Accelerated SPECT Monte Carlo Simulation Using Multiple Projection Sampling and Convolution-Based Forced Detection.
Monte Carlo (MC) is a well-utilized tool for simulating photon transport in single photon emission computed tomography (SPECT) due to its ability to accurately model physical processes of photon transport. As a consequence of this accuracy, it suffers from a relatively low detection efficiency and long computation time. One technique used to improve the speed of MC modeling is the effective and well-established variance reduction technique (VRT) known as forced detection (FD). With this method, photons are followed as they traverse the object under study but are then forced to travel in the direction of the detector surface, whereby they are detected at a single detector location. Another method, called convolution-based forced detection (CFD), is based on the fundamental idea of FD with the exception that detected photons are detected at multiple detector locations and determined with a distance-dependent blurring kernel. In order to further increase the speed of MC, a method named multiple projection convolution-based forced detection (MP-CFD) is presented. Rather than forcing photons to hit a single detector, the MP-CFD method follows the photon transport through the object but then, at each scatter site, forces the photon to interact with a number of detectors at a variety of angles surrounding the object. This way, it is possible to simulate all the projection images of a SPECT simulation in parallel, rather than as independent projections. The result of this is vastly improved simulation time as much of the computation load of simulating photon transport through the object is done only once for all projection angles.The results of the proposed MP-CFD method agrees well with the experimental data in measurements of point spread function (PSF), producing a correlation coefficient (r(2)) of 0.99 compared to experimental data. The speed of MP-CFD is shown to be about 60 times faster than a regular forced detection MC program with similar results.
Liu
Shaoying
S
Department of Electrical and Computer Engineering, McMaster University, Hamilton, ON L8S 4K1 Canada.
King
Michael A
MA
Brill
Aaron B
AB
Stabin
Michael G
MG
Farncombe
Troy H
TH
Phys Med Biol. 2001 Mar;46(3):621-35
11277213
IEEE Trans Med Imaging. 1991;10(3):408-12
18222843
Comput Med Imaging Graph. 2001 Mar-Apr;25(2):117-126
11137788
Phys Med Biol. 1999 Aug;44(8):N183-92
10473218
J Nucl Med. 1992 Apr;33(4):605-12
1552349
Comput Methods Programs Biomed. 1989 Aug;29(4):257-72
2791527
IEEE Trans Nucl Sci. 2008 Jan 1;55(1):560-567
20811587
J Nucl Med. 1991 Jun;32(6):1278-84
2045947