18 March 2008 An efficient depth- and energy-dependent Monte Carlo model for columnar CsI detectors
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Abstract
We developed an efficient, depth- and energy-dependent Monte Carlo model for columnar CsI detectors. The optical photon, electron/positron Monte Carlo package MANTIS developed by our group, was used to generate optical photon response and collection efficiency as a function of the x-ray/electron interaction depth for a realistic scintillator geometry. The detector geometry we used for the simulations was reported in the past and is based on a 500 μm thick columnar CsI scintilator. The resulting depth-dependent optical photon responses were fit to a parametrized Gaussian mixture model. The model parameters were the depth-dependent radial shift of the response peak, the depth dependent widths of the Gaussians, and the depth-dependent magnitude of the Gaussians in the mixture. The depth-dependent optical spread has a maximum spatial shift of 53 μm. The optical collection efficiency at the photo-diode layer followed a power law varying from 90% for interactions at the scintillator exit surface to 20% for interactions at the detector entrance. The responses were consequently incorporated into penMesh, a PENELOPE based Monte Carlo x-ray, electron/positron transport simulation package for generating clinically realistic images of triangular mesh phantoms. The resulting detector responses from this empirical model were compared against the full x-ray/electron/optical photon simulation using the package MANTIS, showing good agreement. The simulation speed, using the optical transport model in penMesh, increases by two orders of magnitude compared to MANTIS.
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Iacovos S. Kyprianou, Gabriel Brackman, Kyle J. Myers, Andreu Badal, Aldo Badano, "An efficient depth- and energy-dependent Monte Carlo model for columnar CsI detectors", Proc. SPIE 6913, Medical Imaging 2008: Physics of Medical Imaging, 69130O (18 March 2008); doi: 10.1117/12.772878; https://doi.org/10.1117/12.772878
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