Simulation of PIXSCAN, a photon counting micro-CT for small animal imaging

Abstract

A main challenge in the development of new detectors is the achievement of a satisfactory comprehension of the instrument behaviour. We present the simulation work developed to understand and characterize an innovative micro-CT scanner. The PIXSCAN scanner is a photon counting device based on hybrid pixel detectors. Its working principle is expected to improve the contrast for soft tissues and to reduce both the scan duration and the dose absorbed by the animal. A prototype of the scanner, PIXSCAN-XPAD2, has been assembled and studied in order to achieve a proof of principle of the system. Simulations by analytical and Monte Carlo methods of the prototype and of the evaluation phantoms have been developed to ensure a satisfactory comprehension of the data. The Monte Carlo simulation was based on the GATE package. It included the complete simulation of photon propagation in matter, together with the modelling of the source spectrum, the scanner geometry and the sensor response. The analytical simulation is much more approximate, but its merit is the rapidity which permits fast preliminary results. Several figures of merit are studied and show good agreement with real data. Hence, the developed simulations can be used as a valid tool for the estimation of the ultimate PIXSCAN performances, in terms of spatial resolution, contrast measurement and dose reduction.

GATE V6: a major enhancement of the GATE simulation platform enabling modelling of CT and radiotherapy

“…Of course, this also makes it important that the software is thoroughly validated. GATE has already been validated for a number of PET and SPECT imaging configurations by comparing simulated and experimental data (Lazaro et al 2004, Staelens et al 2003, Gonias et al 2007, Rey et al 2007, Karakatsanis et al 2006, Schmidtlein et al 2006, Visvikis et al 2006b, Chung et al 2005, Assié et al 2005, Jan et al 2005, Cassol Brunner et al 2009, Chen et al 2009. For radiation therapy, the relevant Geant4 models have already been partly studied (Carrier et al 2004, Pshenichnov et al 2005, Jiang et al 2004, Paganetti 2004, Jarlskog and Paganetti 2008.…”

“…In the same period, GATE has been widely used as a tool to assist SPECT and PET research and developments and a number of conventional SPECT and PET scanners and prototypes have been modelled (e.g., Gonias et al 2007, Karakatsanis et al 2006, Schmidtlein et al 2006, Visvikis et al 2006b, Chung et al 2005, Assié et al 2005, Jan et al 2005. More recently, GATE has also been used to model x-ray computed tomography (CT) scanners (Cassol Brunner et al 2009, Nicol et al 2009, Chen et al 2009.…”

Simulation of a 6 MV Elekta Precise Linac photon beam using GATE/GEANT4

“…The use of GATE has been well validated for PET/SPECT simulations (De Beenhouwer, 2009, Schmidtlein et al 2006. It has also been used for brachytherapy (Thiam et al 2008) and micro-CT applications (Brunner et al 2009). It still relies on GEANT4 validations for radiotherapy applications (Rodrigues et al 2004, Carrier et al 2004, Foppiano et al 2005, Poon and Verhaegen, 2005, Thiam et al 2008.…”