X-ray or gamma ray systems or devices – Specific application – Diffraction – reflection – or scattering analysis
Reexamination Certificate
2003-01-21
2004-05-11
Glick, Edward J. (Department: 2882)
X-ray or gamma ray systems or devices
Specific application
Diffraction, reflection, or scattering analysis
C378S087000
Reexamination Certificate
active
06735279
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
1. Field of the Invention
The invention relates to radiography, and more particularly to radiography systems which combine aspects of both transmission and backscatter radiography, and methods thereof.
2. Background
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.
FIG. 1
is a schematic illustrating the configuration used for conventional transmission radiography. In 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
. In the case of tomography, the object
130
is generally rotated about axis perpendicular to the plane of the figure.
FIG. 2
is a schematic illustrating the configuration used for backscatter radiography. Unlike conventional radiography which relies on transmission, in backscatter radiography radiation is scattered by internal detail
210
within object
230
. In backscatter radiography, 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
arc 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.
In backscatter radiography, illumination of an entire region of the object to be interrogated in a single snapshot has generally only been possible using a pinhole, coded aperture, or a restriction positioned between the object and the radiation detector. This generally results in either extremely inefficient sensing of the radiation, or the introduction of substantial image-obscuring structured noise, thus requiring large exposure times for typical radiation sources. An alternative includes use of a scanning pencil or fan beam for illuminating a temporal sequence of points or lines on the object surface. This also yields long exposure times and decoding algorithms having long calculation times, besides requiring an expensive scanning apparatus.
The equivalent of an optical snapshot camera capable of implementation using relatively inexpensive components which would provide high image resolution and a short exposure time would be desirable for applications which require one-sided imaging of the internal structure of objects.
SUMMARY OF THE INVENTION
A snapshot backscatter radiography (SBR) system and related method includes at least one penetrating radiation source and at least one radiation detector. The radiation detector is interposed between the object to be interrogated and the radiation source. The radiation detector transmits a portion of radiation received from the radiation source to the object. The object backscatters at least a portion of the radiation it receives, with a portion of the scattered radiation being detected by the detector.
Generally, 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. 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 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
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. For example, 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 collimating sheets disposed between the object and the detector. Collimating sheet(s) can be used to improve resolution or help isolate a lateral migration component of the backscattered radiation.
A snapshot backscatter radiography (SBR) based land mine detection system includes at least one penetrating radiation source and at least one radiation detector, wherein the radiation detector is interposed between a volume of earth to be interrogated and the radiation source. The radiation detector transmits a portion of incident 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. In the case of the integrated circuit inspection tool the detector can comprise a CCD array detector. In a preferred embodiment the penetrating radiation source provides selectable radiation energy. This permits generation of a 3-D image of the object interrogated to 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. By processing the radiation data collected by the detector an image of the object can be generated. When at least one collimating sheet is disposed between the object and the detector, the method can include the step of collimating the forward radiation and/or the backscattered radiation. A deconvolving image enhancement technique can in addition be applied to reduce image blurring.
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Jacobs, A.M. et al., Detection/identification of land mines by lateral migration radiography; Detection and Abandoned Land Mines, 1998. Second International Conference of the (IEE Conf. Publ. No. 458), Oct. 12-14, 1998, pages(s): 152-156.*
Lockwood, G.J. et al., Field tests of X-ray backscatter mine detection Detection of Abandoned Land Mines, 1998. Second International Conference on the (IEE Conf. Publ. No. 458), Oct. 12-14, 1998, pages(s): 160-163.*
MacDonald, Jacqueline et al., Alternatives for Landmine Detection, MR-1608-OSTP, (2003)—Jacobs, A. et al., X-ray Backscatter (Paper II)—Appendix M. page(s) 205-223.*
Towe et al., “X-Ray Backscatter Imaging,” IEEE Trans., on Biomed.-Engr., BME-28, 9:646-650, 1981.
Kenney et al., Research Techniques in Nondestructive Testing, Chapter 6, “Dyn
Dugan Edward T.
Jacobs Alan M.
Akerman & Senterfitt
Glick Edward J.
Thomas Courtney
University of Florida
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