Speaker
Description
The SAFIR collaboration has developed a high-
performance PET insert compatible with a Bruker BioSpec 70/30
MRI scanner. This system, named SAFIR-II, was designed to
acquire data at activities of up to 500 MBq, enabling truly
simultaneous preclinical PET-MR imaging for mice and rats
using image acquisition times of up to 5 s.
We present an overview of the system’s design, as well as
several performance evaluations done using low and high activity
measurements. SAFIR-II features an axial FOV of 145 mm
covered by 11’520 LYSO crystals ($2.0 × 2.0 × 13$ mm$^3$), which
are coupled one-to-one to Hamamatsu SiPM arrays. PETA8
ASICs developed at the University of Heidelberg are used to
digitize the SiPM’s analog signals, and read out using Xilinx
Kintex7 FPGAs and 10 GBit SFP+ optical Ethernet links. All
data analysis is handled offline using custom coincidence sorting
software, and reconstructed using STIR. Custom MR-compatible
DC-DC converters and LDO voltage regulators are used to
condition the system’s internal voltages.
SAFIR-II exhibits a coincidence timing resolution of 217 ps
FWHM and a coincidence energy resolution of 11.8 %, with
a peak sensitivity of 2.23 % observed following the NEMA-
NU4 standard. It is capable of resolving 1.8 mm hot rods
within a Derenzo phantom filled with up to 500 MBq $^{18}$F. We
furthermore present an evaluation of the system’s image quality
determined using a NEMA IQ-phantom, and an evaluation of its
MRI-compatibility.
| Field | Detectors and electronics |
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