Monte Carlo simulations of timeofflight PET with doubleended readout: calibration, coincidence resolving times and statistical lower bounds
Here, this paper demonstrates through Monte Carlo simulations that a practical positron emission tomograph with (1) deep scintillators for efficient detection, (2) doubleended readout for depthofinteraction information, (3) fixedlevel analog triggering, and (4) accurate calibration and timing data corrections can achieve a coincidence resolving time (CRT) that is not far above the statistical lower bound. One Monte Carlo algorithm simulates a calibration procedure that uses data from a positron point source. Annihilation events with an interaction near the entrance surface of one scintillator are selected, and data from the two photodetectors on the other scintillator provide depthdependent timing corrections. Another Monte Carlo algorithm simulates normal operation using these corrections and determines the CRT. A third Monte Carlo algorithm determines the CRT statistical lower bound by generating a series of random interaction depths, and for each interaction a set of random photoelectron times for each of the two photodetectors. The most likely interaction times are determined by shifting the depthdependent probability density function to maximize the joint likelihood for all the photoelectron times in each set. Example calculations are tabulated for different numbers of photoelectrons and photodetector time jitters for three 3 × 3 × 30 mm ^{3} scintillators: Lu _{2}SiOmore »
 Authors:

^{[1]}
 Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Molecular Biophysics and Integrated Bioimaging Division
 Publication Date:
 Grant/Contract Number:
 AC0205CH11231; R01EB012524
 Type:
 Accepted Manuscript
 Journal Name:
 Physics in Medicine and Biology
 Additional Journal Information:
 Journal Volume: 62; Journal Issue: 9; Journal ID: ISSN 00319155
 Publisher:
 IOP Publishing
 Research Org:
 Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
 Sponsoring Org:
 USDOE; National Institutes of Health (NIH)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 97 MATHEMATICS AND COMPUTING; 60 APPLIED LIFE SCIENCES; positron emission tomography; calibration; time of flight; scintillator; coincidence resolving time; Monte Carlo; statistical lower bound
 OSTI Identifier:
 1379805
Derenzo, Stephen E. Monte Carlo simulations of timeofflight PET with doubleended readout: calibration, coincidence resolving times and statistical lower bounds. United States: N. p.,
Web. doi:10.1088/13616560/aa6862.
Derenzo, Stephen E. Monte Carlo simulations of timeofflight PET with doubleended readout: calibration, coincidence resolving times and statistical lower bounds. United States. doi:10.1088/13616560/aa6862.
Derenzo, Stephen E. 2017.
"Monte Carlo simulations of timeofflight PET with doubleended readout: calibration, coincidence resolving times and statistical lower bounds". United States.
doi:10.1088/13616560/aa6862. https://www.osti.gov/servlets/purl/1379805.
@article{osti_1379805,
title = {Monte Carlo simulations of timeofflight PET with doubleended readout: calibration, coincidence resolving times and statistical lower bounds},
author = {Derenzo, Stephen E.},
abstractNote = {Here, this paper demonstrates through Monte Carlo simulations that a practical positron emission tomograph with (1) deep scintillators for efficient detection, (2) doubleended readout for depthofinteraction information, (3) fixedlevel analog triggering, and (4) accurate calibration and timing data corrections can achieve a coincidence resolving time (CRT) that is not far above the statistical lower bound. One Monte Carlo algorithm simulates a calibration procedure that uses data from a positron point source. Annihilation events with an interaction near the entrance surface of one scintillator are selected, and data from the two photodetectors on the other scintillator provide depthdependent timing corrections. Another Monte Carlo algorithm simulates normal operation using these corrections and determines the CRT. A third Monte Carlo algorithm determines the CRT statistical lower bound by generating a series of random interaction depths, and for each interaction a set of random photoelectron times for each of the two photodetectors. The most likely interaction times are determined by shifting the depthdependent probability density function to maximize the joint likelihood for all the photoelectron times in each set. Example calculations are tabulated for different numbers of photoelectrons and photodetector time jitters for three 3 × 3 × 30 mm3 scintillators: Lu2SiO5 :Ce,Ca (LSO), LaBr3:Ce, and a hypothetical ultrafast scintillator. To isolate the factors that depend on the scintillator length and the ability to estimate the DOI, CRT values are tabulated for perfect scintillatorphotodetectors. For LSO with 4000 photoelectrons and single photoelectron time jitter of the photodetector J = 0.2 ns (FWHM), the CRT value using the statistically weighted average of corrected trigger times is 0.098 ns FWHM and the statistical lower bound is 0.091 ns FWHM. For LaBr3:Ce with 8000 photoelectrons and J = 0.2 ns FWHM, the CRT values are 0.070 and 0.063 ns FWHM, respectively. For the ultrafast scintillator with 1 ns decay time, 4000 photoelectrons, and J = 0.2 ns FWHM, the CRT values are 0.021 and 0.017 ns FWHM, respectively. Lastly, the examples also show that calibration and correction for depthdependent variations in pulse height and in annihilation and optical photon transit times are necessary to achieve these CRT values.},
doi = {10.1088/13616560/aa6862},
journal = {Physics in Medicine and Biology},
number = 9,
volume = 62,
place = {United States},
year = {2017},
month = {4}
}