Estimation of crystal efficiency with axially compressed sinogram
AssigneeSiemens Medical Solutions USA, Inc.
InventorsMu Chen, Vladimir Panin, Michael E. Casey
Life of this patent
Estimating the term…
Abstract
The present invention provides a method for estimating crystal efficiency in a PET detector that takes axial compression into account. It does so via an iterative methodology in which a μ-map is first generated and then is used to obtain a solution for the equation L ( ɛ i ) = ∑ n ∈ N y n log ∑ i , j ∈ span g ij ɛ i ɛ j x ij - ∑ i , j ∈ span g ij ɛ i ɛ j x ij , wherein gij is a geometric factor for LOR(i,j), εi and εj are the efficiencies for crystal i and crystal j, and xij is the line integral of the source distribution along LOR(i,j). Once efficiencies are determined, they are used to calibrate the PET detector.
Claims5
A method for calibrating a positron emission tomography (PET) detector having a plurality of detector crystals, comprising:
- using a μ-map of said crystals as a calibration phantom;
- computing, by a PET apparatus, a solution for the equation
- L
-
- (
- ɛ
- i
- )
- =
- ∑
- n
- ∈
- N
-
-
- y
- n
-
- log
-
- ∑
- i
- ,
- j
- ∈
- span
-
-
- g
- ij
-
- ɛ
- i
-
- ɛ
- j
-
- x
- ij
- -
- ∑
- i
- ,
- j
- ∈
- span
-
-
- g
- ij
-
- ɛ
- i
-
- ɛ
- j
-
- x
- ij
- ,
- wherein gij is a geometric factor for line of response, LOR(i,j), εi and εj are the efficiencies for crystal i and crystal j, yn is the y-coordinate of an event, and xij is the line integral of a source distribution along LOR(i,j), and wherein the μ-map is used as a source distribution in calculating the line integral xij;
- and
- calibrating the PET detector using L(εi).
Dependencies are inferred from the claim text.