Speaker
Kim-Eigard Hines
(University of Oslo)
Description
COMPET is aiming for high-resolution with a high
sensitivity by the use of a novel detector geometry. In classical
PET detectors where detector elements are mounted radially the
number of photo detectors to be read out scales with the square
of the detector resolution. The lack of depth of interaction information
contributes to a position dependent parallax error. The
COMPET detector overcomes these issues with a geometry that
consists of four modules forming a square barrel, each with five
layers. Each layer consists of 30 LYSO crystals (80×3×2 mm^3)
axially mounted interleaved with 24 wavelength shifting fibers
(80×3×1mm^3). The resulting detector has an effective voxel size
of 0.6×3×2 mm^3. The precise measurement of the gamma ray
point of interaction in three dimensions gives a small parallax
error which is uniform across the field of view thus allowing us to
place the detector elements close to the imaged object, effectively
increasing the sensitivity. There are in total 600 LYSO crystals
with 480 wavelength shifting fibers which are read out separately
with SiPMs. The DAQ chain consists of an analog pre-amplifier
which charge integrates and discharges linearly with a constant
current source. This signal is input to a comparator, and a Time-
Over-Threshold (ToT) signal as output. The ToT signal is input
to an FPGA where energy and event start time is extracted from
a deserializer running at 1 Gbps. One read-out card handles
one layer (54 channels), and a total of twenty read-out cards
are needed to read out all twenty layers. Synchronization is done
with a logic clock distributed by a central coincidence processing
unit (FPGA), and coincidence processing is done asynchronously
with the use of a 1 Gbps UDP/IP network.
Primary author
Kim-Eigard Hines
(University of Oslo)
Co-authors
Erlend Bolle
(University of Oslo (NO))
Michael Rissi
(ETH Zuerich)
Ole Rohne
(EPF group-Department of Physics-University of Oslo)
Mr
Volgyes David
(University of Oslo)
