WO2006122244A2 - Systeme de radiographie a retrodiffusion instantanee -sbr- comportant un systeme a collimation dynamique - Google Patents

Systeme de radiographie a retrodiffusion instantanee -sbr- comportant un systeme a collimation dynamique Download PDF

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Publication number
WO2006122244A2
WO2006122244A2 PCT/US2006/018244 US2006018244W WO2006122244A2 WO 2006122244 A2 WO2006122244 A2 WO 2006122244A2 US 2006018244 W US2006018244 W US 2006018244W WO 2006122244 A2 WO2006122244 A2 WO 2006122244A2
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radiation
detector
image
object region
grid
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PCT/US2006/018244
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English (en)
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WO2006122244A3 (fr
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Alan M. Jacobs
Edward T. Dugan
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University Of Florida Research Foundation, Inc.
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Publication of WO2006122244A2 publication Critical patent/WO2006122244A2/fr
Publication of WO2006122244A3 publication Critical patent/WO2006122244A3/fr

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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
    • G01N23/20—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 using diffraction of the radiation by the materials, e.g. for investigating crystal structure; by using scattering of the radiation by the materials, e.g. for investigating non-crystalline materials; by using reflection of the radiation by the materials
    • G01N23/201—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 using diffraction of the radiation by the materials, e.g. for investigating crystal structure; by using scattering of the radiation by the materials, e.g. for investigating non-crystalline materials; by using reflection of the radiation by the materials by measuring small-angle scattering
    • 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
    • G01N23/20—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 using diffraction of the radiation by the materials, e.g. for investigating crystal structure; by using scattering of the radiation by the materials, e.g. for investigating non-crystalline materials; by using reflection of the radiation by the materials
    • G01N23/203—Measuring back scattering

Definitions

  • the invention relates to radiography, and more particularly to radiography systems which combine aspects of both transmission and backscatter radiography, and methods thereof.
  • Radiography In many industrial, military, security or medical applications, images of the internal structure of objects is required. Radiography is often used for imaging. Radiography generally comprises either conventional transmission radiography or backscatter radiography.
  • Figure 1 is a schematic illustrating the configuration used for conventional transmission radiography, hi conventional radiography, an image is formed by transmitting radiation from a radiation generator 105 through an internal detail 110 within object 130. Attenuated radiation is received by a radiation detector 115 which is disposed on the side of the object opposite to that of the radiation generator 105. hi the case of tomography, the object 130 is generally rotated about axis perpendicular to the plane of the figure.
  • Figure 2 is a schematic illustrating the configuration used for backscatter radiography.
  • backscatter radiography Unlike conventional radiography which relies on transmission, in backscatter radiography radiation is scattered by internal detail 210 within object 230.
  • the radiation generator 205 and radiation detector 215 are on the same side of the object 230. All backscatter radiography techniques allow one-sided imaging of the object since the radiation generator 205 and the radiation detector 215 are located on the same side of the object 230. This is the same imaging configuration that people and animals use for optical viewing of the surroundings. Because of the absence of a refraction process for the penetrating radiation in backscatter radiography, image-gathering lenses cannot be used.
  • a snapshot backscatter radiography (SBR) system and related method includes at least one penetrating radiation source and at least one substantially transmissive radiation detector.
  • the substantially transmissive radiation detector is interposed between the object region to be interrogated and the radiation source.
  • the substantially transmissive radiation detector detects and transmits a portion of forward radiation received from the radiation source to the object region.
  • a "substantially transmissive radiation detector” refers to transmission of a least 20%, and preferably at least 50%, and preferably at least 60%, 70% 80% or higher of the forward radiation from the radiation source.
  • the object region backscatters at least a portion of the radiation it receives, with a portion of the backscattered radiation being detected by the detector.
  • reference (base) radiation data is obtained by using the system without the object present in a low backscatter environment.
  • the base data is then preferably stored prior to interrogating the object.
  • the base data can then be subtracted from the total radiation data measured by the detector which includes information from both the detector structure and spatial variation of the radiation source field, as well as the object structure. This permits generation of an image of the object region.
  • the system can interrogate a wide variety of objects or volumes, such as buried or otherwise unobservable volumes suspected of containing a bomb (e.g. landmine), luggage or cargo, or integrated circuits.
  • the penetrating radiation source can comprise an x-ray, gamma ray, neutron or an electron beam source.
  • the detector can comprise a photostimuable phosphorous-based image plate, TFT-based flat panel detector, or an amorphous silicon panel.
  • the detector can also include a digitizing field screen.
  • the system preferably includes a computer for receiving radiation data from the detector and for performing data and image processing [00010]
  • a radiation source controller is also preferably provided.
  • the radiation source controller can permit the system to produce 3 dimensional (3-D) radiation data which permits the generation of a 3-D image of the object.
  • the radiation source controller can direct the radiation source to provide multiple bursts at varying radiation energy or temporal variation of a radiation energy spectrum.
  • the system can also include one or more collimator grids disposed between the object region and the detector. Collimating grids can be used to improve resolution or help isolate a lateral migration component of the backscattered radiation.
  • the invention also includes an embodiment having dynamic collimators which can further improve measurement sensitivity.
  • a snapshot backscatter radiography (SBR) based land mine detection system includes at least one penetrating radiation source and at least one substantially transmissive radiation detector, wherein the substantially transmissive radiation detector is interposed between a volume of earth to be interrogated and the radiation source.
  • the substantially transmissive radiation detector detects and transmits a portion of incident forward radiation from the radiation source to an object buried in the volume of earth, wherein a portion of radiation scattered by the object is detected by the detector.
  • the radiation source preferably comprises an x-ray source.
  • the radiography system can include a vehicle to add mobility to the system.
  • the invention can also be used for luggage or cargo screening, or as an integrated circuit inspection tool.
  • the detector can comprise a CCD array detector.
  • the penetrating radiation source provides selectable radiation energy. This permits generation of a 3-D image of the object interrogated to be obtained without physically scanning the system or the object by compiling radiation data at a plurality of radiation energies.
  • a snapshot backscatter radiography (SBR) method for imaging an object includes the steps of directing penetrating forward radiation through a detector to an object to be interrogated, the detector transmitting a portion of the penetrating radiation to the object, wherein the object backscatters radiation toward the detector.
  • a snapshot backscatter radiography (SBR) system having dynamic collimators.
  • the system includes at least one penetrating radiation source, and at least one substantially transmissive radiation detector, wherein the substantially transmissive radiation detector is interposed between an object region to be interrogated and the radiation source.
  • the substantially transmissive radiation detector receives and detects forward radiation from the radiation source before transmitting a portion thereof to interrogate the object region. A portion of backscattered radiation from the object region is detected by the detector.
  • At least one dynamically changeable collimating grid having a plurality of spaced apart features is provided.
  • the dynamically changeable collimating grid is disposed in a path of at least one, and preferably both, the path of the forward radiation (collimation grid for illumination) and the path of the backscattered radiation (collimating grid for selective detection).
  • Computer controlled motorized drive systems can be coupled to the collimating grids to control the movement of the grid features during system operation. Feature movements are preferably independent.
  • FIG. 1 is a schematic illustrating the configuration used for conventional transmission radiography.
  • FIG. 2 is a schematic illustrating the configuration used for conventional backscatter radiography.
  • FIG. 3 is a schematic illustrating the configuration used for snapshot backscatter radiography, according to an embodiment of the invention.
  • FIG. 4 is schematic illustrating an alternate SBR configuration including fixed collimators which emphasize the lateral migration signal component of the backscatter radiation signal, according to an embodiment of the invention.
  • FIG. 5 is a schematic illustrating another SBR configuration which includes dynamically changeable collimators for temporally varying the orientation of the illumination beam and the detection selectivity of the substantially transmissive radiation detector, according to an embodiment of the invention.
  • a snapshot backscatter radiography (SBR) system and related method includes at least one penetrating radiation source, and at least one substantially transmissive radiation detector.
  • the substantially transmissive radiation detector is interposed between the object to be interrogated and the radiation source so that the substantially transmissive radiation detector receives and detects forward radiation from the radiation source before transmitting a portion thereof to the object to be interrogated.
  • the object backscatters a portion of the transmitted radiation.
  • a portion of the backscattered radiation is detected by the detector.
  • An image of the object can be obtained by subtracting the incident radiation data, or an estimate thereof, from the total detector data collected. Alternatively, an image of the object can be obtained by subtracting suitably normalized radiation data, or an estimate thereof, from the backscatter data collected by the detector.
  • FIG. 3 is a schematic illustrating a system configuration which can be used for snapshot backscatter radiography (SBR), according to an embodiment of the invention.
  • a snapshot backscatter radiography (SBR) system 300 includes at least one penetrating radiation source 310 and at least one substantially transmissive radiation detector 320, such as a flexible detector sheet.
  • the SBR system 300 can be configured using commercially available radiation generators and detectors. Similar to backscatter radiography, both the radiation source 310 and the substantially transmissive radiation detector 320 are disposed on the same side of the object 330 which includes internal detail 332.
  • the surface of the object or the surface of the medium covering the object, such as the earth, is indicated as reference 335.
  • System 300 can include a radiation source controller 350 and computer 360.
  • Computer 360 preferably includes memory and provides various system functions, such as producing data representing an image of the object interrogated based on radiation data detected by detector 320.
  • a display screen 380 for representing an image of the object interrogated is also preferably provided.
  • the substantially transmissive radiation detector 320 is preferably a digitizing substantially transmissive radiation detector-film screen.
  • computer 350 has at least modest speed and data storage capacity for data processing and driving display 380.
  • 2D or 3D data sufficient to generate an image of the internal structure of objects capable of scattering a portion of incident radiation is acquired in a snapshot illumination of an interrogated area of the object surface.
  • Image data for 2D back-projections can be acquired in a single radiation generator/source burst.
  • Image data for a 3D display can be acquired if a temporal sequence of data sets is obtained at varying x-ray generator voltages. Higher voltages produce higher energy radiation which penetrates correspondingly deeper into the object.
  • photon spectrum tomography Towe & Jacobs, X-ray Backscatter Imaging, IEEE Trans., on Biomed.-Engr., BME-28, p. 646-650, 1981
  • a pulsed radiation (e.g. x-ray) generator with a significant photon energy spectrum variation over the pulse duration provides a useful method of obtaining such information in a single photon source pulse.
  • the temporal resolution of the detector would need to be sufficient to acquire this 3D image data in a single pulse. Otherwise, temporal gating could be employed for a sequence of generator pulses.
  • System 300 is generally contained in a protective and supportive housing 345, which is preferably made from aluminum, or other suitable lightweight materials. Housing 345 holds the various components of system 300 in place. Lightweight housing materials facilitate portability of system 300, which can be advantageous in certain applications.
  • the front of housing 390 as well as detector 320 are both preferably made from flexible materials to conform to a variety of desired shapes.
  • the spacing of detector 320 from source 310 generally depends on the area to be illuminated. For most wide area applications, the spacing from source 310 to detector 320 is generally about the same order of magnitude as the length of detector 320. [00030]
  • the arrangement shown in FIG. 3 implies that the radiation/object interactions of primary consequence are scatterings, although absorption can also be significant.
  • Radiation from the radiation source 310, shown by reference 315 is directed at detector 320 which detects forward radiation 315. This detected radiation pattern is referred to herein as the first- pass data.
  • the detected first-pass data includes information on the spatial variations of the illumination radiation field and the spatial variation of structure and sensitivity of the detector 320.
  • Substantially transmissive radiation detector 320 transmits a portion of the forward radiation received, shown as reference 325, which penetrates surface 335 and strikes internal detail 332 of object 330.
  • the detector medium is generally a detector sheet which provides an area which is at least equal to the illumination area provided by radiation source 310.
  • the internal detail 332 of object 330 then backscatters a portion of the transmitted radiation 325, shown as reference 355.
  • object 330 scatters (reflects) at least 5 to 30% of the illuminating field provided by radiation source 310.
  • a portion of radiation 325 is transmitted through object 330 and is identified in FIG. 3 as transmitted radiation 365.
  • Substantially transmissive radiation detector 320 detects some of the backscattered radiation portion 355, the backscattered radiation pattern referred to herein as the second-pass data.
  • the second-pass data is generated by the backscattered radiation field 355 which emerges from the object or other surface 335 after being scattered by the internal structure of object 330.
  • Data to obtain the desired image of the object can be computed by subtracting the first pass data, or an estimate thereof, from the total detector data measured which comprises the sum of the first and second pass radiation data which includes information on the spatial variations of the radiation field and structure of the detector as well as information on the object structure.
  • the desired image can be obtained by subtracting suitably normalized incident (first-pass) radiation data, or estimate thereof, from the backscatter data collected by the detector.
  • the SBR method can utilize the steps of digitization of the radiation data received by detector 320.
  • a digital image of the object 330 can then be obtained and displayed on screen 380 through simple data manipulation, such as by computer 360. Digitization also permits digital image enhancement techniques to be applied to the radiation data.
  • Radiation source 310 can generally be any penetrating radiation source. Radiation source 310 preferably illuminates the entire area to be interrogated.
  • radiation source 310 can comprise an x-ray source, gamma ray source, neutron source or electron beam source.
  • the radiation source 310 is controlled to provide a photon illumination (energy) spectrum averaged optical depth in object 330 to reach the deepest structure detail desired in the image to be about unity (i.e., one x-ray mean-free-path).
  • the generator voltage is chosen to provide the desired photon illumination (energy) spectrum.
  • the radiation intensity provided by radiation source 310 preferably is sufficiently low so as to not saturate detector 320.
  • first pass reference (base) data is obtained without object 330 and is stored, such as in memory provided by computer 360, prior to interrogating object 330.
  • the base data be updated periodically, such as every day or two, or upon a change of configuration, or a change in source energy. Since only a transmitted reference image is desired, the base radiation data is preferably acquired in an environment which does not backscatter significant radiation back to detector 320. For example, a perfect absorbing medium would be ideal. In practice, an empty room may provide a low backscatter environment.
  • the base radiation data can then be subtracted from the overall radiation detected which includes information from both the detector structure and the spatial variation of the radiation source field as well as the object structure to provide data which permits generation of the desired image of object 330.
  • collimating grid or “collimator grid” refers to a structure used to filter a stream of rays (such as X-rays) so that only those travelling parallel to each other in a certain direction are allowed through.
  • the collimating grids comprise a plurality of radiation absorbing features.
  • the features can be various geometries including fins, slats, screens or plates, and be curvilinear or flat. Regions between respective features are referred to herein as "slits”.
  • the collimator features are oriented essentially perpendicular to the surface of detector 420.
  • the collimating grid enhances the Compton backscatter imaging (CBI) process for photons which experience increased migration along directions perpendicular to the illumination direction, such as along the imaged plane in SBR.
  • CBI Compton backscatter imaging
  • This data acquisition variant can be helpful for the detection and imaging of small, lateral material structure or defects along planes parallel to the object surface, such as feature 455, including small diameter channels, or thin, delaminated regions which are parallel to an object surface.
  • Conventionally applied collimators can also be used to improve image resolution by limiting beam spot size, but generally also increase measurement time.
  • System 400 includes collimator 415 disposed between the radiation source 410 and the substantially transmissive radiation detector 420 which functions as a shutter by blocking transmission of the forward radiation beam 465 over a portion of the area of detector 420.
  • the beam transmitted through detector 420 is identified as reference 485.
  • Housing 490 is also provided.
  • the object (or volume interrogated) 430 shown includes a crack or other void, which provides an airspace 455.
  • Object 430 is shown buried in a medium having a surface 435.
  • the object/medium arrangement is essentially analogous to the arrangement when a land mine is buried in the earth. Land mines are known to include air gaps to permit the fuse mechanism to function properly and to provide directional blasts.
  • Radiation reflected from object 430 is indicated as backscatter beam 475.
  • Airspace 455 permits significantly enhanced lateral migration of radiation along its length. This lateral enhancement results in a larger percentage of radiation transmitted through detector 420 to fit between laterally positioned adjacent collimator plates and reach detector 420 for detection as compared to when object 430 does not include airspace 455.
  • system 400 can be used to identify structures such as landmines, delaminations and other structures which provide significant air spaces.
  • a fixed illumination and detection system may not provide the data necessary to identify potentially important feature details.
  • improved feature resolution can be obtained by accumulating image data over a series of illuminations wherein at least one, and preferably both, the orientation (e.g.
  • an angle of the illuminating beam relative to the object region and the detection selectivity of backscattered radiation provided by the detector are changed during the measurement. For example, if an object in an object region contains internal void channels of unknown direction and location and a detection system having a grid pattern which emphasizes detector response to lateral migration of the employed penetrating radiation according to the invention is used, then a more complete integrated image of the channels can generally be obtained by processing data from a series of illuminating snapshots at several angles.
  • the orientation of the illuminating beam and detection selectivity of backscattered radiation can be changed using collimator grids having a plurality of spaced apart radiation absorbing features, wherein an orientation of the features comprising the grids is adjustable.
  • the features are formed from radiation absorbing materials, such as lead together with a low Z (and/or low density) material such as carbon fiber or aluminum.
  • the positional change(s) of the features is preferably automatic and dynamic, such as through computer controlled motor drives as explained below.
  • the angular- rotation speed of the features is preferably sufficiently fast so that image accumulation during the movement interval can be ignored.
  • the radiation source can remain in a fixed position.
  • the radiation source can be scanned to provide a changeable orientation of the illumination beam.
  • changeable detection selectivity can be provided.
  • a changeable detector response can be provided by rotating the changeable collimating grid for detection selectivity about an axis normal to the object illumination plane.
  • FIG. 5 is schematic illustrating a SBR configuration which includes dynamically changeable collimators for temporally varying the orientation of the illumination beam and the detection selectivity of the substantially transmissive radiation detector, respectively, according to an embodiment of the invention.
  • System 500 is similar to system 400 shown in FIG. 4, except collimator grids 415 and 455 are replaced by dynamically changeable collimating grids 515 and 545, respectively.
  • Changeable collimator grid 515 provides a changeable orientation of the illuminating beam and changeable collimating grid 545 permits changing the detection selectivity of backscattered radiation received by detector 420.
  • Other like features in system 500 are numbered alike as the equivalent features shown in system 400 in FIG. 4.
  • the grids 515 and 545 comprise a series of radiation absorbing features 516.
  • the features rotate.
  • the features can be in one of two (2) positions, in an "open” position when aligned with a surface normal drawn from the surface of detector 420, and a "closed” position when oriented parallel to the surface of detector 420.
  • open regions between respective features 516 are referred to herein as "slits”.
  • grids 515 and 545 can include analogous structure and function analogously to 'Venetian blinds" regarding opening and closing, except individual features 516 comprising grids according to the invention are independently moveable.
  • a computer or processor 560 controls motor controls 565 and 575 which comprise an exemplary structure for dynamically and automatically changing the position of the plurality of features 516 provided by collimating grids 515 and 545, respectively.
  • Features 516 are preferably independently moveable.
  • each feature 516 can have its own independent motor control or independent electronic (e.g. solenoid) switch or magnetic actuator control instead of functioning collectively, analogously to "Venetian blinds," using one or two controllers.
  • the grid features 516 are all the same width, d, and the feature rotation-axes of each grid are also all separated by distance d.
  • the feature rotation angles of the collimator grids 515 and 555 are conveniently measured relative to the normal vector drawn from the surface of the detector 420.
  • the collimator grid is in the configuration provided by a conventional finned-collimator with features oriented perpendicular to the detector plane, such as collimators 415 and 445 shown in FIG. 4.
  • the collimator grids become plane absorbers completely covering the upper and lower surface of detector 420, respectively.
  • Collimator 515 provides the ability to sequentially acquire a series of spatially varying illuminated lines (e.g. angles) in coordination with collimator 545 which permits a different series of line penetrations to reach detector 420.
  • collimator grid 515 functions as a dynamic "shutter" which is in temporal coordination with collimator 545 which provides a dynamically changeable selectivity.
  • Collimator 515 blocks transmission of the forward radiation beam 465 over a portion of the area of detector 420. Movement of features comprising collimator 515 changes the orientation of illuminating beam incident on object volume 430. As noted above, by using a changeable grid to alter the orientation of the illumination, the radiation source 410 can remain in a fixed position. However, although generally not preferred, the radiation source 410 can be scanned to provide a changeable orientation of the illumination beam.
  • Collimator 545 enhances the Compton backscatter imaging (CBI) process for photons which experience increased migration along directions whether parallel, perpendicular or angles in between relative to the illumination direction, such as along the imaged plane in SBR and is particularly useful if an object in an object region contains internal void channels of unknown direction and location.
  • CBI Compton backscatter imaging
  • changeable collimator 545 which provides a plurality of different grid patterns which emphasize detector response to different migration paths of the employed penetrating radiation used, a substantially more complete image of the channels will be possible using a series of illuminating snapshots at several angles to show images of all channels in the integrated image acquired.
  • radiography systems according to the invention having dynamic collimation are not limited to detection of lateral structures or defects lying in planes parallel or substantially parallel to the object surface, such as feature 455.
  • systems according to the invention can also identify structural features lying substantial normal to the surface of the object region.
  • a computer or processor 560 controls motor controls 565 and 575 which dynamically and automatically changes the position of the plurality of features 516 provided by collimating grids 515 and 545, respectively.
  • Features 516 are preferably independently moveable.
  • Motor controls 565 and 575 move features 516 based on computer control. Movement can be mechanical driven as shown, or alternatively, using electronic (e.g. solenoid) switches, or magnetic actuation such as when features 516 comprise magnetic materials (e.g Fe comprising).
  • electronic e.g. solenoid
  • magnetic actuation such as when features 516 comprise magnetic materials (e.g Fe comprising).
  • system 500 For system 500 shown in FIG. 5, the designation of system 500 being a "snapshot" system remains appropriate in that dynamics provided by collimator 515 and 545 occur during a continuous illumination of the object region being imaged.
  • the detector integrates the acquired image continuously during the snapshot illumination.
  • the arrangement shown in FIG. 5 is not a "scanning" modality in that the assignment of pixel coordinates is by detector image acquisition coordinates, not by illumination beam position coordinates.
  • the operation of system 500 is distinct from CT, which also views objects in a series of orientations, but for the entirely different purpose of eliminating the confusion inherent in conventional projection radiography.
  • SBR is well suited to planar object interrogation of surfaces for both placement of the detector and interpretation of the scattered radiation produced image. Independent of the flexibility of the detector medium, it is estimated that SBR can provide useful images of internal structure details of objects if the image size dimension is less than about one-third the radius-of-curvature of the interrogated region object surface. If the detector (e.g. film) is sufficiently flexible to conform to the object surface, this limit should increase to about one- half, or more, depending on the distance to the radiation (e.g. x-ray) generator focal spot from the object surface.
  • Radiography applications wherein internal structure near the surface of an object is to be imaged, can benefit significantly from the backscatter point of view provided by SBR.
  • the substantially transmissive radiation detector 320/420 is disposed in the radiation path so that the radiation which reaches the object 330/430 first passes through the substantially transmissive radiation detector 320/420. Disposing the detector 320/420 in the forward radiation path as shown in FIGs. 3-5 where it detects forward radiation provides certain advantages. In particular, the ability to provide a snapshot image of object 330/430 without the need for mechanical scanning of the radiation source or object rotation.
  • the temporal history of radiation in SBR is unlike either conventional transmission radiography or conventional backscatter radiography.
  • Source generation of penetrating radiation results in a first-pass through detector 320/420.
  • This step is not provided in either conventional transmission radiography or backscatter radiography.
  • Interaction with internal structure of object 330/430 produces reflective scattering which results in a second-pass through substantially transmissive radiation detector 320/420.
  • This step is similar to conventional backscatter radiography, although the radiation incident on the object is transmitted through the substantially transmissive radiation detector in SBR, whereas the radiation incident on the object is provided directly from the radiation source in conventional backscatter radiography.
  • the detector 320 generally needs to store base image data.
  • the detector needs to permit significant radiation to be transmitted therethrough.
  • the detector 320/420 also needs to be capable of receiving multiple images, i.e., be reusable with a minimum of drift.
  • the photostimuable phosphor-based imaging plate commonly referred to as computed radiography, or CR
  • ASP amorphous silicon panel
  • the CR imaging medium is generally thin, uniform, and flexible. X-ray sensitivity and image spatial resolution are sufficient for most applications. Significant care must be exercised in the time between latent image acquisition and photo stimulation in the image reading process including light exclusion. As the technique is conventionally applied, there is a separate image reader device and the imaging plate (film) is transferred from the x- ray illumination device to the reader for image digitizing and display. For application of the CR method to an SBR system, it would be advantageous if image exposure, reading, digitization, and display were accomplished in the same device eliminating the physical transfer of the imaging plate in the process.
  • the geometric featureless quality and physical flexibility of the CR image plate imply a uniform first-pass image and easily-obtained conformity of image acquisition geometry to the object surface. These properties imply relatively straight-forward analysis of the acquired image and post-acquisition processing (e.g., subtraction of the first-pass image).
  • Most ASP detectors are neither thin nor homogeneous, but there are panel models where the associated amplifiers and voltage supplies are placed to the side of the imaging area. Typical panels are heavily shielded against x-ray penetration from the rear which negates the geometric necessities of the SBR system.
  • a major advantage of an ASP detector-film is the inherent, single-step image acquisition process. Data from a sequence of images can be acquired and stored for processing. Image differences obtained from a series of varying x-ray generator voltages can be employed to yield 3D images of internal structure. Image differences obtained from a series of x-ray generator pulses can also form the basis of analysis of the dynamic response of internal structure, such as suggested in the development of dynamic radiography (Kenney & Jacobs, Research Techniques in Nondestructive Testing, Chapter 6, p.217 - 243, Edited by Sharpe, Academic Press, 1977). With sufficient temporal resolution of the panel, a single x- ray generator pulse with time-varying spectrum can be employed to efficiently acquire data for either of these applications.
  • CCD or other chip-based detectors may also be use with the invention in applications where a large area image is not required.
  • Chip based detectors are generally useful when the area to be interrogated is relatively small, such as on the order of several ⁇ ms, tens of ⁇ ms, or hundreds of ⁇ ms, such as a region on an integrated circuit.
  • Thin film transistor arrays TFT-arrays
  • the equivalent of an optical snapshot camera is often desirable for many applications, but has previously only been available using conventional transmission radiography.
  • the SBR system and method described herein advantageously enables snapshot radiography utilizing reflected radiation, for example for applications where a detector cannot be placed behind the object to be interrogated.
  • a clear benefit of the SBR approach is for radiography applications in which there is only one-sided access to the object.
  • scanning electron microscopes (SEM) are commonly used in integrated circuit failure analysis and some process control which requires resolution beyond that provided by standard optical inspections.
  • SEMs scanning electron microscopes
  • One reason for common use of SEMs in integrated circuit processing is because of high image resolution compared to standard optical inspection tools.
  • transmission radiography is generally not possible for interrogating integrated circuits due to the presence of one or more heavily absorptive surfaces. For example, gold may coat the backside of the chip.
  • SBR systems which can interrogate below the surface of a sample
  • conventional SEMs cannot interrogate regions below the surface.
  • SBR systems are expected to be inexpensive relative to SEMs.
  • the SBR system can provide improved image resolution, and provide a resolution comparable to that obtainable from conventional SEMs by including one or more collimators systems to reduce the beam size as required for the desired resolution level.
  • the invention is also helpful where an internal structure element is difficult, or impossible, to image by conventional transmission radiography or even conventional backscatter radiography because of amplification of image contrast during the subsurface migration, such as lateral migration, of the interrogating radiation produced by SBR which can be selectively sensed by proper design of the substantially transmissive radiation detector components.
  • the invention is expected to have a variety of applications as it enables rapid snapshot images of an object or volume of interest and can also be a portable system.
  • the invention can be used as a land mine detection system, for either military or humanitarian use to identify buried land mines.
  • Most buried land mines are made of predominantly plastic which makes it almost impossible to detect the mines accurately with conventional detection techniques.
  • explosives and plastics reflect more photons than soil does, and scatter the photons more widely, which can create more accurate images of the mines.
  • Rocks, wood, roots and other materials create very different images and are generally not confused with land mines using SBR.
  • the system can be small and lightweight, making it readily mobile. Thus, soldiers can carry an SBR system and interrogate the path in front of them before proceeding.
  • landmine detectors can be mounted on a vehicle to create mobile land mine detectors.
  • the invention is expected to be useful for rapidly screening articles within containers, such as luggage or cargo entering airports.
  • the invention is expected to be manufacturable at a significantly reduced cost since it does not require mechanical scanning of the object or any system scanning component,
  • the SBR system can be portable, and provide images faster than conventional scanning systems.
  • the SBR system can also detect explosives, such as plastic explosives, that are generally undetectable by conventional systems used at airports.
  • SBR was tested in a single measurement which successfully imaged a high- contrast feature in an optimal configuration of an SBR system according to the invention using x-rays and a computed radiography (CR) screen detector with the associated image reader replacing the image-analyzing computer.
  • the object (and "structure") was a plastic block on the interrogated surface which included a small (1 cm x 1 mm x 0.1 mm thick) strip of lead. From the SBR image obtained the lead strip was clearly visible, with about 0.1 mm resolution being provided.
  • An exemplary timing sequence of events is provided for a two dynamic collimator grid snapshot radiography system, such as system 500 shown in FIG. 5.
  • the RSD system considered in this example is based on an identical "illumination-side" grid 515 and "object-side” grid 545 with an interposed plane integrating detector 420.
  • the respective grid planes are both parallel to the plane of the detector 420 and are both positioned symmetrically about the normal vector passing through the plane of detector 420 at its center.
  • Grids 515 and 545 are venetion blind-like grids as described above.
  • Grid feature indexing for the purpose of describing the dynamic sequencing herein uses consecutive integers and the "open" slits on either side of a given feature n are designated n a and nj,.
  • the contiguous open, perpendicularly collimated, slits are Ia, lb/2a, 2b/3a, 3b/4a, 4b/5a, etc.
  • slit Ia can be designated by O, lb/la by 1, 2b/3a by 2, 3b/4a by 3, etc.
  • the two grids 515 and 545 are aligned and indexed such that illumination slit n is aligned with object side slit n as shown in FIG. 5.
  • the illumination grid index is I n and the object grid index is O n
  • I] and Oi are aligned
  • I 2 and O 2 are aligned, etc.
  • the object region 430 has a plane surface and the plane of detector 420 as well as the planes of both collimator grids 515 and 545 are positioned parallel to the surface of object region 430.
  • the internal structure of interest is assumed to be a distribution of parallel, narrow void channels that are about 1Od long, where d as noted above is the width of features 516.
  • the long dimension of the features 516 is oriented orthogonal to the direction of the void channels. It is presumed that the mean-free-path of radiation in the object material is about 5d.
  • rotation sequence is as follows: I 1 , I 2 i J41J61 JsivAAi, O 2 i, O 3 i, O 4h O 5 i,... simultaneously at 0 degrees (open) with all other features 516 at 90 degrees (closed) for image accumulation in the first time interval T, where the subscript number represents sequentially numbered features in the respective grids moving in one direction (e.g. left-to- right) from a first end feature designated as feature 1. Note that the spacing between slits in the object-side grid 545 (1Od) is set equal to the length of the narrow void channels (1Od).
  • I 2 J 22 J 425 I 629 Ig 2 ,..., O 2 ,Oi 2 , O 22 ,O 32 ,O 42 ,O 52 ,... simultaneously at 0 degrees with all other features at 90 degrees is used for image accumulation.
  • ⁇ 3j2 3 J43J63 Js3,- • .,O 3 ,Oi 3 ,O 23 ,O 33 ,O 43 ,O5 3 ,... at 0 degrees with other features at 90 degrees are used.
  • This progression continues for a "snapshot" (total) time interval of nineteen intervals (19T) to obtain image data from all the permutations given the constant slit spacing used.
  • image data can be acquired by sampling a variety of spacing distances between slits, such as 1, 2, 3, ... 10.
  • the image data can be analyzed, such as based on appropriate software, to identify the spacing distance which provides the best image resolution.
  • the spacing distance can then be used as described above to obtain image data from all the permutations given the constant slit spacing used.
  • Two snapshots are generally acquired. One snapshot is acquired with the object removed (i.e., the first-pass image, denoted P 1 ).
  • the image Ps P 2 - P 1 is a particular backscatter image.
  • the image Ps has two, very different contributions.
  • One image contribution is formed by radiation scattered back through each pair of opened slits, i.e. radiation which passes through the slit sequence I n -O n -O n .
  • One image contribution is formed by scattered radiation which passes through slits 1Od from the slits of illumination, i.e. radiation which passes through the slit sequence I n -O n -O (n-I o, n+I0) . It is this last contribution which is the image of interest.
  • P Ps - P 3 + P 1 is the desired image of the void channels.
  • the above, more complex, description is intended to show all the relations between the acquired images and the radiation path histories in the object for the example radiographic situation.

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Abstract

L'invention concerne un système de radiographie à rétrodiffusion instantanée (SBR) et un procédé correspondant. Ce système comprend au moins une source de rayonnement pénétrant (310), et au moins un détecteur de rayonnement sensiblement transmissif (320). Le détecteur de rayonnement sensiblement transmissif (320) est interposé entre une zone objet (430) à interroger et la source de rayonnement (310). Le détecteur de rayonnement sensiblement transmissif (320) reçoit et détecte le rayonnement avant (315) de la source de rayonnement (310) avant la transmission d'une partie de ce dernier pour interroger la zone objet (430), une partie du rayonnement à rétrodiffusion (355) délivré par la zone objet (430) est détectée par le détecteur (320). Une grille collimateur (515) remplaçable ayant une pluralité d'éléments d'absorption de rayonnement (516) espacés est couplée à une structure changeant la position de la pluralité d'éléments et est placée au moins dans le trajet du rayonnement avant ou dans le trajet du rayonnement rétrodiffusé. Une image de l'objet peut être obtenue par soustraction du rayonnement avant détecté au niveau du détecteur ou d'une estimation de ce dernier d'un total de tous les rayonnements détectés par le détecteur. La SBR peut être utilisée dans des systèmes d'inspection d'un circuit intégré, de détection de mines terrestres et de filtrage de bagages ou de fret.
PCT/US2006/018244 2005-05-11 2006-05-10 Systeme de radiographie a retrodiffusion instantanee -sbr- comportant un systeme a collimation dynamique WO2006122244A2 (fr)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9442083B2 (en) 2012-02-14 2016-09-13 Aribex, Inc. 3D backscatter imaging system
CN113960086A (zh) * 2021-09-18 2022-01-21 中国航天科工集团第二研究院 一种补偿式背散射探测器栅格准直成像系统及方法
CN113970567A (zh) * 2020-07-22 2022-01-25 同方威视技术股份有限公司 背散射成像装置、控制方法及检查系统

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6735279B1 (en) * 2003-01-21 2004-05-11 University Of Florida Snapshot backscatter radiography system and protocol

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6735279B1 (en) * 2003-01-21 2004-05-11 University Of Florida Snapshot backscatter radiography system and protocol

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
DUGAN EDWARD T ET AL: "Detection of defects in foam thermal insulation using lateral migration backscatter X-ray radiography" PROC SPIE INT SOC OPT ENG; PROCEEDINGS OF SPIE - THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING; PENETRATING RADIATION SYSTEMS AND APPLICATIONS VI 2004, vol. 5541, 2004, pages 47-57, XP002407807 *
DUGAN EDWARD T ET AL: "Development and field testing of a mobile backscatter x-ray lateral migration radiography land mine detection system" PROC SPIE INT SOC OPT ENG; PROCEEDINGS OF SPIE - THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2002, vol. 4742, no. I, 2002, pages 120-131, XP002407806 *
JACOBS A M ET AL: "Detection/identification of land mines by lateral migration radiography" DETECTION OF ABANDONED LAND MINES, 1998. SECOND INTERNATIONAL CONFERENCE ON THE (CONF. PUBL. NO. 458) EDINBURGH, UK 12-14 OCT. 1998, LONDON, UK,IEE, UK, 12 October 1998 (1998-10-12), pages 152-156, XP006505027 ISBN: 0-85296-711-X *
LAMSER D G ET AL: "A Tomographic Imaging System Utilizing X-ray Compton Backscatter" ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY, 1990., PROCEEDINGS OF THE TWELFTH ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE PHILADELPHIA, PA, USA 1-4 NOV. 1990, NEW YORK, NY, USA,IEEE, US, 1 November 1990 (1990-11-01), pages 202-203, XP010035447 ISBN: 0-87942-559-8 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9442083B2 (en) 2012-02-14 2016-09-13 Aribex, Inc. 3D backscatter imaging system
CN113970567A (zh) * 2020-07-22 2022-01-25 同方威视技术股份有限公司 背散射成像装置、控制方法及检查系统
CN113960086A (zh) * 2021-09-18 2022-01-21 中国航天科工集团第二研究院 一种补偿式背散射探测器栅格准直成像系统及方法
CN113960086B (zh) * 2021-09-18 2024-01-02 中国航天科工集团第二研究院 一种补偿式背散射探测器栅格准直成像系统及方法

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