DocumentCode :
2561706
Title :
A comparison of Maximum List-Mode-Likelihood Estimation and Maximum-Likelihood Clustering algorithms for depth calibration in continuous-crystal PET detectors
Author :
Hunter, William C. J. ; Lewellen, Thomas K. ; Miyaoka, Robert S.
Author_Institution :
Dept. of Radiol., Univ. of Washington, Seattle, WA, USA
fYear :
2012
fDate :
Oct. 27 2012-Nov. 3 2012
Firstpage :
3829
Lastpage :
3834
Abstract :
Parallax error in close-proximity applications of thick gamma-ray detectors, such as preclinical or organ-specific Positron Emission Tomography, motivates the need to accurately resolve interaction depth. In our lab, we routinely use a collimated gamma-ray source and apply an iterative maximum-likelihood clustering (MLC) algorithm to calibrate detector response statistics as a function of 3D interaction position. These detector response functions calibrate a signal-probability model that we use to determine the interaction position of events by maximum likelihood estimation. In this work, we compare the accuracy of this clustering algorithm to a more computationally intensive method (MLMLE) that maximizes the list-mode likelihood of a parametric model of the detector response function. Accuracy of the calibrated mean and variance of detector response versus depth are experimentally determined for a slat-shaped detector using a collimated gamma-rays normally incident to the side of the slat. We also verify our experimental findings by Monte-Carlo simulation, where ground truth is known. Our results suggest that MLMLE is more accurate than MLC for estimating the variance of detector response, but these algorithms fair similarly for accurately estimating the mean detector response. However, for the reduced dimensional case considered, the MLC algorithm required nearly 1 minute to execute, while the MLMLE algorithm took just over 10 hours to complete.
Keywords :
Monte Carlo methods; biomedical equipment; calibration; gamma-ray detection; iterative methods; maximum likelihood estimation; positron emission tomography; solid scintillation detectors; 3D interaction position; MLC algorithm; MLMLE algorithm; Monte-Carlo simulation; collimated gamma-ray source; computationally intensive method; continuous-crystal PET detectors; depth calibration; detector response functions; detector response statistics; interaction depth; interaction position; iterative maximum-likelihood clustering algorithms; maximum list-mode-likelihood estimation; organ-specific positron emission tomography; parallax error; parametric model; preclinical positron emission tomography; signal-probability model; slat-shaped detector; thick gamma-ray detectors;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2012 IEEE
Conference_Location :
Anaheim, CA
ISSN :
1082-3654
Print_ISBN :
978-1-4673-2028-3
Type :
conf
DOI :
10.1109/NSSMIC.2012.6551879
Filename :
6551879
Link To Document :
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