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WO2001036997A1 - Imagerie par rayons gamma - Google Patents

Imagerie par rayons gamma Download PDF

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Publication number
WO2001036997A1
WO2001036997A1 PCT/AU2000/001393 AU0001393W WO0136997A1 WO 2001036997 A1 WO2001036997 A1 WO 2001036997A1 AU 0001393 W AU0001393 W AU 0001393W WO 0136997 A1 WO0136997 A1 WO 0136997A1
Authority
WO
WIPO (PCT)
Prior art keywords
gamma
rays
ray
source
detector
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/AU2000/001393
Other languages
English (en)
Inventor
James Richard Tickner
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.)
Commonwealth Scientific and Industrial Research Organization CSIRO
Original Assignee
Commonwealth Scientific and Industrial Research Organization CSIRO
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
Priority claimed from AUPQ4142A external-priority patent/AUPQ414299A0/en
Priority claimed from AUPQ4156A external-priority patent/AUPQ415699A0/en
Application filed by Commonwealth Scientific and Industrial Research Organization CSIRO filed Critical Commonwealth Scientific and Industrial Research Organization CSIRO
Priority to EP00974182A priority Critical patent/EP1257848A4/fr
Priority to AU12591/01A priority patent/AU769926B2/en
Priority to CA002392346A priority patent/CA2392346C/fr
Priority to US10/130,482 priority patent/US6858848B1/en
Publication of WO2001036997A1 publication Critical patent/WO2001036997A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • 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
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/17—Circuit arrangements not adapted to a particular type of detector
    • G01T1/172—Circuit arrangements not adapted to a particular type of detector with coincidence circuit arrangements
    • 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)

Definitions

  • the invention relates to the use of gamma-rays to produce an image of an object.
  • the invention is useful in applications where a 1, 2 or 3-dimensional image is required and there is access to only one side of the object.
  • Gamma-rays are widely used to produce images of extended objects, for example for medical diagnoses.
  • the conventional approach is to measure the attenuation of a gamma-ray beam passing through the object from a source on one side of the object to a detector on the other. If a wide area beam is used together with a position sensitive detector, a two dimensional map of the object is produced.
  • multiple two dimensional slices can be combined using computed tomography (CT) techniques.
  • CT computed tomography
  • PET positron emission tomography
  • gamma-ray means electromagnetic photons having an energy of about 1 keV or more and includes electromagnetic photons normally known as X-rays which range up to about 100 keV.
  • CSI Compton scatter imaging
  • a 2-dimensional image of the radioactive source density can be produced using an Anger camera or a Compton telescope.
  • the former uses a position sensitive gamma-ray detector together with a gamma-ray opaque screen with a small aperture that projects an image of the object being studied onto the detector. Large or multiple apertures can be used to increase the efficiency of the camera, but necessitate the use of mathematical deconvolution techniques to form an image.
  • the Compton telescope makes use of the angle/energy relationship of the Compton scattering process described above to infer the direction of an incident gamma-ray by measuring its interaction with two separate position sensitive detectors.
  • the Compton telescope can be fairly efficient, but again mathematical deconvolution is required to obtain an image. All of these methods suffer from one or more of the following disadvantages:
  • the invention provides an instrument for obtaining information about an object, the instrument including: a source of gamma-rays that is so located with respect to an object to be examined that at least some of the gamma-rays impinge on the object; a gamma-ray detector capable of detecting position and/or time of arrival of incident gamma-rays; a gamma-ray shield surrounding the detector having an aperture for facing at the object to be examined; and means for determining information about the object derived from the position and/or time of arrival at the detector of each gamma-ray passing through the aperture wherein the detector is located on the same side of the object as the source of gamma-rays.
  • the source of gamma-rays is a positron source that is shielded to produce pairs of co-linear and co-incident annihilation gamma-rays.
  • the source may be any source of gamma-rays including a source of co- incident gamma-ray pairs.
  • the invention provides a method including the steps of: generating gamma-rays from a source of gamma-rays causing at least some of the gamma-rays to impact on an object; detecting the position and/or time of arrival of each gamma-ray incident upon a detector; and determining information about the object from the position and/or time of arrival at the detector of the gamma-rays incident upon the detector.
  • the source of gamma-rays is positrons and the method includes the step of generating pairs of co- linear and co-incident gamma-rays by shielding a source of positrons with a suitable shield.
  • the invention is designed to form 3-dimensional images of the electron-density of an arbitrary object that can be viewed from one side only. Variations of the invention can be used to produce 1-dimensional (depth) profiles and 2-dimensional transverse density maps.
  • Figure 1 is a schematic drawing of a preferred embodiment of the invention
  • Figure 2 is a schematic drawing of a second embodiment of the invention
  • Figure 3 is a schematic drawing of a third embodiment of the invention.
  • Figure 4 is a schematic drawing of another embodiment of the invention.
  • Figure 1 shows: (i) a gamma-ray detector (D) which is instrumented to provide the position and time of an incident gamma-ray; (ii) a collimator (C) made of lead or another suitable gamma-ray shielding material containing an aperture (A) in its front face and (iii) a positron source (S) surrounded by sufficient shielding material that positrons emitted by the source are brought to rest and annihilate in the vicinity of the source.
  • D gamma-ray detector
  • C collimator
  • A aperture
  • S positron source
  • the operation of the embodiment is as follows.
  • a positron from the source (S) comes to rest in the shielding surrounding the source and annihilates, producing two 511 keV gamma-rays travelling back-to-back.
  • One of the gamma- rays (1) is detected in detector (D) and the time and position of its arrival noted.
  • the other gamma-ray (2) enters the object being examined (J) and scatters at some point (P) within the object.
  • the scattered gamma-ray is then detected in detector (D) and its position and time of arrival noted.
  • the positions of the two gamma-rays in detector (D) and the time between their arrival suffices to calculate the scattering position (P) .
  • a profile of the probability of scattering and hence the electron-density inside the object (J) can be determined.
  • the electron density in turn can be approximately related to the physical density of matter inside the object.
  • Figure 2 depicts a gamma-ray source (S) producing 2 or more coincident gamma-rays, gamma-ray detectors (D and D') , and a collimator (C) containing an aperture (A) .
  • Gamma-ray (1) is detected in (D') travelling directly from the source and gamma-ray (2) is detected in (D) after scattering at point (P) in the object being studied (J) .
  • Gamma-ray detector (D') can be omitted, with both gamma- rays being detected in detector (D) .
  • Figure 3 depicts a gamma-ray source (S) , gamma- ray detector (D) , and a collimator (C) containing an aperture (A) .
  • Gamma-rays are detected in (D) after scattering at point (P) in the object being studied (J) .
  • Figure 4 depicts a gamma-ray or positron source (S) producing 2 or more coincident gamma-rays, gamma-ray detectors (D and D') , and a collimator (C) containing an aperture (A) .
  • One gamma-ray is detected directly in detector (D) or (D') if used; the other gamma-ray is detected in (D) after scattering at point (P) in the object being studied (J) .
  • Gamma-ray detector (D') can be omitted, with both gamma-rays being detected in detector (D) .
  • Detector (D) may comprise one or more slabs of a scintillator material having a fast light decay time.
  • the slab(s) are read out by a multiplicity of light detectors such as photomultiplier tubes or semiconductor diodes. Timing and possibly amplitude information from these detectors may be used to determine the position and arrival time of an incident gamma-ray. It will be appreciated that this description represents only one possible realisation of detector (D) and other detectors designs could be used without affecting the underlying nature of the invention.
  • the collimator (C) should be sufficiently opaque to gamma-rays to shield the detector (D) from gamma-rays scattered from the object (J) , other than those gamma-rays passing through aperture (A) .
  • the size and form of aperture (A) should be chosen to optimise the spatial resolution and efficiency of the invention.
  • a gamma-ray imaging device as per the first embodiment, with the positron source (S) replaced by a gamma-ray source which produces at least two coincident gamma-rays per decay.
  • One gamma-ray is detected in detector (D) or in a small detector (D') immediately surrounding the source (S) and its time of arrival noted.
  • the other gamma ray scatters from the object (J) and its time and arrival in detector (D) noted.
  • Aperture (A) is made small enough that scattered gamma-rays project an image of object (J) onto detector (D) .
  • the scattering position (P) and hence the density profile of the object (J) can be determined.
  • the penetration of the imaging device into object (J) can be controlled.
  • a gamma-ray imaging device as per the second embodiment, with the source (S) replaced by a gamma-ray source where only one gamma-ray per decay is used. No timing information is measured or used. Such a device would permit a 2-dimensional map of the density of object (J) to be determined, with the density profile over the third coordinate (radial distance from the source (S) ) being averaged.
  • a gamma-ray profiling device as per the first embodiment, with the arrival position of the two gamma-rays in detector (D) not being measured or used. The difference between the arrival times of the two gamma-rays is used to determine the density profile of object (J) in 1-dimension (radial distance from the source (S) ) .
  • the source (S) can either comprise a positron emitting source as in the main invention, or a source producing two coincident gamma-rays as per variation 1 above; in this instance, one of the gamma-rays may be detected in a small detector (D') surrounding the source.
  • Collimator (C) and aperture (A) can be adjusted to control the transverse size of the region of object (J) that is examined.
  • FIGS 2, 3 and 4 illustrate these variations. Other minor variations, within the spirit of the main invention and the variations described above, are also included within the scope of the invention.
  • the invention has utility in the following applications :

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Molecular Biology (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Measurement Of Radiation (AREA)

Abstract

L'invention concerne un instrument et un procédé permettant de déterminer des informations relatives à un objet (J), dont un seul côté est disponible pour un examen. Ce procédé consiste à exposer ledit objet à des rayons gamma, et à mesurer la position et/ou le moment d'arrivée desdits rayons gamma au niveau d'un détecteur (D). L'instrument comprend une source de rayons gamma (S) située de sorte qu'au moins quelques rayons aient un impact sur l'objet, et un détecteur entouré d'une protection (C) possédant une ouverture (A) opposée à l'objet à étudier. Ledit détecteur peut mesurer la position et/ou le moment d'arrivée, au niveau du détecteur, des rayons gamma qui traversent l'ouverture.
PCT/AU2000/001393 1999-11-18 2000-11-14 Imagerie par rayons gamma Ceased WO2001036997A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP00974182A EP1257848A4 (fr) 1999-11-18 2000-11-14 Imagerie par rayons gamma
AU12591/01A AU769926B2 (en) 1999-11-18 2000-11-14 Gamma-ray imaging
CA002392346A CA2392346C (fr) 1999-11-18 2000-11-14 Imagerie par rayons gamma
US10/130,482 US6858848B1 (en) 1999-11-18 2000-11-14 Gamma-ray imaging

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
AUPQ4142 1999-11-18
AUPQ4142A AUPQ414299A0 (en) 1999-11-18 1999-11-18 Gamma ray imaging
AUPQ4156 1999-11-19
AUPQ4156A AUPQ415699A0 (en) 1999-11-19 1999-11-19 Gamma ray imaging

Publications (1)

Publication Number Publication Date
WO2001036997A1 true WO2001036997A1 (fr) 2001-05-25

Family

ID=25646206

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AU2000/001393 Ceased WO2001036997A1 (fr) 1999-11-18 2000-11-14 Imagerie par rayons gamma

Country Status (3)

Country Link
EP (1) EP1257848A4 (fr)
CA (1) CA2392346C (fr)
WO (1) WO2001036997A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003034052A1 (fr) * 2001-10-11 2003-04-24 The Secretary Of State For Defence Appareil d'imagerie gamma
EP2482102A1 (fr) * 2011-02-01 2012-08-01 GSI Helmholtzzentrum für Schwerionenforschung GmbH Dispositif d'imagerie par rayons gamma
US9535016B2 (en) 2013-02-28 2017-01-03 William Beaumont Hospital Compton coincident volumetric imaging
CN111175326A (zh) * 2020-02-28 2020-05-19 北京格物时代科技发展有限公司 探测仪以及探测方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4124804A (en) * 1976-12-17 1978-11-07 Stuart Mirell Compton scatter scintillation camera system
US4638158A (en) * 1984-01-18 1987-01-20 Halliburton Company Gamma ray measurement of earth formation properties using a position sensitive scintillation detector
US5430787A (en) * 1992-12-03 1995-07-04 The United States Of America As Represented By The Secretary Of Commerce Compton scattering tomography
AU3202297A (en) * 1996-08-07 1998-02-25 Northrop Grumman Corporation Two-dimensional imaging backscatter probe

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4124804A (en) * 1976-12-17 1978-11-07 Stuart Mirell Compton scatter scintillation camera system
US4638158A (en) * 1984-01-18 1987-01-20 Halliburton Company Gamma ray measurement of earth formation properties using a position sensitive scintillation detector
US5430787A (en) * 1992-12-03 1995-07-04 The United States Of America As Represented By The Secretary Of Commerce Compton scattering tomography
AU3202297A (en) * 1996-08-07 1998-02-25 Northrop Grumman Corporation Two-dimensional imaging backscatter probe

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP1257848A4 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003034052A1 (fr) * 2001-10-11 2003-04-24 The Secretary Of State For Defence Appareil d'imagerie gamma
EP2482102A1 (fr) * 2011-02-01 2012-08-01 GSI Helmholtzzentrum für Schwerionenforschung GmbH Dispositif d'imagerie par rayons gamma
US9535016B2 (en) 2013-02-28 2017-01-03 William Beaumont Hospital Compton coincident volumetric imaging
CN111175326A (zh) * 2020-02-28 2020-05-19 北京格物时代科技发展有限公司 探测仪以及探测方法

Also Published As

Publication number Publication date
EP1257848A1 (fr) 2002-11-20
EP1257848A4 (fr) 2007-01-24
CA2392346C (fr) 2009-04-14
CA2392346A1 (fr) 2001-05-25

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