TY - GEN
T1 - Fisher information analysis of digital pulse timing
AU - Ruiz-Gonzalez, Maria
AU - Furenlid, Lars R.
N1 - Funding Information: This work is supported in part by NIH/NIBIB under grant no P41- EB002035: The Center for Gamma-ray Imaging. The contribution from Maria Ruiz-Gonzalez is supported in part by the Mexican National Council of Science and Technology (CONACYT) and the Directorate General for International Relations (DGRI) of the Mexican Secretariat of Public Education (SEP) Publisher Copyright: © 2015 IEEE.
PY - 2016/10/3
Y1 - 2016/10/3
N2 - In positron emission tomography (PET), it is possible to obtain useful time-of-flight (TOF) information if the gamma-ray detectors have less than 750 ps timing resolution. Including TOF information to the reconstruction algorithm increases the signal-to-noise ratio (SNR). We obtain timing information by analyzing digital sampled waveforms, where the sampling frequency and number of points acquired affect timing estimation. An efficient data acquisition system acquires the minimum number of samples that contains the most timing information for a desired resolution. We describe a maximum-likelihood (ML) estimation algorithm to assign a time stamp to digital pulses. The method is based on a contracting-grid search algorithm that can be implemented in a field-programmable gate array (FPGA). The Fisher information (FI) matrix that corresponds to the likelihood in the ML estimator quantifies the amount of timing information that can be extracted from the waveforms. Fisher information analyses on different segments of the waveform allow us to determine the amount of data that we need to acquire in order to obtain a desired timing resolution. We present how we simulate waveforms for ML estimation and FI analysis, the ML estimation algorithm and the timing resolution obtained from experimental data using a LaBr3 crystal and two photomultiplier tubes (PMTs). The results show that for lengthening segments of the pulse, timing resolution approaches a limit. This information will be used to build an efficient DAQ with reduced complexity and cost that nonetheless preserves full timing performance.
AB - In positron emission tomography (PET), it is possible to obtain useful time-of-flight (TOF) information if the gamma-ray detectors have less than 750 ps timing resolution. Including TOF information to the reconstruction algorithm increases the signal-to-noise ratio (SNR). We obtain timing information by analyzing digital sampled waveforms, where the sampling frequency and number of points acquired affect timing estimation. An efficient data acquisition system acquires the minimum number of samples that contains the most timing information for a desired resolution. We describe a maximum-likelihood (ML) estimation algorithm to assign a time stamp to digital pulses. The method is based on a contracting-grid search algorithm that can be implemented in a field-programmable gate array (FPGA). The Fisher information (FI) matrix that corresponds to the likelihood in the ML estimator quantifies the amount of timing information that can be extracted from the waveforms. Fisher information analyses on different segments of the waveform allow us to determine the amount of data that we need to acquire in order to obtain a desired timing resolution. We present how we simulate waveforms for ML estimation and FI analysis, the ML estimation algorithm and the timing resolution obtained from experimental data using a LaBr3 crystal and two photomultiplier tubes (PMTs). The results show that for lengthening segments of the pulse, timing resolution approaches a limit. This information will be used to build an efficient DAQ with reduced complexity and cost that nonetheless preserves full timing performance.
KW - Fisher information
KW - LaBr
KW - Maximum-likelihood estimation
KW - PET
KW - timing resolution
UR - http://www.scopus.com/inward/record.url?scp=84994107249&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84994107249&partnerID=8YFLogxK
U2 - 10.1109/NSSMIC.2015.7582146
DO - 10.1109/NSSMIC.2015.7582146
M3 - Conference contribution
T3 - 2015 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2015
BT - 2015 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2015
PB - Institute of Electrical and Electronics Engineers Inc.
T2 - 2015 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2015
Y2 - 31 October 2015 through 7 November 2015
ER -