Fast Monte Carlo-simulator with full collimator and detector response modelling for SPECT.
OBJECTIVE
Monte Carlo (MC)-simulations have proved to be a valuable tool in studying SPECT-reconstruction algorithms. Despite their popularity, the use of Monte Carlo-simulations is still often limited by their large computation demand. This is especially true in situations where full collimator and detector modelling with septal penetration, scatter and X-ray fluorescence needs to be included. This paper presents a rapid and simple MC-simulator, which can effectively reduce the computation times.


METHODS
The simulator was built on the convolution-based forced detection principle, which can markedly lower the number of simulated photons. Full collimator and detector response look-up tables are pre-simulated and then later used in the actual MC-simulations to model the system response. The developed simulator was validated by comparing it against (123)I point source measurements made with a clinical gamma camera system and against (99m)Tc software phantom simulations made with the SIMIND MC-package.


RESULTS
The results showed good agreement between the new simulator, measurements and the SIMIND-package. The new simulator provided near noise-free projection data in approximately 1.5 min per projection with (99m)Tc, which was less than one-tenth of SIMIND's time.


CONCLUSIONS
The developed MC-simulator can markedly decrease the simulation time without sacrificing image quality.
Department of Clinical Physiology and Nuclear Medicine, Joint Authority for Päijät-Häme Social and Health Care, Lahti, Finland. antti.sohlberg@phsotey.fi
Antti O
AO
Sohlberg
Markus T
MT
Kajaste
D007091:Image Processing, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D009010:Monte Carlo Method; D017785:Photons; D015203:Reproducibility of Results; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon / Q000295:instrumentation / Q000379:methods*