Speaker
Prof.
Roger LECOMTE
(Université de Sherbrooke, Nuclear Medicine & Radiobiology)
Description
LabPET is a second-generation APD-based PET scanner featuring quasi-individual
crystal readout and massively parallel digital processing with advanced signal
analysis heuristics for high-performance in vivo molecular imaging of small
animals. The system implements several unique features to enhance throughput and
facilitate complex imaging protocols in live animals. The basic LabPET system
consists of 3072 2x2x10 mm³ scintillators assembled into phoswich LYSO/LGSO pairs,
each read out by an avalanche photodiode. The detectors are arranged into 16 rings
of 192 crystals each, having 16.2 cm in diameter by 37.5 mm axially. The 16 rings
allow for acquisition of 31 effective image slices extending up to 110 mm in
diameter. The dual-crystal readout scheme avoids resolution degradation due to
light- or charge-sharing and enables very high singles count rates with low dead
time in the detector front-end. Advanced parallel digital signal processing and
analysis algorithms are implemented in high-performance programmable devices for
crystal identification, energy discrimination and time stamping of events from
individual pixels. Virtually error-free crystal identification is achieved using an
auto-regressive least-mean square moving average method. Coincidence events are
sorted in real time and recorded in list mode, together with scanner status
information and animal physiological data. The measured intrinsic spatial
resolution of coincidence response functions is 1.2 mm FWHM and 2.3 mm FWTM both
axially and radially, with a near triangular shape confirming the excellent
resolving capability of APD detector arrays. Using a simple linear interpolation
algorithm, preliminary time resolutions of 4.5, 7.5 and 9.6 ns FWHM were obtained
for LYSO-LYSO, LYSO-LGSO and LGSO-LGSO coincidences, respectively. These
resolutions will be improved by implementing digital constant fraction or
artificial neural networks algorithms. Initial images with a resolution phantom
show that 1.2 mm hot rods can be clearly resolved. The scanner is fully integrated
with ancillary devices (injectors, life-sign monitors, blood counter, etc.), all
controlled through a centralized user-interface, allowing a single operator to
perform elaborate imaging protocols with maximum flexibility and efficiency. The
system was designed to provide a fully integrated solution for performing the most
demanding molecular imaging investigations with increased throughput in a busy
research environment.
Authors
Mr
François BÉLANGER
(Université de Sherbrooke, Electrical & Computer Engineering)
Mr
Jules CADORETTE
(CHUS/CRCÉL, Sherbrooke Molecular Imaging Centre)
Mr
Marc-André TÉTRAULT
(Université de Sherbrooke, Electrical & Computer Engineering)
Mr
Martin D. LEPAGE
(Advanced Molecular Imaging (AMI) Inc.)
Mr
Nicolas VISCOGLIOSI
(Université de Sherbrooke, Electrical & Computer Engineering)
Prof.
Roger LECOMTE
(Université de Sherbrooke, Nuclear Medicine & Radiobiology)
Prof.
Réjean FONTAINE
(Université de Sherbrooke, Electrical & Computer Engineering)
Dr
Vitali SELIVANOV
(Advanced Molecular Imaging (AMI) Inc.)
Co-authors
Mr
François LEMIEUX
(Université de Sherbrooke, Electrical & Computer Engineering)
Mr
Ghislain ROBERT
(Advanced Molecular Imaging (AMI) Inc.)
Mr
Hicham SEMMAOUI
(Université de Sherbrooke, Electrical & Computer Engineering)
Mr
Marc-Antoine LEMONDE
(Université de Sherbrooke, Physics)
Ms
Mélanie BERGERON
(Université de Sherbrooke, Physics)