Patent EP0526970A2 successfully refreshed from Google Patents.
EP0526970A2
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EP
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Imaging methods and apparatus
Assignee: University of Utah
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Filing: 1992-06-05
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Granted: —
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Expires: 2012-06-05
Abstract
Abstract A single-photon emission computed tomography system includes three gamma camera heads (22a), (22b), (22c) which are mounted to a gantry (20) for rotation about a subject (12). The subject is injected with a source of emission radiation, which emission radiation is received by the camera heads. A reconstruction processor (112) reconstructs the emission projection data into a distribution of emission radiation sources in the subject. Transmission radiation from a radiation source (30) passes through the subject and is received by one of the camera heads (22a) concurrently with the emission radiation. The transmission radiation data is reconstructed into a three-dimensional computed tomography type image representation of radiation attenuation characteristics of each pixel of the subject. An attenuation correction processor (118) corrects the emission projection data to compensate for attenuation along the path or ray that it traversed. In this manner, an attenuation corrected distribution of emission sources is generated.
Inventors
- 👤 Gengsheng Lawrence Zeng
- 👤 Grant T. Gullberg
- 👤 Chi-Hua Tung
- 👤 Paul E. Christian
- 👤 Hugh T. Morgan
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 16:34
CPC Classifications
A; A61; A61B; A61B6/00; A61B6/44; A61B6/4429; A61B6/02; A61B6/03; A61B6/037; A61B6/48; A61B6/482; A61B6/52; A61B6/5211; A61B6/5229; A61B6/5235; A61B6/58; A61B6/582; A61B6/583; A61B6/589; G; G01; G01T; G01T1/00; G01T1/16; G01T1/161; G01T1/1615; G01T1/29; G01T1/2914; G01T1/2985; G06; G06T; G06T12/00; G06T12/10; A61B5/00; A61B5/103; A61B5/107; A61B5/1077
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
66 words
An imaging system characterised in that it comprises: a plurality of gamma camera heads (22a,b,c) disposed for movement around and facing an examination region (14), each gamma camera head (22a,b,c) receiving radiation emitted from a subject (12) in the examination region (14) and producing output signals indicative thereof; and a transmission radiation source (50) disposed opposite one of the heads (22a) across the examination region (14).
Claim 2
Dependent Claim
109 words
A system according to Claim 1 wherein the subject (12) is injected with a radionuclide of a first energy level and the radiation source (50) generates radiation of a second energy level and wherein each gamma camera head (22a,b,c) provides first and second energy level output signals and further including: second energy correction means (76) for correcting the second energy level signal corresponding to the radiation source (50), from the head (22a) opposite the radiation source (50) in accordance with other photopeak emission photons received by other camera (22b,c) heads, the second energy output signal from each of the camera heads being connected with the second energy correction means.
Claim 3
Dependent Claim
51 words
A system according to Claim 1, wherein the subject (12) is injected with a radiopharmaceutical and further including means (132) for correcting output signals corresponding to the radiopharmaceutical from at least the gamma camera head (22b,c) not opposite the radiation source (50) to compensate for the radiation from the source (50).
Claim 4
Dependent Claim
58 words
A system according to Claim 1 wherein the subject (12) is injected with a radionuclide and further including: means (118) for determining attenuation coefficients from the transmission radiation output signals from the head (22a) opposite the source (50); and means (112) for reconstructing an attenuation corrected image representation of radionuclide distribution from emission radiation signals from the heads.
Claim 5
Independent Claim
58 words
A system according to any preceding claim wherein the transmission radiation source (50) includes one of: a line source; a bar source; a point source; a flat rectangular-shaped source which is small compared to an entrance surface of the collimator; a disc source which is small compared to an entrance surface of the collimator; and, a flood source.
Claim 6
Independent Claim
56 words
A system according to any preceding claim further including a collimator (62) mounted on a radiation receiving face of each gamma camera head (22a,b,c), the collimator (62) mounted to the gamma camera head (22a) opposite the radiation source being one of: a fan beam collimator; a cone beam collimator; an astigmatic collimator; and, a parallel collimator.
Claim 7
Independent Claim
22 words
A system according to any preceding claim wherein the transmission radiation source (50) includes one of an x-ray tube and a radionuclide.
Claim 8
Independent Claim
33 words
A system according to any preceding claim further including source collimator means (15) for restricting radiation from the transmission source (50) to impinge on the one head (22a) across the examination region therefrom.
Claim 9
Independent Claim
24 words
A system according to any preceding claim further including: means (52,54,56,58) for moving the radiation source toward and away from the examination region (14).
Claim 10
Dependent Claim
81 words
A system according to claim 9 further including: circumferential moving means (24,26) for moving the gamma camera heads circumferentially around the examination region; radial moving means (28,30,32) for moving the gamma camera heads radially toward and away from the examination region; and, control means for controlling at least one of the radiation source moving means (52,54,56,58) and the radial moving means (28,30,32) such that the radiation source (50) and the opposite head (22c) maintain a fixed spacing relative to each other.
Claim 11
Independent Claim
45 words
A system according to any preceding claim comprising reconstruction means (112) for processing concurrently received transmission radiation data from the one head (22a) and emission radation data from the heads (22a,b,c) into an attenuation corrected image representation of emission radiation distribution in the examination region.
Claim 12
Dependent Claim
46 words
A system according to Claim 11 wherein the reconstruction means (112) includes: attenuation data processing means (120) for calculating attenuation correction values from the transmission radiation data; emission data processing means for reconstructing the corrected image representation from the attenuation correction values and the emission data.
Claim 13
Independent Claim
140 words
A method of imaging by reconstructing emission projection signals from a multi head gamma camera system to produce a pixelized image of a distribution of emission sources in an attenuating medium (12) the method comprising: projecting radiation through the medium (12) to one of the heads (22a,b,c) as the heads are rotated about the medium (12) and collecting transmission projection data; during the rotation of the heads (22a,b,c) around the medium (12), receiving emission radiation from the emission sources distributed in the medium (12) with the heads (22a,b,c,) and collecting emission projection data; correcting the transmission and emission projection data for cross-talk therebetween; generating attenuation coefficients from the transmission data for the pixelized space; from the emission projection data set and the attenuation coefficient set, reconstructing an image space representation of the distribution of emission sources in the medium (12).
Claim 14
Dependent Claim
92 words
A method according to Claim 13 wherein in the step of transmitting radiation through the examination region, the transmission radiation is either of x-rays from an x-ray tube or gamma radiation emananting from one of: a line source (50) a rectangular source (50), a point source (50), a disc source (50), and a flood source (50); and further including the step of collimating radiation passing from the medium to the heads with at least one of: a fan beam collimator (62) a cone beam collimator, an astigmatic collimator, and a parallel collimator.
Claim 15
Dependent Claim
24 words
A method according to Claim 13 or 14 further including correcting the transmission projection data for scatter and photopeak photons from multi-peak emission radionuclei.
Claim 16
Dependent Claim
93 words
A method according to Claim 13, 14 or 15 wherein the emission and transmission source (50) produce radiation having first and second energies, respectively, and wherein the step of correcting the transmission projection signals includes: measuring first and second energy radiation photons with each (22a,b,c,): substracting a portion of the transmission projection data from the transmission projection data of one of the heads (22a,b,c) to provide corrected transmission projection data; reconstructing a corrected transmission image representation from the corrected transmission projection data, the attenuation coefficients being generated from the corrected transmission image representation.
Claim 17
Dependent Claim
82 words
A method as set forth in Claim 13,14 or 15 wherein the transmission and emission sources (50) produce radiation of the same energy and wherein the step of correcting the transmission projection data for cross-talk includes: monitoring the emission projection data from the two heads (22b,c,) which are not opposite the transmission radiation source (50); subtracting the monitored emission projection data from the simultaneously measured transmission and emission projection data of the head (22c) directly across from the transmission radiation source (50).
Claim 18
Independent Claim
35 words
A method according to any of Claims 13 to 17 wherein the step of generating the attenuation coefficients for the pixelized space includes: correcting the emission projection data for scatter from the transmission source (50).
Claim 19
Dependent Claim
63 words
A method according to Claim 18 when dependent on Claim 16 wherein the correcting step includes: measuring a portion of transmission and emission photons scattering into an emission energy range with the heads (22a,b,c); subtracting the measured portion from the measured emission projection data of the heads (22a,b,c) to generate corrected emission projection data which are reconstructed into the emission source distribution representation.
Claim 20
Dependent Claim
76 words
A method according to Claim 18 when dependent on Claim 17 wherein the correction step includes: measuring a portion of the transmission and emission photons in an emission energy range and detected by the two heads (22b,c) not directly opposite the transmission radiation source (50); substracting the portion from the measured transmission projection data of the heads (22b,c) not directly opposite the radiation source (50) to generate corrected transmission data for reconstruction into the attenuation coefficients.
Claim 21
Independent Claim
86 words
A method of determining an emission source distribution within a subject (12) the method comprising; transmitting radiation photons through only a truncated portion of the subject (12); detecting transmission radiation photons which have passed through the truncated subject portion; determining radiation attenuation properties of the subject from the detected truncated transmission photons; detecting emission radiation photons emitted by emission sources distributed within the subject (12); from the detected emission radiation photons and the attenuation properties, reconstructing a representation of the emission source distribution in the subject.
References Cited (Backward Citations)
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