Maximum likelihood positioning for gammaray imaging detectors with depth of interaction measurement
 Research areas:
 Authors:
 Lerche, Ch. W.; Ros, A.; Monzó, J. M.; Aliaga, R. J.; Ferrando, N.; Martínez, J. D.; Herrero, V.; Esteve, R.; Gadea, R.; Colom, R. J.; Toledo, J.; Mateo, F.; Sebastiá, A.; Sánchez, F.; Benlloch, J. M.
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Type of Publication: 
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Number: 
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Month: 
2009 
Article 
Nucl. Instr. and Meth. Physics A 
604 
12 
359–362 
June 

Keywords:

Depth of interaction, PET, Monolithic scintillation crystal, Maximumlikelihood
Abstract:
The center of gravity algorithm leads to strong artifacts for gammaray imaging detectors that are based on monolithic scintillation crystals and position sensitive photodetectors. This is a consequence of using the centroids as position estimates. The fact that charge division circuits can also be used to compute the standard deviation of the scintillation light distribution opens a way out of this drawback. We studied the feasibility of maximum likelihood estimation for computing the true gammaray photoconversion position from the centroids and the standard deviation of the light distribution. The method was evaluated on a test detector that consists of the position sensitive photomultiplier tube H8500 and a monolithic LSO crystal (). Spatial resolution was measured for the centroids and the maximum likelihood estimates. The results suggest that the maximum likelihood positioning is feasible and partially removes the strong artifacts of the center of gravity algorithm.