Jun 3 – 5, 2022
Parador El Saler, Valencia, Spain
Europe/Zurich timezone

Image quality of a pure Cherenkov TOF PET scanner: a simulation study

Jun 3, 2022, 4:45 PM
15m
Parador El Saler, Valencia, Spain

Parador El Saler, Valencia, Spain

System considerations for pushing TOFPET CTR ≤ 100ps System considerations for TOFPET CTR resolution ≤100ps

Speaker

Mr Gasper Razdevsek (Faculty of Mathematics and Physics, University of Ljubljana, Slovenia)

Description

In positron emission tomography, dense Cherenkov radiators provide an
opportunity for high gamma detection efficiency and excellent CTR.
However, because only a few tens of Cherenkov photons follow a gamma
interaction in the radiator, the detection efficiency and the energy
resolution of a pure Cherenkov detector are an issue. We study gamma
detection efficiency and CTR of PbF$_2$ based detectors with different
surface treatments and photo-detectors (SiPMs with realistic PDE and 70
ps FWHM SPTR) covering one, two, or all crystal faces. We investigate
the potential performance of a full-size Cherenkov PET using the NEMA NU
2-2018 standard and compare image quality with a reference scanner -
Siemens Biograph Vision PET scanner - with the geometry of Cherenkov
scanners based on that of the reference scanner. Monte Carlo simulations
were performed on a super-computing network using GATE, and CASToR was
used for TOF-OSEM image reconstruction. Normalization, scatter, random,
and attenuation correction factors were included in the reconstruction.
Cherenkov scanner with 1-sided readout had similar TOF performance (~210
ps CTR-FWHM) and achieved very similar image quality as the reference
scanner. By using 2-sided (SiPMs at the sides of the crystal) or 6-sided
detector designs with better coincidence detection efficiency and ~120
ps CTR-FWHM, even better image quality was achieved. The main limitation
of our simulation study is not including the noise in the simulation -
especially the dark count events of the SiPMs. We demonstrate that even
though pure Cherenkov scanners have basically no energy resolution, the
scatter fraction is around 50%, compared to 33% with the reference
scanner, and is not prohibitively large. Images comparable to the
state-of-the-art clinical PET scanner can be achieved due to improved
efficiency and CTR attainable with PbF$_2$. Low-cost Cherenkov detectors
could become especially interesting for total-body scanners.

Primary authors

Andrej Seljak (Jozef Stefan Institute (SI)) Mr Gasper Razdevsek (Faculty of Mathematics and Physics, University of Ljubljana, Slovenia) Andrej Studen (Jozef Stefan Institute (SI)) Peter Krizan (University of Ljubljana) Rok Dolenec (Jozef Stefan Institute (SI)) Rok Pestotnik (Jozef Stefan Institute (SI)) Samo Korpar (Jozef Stefan Institute (SI))

Presentation materials