device can be either stationary or can be rotated through a pre-determined set of angles.
- One example of a computed tomography system using a single beam x-ray source and a rotating sample stage is contained in M. D. Bentley, M. C. Ortiz, E. L. Ritman, and J. C. Romero, “The Use of Microcomputed Tomography to Study Microvasculature in Small Rodents,” AJP Regulatory Integrative Comp Physiol, 282, R1267-R1279 (2002), the entire content of which is incorporated herein by reference.
- the object is positioned on an object stage and is rotated through a set of angles. After each rotation of the object, the steps of applying, focusing, impacting, collimating, passing, detecting, and recording are repeated to obtain a series of detected x-ray radiation images.
- the x-ray radiation images can then be reconstructed to form a three-dimensional volume of the object.
- the detected x-ray radiation images can be reconstructed using an image reconstruction algorithm to form the three-dimensional volume of the object.
- the cone-beam reconstruction algorithm developed by Feldkamp, et al. in L. A. Feldkamp, L. C. Davis, and J. W. Kress, “Practical cone-beam algorithm”, J. Opt. Soc. Am., vol.1,612-619 (1984), the entire content of which is herein incorporated by reference can be modified for such purpose.
- the exemplary computed tomography system operates in two different modes.
- a first mode e.g., the computed tomography mode
- the source and detector are rotated about the object, generating a set of three-dimensional cone beam projections for reconstruction into an image.
- a second mode a series of two-dimensional images are acquired from a single projection, resembling a fluoroscopy unit.
- the two-dimensional projection direction is known, it may be mapped into the three-dimensional projection from the first mode, allowing localization of objections.
- Multiple array source elements may be utilized to spatially localize objects of interest.
- the object support stage is set to a first angle and all cathodes of the x-ray source are turned on simultaneously to generate a linear set of x-ray radiation beams.
- Each x-ray detecting unit records an image, such as a projection image of a slice of the object. All images are combined digitally, to form a two-dimensional image of the object for the given angle of the x-ray source. Thus, all slice projections are combined.
- the object support stage is then set to a second angle and the process of acquiring an image repeated. By rotating the stage, a plurality of two-dimensional images (such as 360 images, one each for 1 degree rotation of the sample) of a sample are obtained.
- the images can be combined in real time, or can be electronically stored for later combination.
- the object is rotated through a set of angles, such as 30, 60, or 90 degrees.
- a new set of images are taken after each rotation. Only a few rotations are needed to obtain the sets of images needed to reconstruct the three-dimensional volume of the objects.
- the radial resolution may also be increased by rotating the object by smaller angles, such as 5, 10, or 15 degrees.
- the x-ray source and detector are rotated about the object stage, which is stationary and on which a object is mounted.
- Image acquisition may be performed in a continuous manner with the x-ray source continuously rotating about the object.
- Finer radial resolution may be achieved by performing multiple acquisitions at each rotational angle with or without selectively pulsing each x-ray source.
- the computed tomography device 700 comprises a circular x-ray source 702 , an object stage 704 , and a circular detector 706 .
- the circular x-ray source includes an array of x-ray producing elements facing the center of a source circle.
- the detectors are in a similar arrangement, e.g., in a detector circle, positioned adjacent the source circle.
- near instantaneous single slice imaging can occur limited only by the switching rate of the x-ray source, which can be 10 6 Hz or higher, and the time necessary to acquire a projection, which depends on the sensitivity of the detector and the x-ray flux produced pulse but can be as short as a micro-second.
- current medical computed tomography setups can require at least 250 to 500 msec to acquire a single slice.
- the computed tomography device 800 comprises an electron beam source 802 , an object stage 804 , an area detector 806 .
- the circular x-ray source consists of an array of the x-ray producing elements facing the center of a circle.
- the detectors are in a similar arrangement positioned adjacent the source circle.
- By controlling each of the x-ray sources individually multiple slice projections may be produced, requiring no rotation of the detectors or x-ray source.
- a slight (15 degrees or less) rotation may be incorporated into either the source or the detectors to provide increased radial resolution.
- This setup allows near instantaneous single slice imaging, limited only by the switching rate of the x-ray source and the time necessary to acquire a projection.
- the current medical CT setups require at least 250 to 500 msec to acquire a single slice.
- the computed tomography device 900 comprises an electron beam source 902 , an object stage 904 , an area detector 906 .
- the system is designed to operate in two different modes. First, is the computed tomography mode, where the source and detector are rotated about the object, generating a set of 3-D cone beam projections for reconstruction. The second mode, the system acquires a series of 2-D images from a single projection, resembling a fluoroscopy unit. As the 2-D projection direction is known, it may be mapped into the 3-D projection that was measured first, allowing localization of objections. Multiple array source elements may be utilized to spatially localize objects of interest.
- the computed tomography device 1000 comprises an electron beam source 1002 , an object stage 1004 , an area detector 1006 and a stationary tungsten ring 1008 .
- the source of electrons e.g., a field emission cathode, may be physically pointed or magnetically steered at the stationary tungsten ring that surrounds the object stage. Electrons from the electron source strike the stationary tungsten ring and generate x-ray photons that are directed back at the object.
- Multiple projections of the x-ray may be realized by mechanically moving the electron source such that the electron beam is directed to different locations of the stationary x-ray target ring, e.g., the tungsten ring.
- the object remains stationary, as does the detector.
- a high voltage is applied between the cathode and the target ring to accelerate the electrons to the desired energy.
- imaging techniques associated with computed tomography acquisition can be used.
- additional imaging techniques are available through the exemplary embodiments of a computed tomography device described herein.
- traditional medical computed tomography techniques have required that the x-ray computed tomography tube be turned on in a continuous manner when circling around the patient.
- the nanotube based x-ray source allows tight switching control of the x-ray source, enabling more sophisticated imaging patterns.
- a star shaped pattern may be utilized, sequentially activating sources on opposite sides of the ring.
- the ability to provide short bursts of x-rays may also reduce exposure time to the object; bursts are only needed when the source and detector are positioned at the next angle—the intermediary position does not need the x-ray to be on. Any reduction of dose is of great advantage for the patient. Dose reduction may also be performed at a loss of spatial resolution; by sampling a smaller number of angles. Reducing the angular sampling may be useful in creating a rapid computed tomography screening tool. Rapid, multi-angle computed tomography fluoroscopy also becomes possible, incorporating the time resolution of a normal fluoroscopy machine, with the three-dimensional acquisition capability of the computed tomography. Tight control of the x-ray source allows prospective cardiac gating, essential in improving the image quality associated with cardiac imaging. Furthermore, an addressable x-ray source allows control of the thickness of the imaging slice at the x-ray source.
- Example applications for the exemplary computed tomography devices and methods described herein can include, although not limited to, the following:
- Clinical imaging Clinical imaging applications, such as rapid full body or body part specific imaging, portable imaging units for specific body parts, such as the head for in-field diagnosis of trauma, stroke, and so forth, dynamic contrast studies for perfusion of brain, liver and other organs, gated imaging for moving body parts (lungs, heart, etc.), low dose imaging techniques for screening or pediatric purposes, fluoroscopy and diffraction imaging techniques.
- Small animal imaging Small animal imaging applications, such as small animal computed tomography for observing anatomical structure, rapid screening for identifying animal phenotype, dynamic studies in small animals (with or without contrast agents.
- Industrial applications such as non-destructive testing and container inspections, e.g., customs inspections.
Abstract
Computed tomography device comprising an x-ray source and an x-ray detecting unit. The x-ray source comprises a cathode with a plurality of individually programmable electron emitting units that each emit an electron upon an application of an electric field, an anode target that emits an x-ray upon impact by the emitted electron, and a collimator. Each electron emitting unit includes an electron field emitting material. The electron field emitting material includes a nanostructured material or a plurality of nanotubes or a plurality of nanowires. Computed tomography methods are also provided.
Description
- This application is a divisional patent application which claims the benefit of the filing date of U.S. patent application Ser. No. 10/923,385, filed Aug. 20, 2004, which is a continuation-in-part of U.S. patent application Ser. No. 10/051,183 filed Jan. 22, 2002, which is a continuation-in-part of U.S. patent application Ser. No. 09/679,303 filed Oct. 6, 2000, now U.S. Pat. No. 6,553,096, and is a continuation of U.S. patent application Ser. No. 10/421,931 filed Apr. 24, 2003, the disclosure of which is incorporated herein by reference in its entirety.
- This subject matter was made with Government support under Grant No. N00014-98-1-0597 awarded by Office of Naval Research. The Government has certain rights in the subject matter.
- The present subject matter relates generally to field emission cathodes for x-ray radiation sources. More particularly, the present subject matter relates to carbon nanotube field emission cathodes and methods of manufacture and operation of such cathodes in linear or area x-ray radiation sources with individually addressable multi-beam x-rays suitable for use in diagnostic, imaging, and inspection applications.
- In the description of the background of the present subject matter that follows reference is made to certain structures and methods. Such references should not necessarily be construed as an admission that these structures and methods qualify as prior art under the applicable statutory provisions. Applicants reserve the right to demonstrate that any of the referenced subject matter does not constitute prior art with regard to the present subject matter.
- Computed tomography (CT) technology is widely used for medical, industrial and security imaging purposes. The designs of typical computed tomography machines have gone through major evolutions. For example, for conventional x-ray imaging, a three-dimensional (3-D) object is illuminated to form a two-dimensional (2-D) image. As a result, the spatial resolution in the illumination direction is lost. This limitation can be overcome in computed tomography systems by obtaining projection images of the object in different directions. Typically, the object is stationary while a single x-ray source rotates around the object and produces the images at different rotation angles. The collection of the projected images can then be used to reconstruct a three-dimensional image of the object.
- Rotation of the x-ray source puts considerable demand on the system design and can reduce the imaging speed. An electron-beam computed tomography (EBCT) system can address this problem. In typical EBCT systems, electrons produced by the cathode are scanned across the surface of the anode located in the gantry, which consists of a metal ring or multiple rings. The scanning is accomplished by electrical and magnetic fields. However, the machine is expensive and takes significantly larger space than a regular computed tomography system. Thus, it is highly desirable to have a small stationary x-ray source computed tomography system that is potentially more transportable and cost effective.
- In some systems, such as tomography, the x-ray source is stationary and the object is rotated to collect the projection images. In the micro-computed tomography systems, the x-ray source typically produces a fan beam onto the object. In some cases, a cone beam and two-dimensional detector are used to record the images. The object is rotated and an image is collected at every rotation angle. An example of the two-dimensional area detector consists of a scintillation crystal that converts the x-ray photon to visible light, and a charge-coupled-detector (CCD) camera positioned behind the crystal that captures the image. Solid state and gas detectors are also commonly used.
- From the point of view of image quality, it is preferred to use a monochromatic x-ray. This is because computed tomography measures, essentially, the linear absorption coefficient, which depends on the energy of the incident x-ray photon. However, in most computed tomography systems, with the exception of a synchrotron radiation source, continuous-energy x-ray rather than monochromatic x-ray is used so as to increase the x-ray intensity, and thus reduce the data collection time. In many computed tomography systems, the x-ray source is often placed far away from the object to minimize the non-even spatial distribution of the x-ray radiation from the single x-ray source and the divergence of the x-ray beam. As a result, only a small fraction of the produced x-ray photons are used for imaging.
- It is highly desirable to have an all-stationary computed tomography system. Such a system will reduce or eliminate the need to rotate the x-ray source around the patient. Furthermore, novel x-ray source geometries combined with the precise control of these x-ray sources can allow the development of imaging techniques and the refinement of current data acquisition methods.
- An exemplary embodiment of a computed tomography device comprises an x-ray source, and an x-ray detecting unit. The x-ray source comprises a cathode with a plurality of individually programmable electron emitting units that each emit an electron upon an application of an electric field, an anode target that emits an x-ray upon impact by the emitted electron, and a collimator.
- An exemplary method to operate a computed tomography device, the computed tomography device including an x-ray source, the x-ray source comprising a cathode with a plurality of individually programmable electron emitting units that each emit an electron upon an application of an electric field, an anode target that emits an x-ray upon impact by the emitted electron, a collimator, and an x-ray detecting unit, comprises applying the electric field to at least a first of the plurality of individually programmable electron emitting units to cause the emission of an electron, focusing the emitted electron at one of a plurality of focal points on the anode target, impacting the anode target with the emitted electron to form an emitted x-ray radiation, collimating the emitted x-ray radiation, passing the collimated x-ray radiation through an object, detecting the x-ray radiation with the x-ray detecting unit, and recording the detected x-ray radiation. Some of the objects of the subject matter having been stated hereinabove, and which are addressed in whole or in part by the present subject matter, other objects will become evident as the description proceeds when taken in connection with the accompanying drawings as best described hereinbelow.
- Objects and advantages of the present subject matter will become apparent from the following detailed description of preferred embodiments thereof in connection with the accompanying drawings in which like numerals designate like elements and in which:
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FIG. 1 shows a schematic representation of an exemplary x-ray radiation source. -
FIG. 2 shows current density as a function of voltage for carbon nanotube cathodes having a gap distance between 62 μm and 280 μm. -
FIG. 3 shows a schematic representation of an exemplary embodiment of a collimated monochromatic x-ray radiation source. -
FIG. 4 shows a schematic representation of an exemplary embodiment of a linear x-ray radiation source with a fan-beam. -
FIG. 5 shows a schematic representation of an exemplary embodiment of an arch x-ray radiation source with a cone-beam. -
FIG. 6 shows a schematic representation of an exemplary embodiment of an area x-ray radiation source with a pencil-beam. -
FIG. 7 shows a schematic representation of an exemplary embodiment of a CT system with a linear x-ray radiation source rotated about a stationary stage. -
FIG. 8 shows a schematic representation of an exemplary embodiment of a CT system with a circular x-ray radiation source positioned about a stationary stage. -
FIG. 9 shows a schematic representation of an exemplary embodiment of an x-ray radiation source that can be operated in a computed tomography mode and a single projection mode -
FIG. 10 shows a schematic representation of an exemplary embodiment of a CT system with a ring target, the electron beam strikes the target by reorienting the electron beam source and/or by steering the electron beam. - The x-ray systems and x-ray imaging methodologies for computed tomography disclosed herein are based on our previous disclosures, including U.S. Pat. No. 6,553,096 to Zhou et al. entitled “X-RAY GENERATING MECHANISM USING ELECTRON FIELD EMISSION CATHODE”, U.S. Pat. No. 6,876,724 to Zhou et al. entitled “LARGE-AREA INDIVIDUALLY ADDRESSABLE MULTI-BEAM X-RAY SYSTEM AND METHOD OF FORMING SAME”, and U.S. Pat. No. 6,850,595 to Zhou et al. entitled “X-RAY GENERATING MECHANISM USING ELECTRON FIELD EMISSION CATHODE”, the entire disclosures of all these applications are herein incorporated by reference. U.S. Pat. No. 6,553,096 discloses an x-ray generating device incorporating a nanostructure-containing material. U.S. Pat. No. 6,876,724 discloses a structure to generate x-rays having a plurality of stationary and individually electrically addressable field emissive electron sources with a substrate composed of a field emissive material, such as carbon nanotubes, that can be electrically switched at a predetermined frequency to field emits electrons in a programmable sequence.
- An exemplary embodiment of a computed tomography device comprises an x-ray source and an x-ray detecting unit.
FIG. 1 shows a schematic representation of an exemplaryx-ray radiation source 100. Thex-ray source 100 includes acathode 102 with a plurality of individually programmable electron emitting units 104 that each emit anelectron 106 upon an application of an electric field (E), ananode target 108 that emits anx-ray 110 upon impact by the emittedelectron 106, and acollimator 112. - In exemplary embodiments, the electron emitting unit 104 includes an electron field emitting material. For example, the electron field emitting material can include a nanostructured material. In a further example, the electron field emitting material includes a plurality of nanotubes or a plurality of nanowires. The nanotubes can include inorganic materials. For example, the nanowires can include at least one field emitting material selected from the group consisting of carbon, boron, nitrogen, sulfur, and tungsten. The nanowires can included at least one field emitting material selected from the group consisting of silicon, germanium, carbon, oxygen, indium, cadmium, gallium, oxide, nitrides, silicides and boride. The nanowires can be fabricated by a variety of techniques including chemical vapor deposition, solution synthesis, and laser ablation. The paper by J. Hu, et al., “Chemistry and Physics in One Dimension: Synthesis and Properties of Nanowires and Nanotubes”, Accounts of Chemical Research, Vol. 32, pages 435-445, 1999, the entire content of which is incorporated herein by reference, describes some of these fabrication methods.
- The
cathode 102 can include one or more individually programmable and/or addressable electron emitting units 104 arranged on asupport structure 114. In an exemplary embodiment, the electron emitting unit 104 is one or more electron emitting pixels. The electron emitting pixels can be any suitable electron source. In an exemplary embodiment, the electron emitting pixels are electron field emission sources, such as electron field emitting materials including a plurality of single-wall carbon nanotubes (SWNT), a plurality of multi-wall carbon nanotubes (MWNT), a plurality of double-wall carbon nanotubes (DWNT), or a mixture thereof. Examples of suitable electron field emission sources include the carbon nanotube based electron field emission sources disclosed in U.S. Pat. No. 6,630,772 to Bower et al. entitled “DEVICE COMPRISING CARBON NANOTUBE FIELD EMITTER STRUCTURE AND PROCESS FOR FORMING DEVICE”, the entire disclosure of which is incorporated herein by reference, which discloses a carbon nanotube-based electron emitter structure, U.S. patent application Ser. No. 09/351,537 entitled “DEVICE COMPRISING THIN FILM CARBON NANOTUBE ELECTRON FIELD EMITTER STRUCTURE”, the entire disclosure of which is incorporated herein by reference, which discloses a carbon-nanotube field emitter structure having a high emitted current density, U.S. Pat. No. 6,277,318 to Bower et al. entitled “METHOD FOR FABRICATION OF PATTERNED CARBON NANOTUBE FILMS”, the entire disclosure of which is incorporated herein by reference, which discloses a method of fabricating adherent, patterned carbon nanotube films onto a substrate, U.S. Pat. No. 6,553,096 to Zhou et al. entitled “X-RAY GENERATING MECHANISM USING ELECTRON FIELD EMISSION CATHODE”, the entire disclosure of which is incorporated herein by reference, which discloses an x-ray generating device incorporating a nanostructure-containing material, U.S. Pat. No. 6,965,199 to Stoner et al. entitled “COATED ELECTRODE WITH ENHANCED ELECTRON EMISSION AND IGNITION CHARACTERISTICS”, the entire disclosure of which is incorporated herein by reference, which discloses an electrode including a first electrode material, an adhesion-promoting layer and a carbon nanotube-containing material disposed on at least a portion of the adhesion promoting layer, as well as associated devices incorporating such an electrode, and U.S. Pat. No. 6,787,122 to Zhou entitled “METHOD OF MAKING NANOTUBE-BASED MATERIAL WITH ENHANCED ELECTRON FIELD EMISSION PROPERTIES”, the entire disclosure of which is incorporated herein by reference, which discloses a technique for introducing a foreign species into the nanotube-based material in order to improve the emission properties thereof. - Preferably the electron emitting pixels can be controlled individually, e.g., each electron emitting pixel can be individual electrically addressed and a controller can supply an electronic field to the electron emitting pixel in any desired manner, such as individually, as a group or plurality, in a specified sequence or pattern, or randomly. A suitable method of individual control is disclosed in U.S. Pat. No. 6,876,724, the entire contents of which is hereby incorporated by reference. U.S. Pat. No. 6,876,724 discloses individual control by electrically switching the field emissive electron sources at a predetermined frequency to field emit electrons in a programmable sequence toward an incidence point on a target and to thereby generate x-rays corresponding in frequency and in position to that of the field emissive electron source. Other suitable methods of control are disclosed in U.S. Pat. No. 6,553,096 and in U.S. Pat. No. 6,850,595, the entire content of each is hereby incorporated by reference. Other examples of individual control are disclosed in Brodie and C. A. Spindt, “Vacuum Microelectronics,” Advances in Electronics and Electron Physics, vol. 83, p. 1-106 (1992).
- The x-ray source can further comprise a gate electrode. The exemplary embodiment of an
x-ray source 100 shown inFIG. 1 includes agate electrode 116 located between thecathode 102 and theanode target 108. Thegate electrode 116 can extract the emittedelectron 106 from one or more of the plurality of individually programmable electron emitting units 104 when the electrical field is applied between thegate electrode 116 and the one or more individually programmable electron emitting units 104. For example, the electrical field can be applied such that thegate electrode 116 is at a positive potential with respect to the one or more of the plurality of individually programmable electron emitting units 104. The field strength of the electrical field can be from 0.1 Volt/μm (V/μm) to 100 V/μm, preferably from 0.5 V/μm to 20 V/μm. At least one of the plurality of individually programmable electron emitting units has an emission threshold of less than 3 V/μm for greater than 0.01 mA/cm2 current density, preferably greater than 0.1 mA/cm2 current density, and emits 0.1-100 mA total current. In an exemplary embodiment, the emission current is approximately less than or equal to 100 μA per nanotube at an electrical field of less than 100 V/μm. -
FIG. 2 shows current density (A/cm2 ) as a function of voltage for carbon nanotube cathodes having a gap distance between 62 μm and 280 μm. As the gap distance decreases, the current density also decreases. Table 1 summarizes values of current density for a given electrical field. The values inFIG. 2 and Table 1 are merely examples, and values may vary significantly, depending on the sample preparation and how the measurement is performed.TABLE 1 Emission Characteristics for the Cathode Current Density (mA/cm2) Electrical Field (V/μm) 1 2 10 2.5 100 4 700 5.3 - The emission current-voltage (1-V) characteristics of the single-wall carbon nanotube film shown in
FIG. 2 and Table 1 were measured using a hemispherical current collector with a 1 millimeter (mm) diameter (anode) at 5×10−8 Torr base pressure and different anode-cathode gap distances. As shown in theFIG. 2 and the inset toFIG. 2 , the carbon nanotube film exhibits the classic Fowler-Nordheim behavior with a threshold field of 2 V/μm for 1 mA/cm2 current density. The effective emission area was calculated using a previously described method as disclosed in W. Zhu, C. Bower, O. Zhou, G. P. Kochanski, and S. Jin, Appl. Phys. Left., vol. 75, p. 873, (1999), the entire contents of which are herein incorporated by reference. The corresponding electric fields for various electron current densities are listed in Table 1. Emission current density over 1 A/cm2 was readily achieved. - The emission material was purified single-wall carbon nanotube (SWNT) bundles that were produced by the laser ablation method, as disclosed in O. Zhou, H. Shimoda, B. Gao, S. J. Oh, L. Fleming, and G. Z. Yue, “Materials Science of Carbon Nanotubes: Fabrication, Integration, and Properties of Macroscopic Structures of Carbon Nanotubes”, Acc. Chem. Res, vol. 35 p. 1045-1053 (2002), the entire contents of which are herein incorporated by reference. The emission material contains approximately 95-wt. % SWNT bundles with an average SWNT diameter of 1.4 nanometers (nm) and a bundle diameter of approximately 50 nm. Uniform SWNT film were coated on a flat metal disc by electrophoretic deposition, substantially similar to that disclosed in U.S. patent application Ser. No. 09/996,695, the entire contents of which are herein incorporated by reference. To increase the adhesion between the SWNT coating and the substrate, an iron inter-layer was first deposited on the substrate surface by either thermal evaporation or electrochemical plating before nanotube deposition, substantially similar to that disclosed in U.S. Pat. No. 6,277,318, the entire contents of which are herein incorporated by reference. The thickness and packing density of the nanotube film were controlled by the current, deposition time and the concentration of the nanotube suspension. The films were vacuum annealed at 800° C. before use.
- An exemplary embodiment of a computed tomography device also includes an
x-ray detecting unit 118. Any x-ray detecting unit can be used. For example, the x-ray detecting unit can include an x-ray scintillation material and a digital imaging acquisition device. A suitable digital imaging acquisition device includes a charge-coupled-device (CCD) or a solid state based or gaseous based imaging device. In addition, the computed tomography device can have a control system between the x-ray detecting unit and a controller, a storage device, or a combined controller/storage device 120 for data collection, storage and reconstruction. The digital imaging acquisition device digitally records the x-ray intensity of the x-ray radiation. Depending on the size and orientation of an object being imaged, e.g, an object located on an object support stage, each beam of x-ray radiation can pass through, e.g, transmission x-ray source, or can reflect from, e.g., reflection x-ray source, a portion of the object. The x-ray radiation is then detected by the corresponding x-ray detecting unit. -
FIG. 3 is a schematic representation of an exemplary embodiment of a collimated monochromaticx-ray radiation source 300. The collimated monochromaticx-ray radiation source 300 includes anx-ray source 302 and anx-ray detecting unit 304, both of which can be substantially similar to that described herein with respect toFIG. 1 . In addition, the collimated monochromaticx-ray radiation source 300 includes amonochromator 306 placed in a path of the emittedx-ray 308 after thecollimator 310. An example of a suitable monochromator includes a crystal that selects an x-ray photon with a certain energy. Examples of suitable crystals include a single crystal of graphite or silicon (Si). The energy of the outgoing x-ray beam is selected by the diffraction conditions. A particular diffraction angle is chosen to produce a diffracted beam with a predetermined energy. By choosing different diffraction angles, monochromatic x-ray beams with different energies can be selected. - An exemplary embodiment of a computed tomography system can have an x-ray source having any suitable geometry for directing a desired form of an x-ray beam toward an object of interest, such as medical applications for a patient or an animal and industrial and inspection applications such as for a structure or a container. For example, an x-ray source can be a linear, an arched, and/or an area x-ray source.
-
FIG. 4 is a schematic representation of an exemplary embodiment of a computed tomography device. The computedtomography device 400 comprises a linearscanning x-ray source 402, anobject support stage 404, and adetector 406. The linearscanning x-ray source 402 comprises acathode 408 and ananode target 410 and acollimator 412. Thecathode 408 includes an array of individually programmableelectron emitting units 414 arranged on asupport structure 416. - A suitable arrangement of the plurality of individually programmable
electron emitting units 414 includes arrangement linearly on an axis in a plane. Each individually programmable electron emitting unit is focused at one of a plurality of focal spots on theanode target 410. - The linear scanning x-ray source can have either transmission geometry or reflection geometry. In an example of a linear scanning x-ray source with a transmission geometry, the anode is a metal film which can be either free-standing or deposited on a low-atomic number material, such as carbon. The anode is at a higher electrical potential with the cathode. In one particular example, the anode is electrically grounded. A negative potential is applied to the cathode. A gate electrode, can be included in the x-ray source and can be at a positive potential with respect to the cathode to extract the electrons from the cathode.
- In one particular example, all of the programmable electron emitting units are at the same potential. Each programmable electron emitting unit has a corresponding gate electrode. Electrons are extracted from a particular programmable electron emitting unit when the electrical field established between said unit and the corresponding gate exceeds a critical value (for example 3V/μm or less).
- In another exemplary embodiment, the distance between the anode and the cathode is such that the electrical field due to the anode voltage is sufficient to extract the filed-emitting electrons from the cathode. In this embodiment, a reverse bias voltage is applied on the gate electrode to suppress electron emission from certain emitting units. This reverse bias voltage is scanned across the gate electrode to suppress a first group of electron filed emitting units and/or to activate a second group of programmable electron emitting units.
- Each individually programmable electron emitting unit comprises a layer of electron field emitting material. Individual or groups of electron field emitting material in the layer can form an array or matrix or pattern of electron emitting pixels. In the exemplary embodiment of
FIG. 4 , the electron field emitting material is a layer of carbon nanotubes, but any suitable field emitting material can be used including nanostructured material and nanotubes and nanowires as substantially described herein with respect toFIGS. 1 and 3 . For example, a layer of carbon nanotubes, e.g., single-walled nanotubes, multi-walled nanotubes, double-walled nanotubes, or mixtures thereof. The field emitters can also be lithographically formed Spindt-type tips. - Under an applied potential between the
cathode 404 and agate electrode 418,electrons 420 are emitted from the each of theelectron emitting units 414. The field emission of electrons from the array of electron emitting units can be from a single pixel, a group of pixels, either randomly arranged or in a pattern, or all the pixels, as determined by the controlled application of the applied potential. For example, a bias potential applied between the gate and the cathode extracts electrons. A large, e.g. on the order of 10 to 200 KV/cm or greater, electrical voltage is further established between the gate and the anode to accelerate the emitted electrons to the desired energy level. The emitted electrons from the electron emitting units are accelerated and impinge on theanode target 410, for example, each at a corresponding x-ray emitting pixel. An example of an x-ray emitting pixel includes a thin layer of metal target material, such as copper (Cu) and tungsten (W), a heat dissipating target supporting material.X-ray radiation 422 is emitted from the anode when it is bombarded by the electrons, e.g., the anode is a target for the accelerated electrons. The emitted x-ray radiation passes through thecollimator 412 and optionally a monochromator (not shown inFIG. 4 ). Thecollimator 412 enables each x-ray emitting pixel to generate a particular geometry ofx-ray radiation 422, such as an uniform fan beam geometry. However, any suitable geometry ofx-ray radiation 420 can be formed, including a pencil beam geometry or a cone beam geometry. - The computed
tomography device 400 has anx-ray detector 406. Anexemplary x-ray detector 406 comprises a plurality ofx-ray detecting units 424. Eachx-ray detecting unit 424 includes x-ray scintillation materials and a digital imaging acquisition device, such as a charge-coupled-device (CCD) or a solid state based or gaseous based imaging device. The digital imaging acquisition device digitally records the x-ray intensity of thex-ray radiation 422. Depending on the size and orientation of anobject 426 on theobject support stage 404, each beam ofx-ray radiation 422 can pass through, e.g, transmission x-ray source, or can reflect from, e.g., reflection x-ray source, a portion of theobject 426. Thex-ray radiation 422 is then detected by the correspondingx-ray detecting unit 424. - In the exemplary embodiment illustrated in
FIG. 4 , the x-ray detector includes a two-dimensional matrix of x-ray detecting units. The detection scheme depends on the type of x-ray beams generated by the linear x-ray source. In one embodiment, an x-ray beam with fan-beam geometry is produced from each focal spot on the anode. The fan beam illuminates a slice of theobject 426. The illuminated area is defined by the geometry of the collimator used. The intensity of the x-ray beam from a particular focal spot passing through the object is measured by a pre-selected set of x-ray detection units on the x-ray detector. Each focal spot is associated with a set of x-ray detection units on the x-ray detector. - To collect the images of the object, two modes can be used. In one mode, the electron emitting units are activated one by one to produce an x-ray beam from the anode that is moving through the focal spots sequentially. During scanning, the corresponding x-ray detection unit on the x-ray detector is also switched on to record the image from a particular x-ray beam, e.g., switched on sequentially or one-by-one. In another mode, all the electron emitting units are turned on at the same time. The x-ray detecting units are also switched on at the same time to collect and/or record the images of the object.
- In another embodiment, the collimators are designed such that x-ray radiation with cone-beam geometry is generated from each focal spot. In this case, the electron emitting units are activated sequentially or one-by-one. When a particular unit is turned on, a cone-beam x-ray is generated from the corresponding focal spot on the anode. The x-ray beam illuminates the
entire object 426. The image of the object formed by this particular x-ray beam is collected and/or recorded by the entire x-ray detector. The image is then stored in, for example, a computer. The next electron emitting unit in the sequence is then switched on to generate another image of the entire object, from a different projection angle. The process repeats for all, or a subset of all, the emitting units in the x-ray source. -
FIG. 5 shows a schematic representation of an exemplary embodiment of a computedtomography device 500 with a linearscanning x-ray source 502 arranged as an arch x-ray source. Thex-ray source 502 generates a particular geometry ofx-ray radiation 504, such as a cone beam geometry. However, any suitable geometry ofx-ray radiation 504 can be formed by selection of a suitable collimator, including a pencil beam geometry or a fan beam geometry. In the exemplary embodiment shown inFIG. 5 , the computedtomography device 500 includes a linearscanning x-ray source 502, anobject rotation stage 506, and adetector 508. The linearscanning x-ray source 502 includes a series ofcathodes 510 andcorresponding anode targets 512 lining the arched-shapedsupport structure 514. Thex-ray source 502 andx-ray detecting unit 508 can be substantially similar to that described herein with respect to the x-ray source and x-ray detecting unit ofFIGS. 1 and 3 . - The arched-shaped
support structure 514 is constructed such that each focal spot on the anode is at an equal distance from the center of an object rotation stage, e.g., from a center of rotation of an object stage or from a central rotation axis of the object stage. Further, in a preferred case, the two-dimensional detector has a curved surface so that each detecting unit is also equidistant to the object. - The computed
tomography device 500 inFIG. 5 has anx-ray detector 508. As described herein, the x-ray detecting unit can be of any suitable type and/or any suitable arrangement, based on the geometric form of the x-ray radiation generated by the x-ray source. Similar to the geometry described above, the preferred geometry of the detector surface is a curved one so that each detecting unit is equidistance to the object. Anexemplary x-ray detector 508 comprises a plurality ofx-ray detecting units 516. Eachx-ray detecting unit 516 includes x-ray scintillation materials and a digital imaging acquisition device, such as a charge-coupled-device (CCD) or a solid state based or gaseous based imaging device. The digital imaging acquisition device digitally records the x-ray intensity of thex-ray radiation 504. Depending on the size and orientation of anobject 518 on theobject support stage 506, each beam ofx-ray radiation 504 can pass through, e.g, transmission x-ray source, or can reflect from, e.g., reflection x-ray source, a portion of theobject 518. Thex-ray radiation 504 is then detected by the correspondingx-ray detecting unit 516. -
FIG. 6 shows a schematic representation of an exemplary embodiment of a computedtomography device 600. The computedtomography device 600 includes an areascanning x-ray source 602, anobject rotation stage 604, and adetector 606. The linearscanning x-ray source 602 includes a series ofcathodes 608 andcorresponding anode targets 610 lining the planar-shapedsupport structure 612. Thex-ray source 602 andx-ray detecting unit 606 can be substantially similar to that described herein with respect toFIGS. 1 and 3 . The computedtomography device 600 has an area linearscanning x-ray source 602 arranged as a planar x-ray source generating a particular geometry ofx-ray radiation 614, such as a pencil beam geometry. However, any suitable geometry ofx-ray radiation 614 can be formed by selection of a suitable collimator, including a cone beam geometry or a fan beam geometry. In the exemplary embodiment shown inFIG. 6 , The individually programmable electron emitting units of the cathode are arranged over an area of the planar-shaped support structure and each individually programmable electron emitting unit is focused at one of a plurality of focal spots on theanode target 610. - The computed
tomography device 600 inFIG. 6 has anx-ray detector 606. As described herein, the x-ray detecting unit can be of any suitable type and/or any suitable arrangement, based on the geometric form of the x-ray radiation generated by the x-ray source. Anexemplary x-ray detector 606 comprises a plurality ofx-ray detecting units 616. Eachx-ray detecting unit 616 includes x-ray scintillation materials and a digital imaging acquisition device, such as a charge-coupled-device (CCD) or a solid state based or gaseous based imaging device. The x-ray detecting units can be suitably arranged, such as in a matrix or an array. The digital imaging acquisition device digitally records the x-ray intensity of thex-ray radiation 614. Depending on the size and orientation of anobject 618 on theobject support stage 604, each beam ofx-ray radiation 614 can pass through, e.g, transmission x-ray source, or can reflect from, e.g., reflection x-ray source, a portion of theobject 618. Thex-ray radiation 614 is then detected by the correspondingx-ray detecting unit 616. - A method to operate a computed tomography device includes applying an electric field to at least a first of a plurality of individually programmable electron emitting units. Applying the electric field causes the emission of an electron. The emitted electron is focused at one of a plurality of focal points on an anode target. the emitted electron impacts the anode target to form an emitted x-ray radiation, which is collimated to a geometry, such as a cone beam geometry, a pencil beam geometry, or a fan beam geometry, and passed through an object. The x-ray radiation is then detected by an x-ray detecting unit and recorded.
- The method can be repeated to produce multiple detected x-ray radiation images without rotating the object positioned on the object stage. For example, each of the plurality of individually programmable electron emitting units of the x-ray source can be operated in a particular sequence or operated as a group in a particular pattern to produce an emitted x-ray that illuminates the object in the computed tomography device from a different angle, plane, or other orientation. Accordingly, by repeating the steps of applying, focusing, impacting, collimating, passing, detecting, and recording with respect to a particular sequence or grouping of individually programmable electron emitting units, multiple detected x-ray radiation images can be produced. For example, during the repetition of the operation of the computed tomography device, the electric field is applied to at least a second individually programmable electron emitting unit. Further, the emitted electrons are focused on a second of the plurality of focal points on the anode target when the step of focusing is repeated.
- The step of collimating can produce an x-ray radiation beam of a particular geometry. For example, the collimator can be selected such that the emitted x-ray radiation is collimated to produce a fan beam geometry of x-ray radiation, a pencil beam geometry of x-ray radiation, or a cone beam geometry of x-ray radiation. Each of these x-ray radiation beam geometries has an associated imaging technique, such as a magnified stereo projection image, a parallel projection image, or projection images from different viewing angles for reconstruction of three-dimensional images.
- During the method of operating a computed tomography device, an electric field is applied between the cathode and a gate electrode. The gate electrode is at a positive potential with respect to the individually programmable electron emitting units of the cathode. An exemplary field strength of the electric field is from 0.1 V/μm to 100 V/μm, preferably from 0.5 V/μm to 20 V/μm. The application of the electric field accelerates the emitted electrons to a given energy.
- In another exemplary method, the electric field is established between the gate electrode and at least two of the plurality of individual programmable electron emitting unit sequentially. The electric field is established one individually programmable electron emitting unit or a group of individually programmable electron emitting units at a given time, from a first location on the cathode to a second location on the cathode. The applied electrical field has a predetermined frequency and pulse width. The frequency determines how many times per second the electrical field is switched on. There is a no limitation on the frequency. For example, the frequency can be in the range of 0.01-106 Hz. The pulse width determines the dwell time when the field is switched on. Again there is no limitation on the dwell time. For example, it can be in the range of one micro-second to one minute. At each sequential establishment of the electric field, a view of the object is illuminated and an x-ray image is collected. Thus, over the sequential operation, a plurality of views of the object is collected.
- In another exemplary method of operating a computed tomography device, an electrical field is established between the gate electrode and at least two of the plurality of individually programmable electron emitting units. The electrical field is established sequentially, one individually programmable electron emitting unit at a given time or a group of individually programmable electron emitting units, from a first location on the cathode to a second location on cathode at a given sweep rate. For example, the sweep rate can be in the range of 0.01 Hz to 106 Hz. The sequential establishment of the electrical field illuminates the object and produces a plurality of views that are subsequently collected for later retrieval and/or analysis.
- In one particular embodiment of this subject matter, the frequency and pulse width of the electrical field applied to the gate electrode is synchronized with the data collection time of the x-ray detector. The x-ray radiation is generated only when the x-ray detector is collecting data. Synchronization of x-ray generation and data collection can significantly reduce the amount of unnecessary radiation dosage the object receives during imaging.
- In yet another embodiment of the subject matter, the frequency and the pulse width of the electrical field applied to the gate electrode and thus the frequency and the pulse width of the x-ray produced are synchronized with either a physiological signal, an internal signal from the object, or an external signal source. For example, the frequency and the pulse width of the x-ray generated can be gated by the cardiac or respiratory signals to obtain clear images of moving object.
- For a given object orientation, an x-ray radiation having a cone beam geometry originates from different focal points impinging on the object from different angles. The corresponding two-dimensional projection images are different. This is because the x-ray beams originate from different points in space and have different projection angles. As a result, by collecting a large number of images from a wide viewing angle range, internal structure of the object can be obtained. Thus, in one sweep over the linear x-ray sources, multiple two-dimensional images are acquired in short time without rotating the object. This greatly increases the image acquisition speed.
- To produce a scanning x-ray beam, a pulsed electrical field between the gate and the cathode is swept through the emitting pixels at a given speed. The field is set at a value such that each pixel will emit a certain current for a given duration and in a given sequence, which is determined by the pulse width of the sweeping field. During this process, the voltage between the anode and the gate remains at a constant value. When the electrons impinge on the anode, x-ray radiation emits from the point of impact. As the electrical field sweeps through the cathode, the origin of the x-ray radiation sweeps through the surface of the anode.
- The pulse-width, frequency and sweep rate of the electrical field on the gate are synchronized with the electronics that control the detector such that the images collected are in registry with the positions of the focal points. For example, a controller can synchronize the electric field and the detector.
- During operation of an exemplary computed tomography device, the x-ray radiation from the x-ray source illuminates an object which is supported on the object support stage. The object support stage of an exemplary computed tomography device can be either stationary or can be rotated through a pre-determined set of angles. One example of a computed tomography system using a single beam x-ray source and a rotating sample stage is contained in M. D. Bentley, M. C. Ortiz, E. L. Ritman, and J. C. Romero, “The Use of Microcomputed Tomography to Study Microvasculature in Small Rodents,” AJP Regulatory Integrative Comp Physiol, 282, R1267-R1279 (2002), the entire content of which is incorporated herein by reference.
- In another method to operate a computed tomography, the object is positioned on an object stage and is rotated through a set of angles. After each rotation of the object, the steps of applying, focusing, impacting, collimating, passing, detecting, and recording are repeated to obtain a series of detected x-ray radiation images. The x-ray radiation images can then be reconstructed to form a three-dimensional volume of the object. For example, the detected x-ray radiation images can be reconstructed using an image reconstruction algorithm to form the three-dimensional volume of the object. For example, the cone-beam reconstruction algorithm developed by Feldkamp, et al. in L. A. Feldkamp, L. C. Davis, and J. W. Kress, “Practical cone-beam algorithm”, J. Opt. Soc. Am., vol.1,612-619 (1984), the entire content of which is herein incorporated by reference can be modified for such purpose.
- The exemplary computed tomography system operates in two different modes. In a first mode, e.g., the computed tomography mode, the source and detector are rotated about the object, generating a set of three-dimensional cone beam projections for reconstruction into an image. In a second mode, a series of two-dimensional images are acquired from a single projection, resembling a fluoroscopy unit. As the two-dimensional projection direction is known, it may be mapped into the three-dimensional projection from the first mode, allowing localization of objections. Multiple array source elements may be utilized to spatially localize objects of interest.
- For example, the object support stage is set to a first angle and all cathodes of the x-ray source are turned on simultaneously to generate a linear set of x-ray radiation beams. Each x-ray detecting unit records an image, such as a projection image of a slice of the object. All images are combined digitally, to form a two-dimensional image of the object for the given angle of the x-ray source. Thus, all slice projections are combined. The object support stage is then set to a second angle and the process of acquiring an image repeated. By rotating the stage, a plurality of two-dimensional images (such as 360 images, one each for 1 degree rotation of the sample) of a sample are obtained. The images can be combined in real time, or can be electronically stored for later combination.
- To obtain a set of three-dimensional images of the object, the object is rotated through a set of angles, such as 30, 60, or 90 degrees. A new set of images are taken after each rotation. Only a few rotations are needed to obtain the sets of images needed to reconstruct the three-dimensional volume of the objects. The radial resolution may also be increased by rotating the object by smaller angles, such as 5, 10, or 15 degrees.
- The x-ray source and detector are rotated about the object stage, which is stationary and on which a object is mounted. Image acquisition may be performed in a continuous manner with the x-ray source continuously rotating about the object. Finer radial resolution may be achieved by performing multiple acquisitions at each rotational angle with or without selectively pulsing each x-ray source.
- Multiple exemplary embodiments of a computed tomography device are possible. These exemplary embodiments incorporate some or all of the features previously discussed herein.
- An exemplary embodiment of a computed tomography device is shown in
FIG. 7 . The computedtomography device 700 comprises acircular x-ray source 702, anobject stage 704, and acircular detector 706. The circular x-ray source includes an array of x-ray producing elements facing the center of a source circle. The detectors are in a similar arrangement, e.g., in a detector circle, positioned adjacent the source circle. By controlling each of the circular x-ray sources individually, multiple slice projections can be produced without rotation of the detectors or x-ray source or with only a slight rotation e.g., 15 degrees or less. The slight rotation may be incorporated into either the source or the detectors to provide increased radial resolution. In this embodiment, near instantaneous single slice imaging can occur limited only by the switching rate of the x-ray source, which can be 106 Hz or higher, and the time necessary to acquire a projection, which depends on the sensitivity of the detector and the x-ray flux produced pulse but can be as short as a micro-second. In contrast, current medical computed tomography setups can require at least 250 to 500 msec to acquire a single slice. - Another exemplary embodiment of a computed tomography device is shown in
FIG. 8 . The computedtomography device 800 comprises anelectron beam source 802, anobject stage 804, anarea detector 806. The circular x-ray source consists of an array of the x-ray producing elements facing the center of a circle. The detectors are in a similar arrangement positioned adjacent the source circle. By controlling each of the x-ray sources individually, multiple slice projections may be produced, requiring no rotation of the detectors or x-ray source. A slight (15 degrees or less) rotation may be incorporated into either the source or the detectors to provide increased radial resolution. This setup allows near instantaneous single slice imaging, limited only by the switching rate of the x-ray source and the time necessary to acquire a projection. The current medical CT setups require at least 250 to 500 msec to acquire a single slice. - Another exemplary embodiment of a computed tomography device is shown in
FIG. 9 . The computedtomography device 900 comprises anelectron beam source 902, anobject stage 904, anarea detector 906. The system is designed to operate in two different modes. First, is the computed tomography mode, where the source and detector are rotated about the object, generating a set of 3-D cone beam projections for reconstruction. The second mode, the system acquires a series of 2-D images from a single projection, resembling a fluoroscopy unit. As the 2-D projection direction is known, it may be mapped into the 3-D projection that was measured first, allowing localization of objections. Multiple array source elements may be utilized to spatially localize objects of interest. - Another exemplary embodiment of a computed tomography device is shown in
FIG. 10 . The computedtomography device 1000 comprises anelectron beam source 1002, anobject stage 1004, anarea detector 1006 and astationary tungsten ring 1008. The source of electrons, e.g., a field emission cathode, may be physically pointed or magnetically steered at the stationary tungsten ring that surrounds the object stage. Electrons from the electron source strike the stationary tungsten ring and generate x-ray photons that are directed back at the object. Multiple projections of the x-ray may be realized by mechanically moving the electron source such that the electron beam is directed to different locations of the stationary x-ray target ring, e.g., the tungsten ring. The object remains stationary, as does the detector. A high voltage is applied between the cathode and the target ring to accelerate the electrons to the desired energy. - In exemplary embodiments, imaging techniques associated with computed tomography acquisition can be used. However, additional imaging techniques are available through the exemplary embodiments of a computed tomography device described herein. For example, traditional medical computed tomography techniques have required that the x-ray computed tomography tube be turned on in a continuous manner when circling around the patient. However, the nanotube based x-ray source allows tight switching control of the x-ray source, enabling more sophisticated imaging patterns. For example, instead of the traditional circular path of the imaging x-ray source, a star shaped pattern may be utilized, sequentially activating sources on opposite sides of the ring. Furthermore, the ability to provide short bursts of x-rays may also reduce exposure time to the object; bursts are only needed when the source and detector are positioned at the next angle—the intermediary position does not need the x-ray to be on. Any reduction of dose is of great advantage for the patient. Dose reduction may also be performed at a loss of spatial resolution; by sampling a smaller number of angles. Reducing the angular sampling may be useful in creating a rapid computed tomography screening tool. Rapid, multi-angle computed tomography fluoroscopy also becomes possible, incorporating the time resolution of a normal fluoroscopy machine, with the three-dimensional acquisition capability of the computed tomography. Tight control of the x-ray source allows prospective cardiac gating, essential in improving the image quality associated with cardiac imaging. Furthermore, an addressable x-ray source allows control of the thickness of the imaging slice at the x-ray source.
- Example applications for the exemplary computed tomography devices and methods described herein can include, although not limited to, the following:
- Clinical imaging: Clinical imaging applications, such as rapid full body or body part specific imaging, portable imaging units for specific body parts, such as the head for in-field diagnosis of trauma, stroke, and so forth, dynamic contrast studies for perfusion of brain, liver and other organs, gated imaging for moving body parts (lungs, heart, etc.), low dose imaging techniques for screening or pediatric purposes, fluoroscopy and diffraction imaging techniques.
- Small animal imaging: Small animal imaging applications, such as small animal computed tomography for observing anatomical structure, rapid screening for identifying animal phenotype, dynamic studies in small animals (with or without contrast agents.
- Industrial applications: Industrial applications, such as non-destructive testing and container inspections, e.g., customs inspections.
- Although the present subject matter has been described in connection with preferred embodiments thereof, it will be appreciated by those skilled in the art that additions, deletions, modifications, and substitutions not specifically described may be made without department from the spirit and scope of the subject matter as defined in the appended claims.
- It will be understood that various details of the subject matter may be changed without departing from the scope of the subject matter. Furthermore, the foregoing description is for the purpose of illustration only, and not for the purpose of limitation.
Claims (31)
1. A computed tomography device, comprising:
an x-ray source, the x-ray source comprising a cathode with a plurality of individually programmable electron emitting units that each emit an electron beam upon an application of an electric field, an anode target that emits an x-ray beam upon impact by the emitted electron beam, and
a collimator; and an x-ray detecting unit.
2. The device of claim 1 , wherein each electron emitting unit includes an electron field emitting material.
3. The device of claim 2 , wherein the electron field emitting material includes a nanostructured material.
4. The device of claim 2 , wherein the electron field emitting material includes a plurality of nanotubes or a plurality of nanowires.
5. The device of claim 4 , wherein the nanotubes includes at least one field emitting material selected from the group consisting of carbon, boron, and nitrogen.
6. The device of claim 4 , wherein the nanowires included at least one field emitting material selected from the group consisting of silicon, germanium, carbon, oxygen, oxide, and nitrides.
7. The device of claim 2 , wherein the electron field emitting material includes a plurality of single-wall carbon nanotubes, a plurality of multi-wall carbon nanotubes or a mixture thereof.
8. The device of claim 1 , wherein the x-ray source further comprises a gate electrode to extract the emitted electron from one or more of the plurality of individually programmable electron emitting units when the electrical field is applied between the gate electrode and the one or more individually programmable electron emitting units.
9. The device of claim 8 , wherein the gate electrode is located between the cathode and the anode target.
10. The device of claim 8 , wherein the electrical field is applied such that the gate electrode is at a positive potential with respect to the one or more of the plurality of individually programmable electron emitting units, and a field strength of the electrical field is from 0.1 Volt/micron to 100 Volt/micron.
11. The device of claim 1 0, wherein the field strength is from 0.5 Volt/micron to 20 Volt/micron.
12. The device of claim 8 , wherein the electrical field applied to the gate electrode is controlled by a feedback mechanism from the x-ray detecting unit.
13. The device of claim 1 , further comprising a control system for data collection and reconstruction.
14. The device of claim 1 , further comprising a vacuum container housing the cathode and the anode target.
15. The device of claim 1 , wherein at least one of the plurality of individually programmable electron emitting units has an emission threshold of less than 3 Volt/micron for a current density of greater than 0.01 mA/cm2 and emits 0.1-100 mA total current.
16. The device of claim 15 , wherein the current density is greater than 0.1 mA/cm2.
17. The device of claim 1 , wherein the plurality of individually programmable electron emitting units are arranged linearly on an axis in a plane and each individually programmable electron emitting unit is focused at one of a plurality of focal spots on the anode target.
18. The device of claim 17 , wherein the collimator generates a fan beam geometry of x-ray radiation.
19. The device of claim 1 , wherein the plurality of individually programmable electron emitting units are arranged over an area of a plane and each individually programmable electron emitting unit is focused at one of a plurality of focal spots on the anode target.
20. The device of claim 19 , wherein the collimator generates a fan beam geometry of x-ray radiation.
21. The device of claim 1 , wherein the device is portable.
22. A method to operate a computed tomography device, the computed tomography device including an x-ray source, the x-ray source comprising a cathode with a plurality of individually programmable electron emitting units that each emit an electron beam upon an application of an electric field, an anode target that emits an x-ray beam upon impact by the emitted electron beam, a collimator, and an x-ray detecting unit, the method comprising:
applying the electric field to at least a first of the plurality of individually programmable electron emitting units to cause the emission of an electron beam;
focusing the emitted electron beam at one of a plurality of focal points on the anode target;
impacting the anode target with the emitted electron beam to form an emitted x-ray radiation beam;
collimating the emitted x-ray radiation beam;
passing the collimated x-ray radiation beam through an object;
detecting the x-ray radiation beam -with the x-ray detecting unit; and
processing the detected x-ray radiation image into a tomographic image.
23. The method of claim 22 further comprising repeating the steps of applying, focusing, impacting, collimating, passing, detecting, and processing to produce multiple x-ray radiation images without rotating the object positioned on the object stage, wherein the electric field is applied to at least a second individually programmable electron emitting unit during the repeated step of applying.
24. The method of claim 22 further comprising repeating the steps of applying, focusing, impacting, collimating, passing, detecting, and processing to produce multiple x-ray radiation images without rotating the object positioned on the object stage, wherein the emitted electron beam is focused on a second of the plurality of focal points on the anode target when the step of focusing is repeated.
25. The method of claim 22 , wherein the x-ray source further includes a gate electrode located between the cathode and the anode target and the electrical field is applied such that the gate electrode is at a positive potential with respect to the individually programmable electron emitting unit and a field strength of the electrical field is from 0.1 Volt/micron to 100 volt/micron.
26. The method of claim 25 , wherein the field strength is from 0.5 Volt/micron to 20 Volt/micron.
27. The method of claim 22 , wherein the electron beam emitted from each electron emitting unit is focused at a different one of the plurality of focal spots within a line on the anode target.
28. The method of claim 27 , wherein the collimator generates a fan beam geometry of x-ray radiation.
29. The method of claim 22 , wherein the step of collimating produces a fan beam geometry.
30. A computed tomography device for small animal imaging, comprising:
a field emission x-ray source, wherein the x-ray source can generate a plurality of x-ray beams from a plurality of focal spots which are arranged in a two-dimensional matrix on a surface of an x-ray anode, an area multi-pixel digital x-ray detector, and an object stage placed between the x-ray source and the detector.
31. The device of claim 30 , wherein the x-ray source comprises: a cathode with a plurality of individually programmable electron emitting units that each emit an electron beam upon an application of an electric field, wherein the emitting units are positioned in a two-dimensional matrix on the cathode; an electron focusing device; and an anode target that emits an x-ray beam from a focal spot upon impact by an emitted electron beam.
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Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20080069420A1 (en) * | 2006-05-19 | 2008-03-20 | Jian Zhang | Methods, systems, and computer porgram products for binary multiplexing x-ray radiography |
US20090022264A1 (en) * | 2007-07-19 | 2009-01-22 | Zhou Otto Z | Stationary x-ray digital breast tomosynthesis systems and related methods |
US20090086889A1 (en) * | 2007-09-28 | 2009-04-02 | Ali Bani Hashemi | System and method for tomosynthesis |
WO2009050626A1 (en) * | 2007-10-19 | 2009-04-23 | Koninklijke Philips Electronics N.V. | Imaging system with distributed sources and detectors |
WO2009089947A1 (en) * | 2008-01-15 | 2009-07-23 | Siemens Aktiengesellschaft | Method and device for producing a tomosynthetic 3d x-ray image |
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US7724870B2 (en) | 2008-05-30 | 2010-05-25 | Siemens Medical Solutions Usa, Inc. | Digital tomosynthesis in robotic stereotactic radiosurgery |
US20100239064A1 (en) * | 2005-04-25 | 2010-09-23 | Unc-Chapel Hill | Methods, systems, and computer program products for multiplexing computed tomography |
WO2010131209A1 (en) * | 2009-05-12 | 2010-11-18 | Koninklijke Philips Electronics N.V. | X-ray source with a plurality of electron emitters |
US20100329413A1 (en) * | 2009-01-16 | 2010-12-30 | Zhou Otto Z | Compact microbeam radiation therapy systems and methods for cancer treatment and research |
US20110002441A1 (en) * | 2008-02-22 | 2011-01-06 | Koninklijke Philips Electronics N.V. | High-resolution quasi-static setup for x-ray imaging with distributed sources |
US20110006224A1 (en) * | 2009-07-09 | 2011-01-13 | Maltz Jonathan S | Digital Tomosynthesis in Ion Beam Therapy Systems |
US20110075809A1 (en) * | 2009-09-29 | 2011-03-31 | Jan Boese | Method and device for recording a projection dataset of an object using a plurality of x-ray sources |
US20110080996A1 (en) * | 2009-10-05 | 2011-04-07 | Siemens Medical Solutions Usa, Inc. | Acquisition of Projection Images for Tomosynthesis |
CN102313755A (en) * | 2010-06-30 | 2012-01-11 | Fei公司 | The method of electronic diffraction tomography |
WO2012032435A1 (en) | 2010-09-06 | 2012-03-15 | Koninklijke Philips Electronics N.V. | X-ray imaging with pixelated detector |
US20120097178A1 (en) * | 2010-10-20 | 2012-04-26 | Medtronic Navigation, Inc. | Gated Image Acquisition and Patient Model Construction |
US8358739B2 (en) | 2010-09-03 | 2013-01-22 | The University Of North Carolina At Chapel Hill | Systems and methods for temporal multiplexing X-ray imaging |
WO2013082005A1 (en) * | 2011-11-29 | 2013-06-06 | American Science And Engineering, Inc. | System and methods for multi-beam inspection of cargo in relative motion |
WO2013131402A1 (en) * | 2012-03-09 | 2013-09-12 | 同方威视技术股份有限公司 | Device and method for ray scanning and imaging |
US9271689B2 (en) | 2010-01-20 | 2016-03-01 | General Electric Company | Apparatus for wide coverage computed tomography and method of constructing same |
US20160262710A1 (en) * | 2013-11-06 | 2016-09-15 | Rayence Co, Ltd. | X-ray imaging device including a plurality of x-ray sources |
WO2017173341A1 (en) * | 2016-03-31 | 2017-10-05 | The Regents Of The University Of California | Stationary x-ray source |
US9782136B2 (en) | 2014-06-17 | 2017-10-10 | The University Of North Carolina At Chapel Hill | Intraoral tomosynthesis systems, methods, and computer readable media for dental imaging |
US9807860B2 (en) | 2010-10-20 | 2017-10-31 | Medtronic Navigation, Inc. | Gated image acquisition and patient model construction |
EP3154433A4 (en) * | 2014-06-16 | 2018-03-14 | Loma Linda University | Radiography and computed tomography with high-energy electron beams |
WO2019077580A1 (en) * | 2017-10-19 | 2019-04-25 | University Of Johannesburg | Gamma ray tomographic radiography |
US10835199B2 (en) | 2016-02-01 | 2020-11-17 | The University Of North Carolina At Chapel Hill | Optical geometry calibration devices, systems, and related methods for three dimensional x-ray imaging |
US11145431B2 (en) * | 2016-08-16 | 2021-10-12 | Massachusetts Institute Of Technology | System and method for nanoscale X-ray imaging of biological specimen |
US11152130B2 (en) * | 2016-08-16 | 2021-10-19 | Massachusetts Institute Of Technology | Nanoscale X-ray tomosynthesis for rapid analysis of integrated circuit (IC) dies |
US11437218B2 (en) | 2019-11-14 | 2022-09-06 | Massachusetts Institute Of Technology | Apparatus and method for nanoscale X-ray imaging |
US11490865B2 (en) * | 2017-09-21 | 2022-11-08 | Esspen Gmbh | C-arm X-ray apparatus |
US11778717B2 (en) | 2020-06-30 | 2023-10-03 | VEC Imaging GmbH & Co. KG | X-ray source with multiple grids |
Families Citing this family (73)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7082182B2 (en) * | 2000-10-06 | 2006-07-25 | The University Of North Carolina At Chapel Hill | Computed tomography system for imaging of human and small animal |
US7455757B2 (en) * | 2001-11-30 | 2008-11-25 | The University Of North Carolina At Chapel Hill | Deposition method for nanostructure materials |
US7252749B2 (en) * | 2001-11-30 | 2007-08-07 | The University Of North Carolina At Chapel Hill | Deposition method for nanostructure materials |
US9113839B2 (en) | 2003-04-25 | 2015-08-25 | Rapiscon Systems, Inc. | X-ray inspection system and method |
US8243876B2 (en) | 2003-04-25 | 2012-08-14 | Rapiscan Systems, Inc. | X-ray scanners |
US8223919B2 (en) | 2003-04-25 | 2012-07-17 | Rapiscan Systems, Inc. | X-ray tomographic inspection systems for the identification of specific target items |
GB0525593D0 (en) | 2005-12-16 | 2006-01-25 | Cxr Ltd | X-ray tomography inspection systems |
GB0903198D0 (en) * | 2009-02-25 | 2009-04-08 | Cxr Ltd | X-Ray scanners |
US8451974B2 (en) | 2003-04-25 | 2013-05-28 | Rapiscan Systems, Inc. | X-ray tomographic inspection system for the identification of specific target items |
US8837669B2 (en) | 2003-04-25 | 2014-09-16 | Rapiscan Systems, Inc. | X-ray scanning system |
US7949101B2 (en) | 2005-12-16 | 2011-05-24 | Rapiscan Systems, Inc. | X-ray scanners and X-ray sources therefor |
US20070014148A1 (en) * | 2004-05-10 | 2007-01-18 | The University Of North Carolina At Chapel Hill | Methods and systems for attaching a magnetic nanowire to an object and apparatuses formed therefrom |
US20070009088A1 (en) * | 2005-07-06 | 2007-01-11 | Edic Peter M | System and method for imaging using distributed X-ray sources |
WO2007088497A1 (en) * | 2006-02-02 | 2007-08-09 | Philips Intellectual Property & Standards Gmbh | Imaging apparatus using distributed x-ray sources and method thereof |
JP4878311B2 (en) * | 2006-03-03 | 2012-02-15 | キヤノン株式会社 | Multi X-ray generator |
US9339243B2 (en) | 2006-04-14 | 2016-05-17 | William Beaumont Hospital | Image guided radiotherapy with dual source and dual detector arrays tetrahedron beam computed tomography |
US8983024B2 (en) | 2006-04-14 | 2015-03-17 | William Beaumont Hospital | Tetrahedron beam computed tomography with multiple detectors and/or source arrays |
JP5538880B2 (en) * | 2006-04-14 | 2014-07-02 | ウィリアム・ボーモント・ホスピタル | Tetrahedral beam computed tomography |
US7508909B2 (en) * | 2006-04-24 | 2009-03-24 | Battelle Energy Alliance, Llc | Apparatus and method for inspecting a sealed container |
JP2009538195A (en) * | 2006-05-25 | 2009-11-05 | ウィリアム・ボーモント・ホスピタル | Real-time on-line and off-line treatment dose tracking and feedback process for 3D image-guided adaptive radiotherapy |
US20080056432A1 (en) * | 2006-08-30 | 2008-03-06 | General Electric Company | Reconstruction of CT projection data |
US7706499B2 (en) * | 2006-08-30 | 2010-04-27 | General Electric Company | Acquisition and reconstruction of projection data using a stationary CT geometry |
US7852979B2 (en) * | 2007-04-05 | 2010-12-14 | General Electric Company | Dual-focus X-ray tube for resolution enhancement and energy sensitive CT |
US7885372B2 (en) * | 2007-12-07 | 2011-02-08 | Morpho Detection, Inc. | System and method for energy sensitive computed tomography |
US7809114B2 (en) * | 2008-01-21 | 2010-10-05 | General Electric Company | Field emitter based electron source for multiple spot X-ray |
US8045678B2 (en) * | 2008-03-21 | 2011-10-25 | Mxisystems, Inc. | Dynamically-varied beam energy using a tunable monochromatic X-ray beam |
US8229228B2 (en) * | 2008-09-16 | 2012-07-24 | Robert Bosch Gmbh | Image analysis using a pre-calibrated pattern of radiation |
JP4693884B2 (en) * | 2008-09-18 | 2011-06-01 | キヤノン株式会社 | Multi X-ray imaging apparatus and control method thereof |
US8111803B2 (en) * | 2009-04-29 | 2012-02-07 | General Electric Company | Method for energy sensitive computed tomography using checkerboard filtering |
US8204174B2 (en) * | 2009-06-04 | 2012-06-19 | Nextray, Inc. | Systems and methods for detecting an image of an object by use of X-ray beams generated by multiple small area sources and by use of facing sides of adjacent monochromator crystals |
DE102009040769A1 (en) * | 2009-09-09 | 2011-03-17 | Siemens Aktiengesellschaft | Apparatus and method for examining an object for material defects by means of X-rays |
KR101145628B1 (en) * | 2009-11-26 | 2012-05-15 | 기아자동차주식회사 | Pinhole detection system of fuel cell |
JP2013516278A (en) | 2010-01-05 | 2013-05-13 | ウィリアム・ボーモント・ホスピタル | Intensity-modulated rotating radiation therapy using continuous treatment table rotation / movement and simultaneous cone beam imaging |
EP2539020B1 (en) | 2010-02-24 | 2017-03-22 | Accuray Incorporated | Gantry image guided radiotherapy system |
US9687200B2 (en) | 2010-06-08 | 2017-06-27 | Accuray Incorporated | Radiation treatment delivery system with translatable ring gantry |
DE102010013359A1 (en) * | 2010-03-30 | 2011-10-06 | Siemens Aktiengesellschaft | Substrate with carbon nanotubes, use therefor and method of transferring carbon nanotubes |
DE102010019991A1 (en) * | 2010-05-10 | 2011-11-10 | Siemens Aktiengesellschaft | computed Tomography system |
US8559596B2 (en) | 2010-06-08 | 2013-10-15 | Accuray Incorporated | Target Tracking for image-guided radiation treatment |
DE102010062402B4 (en) * | 2010-12-03 | 2016-10-27 | Siemens Healthcare Gmbh | Method for obtaining a 3 D reconstruction of an object and X-ray image recording device |
US8536547B2 (en) | 2011-01-20 | 2013-09-17 | Accuray Incorporated | Ring gantry radiation treatment delivery system with dynamically controllable inward extension of treatment head |
US10849574B2 (en) * | 2011-06-22 | 2020-12-01 | Medtronic Navigation, Inc. | Interventional imaging |
KR101773960B1 (en) * | 2011-06-30 | 2017-09-12 | 한국전자통신연구원 | Tomosynthesis system |
EP2765408B1 (en) * | 2011-10-04 | 2018-07-25 | Nikon Corporation | X-ray device, x-ray irradiation method, and manufacturing method for structure |
EP2826056B1 (en) * | 2012-03-16 | 2023-07-19 | Nano-X Imaging Ltd | X-ray emitting device |
CN104205285B (en) * | 2012-03-19 | 2017-05-31 | 皇家飞利浦有限公司 | For the gradual x-ray focal spot movement of the gradual conversion between monoscopic and the observation of stereoscopic fields of view |
WO2013184213A2 (en) * | 2012-05-14 | 2013-12-12 | The General Hospital Corporation | A distributed, field emission-based x-ray source for phase contrast imaging |
JP6295254B2 (en) | 2012-08-16 | 2018-03-14 | ナノックス イメージング ピーエルシー | X-ray emission device |
US9460823B2 (en) | 2012-09-10 | 2016-10-04 | Telesecurity Sciences, Inc. | Dynamic beam aperture control to reduce radiation dose using collimator |
CN103901493B (en) * | 2012-12-27 | 2016-12-28 | 同方威视技术股份有限公司 | A kind of no frame CT device |
CN103901488A (en) * | 2012-12-27 | 2014-07-02 | 同方威视技术股份有限公司 | Fixed type CT apparatus |
KR20140106291A (en) * | 2013-02-26 | 2014-09-03 | 삼성전자주식회사 | X-ray imaging system having flat panel type X-ray generator, and X-ray generator, and electron emission device |
US9778391B2 (en) * | 2013-03-15 | 2017-10-03 | Varex Imaging Corporation | Systems and methods for multi-view imaging and tomography |
CA2906973C (en) * | 2013-04-04 | 2020-10-27 | Illinois Tool Works Inc. | Helical computed tomography |
KR20150001215A (en) * | 2013-06-26 | 2015-01-06 | 삼성전자주식회사 | Apparatus and method of photographing breast image using x-ray |
JP6188470B2 (en) * | 2013-07-24 | 2017-08-30 | キヤノン株式会社 | Radiation generator and radiation imaging system using the same |
KR20150051820A (en) * | 2013-11-05 | 2015-05-13 | 삼성전자주식회사 | Penetrative plate X-ray generating apparatus and X-ray imaging system |
US10269527B2 (en) | 2013-11-27 | 2019-04-23 | Nanox Imaging Plc | Electron emitting construct configured with ion bombardment resistant |
KR102234422B1 (en) * | 2014-02-07 | 2021-03-31 | 주식회사 바텍 | X-ray photographing apparatus |
GB2531326B (en) * | 2014-10-16 | 2020-08-05 | Adaptix Ltd | An X-Ray emitter panel and a method of designing such an X-Ray emitter panel |
US10390774B2 (en) * | 2014-11-19 | 2019-08-27 | Guy M. Besson | Annular ring target multi-source CT system |
US10436721B2 (en) * | 2015-07-22 | 2019-10-08 | UHV Technologies, Inc. | X-ray imaging and chemical analysis of plant roots |
US10076292B2 (en) | 2015-10-16 | 2018-09-18 | General Electric Company | Systems and methods for x-ray tomography having retrograde focal positioning |
US10448910B2 (en) * | 2016-02-03 | 2019-10-22 | Globus Medical, Inc. | Portable medical imaging system |
US10991539B2 (en) * | 2016-03-31 | 2021-04-27 | Nano-X Imaging Ltd. | X-ray tube and a conditioning method thereof |
US11282668B2 (en) * | 2016-03-31 | 2022-03-22 | Nano-X Imaging Ltd. | X-ray tube and a controller thereof |
CN109152561B (en) * | 2016-05-11 | 2023-04-04 | 皇家飞利浦有限公司 | Anatomically adjusted acquisition with a stationary multi-source X-ray system |
US10585206B2 (en) | 2017-09-06 | 2020-03-10 | Rapiscan Systems, Inc. | Method and system for a multi-view scanner |
CN112567893A (en) * | 2018-05-25 | 2021-03-26 | 微-X有限公司 | Device for applying beam forming signal processing to RF modulation X-ray |
JP7143567B2 (en) * | 2018-09-14 | 2022-09-29 | 株式会社島津テクノリサーチ | Material testing machine and radiation CT equipment |
US11448605B2 (en) * | 2019-02-14 | 2022-09-20 | Psylotech, Inc. | Scanner load frame |
US11212902B2 (en) | 2020-02-25 | 2021-12-28 | Rapiscan Systems, Inc. | Multiplexed drive systems and methods for a multi-emitter X-ray source |
DE102020111182A1 (en) * | 2020-04-24 | 2021-10-28 | Helmholtz-Zentrum Dresden - Rossendorf E. V. | Transmission imaging apparatus and method |
US11409019B1 (en) | 2021-04-19 | 2022-08-09 | Micro-X Limited | Device for producing high resolution backscatter images |
Citations (89)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2842706A (en) * | 1956-03-01 | 1958-07-08 | Dobischek Dietrich | Cold cathode vacuum tube |
US3733484A (en) * | 1969-10-29 | 1973-05-15 | Walter C Mc Crone Associates I | Control for electron microprobe |
US3753020A (en) * | 1971-11-26 | 1973-08-14 | Philips Electronics And Pharm | Multi-anode x-ray tube |
US3783288A (en) * | 1972-06-26 | 1974-01-01 | Field Emission Corp | Pulsed vacuum arc operation of field emission x-ray tube without anode melting |
US3932756A (en) * | 1974-06-24 | 1976-01-13 | Sybron Corporation | X-ray detector for a panoramic X-ray device |
US4012656A (en) * | 1974-12-09 | 1977-03-15 | Norman Ralph L | X-ray tube |
US4253221A (en) * | 1979-06-14 | 1981-03-03 | Georgia Tech Research Institute | Method of producing low voltage field emission cathode structure |
US4289969A (en) * | 1978-07-10 | 1981-09-15 | Butler Greenwich Inc. | Radiation imaging apparatus |
US4382184A (en) * | 1978-11-24 | 1983-05-03 | Cardiac Imaging Limited Partnership | Apparatus and method for simultaneously displaying relative displacements of a fluctuating biological object |
US4780612A (en) * | 1987-01-30 | 1988-10-25 | Hughes Aircraft Company | Method and apparatus for multiplexing signals from electromagnetic radiation detectors |
US4809308A (en) * | 1986-02-20 | 1989-02-28 | Irt Corporation | Method and apparatus for performing automated circuit board solder quality inspections |
US4926452A (en) * | 1987-10-30 | 1990-05-15 | Four Pi Systems Corporation | Automated laminography system for inspection of electronics |
US4958365A (en) * | 1981-10-21 | 1990-09-18 | Elscint Ltd. | Medical imaging device using triggered plasma cathode flash X-ray source |
US5129850A (en) * | 1991-08-20 | 1992-07-14 | Motorola, Inc. | Method of making a molded field emission electron emitter employing a diamond coating |
US5138237A (en) * | 1991-08-20 | 1992-08-11 | Motorola, Inc. | Field emission electron device employing a modulatable diamond semiconductor emitter |
US5245648A (en) * | 1991-04-05 | 1993-09-14 | The United States Of America As Represented By The United States Department Of Energy | X-ray tomographic image magnification process, system and apparatus therefor |
US5305363A (en) * | 1992-01-06 | 1994-04-19 | Picker International, Inc. | Computerized tomographic scanner having a toroidal x-ray tube with a stationary annular anode and a rotating cathode assembly |
US5412703A (en) * | 1993-02-04 | 1995-05-02 | Institute For Radiological Image Science, Inc. | Reduced partial volume artifacts in image reconstruction, with application to X-ray computed tomography |
US5424054A (en) * | 1993-05-21 | 1995-06-13 | International Business Machines Corporation | Carbon fibers and method for their production |
US5557105A (en) * | 1991-06-10 | 1996-09-17 | Fujitsu Limited | Pattern inspection apparatus and electron beam apparatus |
US5594770A (en) * | 1994-11-18 | 1997-01-14 | Thermospectra Corporation | Method and apparatus for imaging obscured areas of a test object |
US5616368A (en) * | 1995-01-31 | 1997-04-01 | Lucent Technologies Inc. | Field emission devices employing activated diamond particle emitters and methods for making same |
US5623180A (en) * | 1994-10-31 | 1997-04-22 | Lucent Technologies Inc. | Electron field emitters comprising particles cooled with low voltage emitting material |
US5637950A (en) * | 1994-10-31 | 1997-06-10 | Lucent Technologies Inc. | Field emission devices employing enhanced diamond field emitters |
US5648699A (en) * | 1995-11-09 | 1997-07-15 | Lucent Technologies Inc. | Field emission devices employing improved emitters on metal foil and methods for making such devices |
US5726524A (en) * | 1996-05-31 | 1998-03-10 | Minnesota Mining And Manufacturing Company | Field emission device having nanostructured emitters |
US5754437A (en) * | 1996-09-10 | 1998-05-19 | Tektronix, Inc. | Phase measurement apparatus and method |
US5764683A (en) * | 1996-02-12 | 1998-06-09 | American Science And Engineering, Inc. | Mobile X-ray inspection system for large objects |
US5773834A (en) * | 1996-02-13 | 1998-06-30 | Director-General Of Agency Of Industrial Science And Technology | Method of forming carbon nanotubes on a carbonaceous body, composite material obtained thereby and electron beam source element using same |
US5773921A (en) * | 1994-02-23 | 1998-06-30 | Keesmann; Till | Field emission cathode having an electrically conducting material shaped of a narrow rod or knife edge |
US5910974A (en) * | 1995-03-20 | 1999-06-08 | Siemens Aktiengesellschaft | Method for operating an x-ray tube |
US6019656A (en) * | 1997-11-29 | 2000-02-01 | Electronics And Telecommunications Research Institute | Method of fabricating a field emission device by using carbon nano-tubes |
US6028911A (en) * | 1998-08-03 | 2000-02-22 | Rigaku Industrial Corporation | X-ray analyzing apparatus with enhanced radiation intensity |
US6057637A (en) * | 1996-09-13 | 2000-05-02 | The Regents Of The University Of California | Field emission electron source |
US6087765A (en) * | 1997-12-03 | 2000-07-11 | Motorola, Inc. | Electron emissive film |
US6097138A (en) * | 1996-09-18 | 2000-08-01 | Kabushiki Kaisha Toshiba | Field emission cold-cathode device |
US6097788A (en) * | 1998-04-14 | 2000-08-01 | Siemens Aktiengesellschaft | Method and apparatus for multi-planar radiation emission for imaging |
US6125167A (en) * | 1998-11-25 | 2000-09-26 | Picker International, Inc. | Rotating anode x-ray tube with multiple simultaneously emitting focal spots |
US6178226B1 (en) * | 1997-08-18 | 2001-01-23 | Siemens Aktiengesellschaft | Method for controlling the electron current in an x-ray tube, and x-ray system operating according to the method |
US6192104B1 (en) * | 1998-11-30 | 2001-02-20 | American Science And Engineering, Inc. | Fan and pencil beams from a common source for x-ray inspection |
US6250984B1 (en) * | 1999-01-25 | 2001-06-26 | Agere Systems Guardian Corp. | Article comprising enhanced nanotube emitter structure and process for fabricating article |
US6259765B1 (en) * | 1997-06-13 | 2001-07-10 | Commissariat A L'energie Atomique | X-ray tube comprising an electron source with microtips and magnetic guiding means |
US6271923B1 (en) * | 1999-05-05 | 2001-08-07 | Zygo Corporation | Interferometry system having a dynamic beam steering assembly for measuring angle and distance |
US6277318B1 (en) * | 1999-08-18 | 2001-08-21 | Agere Systems Guardian Corp. | Method for fabrication of patterned carbon nanotube films |
US6280697B1 (en) * | 1999-03-01 | 2001-08-28 | The University Of North Carolina-Chapel Hill | Nanotube-based high energy material and method |
US20010019601A1 (en) * | 2000-03-06 | 2001-09-06 | Rigaku Corporation | X-ray generator |
US6334939B1 (en) * | 2000-06-15 | 2002-01-01 | The University Of North Carolina At Chapel Hill | Nanostructure-based high energy capacity material |
US6385292B1 (en) * | 2000-12-29 | 2002-05-07 | Ge Medical Systems Global Technology Company, Llc | Solid-state CT system and method |
US20020085674A1 (en) * | 2000-12-29 | 2002-07-04 | Price John Scott | Radiography device with flat panel X-ray source |
US20020094064A1 (en) * | 2000-10-06 | 2002-07-18 | Zhou Otto Z. | Large-area individually addressable multi-beam x-ray system and method of forming same |
US20020110996A1 (en) * | 2000-12-08 | 2002-08-15 | Si Diamond Technology, Inc. | Low work function material |
US6440761B1 (en) * | 1999-05-24 | 2002-08-27 | Samsung Sdi Co., Ltd. | Carbon nanotube field emission array and method for fabricating the same |
US6445122B1 (en) * | 2000-02-22 | 2002-09-03 | Industrial Technology Research Institute | Field emission display panel having cathode and anode on the same panel substrate |
US20030002627A1 (en) * | 2000-09-28 | 2003-01-02 | Oxford Instruments, Inc. | Cold emitter x-ray tube incorporating a nanostructured carbon film electron emitter |
US6510195B1 (en) * | 2001-07-18 | 2003-01-21 | Koninklijke Philips Electronics, N.V. | Solid state x-radiation detector modules and mosaics thereof, and an imaging method and apparatus employing the same |
US6529575B1 (en) * | 2002-04-29 | 2003-03-04 | Ge Medical Systems Global Technology Company, Llc | Adaptive projection filtering scheme for noise reduction |
US20030048868A1 (en) * | 2001-08-09 | 2003-03-13 | Bailey Eric M. | Combined radiation therapy and imaging system and method |
US6545396B1 (en) * | 1999-10-21 | 2003-04-08 | Sharp Kabushiki Kaisha | Image forming device using field emission electron source arrays |
US6553096B1 (en) * | 2000-10-06 | 2003-04-22 | The University Of North Carolina Chapel Hill | X-ray generating mechanism using electron field emission cathode |
US6560309B1 (en) * | 1999-11-28 | 2003-05-06 | Siemens Aktiengesellschaft | Method for examining a body region executing a periodic motion |
US20030102222A1 (en) * | 2001-11-30 | 2003-06-05 | Zhou Otto Z. | Deposition method for nanostructure materials |
US20030103666A1 (en) * | 2001-12-05 | 2003-06-05 | General Electric Company One Research Circle | Iterative X-ray scatter correction method and apparatus |
US6621887B2 (en) * | 2001-10-15 | 2003-09-16 | General Electric Company | Method and apparatus for processing a fluoroscopic image |
US6674837B1 (en) * | 2001-06-15 | 2004-01-06 | Nan Crystal Imaging Corporation | X-ray imaging system incorporating pixelated X-ray source and synchronized detector |
US20040017888A1 (en) * | 2002-07-24 | 2004-01-29 | Seppi Edward J. | Radiation scanning of objects for contraband |
US20040065465A1 (en) * | 2002-10-03 | 2004-04-08 | Koninklijke Philips Electronics N.V. | Symmetrical multiple-slice computed tomography data management system |
US20040108298A1 (en) * | 2002-07-03 | 2004-06-10 | Applied Nanotechnologies, Inc. | Fabrication and activation processes for nanostructure composite field emission cathodes |
US20040114721A1 (en) * | 2000-10-06 | 2004-06-17 | Applied Nanotechnologies, Inc. | Devices and methods for producing multiple x-ray beams from multiple locations |
US6754300B2 (en) * | 2002-06-20 | 2004-06-22 | Ge Medical Systems Global Technology Company, Llc | Methods and apparatus for operating a radiation source |
US6760407B2 (en) * | 2002-04-17 | 2004-07-06 | Ge Medical Global Technology Company, Llc | X-ray source and method having cathode with curved emission surface |
USRE38561E1 (en) * | 1995-02-22 | 2004-08-03 | Till Keesmann | Field emission cathode |
US6787122B2 (en) * | 2001-06-18 | 2004-09-07 | The University Of North Carolina At Chapel Hill | Method of making nanotube-based material with enhanced electron field emission properties |
US6852973B2 (en) * | 2002-04-10 | 2005-02-08 | Sii Nanotechnology Inc. | Scanning charged particle microscope |
US20050028554A1 (en) * | 2000-05-31 | 2005-02-10 | Alfred Wanner | Multistoreyed bath condenser |
US20050084073A1 (en) * | 2003-10-15 | 2005-04-21 | Seppi Edward J. | Multi-energy x-ray source |
US20050117701A1 (en) * | 2003-12-01 | 2005-06-02 | Nelson James M. | Backscatter imaging using hadamard transform masking |
US20050175151A1 (en) * | 2004-02-05 | 2005-08-11 | Ge Medical Systems Global Technology Company, Llc | Emitter array configurations for a stationary ct system |
US6950493B2 (en) * | 2003-06-25 | 2005-09-27 | Besson Guy M | Dynamic multi-spectral CT imaging |
US7027558B2 (en) * | 2001-10-26 | 2006-04-11 | Siemens Medical Solutions Usa, Inc. | X-ray therapy electronic portal imaging system and method for artifact reduction |
US7046757B1 (en) * | 2005-04-18 | 2006-05-16 | Siemens Medical Solutions Usa, Inc. | X-ray scatter elimination by frequency shifting |
US7082182B2 (en) * | 2000-10-06 | 2006-07-25 | The University Of North Carolina At Chapel Hill | Computed tomography system for imaging of human and small animal |
US7085351B2 (en) * | 2000-10-06 | 2006-08-01 | University Of North Carolina At Chapel Hill | Method and apparatus for controlling electron beam current |
US7220971B1 (en) * | 2004-12-29 | 2007-05-22 | The University Of North Carolina At Chapel Hill | Multi-pixel electron microbeam irradiator systems and methods for selectively irradiating predetermined locations |
US7227924B2 (en) * | 2000-10-06 | 2007-06-05 | The University Of North Carolina At Chapel Hill | Computed tomography scanning system and method using a field emission x-ray source |
US7245692B2 (en) * | 2005-04-25 | 2007-07-17 | The University Of North Carolina At Chapel Hill | X-ray imaging systems and methods using temporal digital signal processing for reducing noise and for obtaining multiple images simultaneously |
US20080031400A1 (en) * | 2004-05-06 | 2008-02-07 | Luc Beaulieu | 3D Localization Of Objects From Tomography Data |
US20080069420A1 (en) * | 2006-05-19 | 2008-03-20 | Jian Zhang | Methods, systems, and computer porgram products for binary multiplexing x-ray radiography |
US7751528B2 (en) * | 2007-07-19 | 2010-07-06 | The University Of North Carolina | Stationary x-ray digital breast tomosynthesis systems and related methods |
US20100239064A1 (en) * | 2005-04-25 | 2010-09-23 | Unc-Chapel Hill | Methods, systems, and computer program products for multiplexing computed tomography |
Family Cites Families (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3921022A (en) | 1974-09-03 | 1975-11-18 | Rca Corp | Field emitting device and method of making same |
DE4139150C1 (en) | 1991-11-28 | 1993-06-24 | Siemens Ag, 8000 Muenchen, De | Computer tomograph with part ring formed X=ray source and detector - has double ring system without complementary interpolation |
US5448607A (en) * | 1994-02-08 | 1995-09-05 | Analogic Corporation | X-ray tomography system with gantry pivot and translation control |
US5872422A (en) | 1995-12-20 | 1999-02-16 | Advanced Technology Materials, Inc. | Carbon fiber-based field emission devices |
US5976444A (en) | 1996-09-24 | 1999-11-02 | The United States Of America As Represented By The Secretary Of The Navy | Nanochannel glass replica membranes |
US6630772B1 (en) | 1998-09-21 | 2003-10-07 | Agere Systems Inc. | Device comprising carbon nanotube field emitter structure and process for forming device |
US6333968B1 (en) * | 2000-05-05 | 2001-12-25 | The United States Of America As Represented By The Secretary Of The Navy | Transmission cathode for X-ray production |
US20040213378A1 (en) | 2003-04-24 | 2004-10-28 | The University Of North Carolina At Chapel Hill | Computed tomography system for imaging of human and small animal |
US6459767B1 (en) | 2000-12-12 | 2002-10-01 | Oxford Instruments, Inc. | Portable x-ray fluorescence spectrometer |
US6650730B2 (en) | 2001-01-23 | 2003-11-18 | Fartech, Inc. | Filter assembly for X-ray filter system for medical imaging contrast enhancement |
US6949877B2 (en) | 2001-03-27 | 2005-09-27 | General Electric Company | Electron emitter including carbon nanotubes and its application in gas discharge devices |
US6965199B2 (en) | 2001-03-27 | 2005-11-15 | The University Of North Carolina At Chapel Hill | Coated electrode with enhanced electron emission and ignition characteristics |
-
2004
- 2004-08-20 US US10/923,385 patent/US7082182B2/en not_active Expired - Lifetime
-
2006
- 2006-05-25 US US11/441,281 patent/US20070009081A1/en not_active Abandoned
Patent Citations (99)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2842706A (en) * | 1956-03-01 | 1958-07-08 | Dobischek Dietrich | Cold cathode vacuum tube |
US3733484A (en) * | 1969-10-29 | 1973-05-15 | Walter C Mc Crone Associates I | Control for electron microprobe |
US3753020A (en) * | 1971-11-26 | 1973-08-14 | Philips Electronics And Pharm | Multi-anode x-ray tube |
US3783288A (en) * | 1972-06-26 | 1974-01-01 | Field Emission Corp | Pulsed vacuum arc operation of field emission x-ray tube without anode melting |
US3932756A (en) * | 1974-06-24 | 1976-01-13 | Sybron Corporation | X-ray detector for a panoramic X-ray device |
US4012656A (en) * | 1974-12-09 | 1977-03-15 | Norman Ralph L | X-ray tube |
US4289969A (en) * | 1978-07-10 | 1981-09-15 | Butler Greenwich Inc. | Radiation imaging apparatus |
US4382184A (en) * | 1978-11-24 | 1983-05-03 | Cardiac Imaging Limited Partnership | Apparatus and method for simultaneously displaying relative displacements of a fluctuating biological object |
US4253221A (en) * | 1979-06-14 | 1981-03-03 | Georgia Tech Research Institute | Method of producing low voltage field emission cathode structure |
US4958365A (en) * | 1981-10-21 | 1990-09-18 | Elscint Ltd. | Medical imaging device using triggered plasma cathode flash X-ray source |
US4809308A (en) * | 1986-02-20 | 1989-02-28 | Irt Corporation | Method and apparatus for performing automated circuit board solder quality inspections |
US4780612A (en) * | 1987-01-30 | 1988-10-25 | Hughes Aircraft Company | Method and apparatus for multiplexing signals from electromagnetic radiation detectors |
US4926452A (en) * | 1987-10-30 | 1990-05-15 | Four Pi Systems Corporation | Automated laminography system for inspection of electronics |
US5245648A (en) * | 1991-04-05 | 1993-09-14 | The United States Of America As Represented By The United States Department Of Energy | X-ray tomographic image magnification process, system and apparatus therefor |
US5557105A (en) * | 1991-06-10 | 1996-09-17 | Fujitsu Limited | Pattern inspection apparatus and electron beam apparatus |
US5129850A (en) * | 1991-08-20 | 1992-07-14 | Motorola, Inc. | Method of making a molded field emission electron emitter employing a diamond coating |
US5138237A (en) * | 1991-08-20 | 1992-08-11 | Motorola, Inc. | Field emission electron device employing a modulatable diamond semiconductor emitter |
US5305363A (en) * | 1992-01-06 | 1994-04-19 | Picker International, Inc. | Computerized tomographic scanner having a toroidal x-ray tube with a stationary annular anode and a rotating cathode assembly |
US5412703A (en) * | 1993-02-04 | 1995-05-02 | Institute For Radiological Image Science, Inc. | Reduced partial volume artifacts in image reconstruction, with application to X-ray computed tomography |
US5424054A (en) * | 1993-05-21 | 1995-06-13 | International Business Machines Corporation | Carbon fibers and method for their production |
US5773921A (en) * | 1994-02-23 | 1998-06-30 | Keesmann; Till | Field emission cathode having an electrically conducting material shaped of a narrow rod or knife edge |
USRE38223E1 (en) * | 1994-02-23 | 2003-08-19 | Till Keesmann | Field emission cathode having an electrically conducting material shaped of a narrow rod or knife edge |
US20040036402A1 (en) * | 1994-02-23 | 2004-02-26 | Till Keesmann | Field emission cathode using carbon fibers |
US5623180A (en) * | 1994-10-31 | 1997-04-22 | Lucent Technologies Inc. | Electron field emitters comprising particles cooled with low voltage emitting material |
US5637950A (en) * | 1994-10-31 | 1997-06-10 | Lucent Technologies Inc. | Field emission devices employing enhanced diamond field emitters |
US5594770A (en) * | 1994-11-18 | 1997-01-14 | Thermospectra Corporation | Method and apparatus for imaging obscured areas of a test object |
US5616368A (en) * | 1995-01-31 | 1997-04-01 | Lucent Technologies Inc. | Field emission devices employing activated diamond particle emitters and methods for making same |
USRE38561E1 (en) * | 1995-02-22 | 2004-08-03 | Till Keesmann | Field emission cathode |
US5910974A (en) * | 1995-03-20 | 1999-06-08 | Siemens Aktiengesellschaft | Method for operating an x-ray tube |
US5648699A (en) * | 1995-11-09 | 1997-07-15 | Lucent Technologies Inc. | Field emission devices employing improved emitters on metal foil and methods for making such devices |
US5764683A (en) * | 1996-02-12 | 1998-06-09 | American Science And Engineering, Inc. | Mobile X-ray inspection system for large objects |
US5764683B1 (en) * | 1996-02-12 | 2000-11-21 | American Science & Eng Inc | Mobile x-ray inspection system for large objects |
US5773834A (en) * | 1996-02-13 | 1998-06-30 | Director-General Of Agency Of Industrial Science And Technology | Method of forming carbon nanotubes on a carbonaceous body, composite material obtained thereby and electron beam source element using same |
US5726524A (en) * | 1996-05-31 | 1998-03-10 | Minnesota Mining And Manufacturing Company | Field emission device having nanostructured emitters |
US5754437A (en) * | 1996-09-10 | 1998-05-19 | Tektronix, Inc. | Phase measurement apparatus and method |
US6057637A (en) * | 1996-09-13 | 2000-05-02 | The Regents Of The University Of California | Field emission electron source |
US6097138A (en) * | 1996-09-18 | 2000-08-01 | Kabushiki Kaisha Toshiba | Field emission cold-cathode device |
US6259765B1 (en) * | 1997-06-13 | 2001-07-10 | Commissariat A L'energie Atomique | X-ray tube comprising an electron source with microtips and magnetic guiding means |
US6178226B1 (en) * | 1997-08-18 | 2001-01-23 | Siemens Aktiengesellschaft | Method for controlling the electron current in an x-ray tube, and x-ray system operating according to the method |
US6019656A (en) * | 1997-11-29 | 2000-02-01 | Electronics And Telecommunications Research Institute | Method of fabricating a field emission device by using carbon nano-tubes |
US6087765A (en) * | 1997-12-03 | 2000-07-11 | Motorola, Inc. | Electron emissive film |
US6097788A (en) * | 1998-04-14 | 2000-08-01 | Siemens Aktiengesellschaft | Method and apparatus for multi-planar radiation emission for imaging |
US6028911A (en) * | 1998-08-03 | 2000-02-22 | Rigaku Industrial Corporation | X-ray analyzing apparatus with enhanced radiation intensity |
US6125167A (en) * | 1998-11-25 | 2000-09-26 | Picker International, Inc. | Rotating anode x-ray tube with multiple simultaneously emitting focal spots |
US6192104B1 (en) * | 1998-11-30 | 2001-02-20 | American Science And Engineering, Inc. | Fan and pencil beams from a common source for x-ray inspection |
US6250984B1 (en) * | 1999-01-25 | 2001-06-26 | Agere Systems Guardian Corp. | Article comprising enhanced nanotube emitter structure and process for fabricating article |
US6280697B1 (en) * | 1999-03-01 | 2001-08-28 | The University Of North Carolina-Chapel Hill | Nanotube-based high energy material and method |
US6271923B1 (en) * | 1999-05-05 | 2001-08-07 | Zygo Corporation | Interferometry system having a dynamic beam steering assembly for measuring angle and distance |
US6440761B1 (en) * | 1999-05-24 | 2002-08-27 | Samsung Sdi Co., Ltd. | Carbon nanotube field emission array and method for fabricating the same |
US6277318B1 (en) * | 1999-08-18 | 2001-08-21 | Agere Systems Guardian Corp. | Method for fabrication of patterned carbon nanotube films |
US6545396B1 (en) * | 1999-10-21 | 2003-04-08 | Sharp Kabushiki Kaisha | Image forming device using field emission electron source arrays |
US6560309B1 (en) * | 1999-11-28 | 2003-05-06 | Siemens Aktiengesellschaft | Method for examining a body region executing a periodic motion |
US6445122B1 (en) * | 2000-02-22 | 2002-09-03 | Industrial Technology Research Institute | Field emission display panel having cathode and anode on the same panel substrate |
US6456691B2 (en) * | 2000-03-06 | 2002-09-24 | Rigaku Corporation | X-ray generator |
US20010019601A1 (en) * | 2000-03-06 | 2001-09-06 | Rigaku Corporation | X-ray generator |
US20050028554A1 (en) * | 2000-05-31 | 2005-02-10 | Alfred Wanner | Multistoreyed bath condenser |
US6334939B1 (en) * | 2000-06-15 | 2002-01-01 | The University Of North Carolina At Chapel Hill | Nanostructure-based high energy capacity material |
US20030002627A1 (en) * | 2000-09-28 | 2003-01-02 | Oxford Instruments, Inc. | Cold emitter x-ray tube incorporating a nanostructured carbon film electron emitter |
US6553096B1 (en) * | 2000-10-06 | 2003-04-22 | The University Of North Carolina Chapel Hill | X-ray generating mechanism using electron field emission cathode |
US20020094064A1 (en) * | 2000-10-06 | 2002-07-18 | Zhou Otto Z. | Large-area individually addressable multi-beam x-ray system and method of forming same |
US7359484B2 (en) * | 2000-10-06 | 2008-04-15 | Xintek, Inc | Devices and methods for producing multiple x-ray beams from multiple locations |
US20060018432A1 (en) * | 2000-10-06 | 2006-01-26 | The University Of North Carolina At Chapel Hill | Large-area individually addressable multi-beam x-ray system and method of forming same |
US6876724B2 (en) * | 2000-10-06 | 2005-04-05 | The University Of North Carolina - Chapel Hill | Large-area individually addressable multi-beam x-ray system and method of forming same |
US20030142790A1 (en) * | 2000-10-06 | 2003-07-31 | Zhou Otto Z. | X-ray generating mechanism using electron field emission cathode |
US20040114721A1 (en) * | 2000-10-06 | 2004-06-17 | Applied Nanotechnologies, Inc. | Devices and methods for producing multiple x-ray beams from multiple locations |
US7082182B2 (en) * | 2000-10-06 | 2006-07-25 | The University Of North Carolina At Chapel Hill | Computed tomography system for imaging of human and small animal |
US6850595B2 (en) * | 2000-10-06 | 2005-02-01 | The University Of North Carolina At Chapel Hill | X-ray generating mechanism using electron field emission cathode |
US7085351B2 (en) * | 2000-10-06 | 2006-08-01 | University Of North Carolina At Chapel Hill | Method and apparatus for controlling electron beam current |
US7227924B2 (en) * | 2000-10-06 | 2007-06-05 | The University Of North Carolina At Chapel Hill | Computed tomography scanning system and method using a field emission x-ray source |
US20020110996A1 (en) * | 2000-12-08 | 2002-08-15 | Si Diamond Technology, Inc. | Low work function material |
US6385292B1 (en) * | 2000-12-29 | 2002-05-07 | Ge Medical Systems Global Technology Company, Llc | Solid-state CT system and method |
US20020085674A1 (en) * | 2000-12-29 | 2002-07-04 | Price John Scott | Radiography device with flat panel X-ray source |
US6674837B1 (en) * | 2001-06-15 | 2004-01-06 | Nan Crystal Imaging Corporation | X-ray imaging system incorporating pixelated X-ray source and synchronized detector |
US6787122B2 (en) * | 2001-06-18 | 2004-09-07 | The University Of North Carolina At Chapel Hill | Method of making nanotube-based material with enhanced electron field emission properties |
US6510195B1 (en) * | 2001-07-18 | 2003-01-21 | Koninklijke Philips Electronics, N.V. | Solid state x-radiation detector modules and mosaics thereof, and an imaging method and apparatus employing the same |
US20030048868A1 (en) * | 2001-08-09 | 2003-03-13 | Bailey Eric M. | Combined radiation therapy and imaging system and method |
US6621887B2 (en) * | 2001-10-15 | 2003-09-16 | General Electric Company | Method and apparatus for processing a fluoroscopic image |
US7027558B2 (en) * | 2001-10-26 | 2006-04-11 | Siemens Medical Solutions Usa, Inc. | X-ray therapy electronic portal imaging system and method for artifact reduction |
US20050133372A1 (en) * | 2001-11-30 | 2005-06-23 | The University Of North Carolina | Method and apparatus for attaching nanostructure-containing material onto a sharp tip of an object and related articles |
US20030102222A1 (en) * | 2001-11-30 | 2003-06-05 | Zhou Otto Z. | Deposition method for nanostructure materials |
US20030103666A1 (en) * | 2001-12-05 | 2003-06-05 | General Electric Company One Research Circle | Iterative X-ray scatter correction method and apparatus |
US6852973B2 (en) * | 2002-04-10 | 2005-02-08 | Sii Nanotechnology Inc. | Scanning charged particle microscope |
US6760407B2 (en) * | 2002-04-17 | 2004-07-06 | Ge Medical Global Technology Company, Llc | X-ray source and method having cathode with curved emission surface |
US6529575B1 (en) * | 2002-04-29 | 2003-03-04 | Ge Medical Systems Global Technology Company, Llc | Adaptive projection filtering scheme for noise reduction |
US6754300B2 (en) * | 2002-06-20 | 2004-06-22 | Ge Medical Systems Global Technology Company, Llc | Methods and apparatus for operating a radiation source |
US20040108298A1 (en) * | 2002-07-03 | 2004-06-10 | Applied Nanotechnologies, Inc. | Fabrication and activation processes for nanostructure composite field emission cathodes |
US20040017888A1 (en) * | 2002-07-24 | 2004-01-29 | Seppi Edward J. | Radiation scanning of objects for contraband |
US20040065465A1 (en) * | 2002-10-03 | 2004-04-08 | Koninklijke Philips Electronics N.V. | Symmetrical multiple-slice computed tomography data management system |
US6950493B2 (en) * | 2003-06-25 | 2005-09-27 | Besson Guy M | Dynamic multi-spectral CT imaging |
US20050084073A1 (en) * | 2003-10-15 | 2005-04-21 | Seppi Edward J. | Multi-energy x-ray source |
US20050117701A1 (en) * | 2003-12-01 | 2005-06-02 | Nelson James M. | Backscatter imaging using hadamard transform masking |
US20050175151A1 (en) * | 2004-02-05 | 2005-08-11 | Ge Medical Systems Global Technology Company, Llc | Emitter array configurations for a stationary ct system |
US20080031400A1 (en) * | 2004-05-06 | 2008-02-07 | Luc Beaulieu | 3D Localization Of Objects From Tomography Data |
US7220971B1 (en) * | 2004-12-29 | 2007-05-22 | The University Of North Carolina At Chapel Hill | Multi-pixel electron microbeam irradiator systems and methods for selectively irradiating predetermined locations |
US7046757B1 (en) * | 2005-04-18 | 2006-05-16 | Siemens Medical Solutions Usa, Inc. | X-ray scatter elimination by frequency shifting |
US7245692B2 (en) * | 2005-04-25 | 2007-07-17 | The University Of North Carolina At Chapel Hill | X-ray imaging systems and methods using temporal digital signal processing for reducing noise and for obtaining multiple images simultaneously |
US20100239064A1 (en) * | 2005-04-25 | 2010-09-23 | Unc-Chapel Hill | Methods, systems, and computer program products for multiplexing computed tomography |
US20080069420A1 (en) * | 2006-05-19 | 2008-03-20 | Jian Zhang | Methods, systems, and computer porgram products for binary multiplexing x-ray radiography |
US7751528B2 (en) * | 2007-07-19 | 2010-07-06 | The University Of North Carolina | Stationary x-ray digital breast tomosynthesis systems and related methods |
Cited By (56)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20100239064A1 (en) * | 2005-04-25 | 2010-09-23 | Unc-Chapel Hill | Methods, systems, and computer program products for multiplexing computed tomography |
US8155262B2 (en) | 2005-04-25 | 2012-04-10 | The University Of North Carolina At Chapel Hill | Methods, systems, and computer program products for multiplexing computed tomography |
US8189893B2 (en) | 2006-05-19 | 2012-05-29 | The University Of North Carolina At Chapel Hill | Methods, systems, and computer program products for binary multiplexing x-ray radiography |
US20080069420A1 (en) * | 2006-05-19 | 2008-03-20 | Jian Zhang | Methods, systems, and computer porgram products for binary multiplexing x-ray radiography |
US20090022264A1 (en) * | 2007-07-19 | 2009-01-22 | Zhou Otto Z | Stationary x-ray digital breast tomosynthesis systems and related methods |
WO2009012453A1 (en) * | 2007-07-19 | 2009-01-22 | The University Of North Carolina At Chapel Hill | Stationary x-ray digital breast tomosynthesis systems and related methods |
US7751528B2 (en) | 2007-07-19 | 2010-07-06 | The University Of North Carolina | Stationary x-ray digital breast tomosynthesis systems and related methods |
US20090086889A1 (en) * | 2007-09-28 | 2009-04-02 | Ali Bani Hashemi | System and method for tomosynthesis |
US7936858B2 (en) * | 2007-09-28 | 2011-05-03 | Siemens Medical Solutions Usa, Inc. | System and method for tomosynthesis |
WO2009050626A1 (en) * | 2007-10-19 | 2009-04-23 | Koninklijke Philips Electronics N.V. | Imaging system with distributed sources and detectors |
WO2009089947A1 (en) * | 2008-01-15 | 2009-07-23 | Siemens Aktiengesellschaft | Method and device for producing a tomosynthetic 3d x-ray image |
US20100034450A1 (en) * | 2008-01-15 | 2010-02-11 | Thomas Mertelmeier | Method and device for producing a tomosynthetic 3d x-ray image |
US20110002441A1 (en) * | 2008-02-22 | 2011-01-06 | Koninklijke Philips Electronics N.V. | High-resolution quasi-static setup for x-ray imaging with distributed sources |
US8491188B2 (en) | 2008-02-22 | 2013-07-23 | Koninklijke Philips N.V. | High-resolution quasi-static setup for X-ray imaging with distributed sources |
US7724870B2 (en) | 2008-05-30 | 2010-05-25 | Siemens Medical Solutions Usa, Inc. | Digital tomosynthesis in robotic stereotactic radiosurgery |
WO2009151197A1 (en) * | 2008-06-13 | 2009-12-17 | 한국전기연구원 | X-ray tube using nano-structure material and system using the same |
US20100329413A1 (en) * | 2009-01-16 | 2010-12-30 | Zhou Otto Z | Compact microbeam radiation therapy systems and methods for cancer treatment and research |
US8995608B2 (en) | 2009-01-16 | 2015-03-31 | The University Of North Carolina At Chapel Hill | Compact microbeam radiation therapy systems and methods for cancer treatment and research |
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WO2010131209A1 (en) * | 2009-05-12 | 2010-11-18 | Koninklijke Philips Electronics N.V. | X-ray source with a plurality of electron emitters |
US8989351B2 (en) | 2009-05-12 | 2015-03-24 | Koninklijke Philips N.V. | X-ray source with a plurality of electron emitters |
CN102422364A (en) * | 2009-05-12 | 2012-04-18 | 皇家飞利浦电子股份有限公司 | X-ray source with a plurality of electron emitters |
US20110006224A1 (en) * | 2009-07-09 | 2011-01-13 | Maltz Jonathan S | Digital Tomosynthesis in Ion Beam Therapy Systems |
US8559591B2 (en) * | 2009-09-29 | 2013-10-15 | Siemens Aktiengesellschaft | Method and device for recording a projection dataset of an object using a plurality of X-ray sources |
US20110075809A1 (en) * | 2009-09-29 | 2011-03-31 | Jan Boese | Method and device for recording a projection dataset of an object using a plurality of x-ray sources |
US8254518B2 (en) | 2009-10-05 | 2012-08-28 | Siemens Medical Solutions Usa, Inc. | Acquisition of projection images for tomosynthesis |
US20110080996A1 (en) * | 2009-10-05 | 2011-04-07 | Siemens Medical Solutions Usa, Inc. | Acquisition of Projection Images for Tomosynthesis |
US9271689B2 (en) | 2010-01-20 | 2016-03-01 | General Electric Company | Apparatus for wide coverage computed tomography and method of constructing same |
CN102313755A (en) * | 2010-06-30 | 2012-01-11 | Fei公司 | The method of electronic diffraction tomography |
US8358739B2 (en) | 2010-09-03 | 2013-01-22 | The University Of North Carolina At Chapel Hill | Systems and methods for temporal multiplexing X-ray imaging |
WO2012032435A1 (en) | 2010-09-06 | 2012-03-15 | Koninklijke Philips Electronics N.V. | X-ray imaging with pixelated detector |
US9599577B2 (en) | 2010-09-06 | 2017-03-21 | Koninklijke Philips N.V. | X-ray imaging with pixelated detector |
US9807860B2 (en) | 2010-10-20 | 2017-10-31 | Medtronic Navigation, Inc. | Gated image acquisition and patient model construction |
US9769912B2 (en) * | 2010-10-20 | 2017-09-19 | Medtronic Navigation, Inc. | Gated image acquisition and patient model construction |
US20120097178A1 (en) * | 2010-10-20 | 2012-04-26 | Medtronic Navigation, Inc. | Gated Image Acquisition and Patient Model Construction |
US9541510B2 (en) | 2011-11-29 | 2017-01-10 | American Science And Engineering, Inc. | System and methods for multi-beam inspection of cargo in relative motion |
WO2013082005A1 (en) * | 2011-11-29 | 2013-06-06 | American Science And Engineering, Inc. | System and methods for multi-beam inspection of cargo in relative motion |
US9448325B2 (en) | 2012-03-09 | 2016-09-20 | Nutech Company Limited | Apparatus and method for ray scanning imaging |
RU2571170C1 (en) * | 2012-03-09 | 2015-12-20 | Ньюктек Компани Лимитед | Device and method for scanning visualisation |
WO2013131402A1 (en) * | 2012-03-09 | 2013-09-12 | 同方威视技术股份有限公司 | Device and method for ray scanning and imaging |
US20160262710A1 (en) * | 2013-11-06 | 2016-09-15 | Rayence Co, Ltd. | X-ray imaging device including a plurality of x-ray sources |
EP3154433A4 (en) * | 2014-06-16 | 2018-03-14 | Loma Linda University | Radiography and computed tomography with high-energy electron beams |
US9995695B2 (en) | 2014-06-16 | 2018-06-12 | Loma Linda University | Radiography and computed tomography with high-energy electron beams |
US9782136B2 (en) | 2014-06-17 | 2017-10-10 | The University Of North Carolina At Chapel Hill | Intraoral tomosynthesis systems, methods, and computer readable media for dental imaging |
US9907520B2 (en) | 2014-06-17 | 2018-03-06 | The University Of North Carolina At Chapel Hill | Digital tomosynthesis systems, methods, and computer readable media for intraoral dental tomosynthesis imaging |
US10835199B2 (en) | 2016-02-01 | 2020-11-17 | The University Of North Carolina At Chapel Hill | Optical geometry calibration devices, systems, and related methods for three dimensional x-ray imaging |
WO2017173341A1 (en) * | 2016-03-31 | 2017-10-05 | The Regents Of The University Of California | Stationary x-ray source |
US11123027B2 (en) | 2016-03-31 | 2021-09-21 | The Regents Of The University Of California | Stationary X-ray source |
US11534118B2 (en) | 2016-03-31 | 2022-12-27 | The Regents Of The University Of California | Stationary X-Ray source |
US11145431B2 (en) * | 2016-08-16 | 2021-10-12 | Massachusetts Institute Of Technology | System and method for nanoscale X-ray imaging of biological specimen |
US11152130B2 (en) * | 2016-08-16 | 2021-10-19 | Massachusetts Institute Of Technology | Nanoscale X-ray tomosynthesis for rapid analysis of integrated circuit (IC) dies |
US11490865B2 (en) * | 2017-09-21 | 2022-11-08 | Esspen Gmbh | C-arm X-ray apparatus |
WO2019077580A1 (en) * | 2017-10-19 | 2019-04-25 | University Of Johannesburg | Gamma ray tomographic radiography |
US11415722B2 (en) | 2017-10-19 | 2022-08-16 | University Of Johannesburg | Gamma ray tomographic radiography |
US11437218B2 (en) | 2019-11-14 | 2022-09-06 | Massachusetts Institute Of Technology | Apparatus and method for nanoscale X-ray imaging |
US11778717B2 (en) | 2020-06-30 | 2023-10-03 | VEC Imaging GmbH & Co. KG | X-ray source with multiple grids |
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