Open AccessMonte carlo study of the effect of collimator thickness on T-99m source response in single photon emission computed tomography
Author(s) -
Jalil Pirayesh Islamian,
Mohammad Taghi Bahreyni Toossi,
Mehdi Momennezhad,
Seyed Rasoul Zakavi,
Ramin Sadeghi,
Michael Ljungberg
Publication year - 2012
Publication title -
world journal of nuclear medicine
Language(s) - English
Resource type - Journals
eISSN - 1607-3312
pISSN - 1450-1147
DOI - 10.4103/1450-1147.103419
Subject(s) - collimator , imaging phantom , monte carlo method , image resolution , optics , single photon emission computed tomography , nuclear medicine , physics , image quality , collimated light , point source , compton scattering , spect imaging , photon , correction for attenuation , attenuation , medicine , computer science , mathematics , computer vision , image (mathematics) , laser , statistics
In single photon emission computed tomography (SPECT), the collimator is a crucial element of the imaging chain and controls the noise resolution tradeoff of the collected data. The current study is an evaluation of the effects of different thicknesses of a low-energy high-resolution (LEHR) collimator on tomographic spatial resolution in SPECT. In the present study, the SIMIND Monte Carlo program was used to simulate a SPECT equipped with an LEHR collimator. A point source of (99m)Tc and an acrylic cylindrical Jaszczak phantom, with cold spheres and rods, and a human anthropomorphic torso phantom (4D-NCAT phantom) were used. Simulated planar images and reconstructed tomographic images were evaluated both qualitatively and quantitatively. According to the tabulated calculated detector parameters, contribution of Compton scattering, photoelectric reactions, and also peak to Compton (P/C) area in the obtained energy spectrums (from scanning of the sources with 11 collimator thicknesses, ranging from 2.400 to 2.410 cm), we concluded the thickness of 2.405 cm as the proper LEHR parallel hole collimator thickness. The image quality analyses by structural similarity index (SSIM) algorithm and also by visual inspection showed suitable quality images obtained with a collimator thickness of 2.405 cm. There was a suitable quality and also performance parameters' analysis results for the projections and reconstructed images prepared with a 2.405 cm LEHR collimator thickness compared with the other collimator thicknesses.