WO2007131038A2 - Scanner et procede de transmission et d'imagerie par diffusion - Google Patents

Scanner et procede de transmission et d'imagerie par diffusion Download PDF

Info

Publication number
WO2007131038A2
WO2007131038A2 PCT/US2007/068040 US2007068040W WO2007131038A2 WO 2007131038 A2 WO2007131038 A2 WO 2007131038A2 US 2007068040 W US2007068040 W US 2007068040W WO 2007131038 A2 WO2007131038 A2 WO 2007131038A2
Authority
WO
WIPO (PCT)
Prior art keywords
radiation
scatter
detector
detectors
detect
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US2007/068040
Other languages
English (en)
Other versions
WO2007131038A3 (fr
Inventor
David P. Rohler
Steven H. Izen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
MULTI-DIMENSIONAL IMAGING Inc
Multi Dimensional Imaging Inc
Original Assignee
MULTI-DIMENSIONAL IMAGING Inc
Multi Dimensional Imaging Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by MULTI-DIMENSIONAL IMAGING Inc, Multi Dimensional Imaging Inc filed Critical MULTI-DIMENSIONAL IMAGING Inc
Publication of WO2007131038A2 publication Critical patent/WO2007131038A2/fr
Anticipated expiration legal-status Critical
Publication of WO2007131038A3 publication Critical patent/WO2007131038A3/fr
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/29—Measurement performed on radiation beams, e.g. position or section of the beam; Measurement of spatial distribution of radiation
    • G01T1/2914—Measurement of spatial distribution of radiation
    • G01T1/2985—In depth localisation, e.g. using positron emitters; Tomographic imaging (longitudinal and transverse section imaging; apparatus for radiation diagnosis sequentially in different planes, steroscopic radiation diagnosis)
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/40—Arrangements for generating radiation specially adapted for radiation diagnosis
    • A61B6/4007—Arrangements for generating radiation specially adapted for radiation diagnosis characterised by using a plurality of source units
    • A61B6/4014—Arrangements for generating radiation specially adapted for radiation diagnosis characterised by using a plurality of source units arranged in multiple source-detector units

Definitions

  • the present invention relates generally to scanning systems for inspection and medical applications and, more particularly, to a cone-beam computed tomography scanner for simultaneous transmission and scatter imaging.
  • x-ray imaging for medical and nondestructive testing (NDT) applications is done by measuring transmitted photons.
  • Transmitted photons are those that do not interact with the scanned object.
  • Scattered photons can also be measured and can provide different information about the scattering material.
  • X-ray systems are commonly employed for the inspection of materials or containers by illuminating the material or container with either a fan beam or a pencil beam of x-rays and detecting x-ray photons that are either transmitted through the material or scattered by the material into detectors disposed at an orientation other than directly in line with the beam.
  • Such detectors that are not in line with the illuminating beam are referred to herein as scatter detectors, e.g., backscatter detectors.
  • a fan beam may be used for illumination when only a transmission image is to be obtained.
  • the spatial resolution of the image is determined primarily by the size and spacing of segmented transmission detectors.
  • the fan beam impinges on the container, creating an irradiated swath, and the segmented detectors are then used to identify the transmissivity of each detector-sized element along the irradiated swath. This information is then used to create an image of the irradiated swath of the container.
  • the container is then moved horizontally, and another swath is irradiated and imaged. In practice, this motion is typically continuous, with the object moving on a conveyor belt, or otherwise pulled past the x-ray system.
  • the x-ray source could move at a known speed and gather equivalent information.
  • FIG. 1 illustrates a conventional inspection system 10, which includes a pencil-beam x-ray source 12 that provides pencil-beam x-ray radiation incident on an object 14.
  • the inspection system includes a fixed transmission x-ray detector 16 to detect radiation transmitted through an object being scanned and a pair of fixed scatter x-ray detectors 18 to detect scattered radiation at approximately zero degrees relative to the incident x-ray pencil beam (often referred to as "true backscatter.")
  • the use of the pencil-beam x-ray source requires mechanical raster scanning of the x-ray source to image the object, which can be relatively slow.
  • the present invention provides a scanning device for rapid, panoramic, simultaneous transmission and scatter imaging.
  • the scanning device employs flood illumination and is configured to provide simultaneous transmission and scatter imaging at multiple and/or variable scatter positions.
  • the provision of simultaneous transmission and scatter imaging at multiple and/or variable scatter positions facilitates, among other things, generation of panoramic views of scanned objects in real time.
  • One aspect of the invention relates to a scanning device that includes a first source of penetrating radiation that provides a cone beam of radiation for irradiating a subject; a first detector positionable to detect at least radiation transmitted through the subject; and a second detector positionable to detect scatter radiation at angles other than zero degrees.
  • the scanning device is configured for simultaneous detection of transmission and scatter radiation.
  • the second detector is movable to detect scatter radiation at multiple scatter angles.
  • the scanning device includes a third detector positionable to detect scatter radiation at angles other than zero degrees.
  • the second and third detectors are movable to detect scatter radiation at multiple scatter angles.
  • the second and third detectors are positionable to detect scatter radiation and variable scatter angles.
  • the scanning device includes a second source of penetrating radiation. According to another aspect, the scanning device includes a third source of penetrating radiation.
  • a scanning device that includes a first source of penetrating radiation that provides a cone beam of radiation for irradiating a subject; a pair of detectors, where a first detector is positionable to detect radiation transmitted through the subject, and a second detector is positionable to detect scatter radiation at multiple scatter angles, the pair of detectors generating signals in response to received radiation; and a processor that receives and processes the signals from the detectors to provide real-time panoramic views of the subject.
  • Another aspect of the invention relates to an inspection system that includes a first source of penetrating radiation that provides a cone beam of radiation for irradiating an object; a first detector positioned to receive at least transmitted radiation; and a second detector positioned to receive at least scatter radiation, the first source and the first and second detectors mounted for rotation about the object.
  • Another aspect of the invention relates to an inspection system that includes a first source of penetrating radiation that provides a cone beam of radiation for irradiating an object; and a pair of detectors, where a first detector is positionable to detect radiation transmitted through the subject, and a second detector is positionable to detect scatter radiation at multiple scatter angles.
  • Another aspect of the invention relates to an inspection system that includes a flood source of penetrating radiation; a first pencil-beam radiation detector; a second pencil-beam radiation detector, wherein the first and second pencil beam detectors are positioned to simultaneously detect transmission and scatter radiation.
  • the pencil-beam detectors are positionable to detect scatter radiation at multiple scatter angles. According to another aspect, the pencil-beam detectors are movable to detect scatter radiation at variable scatter angles.
  • the pencil-beam detectors are positionable to detect scatter radiation at scatter angles of at least about 45 degrees relative to the angle of radiation from the source. According to another aspect, the pencil-beam detectors are positionable to detect scatter radiation at scatter angles between at least about 0 degrees and about 90 degrees relative to the angle of radiation from the source
  • the source and pencil-beam detectors are mounted for rotation about an axis.
  • Another aspect of the invention relates to a method of characterizing an object. The method includes illuminating the object with penetrating flood radiation; detecting radiation transmitted through the object and generating transmitted radiation signals; detecting radiation scattered by the object at angles other than zero degrees and generating scattered radiation signals; and determining at least one characteristic of the object based at least on the transmitted and scattered radiation signals
  • the transmitted radiation and scatter radiation are detected simultaneously.
  • the method includes generating a real-time panoramic view of the object based at least on the scattered radiation signals.
  • the method includes converting the transmitted and scattered radiation signals into a three-dimensional volumetric representation of the object.
  • the real-time panoramic view is inherently registered to the three-dimensional volumetric representation of the object.
  • detecting radiation scattered by the object includes positioning a first detector at about +45 degrees and a second detector at about -45 degrees relative to an axis along which the flood radiation is transmitted.
  • FIG. 1 is a diagrammatic illustration of a conventional x-ray inspection device
  • FIG. 2 is a diagrammatic illustration of an exemplary computed tomography scanner configured as an inspection device for use in an airport setting;
  • FIG. 3 is a cross-sectional diagrammatic illustration of a computed tomography scanner having one radiation source and two radiation detectors in accordance with one exemplary embodiment
  • FIG. 4 is a diagrammatic illustration of an exemplary cone-beam detector bed for use in connection with the computed tomography scanner
  • FIG. 5 is a diagrammatic illustration of a portion of a collimator for use in connection with the computed tomography scanner
  • FIG. 6 is a cross-sectional diagrammatic illustration of a computed tomography scanner having one radiation source and three radiation detectors in accordance with another exemplary embodiment
  • FIG. 7 is a cross-sectional diagrammatic illustration of a computed tomography scanner having three radiation sources and three radiation detectors in accordance with another exemplary embodiment
  • FIG. 8 is a diagrammatic illustration of a helical locus of source travels for the radiation sources illustrated in FIG. 7;
  • FIG. 9 is a diagrammatic illustration of a scatter model for use in connection with the computed tomography scanner.
  • FIG. 10 is a diagrammatic illustration of a three-wedge phantom for use in simulated scatter images
  • FIG. 11 is a simulated scatter image at about zero degrees for the three- wedge phantom of FIG. 10, along with corresponding line and saturation plots;
  • FIG. 12 is a simulated scatter image at about 90 degrees for the three- wedge phantom of FIG. 10, along with corresponding line plots;
  • FIG. 13 is a diagrammatic illustration of the three-wedge phantom of FIG. 10 along with a cylinder for use in simulated scatter images;
  • FIG. 14 is a diagrammatic illustration of a PVC ball disposed between two aluminum plates phantom for use in simulated scatter images.
  • FIG. 15 is a diagrammatic illustration of a PVC ball disposed in a corner formed by two aluminum plates phantom for use in simulated scatter images.
  • the present disclosure provides a scanning device for simultaneous transmission and scatter imaging.
  • the scanning device includes a flood illumination source, e.g., a cone-beam x-ray source, and is configured to provide simultaneous transmission and scatter imaging at multiple and/or variable scatter positions.
  • a flood illumination source e.g., a cone-beam x-ray source
  • the provision of simultaneous transmission and scatter imaging at multiple and/or variable scatter positions facilitates, among other things, generation of panoramic views of scanned objects in real time and scatter images registered to full-volume transmission CT images.
  • a scanning device 30 (also referred to as a computed tomography (CT) scanner, a scanner, a backscatter scanner or a computed tomography-backscatter (CTB) scanner) for simultaneous transmission and scatter imaging is provided.
  • the scanning device 30 is configured as an inspection system for use in imaging or otherwise inspecting luggage, baggage or other objects (indicated generally as 32) as they pass along a conveyor system 34.
  • the computed tomography system includes a plurality of radiation sources 36, e.g., cone-beam x-ray sources, and detectors, e.g., cone-beam detectors 38, that are configured to detect simultaneously transmission radiation and scattered radiation at multiple scattering angles.
  • the sources 36 and detectors 38 are mounted on a gantry 40, e.g., a rotating gantry, for rotation about an axis, e.g., a longitudinal axis along which the objects 32 move on the conveyor system 34.
  • the scanning device may be configured with a variable number of sources and detectors without departing from the scope of the present invention.
  • the detectors 38 are configured to generate signals indicative of received transmission and/or scatter radiation.
  • the signals may be passed to one or more reconstruction processors (indicated generally as reconstruction processor 42), where transmission and/or scatter images may be generated based on the detected transmission and/or scatter radiation.
  • Images, e.g., panoramic scatter images generated based on collected scatter data, transmission images, and/or full-volume CT images may be rendered on a suitable human-readable display 44.
  • FIG. 3 a sectional view of an exemplary scanning device 50 (also referred to simply as a scanner) is provided.
  • the plane defined by the rotation of the x-ray source will be called the axial plane.
  • the center of rotation of the x-ray source will be called the isocenter.
  • the axis parallel to the conveyor belt travel will be called the longitudinal axis or the z-axis. This axis is perpendicular to the axial plane.
  • the axis defined by the line through the x-ray source, the isocenter and the center of the detector bed will be called the transmission axis or the y-axis 54.
  • the axis perpendicular to the transmission axis on the axial plane will be called the detector fan axis or the x-axis.
  • Angle 55 shows one exemplary scatter angle. It will be appreciated that the axis orientations are chosen so that the x, y, and z axes together form a right-handed coordinate system.
  • the scanner 50 includes a first source of penetrating radiation 52, e.g., an x-ray source configured to provide cone beam or flood radiation for irradiating a subject.
  • the scanner 50 includes a pair of detectors, for example, a first detector 56 positioned to receive transmission radiation, e.g., radiation from the source that is transmitted through the subject and detected by the first detector, and a second detector 58 positioned to received scatter radiation, e.g., radiation from the source that is scattered by the subject at one or more scattering angles.
  • a focal spot 60 is designated with respect to the second detector 58.
  • the scanner may be configured with more than one radiation source, e.g., with two radiation sources or with three radiation sources, as well as with more than two detectors, e.g., with three or more detectors.
  • Each detector is configured with and segmented by a focus collimator 62
  • the first detector 56 includes a focus collimator 62 (also referred to simply as a collimator) that functions to provide scatter rejection, that is, rejection of scatter radiation from the object being scanned.
  • the second detector 58 is configured with a focus collimator 62 that functions to form or otherwise focus the incident scatter radiation into a pencil-beam scatter signal.
  • the detectors may be referred to as pencil-beam detectors, which, in one embodiment, refers to a detector having a focus collimator that segments a full detector into a number of pencil-beam detector elements.
  • FIG. 4 illustrates an exemplary cone-beam detector bed 56, 58, 64 with an array of detector channels defined by the focus collimator.
  • the detector bed includes focus collimation devices so that each detector channel sees or otherwise receives only those x-rays that are traveling approximately on a line from the source.
  • these collimation devices are configured to provide scatter rejection, while for scatter acquisitions, these collimation devices provide a means for forming a pencil- beam scatter measurement.
  • FIG. 5 illustrates a portion of a focus collimator 62, where dimension "a” corresponds to detector size, dimension "b” corresponds to collimator height and dimension "c" corresponds to detector to object distance. It has been found that photon count is proportional to (a/b) 2 , not detector-to-object distance. It will be appreciated that the dimensions of the focus collimator may be selected depending upon various performance considerations, such as desired spatial resolution.
  • the source(s) and detector(s) may be mounted to a gantry for rotation about an object-receiving aperture defined by the gantry.
  • the detectors may be individually positionable on the gantry.
  • the detectors also may rotate as a group about the subject-receiving aperture.
  • the detectors may be radially and circumferentially adjustable to vary their distance from the object being scanned and spacing on the gantry. Position adjustment of the detectors may be accomplished via suitable motors, drive assemblies and guide tracks.
  • the Scanning device 50 includes a source of penetrating radiation 52, e.g., an x-ray source configured to provide cone-beam x-rays, as well as three detectors.
  • a first detector 56 is positioned to receive transmission radiation, e.g., radiation that has been transmitted through the object under scan.
  • a second detector 58 (having a focal spot 60) and a third detector 64 (having a focal spot 66) are positioned to simultaneously detect scatter radiation, e.g., radiation scattered by the object under scan.
  • the detectors 56, 58 may be configured with suitable focus collimators (causing the detectors to function as pencil-beam detectors for scatter detection).
  • the source and detectors may be mounted for rotation about the subject scanning area.
  • one or more detectors may be configured to move independently of the source, thereby providing the ability to detect scatter radiation at a variety of scatter angles.
  • the detectors may be positionable and/or movable to detect scatter radiation at non-zero scatter angles.
  • non-zero scatter angles is meant to include angles in addition to or other than “true backscatter" angles
  • the detectors may be positioned to receive scatter radiation at angles of about 20 degrees to about 50 degrees. Alternatively, the detectors may be positioned to receive scatter radiation at angles of about +/- 45 degrees. Alternatively, the detectors may be positioned to receive scatter radiation at angles of about zero degrees to about 90 degrees.
  • the scanner 50 includes three sources of penetrating radiation 52, 68, 70, e.g., x-ray source configured to provide cone-beam x-rays, as well as three detectors.
  • a first detector 56 is positioned to receive transmission radiation, e.g., radiation that has been transmitted through the object under scan, from source 52 and scatter radiation from sources 68 and 70 scattered by the object under scan.
  • a second detector 58 is positioned to receive transmission radiation, e.g., radiation that has been transmitted through the object under scan, from source 68 and scatter radiation from sources 52 and 70 scattered by the object under scan.
  • a third detector 64 is positioned to receive transmission radiation, e.g., radiation that has been transmitted through the object under scan, from source 70 and scatter radiation from sources 52 and 68 scattered by the object under scan.
  • the detectors 56, 58, 64 may be configured with suitable focus collimators (causing the detectors to function as pencil-beam detectors for scatter detection).
  • the sources and detectors may be mounted for rotation about the subject scanning area.
  • one or more detectors may be configured to move independently of the source, thereby providing the ability to detect scatter radiation at a variety of scatter angles.
  • the device may be configured such that the source and detectors move in a consistent manner relative to one another, e.g., the detectors move together with a rotating gantry.
  • FIG. 8 shows exemplary helical paths 72, 74, 76 representative of the locus of source travel.
  • the source and detector embodiments described above provide a scanner having simultaneous transmission and scatter imaging.
  • the scanner is configured for detecting scatter radiation at multiple and/or variable scatter angles (include non-zero or non-backscatter angles) that facilitates fast, real-time panoramic imaging, which is registered to the transmission x-ray, and registered to any CT volume images reconstructed from the collected data.
  • the exemplary scanners described above may be operated in one of a variety of configurations to achieve high throughput and simultaneous transmission and scatter data acquisition.
  • all three x-ray tubes are on simultaneously and each x-ray signal is coded with a modulation signature.
  • detector 64 receives a transmission signal from source 68 and receives scatter signals from sources 52 and 66 at a scatter angle of about 120 degrees.
  • detector 64 (along with the associated processing circuitry) separates primary and scattered signals by demodulation.
  • identical, synchronous acquisition occurs with detectors 56 and 58. It will be appreciated that the geometric position of each transmission signal is determined by the position of the detector channel relative to its source position.
  • each scatter signal is determined by the position of the detector channel and the direction of its focused scatter collimator. It will be appreciated that many other configurations are represented by this imaging device. The following describes the characteristics and impact of some of the configuration differences.
  • Multiple x-ray sources a. The use of multiple x-ray sources in a configuration improves system throughput. b. When multiple x-ray sources are used, the signal from each x-ray source is encoded in such a way that its signature can be decoded at each detector. c. For a given detector bed, the encoding/decoding method effectively separates the transmission signal from the scatter signal. d. The encoding/decoding can be accomplished, for example, with (1 ) a modulation/demodulation technique or (2) a time-sliced pulsing scheme.
  • the scanner includes at least two detector beds - one for the transmission signal and one for the scatter signal.
  • a minimum configuration shown in FIG. 3, includes one x-ray source, a detector bed opposite the source and another detector bed positioned appropriately for the desired nominal scatter angle.
  • the use of more than one detector bed, associated with one x-ray source, for scatter measurement can be configured to provide independent measurements at multiple scatter angles. Such a configuration can provide improved contrast resolution, d. Configurations are possible in which one or more of the x-ray sources are present without a corresponding transmission detector bed. In these cases, the x-ray source would provide additional independent scatter measurements at appropriate scatter angles for each detector bed.
  • Configuration of detector bed a. The size and spacing of the detector channels in a detector bed will impact the scanner's spatial resolution. b. The fan extent of the detector bed determines the extent of the circle that encompasses the objects to be scanned. c. The longitudinal extent of the detector bed determines the size of the swath that can be scanned during each gantry rotation, and thus how far the conveyor belt can be moved during one gantry rotation. d. Possible geometric configurations for the detector bed include (1 ) spherical, focused at the x-ray focal spot , (2) cylindrical, focused at the x-ray focal spot, or (3) focused at the isocenter
  • a cylindrical detector bed positioned 50 cm from the scanner center, consisting of 1000 horizontal channels, spaced at 1 mm increments would provide scan circle coverage of approximately 52.7 cm.
  • Simultaneous transmission and scatter measurements may be made at a multiplicity of view angles, using the concepts of cone-beam CT scanning, with either spiral or circular trajectories.
  • samples are taken at specified angular positions. For example, if samples are taken every Vz degree, then 720 samples will be taken for each gantry rotation. If the gantry is rotating, for example, at 180 rpm, then samples will be taken every 460 ⁇ sec.
  • a transmission and/or scatter measurement will be taken for each detector array. For example, with the configuration illustrated in FIG. 7, at each sample, the following measurements will be made. 1.
  • Detector 56 a. transmission measurement from Source 52, b. scatter measurement from Source 68, c.
  • Detector 58 a. transmission measurement from Source 68, b. scatter measurement from Source 52, c. scatter measurement from Source 70.
  • Detector 64 a. transmission measurement from Source 70, b. scatter measurement from Source 52, c. scatter measurement from Source 68.
  • spiral scanning as the gantry rotates, the conveyor is translating the objects.
  • the speed, c of the conveyor (cm/sec) in relationship to the speed, g , of the gantry (rotations/sec) determines the pitch, P, of the scan according the following formula.
  • the gantry rotation speed is typically limited by the physical constraints of the CT system, for example, 180 rpm or 3 rotations/second.
  • the pitch is limited by the size of the detector in the longitudinal direction. For example, if the detector bed contains 384 rows of detectors spaced at 1 mm intervals, the pitch is limited according to Table 1 below. Based on those pitch values, the conveyor speed can be computed as shown in the table below.
  • Table 1 Maximum scan pitch and conveyor speed for various numbers of source/detector pairs
  • Volume images of attenuation can be obtained from the transmission data using cone beam tomography reconstruction algorithms.
  • the standard Feldkamp (FDK) approximate reconstruction algorithm or the Katsevich Exact Cone-Beam Reconstruction algorithm could be used.
  • FDK Feldkamp
  • Katsevich Exact Cone-Beam Reconstruction algorithm For multiple sources, novel cone-beam reconstruction algorithms uniquely designed for the multiple spiral trajectories shown in FIG. 8 will be employed. These novel algorithms will be similar to the FDK or Katsevich algorithms, but adapted to the extant geometry.
  • Projection images of the scatter data can be generated from the measured scatter data.
  • One method for producing projection images from the scatter data is as follows: (1 ) reconstruct voxel data using modified cone-beam reconstruction algorithms and (2) re-project the resultant voxel data at a multiplicity of views.
  • the projection images can be generated directly from the measured scatter data without an intermediate volume reconstruction.
  • the transmission data can be used make corrections for attenuation to improve the scatter imagery.
  • These projection images will be similar to backscatter images obtained on current pencil-beam backscatter imaging devices except that, here, the object can be viewed from any/all perspectives - a panoramic display.
  • the scatter data can be reconstructed on voxels comprising a full volume field-of-view using cone-beam reconstruction algorithms similar to the FDK or the Katsevich algorithm, but also modified for backscatter acquisition, attenuation correction, and for multiple spiral source trajectories.
  • the resultant volume data can be viewed as multi-planar slices or as volume (opaque or transparent) objects using standard, widely available medical imaging software.
  • Another suitable reconstruction option combines the volume transmission and scatter data in a manner that highlights certain material contrast.
  • This combined data can be viewed as multi-planar slices or as volume (opaque or transparent) objects, with or without pseudo-color coding.
  • scatter image generation is based on a simple model for the scanner, which is quantitatively accurate.
  • the model takes into account an x-ray source 80 which provides penetrating radiation 82 that penetrates a subject 84 (having voxel 86) under scan, whereby scattered radiation 88 (scattered at angle 90) is generated and detected by a suitable detector 92.
  • the model accounts for incident flux, incoming attenuation, e.g., attenuation coefficient at incident energy, photon scattering, outgoing attenuation, e.g., an attenuation coefficient at scattered energy, and detection parameters.
  • the scatter image model is given by Equation 1 where I is the scattered flux per detector steradian, I 0 is the incident flux, Fi is the incoming attenuation ,
  • ⁇ - N n is the electrons per unit volume
  • — L is the probability of scattering per
  • Simulations have been performed to verify the performance of the herein described Scanning device.
  • the following exemplary parameters were used in one or more simulations.
  • the parameters are provided merely for the sake of example, and are not meant to limit aspects of the invention in any way.
  • Incident energy 80 kev, 15mA
  • Source distance 40.0 cm
  • the scanner simulator was developed to compute scatter acquisitions for a variety of simple geometric objects. It has been found that the device and model employed with the device is quantitatively accurate for single scattering.
  • FIG. 10 shows a three-wedge phantom where the top wedge corresponds to aluminum, the middle wedge corresponds to polyvinylchloride (PVC) and the bottom wedge corresponds to water.
  • FIG. 11 shows a simulated scatter image at zero degrees of the three-wedge phantom of FIG. 10, along with corresponding line and saturation plots.
  • FIG. 12 illustrates the three wedges based on scatter data collected at ninety degrees, along with associated line plots.
  • FIG. 13 schematically depicts the subject of another simulation performed based on three-wedge phantoms with cylinders made of aluminum, PVC and water. Scatter image simulations were generated with a view from the front and back as well as a panorama with scatter angles of zero degrees, forty-five degrees and ninety degrees. The simulated images were found to demonstrate concepts related to shadowing and transparency, which should prove useful in various threat detection applications.
  • FIG. 14 schematically depicts the subject of another simulation performed based on a PVC ball that was 4.8 centimeters in diameter disposed between a pair of aluminum plates simulated to be 1.2 centimeters thick. It is noted that the ball may be seen through the aluminum at detector angles at forty-five degrees and at ninety degrees.
  • FIG. 15 schematically depicts the subject of another simulation performed based on a PVC ball of 4.8 centimeters in diameter disposed in a corner created by a pair of aluminum plates having thicknesses of 6 centimeters. It is noted that at a scatter angle of zero degrees, the ball is shielded on two sides by aluminum. While the ball is not physically obscured, it lacks scatter contrast. It is noted that at forty-five degrees, while the ball is shielded on two sides by the aluminum, oblique illumination provides shadowing and a relatively large scatter contrast. This was found to be especially true when in a configuration, involving, for example, one radiation source and two detectors disposed at plus forty-five degrees and minus forty-five degrees. It is noted that an alternative configuration may involve two sources and one detector.
  • Narrow collimation is an important component of the proposed imaging system. Although the collimation allows image formation under flood illumination, it reduces the number of photons arriving at any given detector element.
  • a signal- to-noise ratio calculation for the proposed acquisition geometry indicates that not only is a flood illumination scatter imaging system feasible, but is preferred to that of the conventional pencil-beam backscatter imaging system (shown, for example, in FIG. 1 )
  • the signal to noise ratio for a backscatter reconstruction from 720 projections was calculated based on the following parameters:
  • Xray source 1.01 x 10 9 photons/s at 40OmA on a 0.01 x 0.01 cm 2 detector.
  • Source to scatterer distance 62.5 cm Scatterer to detector distance: 52.5cm Acquisition time: 0.25 s
  • Detector element size 0.4 x 0.4 cm 2
  • the values for these parameters were chosen to realistically model the backscatter imaging system.
  • the signal to noise ratio was computed for the reconstruction of several materials of varying Z and size. From the scanning geometry, the detector source strength and the physical characteristics of the object to be imaged, the expected number I of photon counts per detector were determined. The SNR is calculated by the formula
  • Table 2 indicates the expected counts and SNR for each of these scenarios along with the expected counts and SNR for the conventional pencil beam illumination method.
  • a conventional method for producing backscatter images utilizes a pencil- beam scanning method in which a collimated x-ray beam illuminates an object at a multiplicity of raster positions. At each of the raster positions, a measurement of the x-ray signal is taken and an image is generated from the varying measurements over the raster positions.
  • FIG. 1 illustrates an example configuration for a conventional pencil-beam illumination and detection system.
  • Table 2 Photon counts for Flood Illumination and Pencil Beam Illumination with and without attenuation included.
  • the following discussion provides an estimate of photon counts for the proposed flood illumination backscatter tomography system and compare with photon count estimates for the pencil beam illumination system.
  • an x-ray source of the same intensity is assumed.
  • flood illumination at each acquisition the x-ray source fully illuminates the object.
  • pencil beam illumination it may take one or more pencil beams to fully illuminate the blob. Assuming that the pencil-beam illumination fully covers the blob with no overlaps between each illumination, the total flux on the blob during all acquisitions in the pencil beam system exactly matches the flux on the blob during each acquisition in the flood illumination, collimated detection system.
  • This section describes a simple model to compute the expected scattered flux from a rectangular blob of dimensions LxWxH oriented so that the incident flux is in the x direction, which is defined to be transverse to the face of area WH. After the model is developed, it will be applied to a specific example.
  • the total flux (photons per unit area) of the scattered photons arriving on the detector is the same for the pencil beam illumination and for flood illumination.
  • the relative signal strength between the two methods is determined by the relative sizes of the detector, and by the relative acquisition times. A similar analysis can be performed for other scattering angles.

Landscapes

  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Molecular Biology (AREA)
  • Medical Informatics (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Biomedical Technology (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Pathology (AREA)
  • Radiology & Medical Imaging (AREA)
  • Biophysics (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Surgery (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)
  • Apparatus For Radiation Diagnosis (AREA)

Abstract

La présente invention concerne un dispositif de balayage qui est configuré pour la transmission et l'imagerie par diffusion simultanées dans des positions de diffusion multiples et/ou variables. Le dispositif de balayage inclut au moins une source de faisceau conique de rayonnement pénétrant et au moins deux détecteurs, où un des détecteurs est positionné pour recevoir au moins le rayonnement transmis et l'autre des détecteurs est positionné pour recevoir au moins le rayonnement de diffusion. Le dispositif de balayage facilite la génération en temps réel de vues panoramiques basées sur le rayonnement de diffusion détecté.
PCT/US2007/068040 2006-05-02 2007-05-02 Scanner et procede de transmission et d'imagerie par diffusion Ceased WO2007131038A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US79678406P 2006-05-02 2006-05-02
US60/796,784 2006-05-02

Publications (2)

Publication Number Publication Date
WO2007131038A2 true WO2007131038A2 (fr) 2007-11-15
WO2007131038A3 WO2007131038A3 (fr) 2008-11-20

Family

ID=38668511

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2007/068040 Ceased WO2007131038A2 (fr) 2006-05-02 2007-05-02 Scanner et procede de transmission et d'imagerie par diffusion

Country Status (1)

Country Link
WO (1) WO2007131038A2 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009101572A3 (fr) * 2008-02-14 2010-03-11 Koninklijke Philips Electronics N.V. Appareil à rayons x, en particulier pour des applications de sécurité
EP2278305A1 (fr) * 2009-07-24 2011-01-26 GE Sensing & Inspection Technologies GmbH Dispositif de vérification automatisée et/ou de mesure d'un nombre de composants essentiellement identiques à l'aide de rayons x
US9851291B2 (en) 2016-05-02 2017-12-26 Hamilton Associates, Inc. Realtime optical method and system for detecting and classifying biological and non-biological particles
CN116224457A (zh) * 2021-12-30 2023-06-06 同方威视技术股份有限公司 多射线源检查设备和检查方法
US20230346323A1 (en) * 2022-04-28 2023-11-02 Canon Medical Systems Corporation X-ray ct apparatus
WO2024193285A1 (fr) * 2023-03-22 2024-09-26 同方威视技术股份有限公司 Dispositif, procédé et système d'inspection

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6687326B1 (en) * 2001-04-11 2004-02-03 Analogic Corporation Method of and system for correcting scatter in a computed tomography scanner

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009101572A3 (fr) * 2008-02-14 2010-03-11 Koninklijke Philips Electronics N.V. Appareil à rayons x, en particulier pour des applications de sécurité
EP2278305A1 (fr) * 2009-07-24 2011-01-26 GE Sensing & Inspection Technologies GmbH Dispositif de vérification automatisée et/ou de mesure d'un nombre de composants essentiellement identiques à l'aide de rayons x
CN101963620A (zh) * 2009-07-24 2011-02-02 Ge传感与检测技术有限公司 一种采用x射线自动测试和/或测量多个基本相同的元件的系统
US8351567B2 (en) 2009-07-24 2013-01-08 Ge Sensing & Inspection Technologies Gmbh Method and system for the automated testing and/or measuring of a plurality of substantially identical components using X-ray radiation
EP3410103A1 (fr) * 2009-07-24 2018-12-05 GE Sensing & Inspection Technologies GmbH Dispositif de vérification automatisée et/ou de mesure d'un nombre de composants essentiellement identiques à l'aide de rayons x
US9851291B2 (en) 2016-05-02 2017-12-26 Hamilton Associates, Inc. Realtime optical method and system for detecting and classifying biological and non-biological particles
US10908064B2 (en) 2016-05-02 2021-02-02 Hamilton Associates, Inc. Realtime optical method and system for detecting and classifying biological and non-biological particles
CN116224457A (zh) * 2021-12-30 2023-06-06 同方威视技术股份有限公司 多射线源检查设备和检查方法
US20230346323A1 (en) * 2022-04-28 2023-11-02 Canon Medical Systems Corporation X-ray ct apparatus
US12465299B2 (en) * 2022-04-28 2025-11-11 Canon Medical Systems Corporation X-ray CT apparatus
WO2024193285A1 (fr) * 2023-03-22 2024-09-26 同方威视技术股份有限公司 Dispositif, procédé et système d'inspection

Also Published As

Publication number Publication date
WO2007131038A3 (fr) 2008-11-20

Similar Documents

Publication Publication Date Title
US8532259B2 (en) Method and apparatus for computed imaging backscatter radiography
US8000436B2 (en) Radiation scanning units including a movable platform
US7778383B2 (en) Effective dual-energy x-ray attenuation measurement
US7672422B2 (en) Radiation scanning of objects for contraband
US8472583B2 (en) Radiation scanning of objects for contraband
US7672426B2 (en) Radiation scanning units with reduced detector requirements
CN101231254B (zh) 双源三维立体成像系统和成像方法
EP2273257B1 (fr) Système d'imagerie utilisant un balayage à trajectoire en ligne droite et procédé correspondant
JP2515973B2 (ja) 投影式ラジオグラフイツクシステムおよび放射線検出器
US20100166285A1 (en) System and method for acquiring image data
CN1794951A (zh) 扇形射束相干散射计算机断层摄影
CN1947001A (zh) 通过确保在一个时刻只有一个源在发射辐射而对包括多个源的反向散射检查入口中的串扰的消除
CN101900694B (zh) 基于直线轨迹扫描的双能欠采样物质识别系统和方法
US6380540B1 (en) Radiation imaging using simultaneous emission and transmission
JP2007508561A (ja) 非対称ｃｓｃｔ
WO2007131038A2 (fr) Scanner et procede de transmission et d'imagerie par diffusion
US20080073539A1 (en) Attenuation correction for SPECT imaging using non-classical orbits of many small gamma cameras
US20080170658A1 (en) System and method for ct imaging with increased sampling and reduced artifacts
US7502437B2 (en) Focused coherent-scatter computer tomography
CN201043954Y (zh) 一种多段直线轨迹成像的货物安全检查系统

Legal Events

Date Code Title Description
NENP Non-entry into the national phase

Ref country code: DE

121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 07761751

Country of ref document: EP

Kind code of ref document: A2