Monte Carlo simulations: A useful tool to extend in vivo calibrations and explore alternative approaches

Kramer, Gary H.; Burns, Linda C.; Thind, Kundan

doi:10.1093/oxfordjournals.rpd.a006302

Cited by 4 publications

(3 citation statements)

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“…Typical calibration coefficients are assessed using physical phantoms and real measurements or via Monte Carlo simulations associated to realistic voxelized phantoms. 3,4) Using these calibration coefficients, i.e. counting efficiency, the retained activity can be deduced from the measured counting rate.…”

Section: Counting Efficiency and MC Simulationsmentioning

confidence: 99%

“…To go towards a more realistic calibration, voxelized phantoms associated to Monte Carlo (MC) calculations have proven to be the most promising solution. [3][4] However, MC simulations are time consuming depending on the complexity of the input file, particularly the way the phantom, the source and the detectors are coded with voxel grids. To define realistic models of the human body, millions of voxels are required.…”

Section: Introductionmentioning

confidence: 99%

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Efficient Calculation of in vivo Efficiency Curves Using Variance Reduction Techniques

Farah

Broggio

Franck

2011

Progress in Nuclear Science and Technology

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To optimize the in vivo lung monitoring of nuclear workers, realistic calibration coefficients are assessed using 3D anthropomorphic models and Monte Carlo simulations. In this study, a Livermore voxel phantom and the torso of the ICRP adult female reference voxel phantom were used. Monte Carlo MCNPX simulations were achieved to compute the calibration curve for a typical germanium counting system with a photon source of energy ranging from 15 keV to 1.4 MeV. However, photons of low energy are highly attenuated by body compounds while high energy photons are too penetrative to interact in the detectors. Hence, statistically insufficient counting efficiency values are obtained for both energy ranges. Thus, MCNPX variance reduction techniques were considered here to accelerate the simulations. The variance reduction techniques used were: the source biasing to favor low energy emissions; the emission direction biasing to select emission towards detectors; the forced collision to improve high energy photons interaction in germanium active cells. These techniques reduced the computing time by a factor of 20 and improved the associated statistical error with no significant variation in counting efficiency. Cell importance, mesh tally, weight windows and exponential transform variance reduction techniques were also tested to further accelerate computation.

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Section: Counting Efficiency and MC Simulationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Efficient Calculation of in vivo Efficiency Curves Using Variance Reduction Techniques

Farah

Broggio

Franck

2011

Progress in Nuclear Science and Technology

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“…The anthropomorphic 3D models used for Monte Carlo (MC) computation in radioprotection (Kramer et al 2003b;Lee et al 2007a;Zhang et al 2008) and related fields (Alghamdi et al 2007;Zankl et al 1988) are referred to as voxel phantoms. Up to now, these are the only possible descriptions of anthropomorphic models accepted by the different MC codes [MCNP(X), GEANT, PENELOPE, etc.].…”

Section: Introductionmentioning

confidence: 99%

Creation and Use of Adjustable 3d Phantoms: Application for the Lung Monitoring of Female Workers

Farah¹,

Broggio²,

Franck³

2010

Health Physics

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In vivo counting measurements, used for the monitoring of workers with internal contamination risks, are based on the use of calibration physical phantoms. However, such phantoms do not exist for female subjects. Computational calibration using numerical representations, Mesh and non-uniform rational basis spline (NURBS) geometries, was thus considered. The study presented here is focused on the creation of different female thoracic phantoms with various breast sizes and chest girths. These 3D models are used to estimate the radiation attenuation with morphology and the resulting variation of the calibration coefficient of a typical 4-germanium in vivo counting system. A basic Mesh female thoracic phantom was created from the International Commission on Radiological Protection Adult Female Reference Computational Phantom. Using this basic phantom, different chest girths (85, 90, 100, 110, and 120) and cup sizes (A to F) were created representing the most common thoracic female morphologies, as recommended by the available and relevant literature. Variation of breast tissue composition and internal organ volumes with morphology were also considered. As a result, 34 thoracic female phantoms were created combining different cup sizes and chest girths. For the 85 chest girth, at very low energies (15 keV), a relative counting efficiency variation of about 85% was observed between the A and E cups. As a result of this study, breast size dependent calibration coefficients, between 15 keV and 1.4 MeV, were obtained and tabulated for a typical lung counting germanium system.

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CRUCIAL PARAMETERS FOR PROPER SIMULATION OF THE DETECTOR USED ININ VIVOMEASUREMENTS

Vrba

2016

Radiat Prot Dosimetry

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Mathematical calibration is an increasingly popular technique among laboratories with a whole- or partial-body counters. A mathematical calibration employing a voxel phantom and Monte Carlo radiation transport code simulations has many benefits and can overcome many limitations of detector efficiency calibration using physical anthropomorphic phantoms. This publication tries to identify key factors for detector modelling. The influence of such parameters depends on energy and thus is studied in the gamma energy range of detectable radionuclides, i.e. from 15 keV to 1.5 MeV.

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Monte Carlo simulations: A useful tool to extend in vivo calibrations and explore alternative approaches

Cited by 4 publications

References 0 publications

Efficient Calculation of in vivo Efficiency Curves Using Variance Reduction Techniques

Efficient Calculation of in vivo Efficiency Curves Using Variance Reduction Techniques

Creation and Use of Adjustable 3d Phantoms: Application for the Lung Monitoring of Female Workers

CRUCIAL PARAMETERS FOR PROPER SIMULATION OF THE DETECTOR USED ININ VIVOMEASUREMENTS

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