TY - JOUR
T1 - Monte Carlo-based compensation for patient scatter, detector scatter, and crosstalk contamination in In-111 SPECT imaging
AU - Moore, Stephen C.
AU - Ouyang, Jinsong
AU - Park, Mi Ae
AU - El Fakhri, Georges
N1 - Funding Information:
This work was supported by NIH Grants RO1-EB001989, RO1-EB000802, and RO1-EB005876.
PY - 2006/12/20
Y1 - 2006/12/20
N2 - We have incorporated Monte Carlo (MC)-based estimates of patient scatter, detector scatter, and crosstalk into an iterative reconstruction algorithm, and compared its performance to that of a general spectral (GS) approach. We extended the MC-based reconstruction algorithm of de Jong et al. by (1) using the "Delta scattering" method to determine photon interaction points, (2) simulating scatter maps for many energy bins simultaneously, and (3) decoupling the simulation of the object and detector by using pre-stored point spread functions (PSF) that included all collimator and detector effects. A numerical phantom was derived from a segmented CT scan of a torso phantom. The relative values of In-111 activity concentration simulated in soft tissue, liver, spine, left lung, right lung, and five spherical tumors (1.3-2.0 cm diam.) were 1.0, 1.5, 1.5, 0.3, 0.5, and 10.0, respectively. GS scatter projections were incorporated additively in an OSEM reconstruction (6 subsets×10 projections×2 photopeak windows). After three iterations, GS scatter projections were replaced by MC-estimated scatter projections for two additional iterations. MC-based compensation was quantitatively compared to GS-based compensation after five iterations. The bias of organ activity estimates ranged from -13% to -6.5% (GS), and from -1.4% to +5.0% (MC); tumor bias ranged from -20.0% to +10.0% for GS (mean±std.dev.=-4.3±11.9%), and from -2.2 to +18.8% for MC (+4.1±8.6%). Image noise in all organs was less with MC than with GS.
AB - We have incorporated Monte Carlo (MC)-based estimates of patient scatter, detector scatter, and crosstalk into an iterative reconstruction algorithm, and compared its performance to that of a general spectral (GS) approach. We extended the MC-based reconstruction algorithm of de Jong et al. by (1) using the "Delta scattering" method to determine photon interaction points, (2) simulating scatter maps for many energy bins simultaneously, and (3) decoupling the simulation of the object and detector by using pre-stored point spread functions (PSF) that included all collimator and detector effects. A numerical phantom was derived from a segmented CT scan of a torso phantom. The relative values of In-111 activity concentration simulated in soft tissue, liver, spine, left lung, right lung, and five spherical tumors (1.3-2.0 cm diam.) were 1.0, 1.5, 1.5, 0.3, 0.5, and 10.0, respectively. GS scatter projections were incorporated additively in an OSEM reconstruction (6 subsets×10 projections×2 photopeak windows). After three iterations, GS scatter projections were replaced by MC-estimated scatter projections for two additional iterations. MC-based compensation was quantitatively compared to GS-based compensation after five iterations. The bias of organ activity estimates ranged from -13% to -6.5% (GS), and from -1.4% to +5.0% (MC); tumor bias ranged from -20.0% to +10.0% for GS (mean±std.dev.=-4.3±11.9%), and from -2.2 to +18.8% for MC (+4.1±8.6%). Image noise in all organs was less with MC than with GS.
KW - Indium-111
KW - Monte Carlo
KW - Quantitation
KW - SPECT
KW - Scatter compensation
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U2 - 10.1016/j.nima.2006.08.079
DO - 10.1016/j.nima.2006.08.079
M3 - Article
AN - SCOPUS:33751419086
SN - 0168-9002
VL - 569
SP - 472
EP - 476
JO - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
JF - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
IS - 2 SPEC. ISS.
ER -