Random coincidence reduction in positron emission tomography using tangential time-of-flight mask

1. A method of reducing random events in positron emission tomography (PET) list mode data, the method comprising:

obtaining, for a PET scanner having a given reconstruction field of view (FOV), time-of-flight (TOF) prompt list-mode count data that includes TOF information, the TOF prompt list-mode count data including a plurality of entries;

filtering the obtained prompt list-mode count data by removing those entries in the obtained prompt list-mode count data that represent emission points lying outside a tangential TOF mask to obtain filtered list-mode count data; and

performing reconstruction on the filtered list-mode count data to generate a PET image.

2. The method of claim 1 , wherein the filtering step comprises:

removing each entry for which the following inequality, representing the tangential TOF mask, is not satisfied:

c

2

⁢



t

a

-

t

b



⁢

cos

⁢

⁢

θ

≤

d

2

4

-

s

2

+

n

⁢

⁢

σ

T

⁢

⁢

O

⁢

⁢

F

wherein t a and t b are respective arrival times of events a and b included in the entry, c/2 is a conversion factor to convert time into distance, θ is an axial tilt angle with respect to the transverse plane of a line-of-response represented by the entry, d is a diameter of the reconstruction FOV, s is a radial value of the line-of-response represented by the entry, σ ToF is a standard deviation of the PET scanner timing resolution converted into a spatial domain, and n is a predetermined value.

3. The method of claim 1 , further comprising determining the tangential TOF mask based on a standard deviation of the PET scanner timing resolution.

4. A method of reducing random events in positron emission tomography (PET) list mode data, the method comprising:

obtaining, for a PET scanner having a given reconstruction field of view (FOV), time-of-flight (TOF) delay list-mode count data that includes TOF information, the TOF delay list-mode count data including a plurality of entries;

filtering the obtained delay list-mode count data by removing those entries in the obtained delay list-mode count data that represent emission points lying outside a tangential TOF mask to obtain filtered list mode count data; and

performing reconstruction on the filtered list-mode count data to generate a PET image.

5. The method of claim 4 , further comprising determining the tangential TOF mask based on a standard deviation of the PET scanner timing resolution.

6. An apparatus for reducing random events in positron emission tomography (PET) list mode data, the apparatus comprising:

a memory storing, for a PET scanner having a given reconstruction field of view (FOV), time-of-flight (TOF) prompt list-mode count data that includes TOF information, the TOF prompt list-mode count data including a plurality of entries; and

a processor configured to filter the obtained prompt list-mode count data by removing those entries in the obtained prompt list-mode count data that represent emission points lying outside a tangential TOF mask to obtain filtered list-mode count data, and perform reconstruction on the filtered list-mode count data to generate a PET image.

7. The apparatus of claim 6 , wherein the processor is further configured to:

remove each entry for which the following inequality, representing the tangential TOF mask, is not satisfied:

c

2

⁢



t

a

-

t

b



⁢

cos

⁢

⁢

θ

≤

d

2

4

-

s

2

+

n

⁢

⁢

σ

T

⁢

⁢

O

⁢

⁢

F

wherein t a and t b are respective arrival times of events a and b included in the entry, c/2 is a conversion factor to convert time into distance, θ is an axial tilt angle with respect to the transverse plane of a line-of-response represented by the entry, d is a diameter of the reconstruction FOV, s is a radial value of the line-of-response represented by the entry, σ TOF is a standard deviation of the PET scanner timing resolution converted into a spatial domain, and n is a predetermined value.

8. The apparatus of claim 6 , wherein the processor is further configured to determine the tangential TOF mask based on a standard deviation of the PET scanner timing resolution.

9. An apparatus for reducing random events in positron emission tomography (PET) list mode data, the apparatus comprising:

a memory storing, for a PET scanner having a given reconstruction field of view (FOV), time-of-flight (TOF) delay list-mode count data that includes TOF information, the TOF delay list-mode count data including a plurality of entries; and

a processor configured to filter the obtained delay list-mode count data by removing those entries in the obtained delay list-mode count data that represent emission points lying outside a tangential TOF mask to obtain filtered list-mode count data, and perform reconstruction on the filtered list-mode count data to generate a PET image.

10. The apparatus of claim 9 , wherein the processor is further configured to determine the tangential TOF mask based on a standard deviation of the PET scanner timing resolution.

11. A non-transitory computer-readable medium storing a program that, when executed by a processor, causes the processor to perform a method, comprising:

obtaining, for a PET scanner having a given reconstruction field of view (FOV), time-of-flight (TOF) prompt list-mode count data that includes TOF information, the TOF prompt list-mode count data including a plurality of entries;

filtering the obtained prompt list-mode count data by removing those entries in the obtained prompt list-mode count data that represent emission points lying outside a tangential TOF mask to obtain filtered list-mode count data; and

performing reconstruction on the filtered list-mode count data to generate a PET image.

12. The computer-readable medium of claim 11 , wherein the method further comprises determining the tangential TOF mask based on a standard deviation of the PET scanner timing resolution.