%0 Generic
%A Salvado, D
%A Erlandsson, K
%A Hutton, BF
%C Strasbourg, France
%D 2016
%F discovery:10052278
%I IEEE
%K Science & Technology, Technology, Physical Sciences, Life Sciences & Biomedicine, Engineering, Electrical & Electronic, Nuclear Science & Technology, Physics, Applied, Radiology, Nuclear Medicine & Medical Imaging, Engineering, Physics, geometrical calibration, minification, SPECT/MR, PINHOLE SPECT, RECONSTRUCTION
%T Effects of the Collimator Magnification Factor in the Geometrical Calibration of SPECT Systems
%U https://discovery.ucl.ac.uk/id/eprint/10052278/
%X In compact systems, precise measurement in the  projection space may be compromised due to minification.  The objective of this work is to investigate the impact of the  magnification factor in a model-based calibration procedure. This  has direct relevance to the geometrical calibration of the clinical  INSERT camera.  Projection data from three point sources were simulated for a  single pinhole collimator with magnification and single pinhole  and slit-slat collimators with minification, for 100 noise realizations  and 3 count levels. Model-based calibration was performed  to estimate geometric parameters and data corresponding to  a Derenzo phantom were simulated and reconstructed with  true and worst-case estimates for each collimator. Experimental  projection data were acquired with an INSERT prototype  camera and four 99mTc line sources in different locations within  the FoV. The collimator-CoR distance was varied in order to  obtain different minifications and model-based calibration was  performed.  The results from the simulations suggest that calibration is  less robust when minification is present, with higher biased  calibration parameters, which result in activity underestimation.  For experimental data, estimated parameters improved with a  higher magnification factor, in line with the simulation results.  However, some inconsistencies in the results suggest that there is  still room for improvements.  To conclude, geometric calibration of SPECT systems is more  sensitive to minification than magnification, which will impact  image quality.
%Z This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.