Method for determining data normalization factors for image reconstruction

Claim 3

A method in accordance with claim 1 wherein after acquiring the two-dimensional normalization scan S(r,φ,z) data, said method further comprises the steps of: adding together direct data planes of the scan S(r,φ,z) data; determining the average direct data plane for the scanner; and dividing each row of the average direct data plane by an expected sinogram profile of a rod source.

Claim 4

A method in accordance with claim 2 wherein said method further comprises the steps of: determining geometric factors g(r,φ).

Claim 5

A method in accordance with claim 3 wherein the geometric factors g(r,φ) are determined from an average of every N'th sinogram row, where N is selected.

Claim 6

A method in accordance with claim 4 wherein N is selected to be equal to 6, 12 or 336.

Claim 7

A method in accordance with claim 3 wherein the geometric factors g(r,φ) are determined from a geometric mean.

Claim 8

A method in accordance with claim 3 wherein said method further comprises the step of: performing a deadtime correction on the geometric factors g(r,φ).

Claim 9

A method in accordance with claim 1 wherein the three-dimensional phantom acquisition scan S(u,v,φ,⊖) data is acquired by limiting the range of the projection plane width u to cover the phantom only and said method further comprises the steps of: limiting the range of the projection plane width u to cover the phantom only; dividing the phantom data S(u,v,φ,⊖) by a geometric factor g(u,φ) to produce a sinogram S'(u,v,φ,⊖); determining a mean sinogram row S'(u) from the mean of the rows of sinogram S'(u,v,φ,⊖); dividing sinogram S'(u,v,φ,⊖) by the mean sinogram S'(u) to produce a sinogram S"(u,v,φ,⊖); and performing a crystal-averaging scheme on sinogram S"(u,v,φ,⊖) to produce a crystal efficiency array e(X,Z).

Claim 10

A method in accordance with claim 1 wherein the three-dimensional normalization data array N(u,v,φ,⊖) is equal to 1/[g(u,φ)e(X 1 Z 1 )e(X 2 Z 2 )] where g(u,φ) are geometric factors and e(X 1 Z 1 )e(X 2 Z 2 ) are representative of crystal efficiency.

Claim 13

A system in accordance with claim 10 wherein said system processes the two-dimensional normalization scan S(r,φ,z) data by: adding together direct data planes obtained from a scan performed using a rod source; determining an average direct data plane for the scanner; and dividing each row of the average direct data plane by the expected sinogram profile of the rod source.

Claim 14

A system in accordance with claim 10 wherein geometric factors g(r,φ) are determined by said system from the two-dimensional normalization scan S(r,φ,z) data.

Claim 15

A system in accordance with claim 10 wherein the three-dimensional phantom acquisition scan S(u,v,φ,⊖) data is acquired by limiting the range of the projection plane width u to cover the phantom only and a crystal efficiency array e(X,Z) is generated by said system by: dividing the phantom data by a geometric factor g(u,φ) to produce a sinogram S'(u,v,φ,⊖); determining a mean sinogram row S'(u) from a mean of the rows of sinogram S'(u,v,φ,⊖); dividing sinogram S'(u,v,φ,⊖) by the mean sinogram S'(u) to produce a sinogram S"(u,v,φ,⊖); and performing a crystal-averaging scheme on sinogram S"(u,v,φ,⊖) to generate the crystal efficiency array e(X,Z).

Claim 16

A system in accordance with claim 10 wherein the three-dimensional normalization data array N(u,v,φ,⊖) is equal to 1/[g(u,φ)e(X 1 Z 1 )e(X 2 Z 2 )] where g(u,φ) are geometric factors and e(X 1 Z 1 )e(X 2 Z 2 ) are representative of crystal efficiency.

Claim 17

A processor programmed for creating a data normalization array for use in normalizing data acquired from a positron emission tomograph scan to be used in generating a three-dimensional image, a memory storage being coupled to said processor for storing two-dimensional normalization scan S(r,φ,z) data and three-dimensional phantom scan S(u,v,φ,⊖) data, said processor programmed to create a three-dimensional normalization data array N(u,v,φ,⊖) from the two-dimensional normalization scan S(r,φ,z) data and the three-dimensional phantom scan S(u,v,φ,⊖) data.

Claim 18

A processor programmed for creating a data normalization array for use in normalizing data acquired from a positron emission tomograph scan to be used in generating a three-dimensional image, a memory storage being coupled to said processor for storing two-dimensional normalization scan S(r,φ,z) data and three-dimensional phantom scan S(u,v,φ,⊖) data, said processor programmed to create a three-dimensional normalization data array N(u,v,φ,⊖) from the two-dimensional normalization scan S(r,φ,z) data and the three-dimensional phantom scan S(u,v,φ,⊖) data.

Claim 19

A processor in accordance with claim 15 wherein said processor processes the two-dimensional normalization scan S(r,φ,z) data by: adding together direct data planes obtained from a scan performed using a rod source; determining an average direct data plane for the scanner; and dividing each row of the average direct data plane by the expected sinogram profile of the rod source.

Claim 20

A processor in accordance with claim 15 wherein geometric factors g(r,φ) are determined by said processor from the two-dimensional normalization scan S(r,φ,z) data.

Claim 21

A processor in accordance with claim 15 wherein the three-dimensional phantom acquisition scan S(u,v,φ,⊖) data is acquired by limiting the range of the projection plane width u to cover the phantom only and a crystal efficiency array e(X,Z) is generated by said processor by: dividing the phantom data by a geometric factor g(u,φ) to produce a sinogram S'(u,v,φ,⊖); determining a mean sinogram row S'(u) from a mean of the rows of sinogram S'(u,v,φ,⊖); dividing sinogram S'(u,v,φ,⊖) by the mean sinogram S'(u) to produce a sinogram S"(u,v,φ,⊖); and performing a crystal-averaging scheme on sinogram S"(u,v,φ,⊖) to produce a crystal efficiency array e(X,Z).

Claim 22

A processor in accordance with claim 15 wherein the three-dimensional normalization data array N(u,v,φ,⊖) is equal to 1/[g(u,φ)e(X 1 Z 1 )e(X 2 Z 2 )] where g(u,φ) are geometric factors and e(X 1 Z 1 )e(X 2 Z 2 ) are representative of crystal efficiency.