Speaker
Dr
Carole Lartizien
(Creatis laboratory, UMR CNRS 5515 et INSERM U630, Villeurbanne, France)
Description
Objectives: Recent advances in PET systems dedicated to small animal imaging have
provided new ways to perform biologic research. They consecutively increased the need
to develop realistic simulation models that allows optimizing acquisition and
reconstruction protocols in order to improve image quantification and detection.
PET-SORTEO is a Monte Carlo-based simulator that enables the fast generation of
realistic PET data for the geometry of cylindrical PET scanners. It has been shown to
accurately reproduce data of the human ECAT EXACT HR+ scanner and of the rodent
CTI-Concorde MicroPET R4 system. Our aim is to adapt and configure this simulation
tool for the MicroPET Focus 220, which belongs to the last generation of rodent and
primate systems. Our originality, as compared with a recent simulation study using
the Gate platform based on the Geant4 toolkit package, is that we demonstrate the
feasibility to achieve realistic simulations of whole-body biological distributions
in a very short computation time.
Method: This validation study is carried out against actual measurements either
performed on the actual Focus 220 scanner of the ARC Seibersdorf center or using
performances measurements available in the literature, following the experimental
protocol by Tai et al. The comparison of simulated and experimental performance
measurements includes spatial resolution, sensitivity, energy spectra, scatter
fraction and count rates. Realistic simulated whole-body mice acquisitions are also
generated using the Moby phantom from Segars et al with different acquisition
configurations, including dynamic studies. Realistic time activity curves are derived
from experimental acquisitions on the Focus system of the ARC Seibersdorf center.
Results: Preliminary results were achieved for the comparison of spatial resolution
measurements. Experimental data were acquired using a 18F point source embedded in a
0.3 mm inner diameter capillary tube. The point source was located at the centre of
one detector block and at the centre of the transverse FOV and moved in the vertical
direction by steps up to the edge of the FOV (100 mm). Acquisition at each step was
performed with an energy window of 250–750 keV and a timing window of 10 ns.
Simulated data were Fourier rebinned (FORE) to form 2D sinograms and subsequently
reconstructed using 2D FBP with a ramp filter cutoff at the Nyquist frequency and
OSEM with 4 iterations and 16 subsets. The image spatial resolution was measured as
the FWHM and the FWTM of a Gaussian profile fit to the measured resolution profile.
These experimental data were compared to simulated data that were generated following
a similar acquisition and reconstruction protocol. Experimental and simulated data
are well superimposed with a discrepancy lower than 5%. Experimental data were also
acquired to measure the system sensitivity, scatter fraction and NEC rates. Our
ongoing work is to simulate equivalent acquisition protocols. Comparative results
will be presented at the conference together with realistic simulated mice acquisitions.
Author
Dr
Carole Lartizien
(Creatis laboratory, UMR CNRS 5515 et INSERM U630, Villeurbanne, France)
Co-authors
Dr
Anthonin Reilhac
(CERMEP, Lyon, France)
Dr
Claudia Kuntner
(Health Physics Division, ARC Seibersdorf research,Seibersdorf, Austria)
