US5414622A
Expired / Lapsed
US
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Method and apparatus for back projecting image data into an image matrix location
Assignee: Individual
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Filing: 1988-02-01
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Granted: 1995-05-09
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Expires: 2008-02-01
Abstract
Abstract The present invention includes a back projector (44) suitable for assisting in the reconstruction of computerized tomography projection data. In particular it provides a fast and universal back projection system which can accomodate virtually any scanner geometry. The back projector (44) is based on an algorithm which involves the scaling of an image matrix pixel location to determine a pointer into a projection data memory (114). A linearization memory (112) contains pointers into a projection data memory (114). The location of the pixel is used to determine the proper location within the linearization memory (112) preferably using a linear interpolation process. The projection data contained in memory (114) is also preferably extracted using a similar interpolation process.
Inventors
- 👤 Ronald G. Walters
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 00:28
CPC Classifications
G; G06; G06T; G06T12/00; G06T12/20
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
136 words
An apparatus for back projecting data provided by a CT scanner or other object image scanner into an image matrix location, wherein the data are associated with a particular view of a test subject, comprising: a. a projection data memory means for storing projection data; b. a linearization pointer memory means for storing a set of projection data memory pointers; c. scaling means operatively connected to the linearization pointer memory means for selecting a member of the set of projection data memory pointers; d. means operatively connected to the scaling means and the projection data memory means for determining, based on the selected projection data memory pointer, the projection data associated with the image matrix location; and e. means operatively connected to the determining means for accumulating the projection data associated with the image matrix location.
Claim 2
Independent Claim
136 words
An apparatus for back projecting data provided by a CT scanner or other object image scanner into an image matrix location, wherein the data are associated with a particular view of a test subject, comprising: a. a projection data memory means for storing projection data; b. a linearization pointer memory means for storing a set of projection data memory pointers; c. scaling means operatively connected to the linearization pointer memory means for selecting a member of the set of projection data memory pointers; d. means operatively connected to the scaling means and the projection data memory means for determining, based on the selected projection data memory pointer, the projection data associated with the image matrix location; and e. means operatively connected to the determining means for accumulating the projection data associated with the image matrix location.
Claim 3
Dependent Claim
28 words
The apparatus of claim 1, wherein the scaling means and the determining means each comprises means for interpolating between adjacent data, thereby increasing the accuracy of the apparatus.
Claim 4
Dependent Claim
34 words
The apparatus of claim 1, wherein the apparatus is suitable for daisy-chaining with other such apparatus, whereby data associated with a plurality of views can be simultaneously back projected into the image matrix location.
Claim 5
Dependent Claim
175 words
The apparatus of claim 1, wherein the view is provided by a fan having a center and an apex, said apparatus further comprising: (a) means for providing an S value for the image matrix location, wherein the S value is a function of the distance of the image matrix location from a line extending from the apex of the fan through the center of a scan circle and an E value for the image matrix location, wherein the E value is a function of the distance of the image matrix location from a line passing through the apex of the fan and substantially perpendicular to a line from the apex of the fan through the center of the scan circle; and further wherein: (b) the scaling means comprises: (i) a 1/E memory means for storing a plurality of 1/E values; and (ii) means for multiplying the 1/E value for the image matrix location by the S value for the image matrix location to determine the projection data memory pointer associated with the image matrix location.
Claim 6
Dependent Claim
179 words
The apparatus of claim 1, wherein: (a) there is an S value and a T value, each associated with an image matrix location, wherein the T value is a function of the distance of the image matrix location from a line passing through a scan circle center and substantially perpendicular to a line passing from an apex through the scan circle center, and the S value is a function of the distance of the image matrix location from a line extending from the apex of the fan through the center of the scan circle, and an E value which is a function of the sum of the T value and the distance from the apex to the scan circle center; (b) the scaling means comprises: (i) a 1/E memory means for storing a plurality of 1/E values which are selected by the T values; and (ii) means for multiplying the 1/E value for the image matrix location by the S value for the image matrix location to determine the projection data memory pointer associated with the image matrix location.
Claim 7
Dependent Claim
165 words
A medical CT scanner for analyzing a patient to provide projection data to an image matrix location for a particular view of the patient, comprising: a. means for directing a beam of radiation through the patient; b. means responsive to the radiation passing through the patient for providing projection data indicative of the density of the patient; c. a projection data memory means operatively connected to the providing means for storing the projection data; d. a linearization pointer memory means for storing a set of projection data memory pointers; e. scaling means operatively connected to the linearization pointer memory means for selecting a member of the set of projection data memory pointers; f. means operatively connected to the scaling means and the projection data memory means for determining, based on the selected projection data memory pointer, the projection data associated with the image matrix location; and g. means operatively connected to the determining means for accumulating the projection data associated with the image matrix location.
Claim 8
Dependent Claim
165 words
A medical CT scanner for analyzing a patient to provide projection data to an image matrix location for a particular view of the patient, comprising: a. means for directing a beam of radiation through the patient; b. means responsive to the radiation passing through the patient for providing projection data indicative of the density of the patient; c. a projection data memory means operatively connected to the providing means for storing the projection data; d. a linearization pointer memory means for storing a set of projection data memory pointers; e. scaling means operatively connected to the linearization pointer memory means for selecting a member of the set of projection data memory pointers; f. means operatively connected to the scaling means and the projection data memory means for determining, based on the selected projection data memory pointer, the projection data associated with the image matrix location; and g. means operatively connected to the determining means for accumulating the projection data associated with the image matrix location.
Claim 9
Dependent Claim
34 words
The scanner of claim 6, wherein the scanner is suitable for daisy-chaining with other such scanners, whereby data associated with a plurality of views can be simultaneously back projected into the image matrix location.
Claim 10
Dependent Claim
170 words
The scanner of claim 6, wherein the view is provided by a fan having a center and an apex and further comprising; (a) means for providing an S value for the image matrix location, wherein the S value is a function of the distance of the image matrix location from a line extending from the apex through the center of a scan circle, and an E value for the image matrix location, wherein the E value is a function of the distance of the image matrix location from a line passing through the apex of the fan and substantially perpendicular to a line from the apex of the fan through the center of the scan circle; and wherein: (b) the scaling means comprises: (i) a 1/E memory means for storing a plurality of 1/E values; and (ii) means for multiplying the 1/E value for the image matrix location by the S value for the image matrix location to determine the projection data memory pointer associated with the image matrix location.
Claim 11
Dependent Claim
181 words
The scanner of claim 6, further comprising: a. means for providing an S value and a T value, each associated with an image matrix location, wherein the T value is a function of the distance of the image matrix location from a line passing through a scan circle center and substantially perpendicular to a line passing from an apex through the scan circle center, and the S value is a function of the distance of the image matrix location from a line extending from the apex of the fan through the center of the scan circle, and an E value which is a function of the sum of the T value and the distance from the apex to the scan circle center; b. the scaling means comprises: (i) a 1/E memory means for storing a plurality of 1/E values which are selected by the T values; and (ii) means for multiplying the 1/E value for the image matrix location by the S value for the image matrix location to determine the projection data memory pointer associated with the image matrix location.
Claim 12
Dependent Claim
28 words
The scanner of claim 6, wherein the scaling means and the determining means each comprises means for interpolating between adjacent data, thereby increasing the accuracy of the apparatus.
Claim 13
Independent Claim
127 words
A method for back projecting data provided by a CT scanner or other object image scanner into an image matrix location, wherein the data are associated with a particular view of a test subject, comprising: a. storing projection data having an arbitrary distribution in a projection data memory; b. storing projection data memory pointers in a linearization pointer memory; c. establishing a linearly sampled projection line evenly divided in a manner corresponding to the linearization pointer memory; d. scaling the image matrix location to determine the projection data memory pointer associated with the image matrix location; e. based on the determined projection data memory pointer, determining the projection data associated with the image matrix location; and f. summing the projection data into the associated image matrix location.
Claim 14
Independent Claim
127 words
A method for back projecting data provided by a CT scanner or other object image scanner into an image matrix location, wherein the data are associated with a particular view of a test subject, comprising: a. storing projection data having an arbitrary distribution in a projection data memory; b. storing projection data memory pointers in a linearization pointer memory; c. establishing a linearly sampled projection line evenly divided in a manner corresponding to the linearization pointer memory; d. scaling the image matrix location to determine the projection data memory pointer associated with the image matrix location; e. based on the determined projection data memory pointer, determining the projection data associated with the image matrix location; and f. summing the projection data into the associated image matrix location.
Claim 15
Dependent Claim
25 words
The method of claim 11, wherein the scaling and determining steps each comprises interpolating between adjacent data, whereby the accuracy of the method is increased.
Claim 16
Dependent Claim
32 words
The method of claim 11, wherein the method is simultaneously applied to data from a plurality of views to back project data from the plurality of views into the image matrix location.
Claim 17
Dependent Claim
169 words
The method of claim 11, wherein: a. the view is provided by a fan having a center and an apex; b. there is an S value for the image matrix location, wherein the S value is a function of the distance of the image matrix location from a line extending from the apex of the fan through the center of a scan circle, and an E value for the image matrix location, wherein the E value is a function of the distance of the image matrix location from a line passing through the apex of the fan and substantially perpendicular to a line from the apex of the fan through the center of the scan circle; and c. the scaling step comprises: (i) selecting a 1/E value from a 1/E memory according to the E value; and (ii) multiplying the 1/E value for the image matrix location by the S value for the image matrix location to determine the projection data memory pointer associated with the image matrix location.
Claim 18
Dependent Claim
178 words
The method of claim 11, wherein: a. there is an S value and a T value, each associated with an image matrix location, wherein the T value of the image matrix location is a function of the distance from a line passing through a scan circle center and substantially perpendicular to a line passing from an apex through a scan circle center, and the S value is a function of the distance of the image matrix location with a line extending from the apex of the fan through the center of the scan circle, and an E value which is a function of the sum of the T value and the distance from the apex to the scan circle center; (b) the scaling step comprises: (i) selecting a 1/E value, as determined by a T value, from a memory having a plurality of 1/E values; and (ii) multiplying the 1/E value for the image matrix location by the S value for the image matrix location to determine the projection data memory pointer associated with the image matrix location.
Claim 19
Independent Claim
129 words
A method for analyzing a patient to provide projection data to an image matrix location for a particular view of the patient, comprising: a. directing a beam of radiation through the patient; b. based on the radiation passing through the patient, providing projection data indicative of the density of the patient; c. storing the projection data in a projection data memory; d. storing projection data memory pointers in a linearization pointer memory; e. establishing a linearly sampled projection line evenly divided in a manner corresponding to the linearization pointer memory; f. scaling the image matrix location to determine the projection data memory pointer associated with the image matrix location; and g. based on the determined projection data memory pointer, determining the projection data associated with the image matrix location.
Claim 20
Independent Claim
129 words
A method for analyzing a patient to provide projection data to an image matrix location for a particular view of the patient, comprising: a. directing a beam of radiation through the patient; b. based on the radiation passing through the patient, providing projection data indicative of the density of the patient; c. storing the projection data in a projection data memory; d. storing projection data memory pointers in a linearization pointer memory; e. establishing a linearly sampled projection line evenly divided in a manner corresponding to the linearization pointer memory; f. scaling the image matrix location to determine the projection data memory pointer associated with the image matrix location; and g. based on the determined projection data memory pointer, determining the projection data associated with the image matrix location.
Claim 21
Dependent Claim
25 words
The method of claim 16, wherein the scaling and determining steps each comprises interpolating between adjacent data, whereby the accuracy of the method is increased.
Claim 22
Dependent Claim
32 words
The method of claim 16, wherein the method is simultaneously applied to data from a plurality of views to back project data from the plurality of views into the image matrix location.
Claim 23
Dependent Claim
169 words
The method of claim 16, wherein: a. the view is provided by a fan having a center and an apex; b. there is an S value for the image matrix location, wherein the S value is a function of the distance of the image matrix location from a line extending from the apex of the fan through the center of a scan circle, and an E value for the image matrix location, wherein the E value is a function of the distance of the image matrix location from a line passing through the apex of the fan and substantially perpendicular to a line from the apex of the fan through the center of the scan circle; and c. the scaling step comprises: (i) selecting a 1/E value from a 1/E memory according to the E value; and (ii) multiplying the 1/E value for the image matrix location by the S value for the image matrix location to determine the projection data memory pointer associated with the image matrix location.
Claim 24
Dependent Claim
112 words
The method of claim 16, wherein: a. there is an S value and a T value, each associated with an image matrix location, each representing substantially perpendicular distances from a scan circle center, the T value being measured along a line substantially collinear with that passing from an apex through a scan circle center; b. the scaling step comprises: (i) selecting a 1/E value, as determined by a T value, from a memory having a plurality of 1/E values; and (ii) multiplying the 1/E value for the image matrix location by the S value for the image matrix location to determine the projection data memory pointer associated with the image matrix location.
Claim 25
Independent Claim
366 words
A method for creating a sectional image of a patient, comprising: a. generating a fan of radiation having a center and an apex and directing the fan of radiation through the patient to provide a large plurality of views of the patient; b. sensing the radiation passing through the patient to provide projection data corresponding to the large plurality of views of the patient and placing the projection data in a projection data memory; c. for a given several views of the patient, serially selecting a plurality of image matrix locations wherein there is an S value for each image matrix location which is a function of the distance of the image matrix location from a line extending from the apex of the fan through the center of a scan circle, and an E value for the image matrix location, wherein the E value is a function of the distance of the image matrix location from a line passing through the apex of the fan substantially perpendicular to a line from the apex of the fan through the center of the scan circle; d. simultaneously back projecting data from several of the large plurality of views into the selected image matrix location, wherein each back projection comprises; (i) storing projection data memory pointers in a linearization pointer memory; (ii) establishing a linearly sampled projection line evenly divided in a manner corresponding to the linearization pointer memory; (iii) scaling the image matrix location to determine the projection data memory pointer associated with the image matrix location, wherein the scaling step comprises: (A) selecting a 1/E value from a 1/E memory according to the E value; and (B) multiplying the 1/E value for the image matrix location by the S value for the image matrix location to determine the projection data memory pointer associated with the image matrix location; and (iv) based on the determined projection data memory pointer, determining the projection data associated with the selected image matrix location; e. following the back projection process for a given several views of the patient, indexing to another several of the large plurality of views; and f. displaying the sectional image of the patient developed in the image matrix.
Claim 26
Independent Claim
366 words
A method for creating a sectional image of a patient, comprising: a. generating a fan of radiation having a center and an apex and directing the fan of radiation through the patient to provide a large plurality of views of the patient; b. sensing the radiation passing through the patient to provide projection data corresponding to the large plurality of views of the patient and placing the projection data in a projection data memory; c. for a given several views of the patient, serially selecting a plurality of image matrix locations wherein there is an S value for each image matrix location which is a function of the distance of the image matrix location from a line extending from the apex of the fan through the center of a scan circle, and an E value for the image matrix location, wherein the E value is a function of the distance of the image matrix location from a line passing through the apex of the fan substantially perpendicular to a line from the apex of the fan through the center of the scan circle; d. simultaneously back projecting data from several of the large plurality of views into the selected image matrix location, wherein each back projection comprises; (i) storing projection data memory pointers in a linearization pointer memory; (ii) establishing a linearly sampled projection line evenly divided in a manner corresponding to the linearization pointer memory; (iii) scaling the image matrix location to determine the projection data memory pointer associated with the image matrix location, wherein the scaling step comprises: (A) selecting a 1/E value from a 1/E memory according to the E value; and (B) multiplying the 1/E value for the image matrix location by the S value for the image matrix location to determine the projection data memory pointer associated with the image matrix location; and (iv) based on the determined projection data memory pointer, determining the projection data associated with the selected image matrix location; e. following the back projection process for a given several views of the patient, indexing to another several of the large plurality of views; and f. displaying the sectional image of the patient developed in the image matrix.
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| 7.5 Years (Year 8) | 2002-05-08 | 2002-11-07 | 2003-05-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-05-08 | 2006-11-07 | 2007-05-09 | $7700.00 | Window Closed / Lapsed |