Conversion coefficients for determination of dispersed photon dose during radiotherapy: NRUrad input code for MCNP

Beni, Mehrdad Shahmohammadi; Ng, C. Y. P.; Krstić, Dragana; Nikezić, D.; Yu, K.N.

doi:10.1371/journal.pone.0174836

Cited by 13 publications

(22 citation statements)

References 19 publications

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“…The Los Alamos Monte Carlo N-Particle transport code version 6 (MCNP6) provides accurate consideration of fundamental particle interactions with matter, supports sophisticated geometry models, and allows for simulations of the photon/electron transport energy below the conventional 1-kilovolt limit 34,35 . MCNP has been demonstrated to be sufficiently accurate in a wide range of radiation applications, such as metal cytotoxic effects 36 , medical linear accelerator 37 , neutron biological effects 38 , plutonium content verification 39 , neutron detector design 40 , and radiotherapy treatment planning 41,42 .…”

Section: Introductionmentioning

confidence: 99%

Radiation Dosimetry of Inhaled Radioactive Aerosols: CFPD and MCNP Transport Simulations of Radionuclides in the Lung

Talaat

Baldez

et al. 2019

Sci Rep

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Despite extensive efforts in studying radioactive aerosols, including the transmission of radionuclides in different chemical matrices throughout the body, the internal organ-specific radiation dose due to inhaled radioactive aerosols has largely relied on experimental deposition data and simplified human phantoms. Computational fluid-particle dynamics (CFPD) has proven to be a reliable tool in characterizing aerosol transport in the upper airways, while Monte Carlo based radiation codes allow accurate simulation of radiation transport. The objective of this study is to numerically assess the radiation dosimetry due to particles decaying in the respiratory tract from environmental radioactive exposures by coupling CFPD with Monte Carlo N-Particle code, version 6 (MCNP6). A physiologically realistic mouth-lung model extending to the bifurcation generation G9 was used to simulate airflow and particle transport within the respiratory tract. Polydisperse aerosols with different distributions were considered, and deposition distribution of the inhaled aerosols on the internal airway walls was quantified. The deposition mapping of radioactive aerosols was then registered to the respiratory tract of an image-based whole-body adult male model (VIP-Man) to simulate radiation transport and energy deposition. computer codes were developed for geometry visualization, spatial normalization, and source card definition in MCNP6. Spatial distributions of internal radiation dosimetry were compared for different radionuclides (131 i, 134,137 cs, 90 Sr-90 Y, 103 Ru and 239,240 Pu) in terms of the radiation fluence, energy deposition density, and dose per decay. Radioactive aerosols arise from various sources such as nuclear accidents, natural decay processes, and the decommissioning of nuclear reactors 1-3. Highly radioactive micro-particles were released to the surrounding environment in the Chernobyl and Fukushima Daiichi accidents 1,4. The aerosol particles released from accidents and natural decay processes may remain suspended in the air for extended periods, be incorporated into soil particles that can reenter the air, or be inhaled by humans or animals. When aerosol particles are inhaled, a fraction of the inhaled particles deposit in the respiratory tract, while the rest is exhaled out 5-9. The deposition fraction is dependent on many parameters such as the geometry of the respiratory airways, the particle size of the inhaled aerosol, and the breathing condition 10,11. Inhaled radioactive aerosols can expose internal organs to radiation for extended periods and may induce a spectrum of functional and morphological changes, such as genetic mutations and carcinogenesis 12,13. Their severity can be related to the absorbed radiation dose in the different specific tissues, which is further related to the number of radioactive particles inhaled, how long they stay, and the type of radiation they emit. Unlike fat and muscles being the main internal defense to external exposures, there is nothing to protect cells and tissues of sus...

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Section: Introductionmentioning

confidence: 99%

Radiation Dosimetry of Inhaled Radioactive Aerosols: CFPD and MCNP Transport Simulations of Radionuclides in the Lung

Talaat

Baldez

et al. 2019

Sci Rep

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“…electrons were implemented, and dose dispersion [5] in the film active layer was also considered. The realistic amount of energy transferred to the EBT3 film active layer was obtained through Monte Carlo simulation and determination of the calibration coefficient R (=DA/DE) [6,7], where DA was the actual dose delivered to the EBT3 film active layer and DE was the dose recorded by an external ionization chamber.…”

Section: Methodsmentioning

confidence: 99%

“…The Net ROD was defined as (5) where unexposed and exposed were the reflected light intensities from the unexposed and exposed film to X-ray, respectively. The numerical simulations presented in this paper were executed on a supercomputer with Intel ® Xeon E5-2630 v3 2.40 GHz using 32 physical cores and hyper-threaded to 64.…”

Section: Computation Schemementioning

confidence: 99%

“…In the present work, Monte Carlo simulation was employed to model the interactions of X-ray photons and the generated secondary electrons in the EBT3 film active layer using the Monte Carlo N-Particle (MCNP) code package [4]. In our Monte Carlo model, the interaction and the transport of the generated secondary electrons were implemented, and dose dispersion [5] in the film active layer was also considered. The realistic amount of energy transferred to the EBT3 film active layer was obtained through Monte Carlo simulation and determination of the calibration coefficient R (=D A /D E ) [6,7], where D A was the actual dose delivered to the EBT3 film active layer and D E was the dose recorded by an external ionization chamber.…”

Section: Introductionmentioning

confidence: 99%

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Modeling kV X-ray-Induced Coloration in Radiochromic Films

et al. 2018

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Commercially available radiochromic films are primarily designed for clinical X-ray dosimetry. These films change color upon exposures to radiation as a result of solid-state polymerization (SSP). Built on a previous model developed for SSP upon exposures to ultraviolet (UV) radiation, a new model was developed in the present work for X-ray-induced coloration in Gafchromic EBT3 films. Monte Carlo simulations using the Monte Carlo N-Particle (MCNP) code were employed to model the transport and interaction of photons and the generated secondary electrons within the film active layer. The films were exposed to continuous-energy photon beams. The dose D E in the external radiation detector (i.e., ionization chamber) was determined and the realistic dose D A in the film active layer was then obtained using the calibration coefficient R (=D A /D E ). The finite element method (FEM) was used to solve the classical steady-state Helmholtz equation using the multifrontal massively parallel sparse direct solver (MUMPS). An extensive grid independence test was carried out and the numerical stability of the present model was ensured. The reflected light intensity from the film surface was used to theoretically obtain the net reflective optical density of the film exposed to X-ray. Good agreement was obtained between the experimental and theoretical results of the net reflective optical density of the film. For X-ray doses >~600 cGy, due to the already formed densely cross-linked structure in the active layer of the EBT3 film so further bond formation was less likely, the reflected light intensity from the film surface increased at a relatively lower rate when compared to those for dose values <~600 cGy.

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“…dose-response curves were understandably obtained for X-rays, development of a theoretical model in the atomic scale using X-ray data would involve added complications of ionization, non-uniform energy deposition, as well as dispersed doses [19] caused by secondary electrons set in motion by the indirectly ionizing X-ray photons. Such complications will inevitably introduce added uncertainties to the model and might overshadow the basic SSP processes.…”

Section: Atomic Scale Modelmentioning

confidence: 99%

Modeling Coloration of a Radiochromic Film with Molecular Dynamics-Coupled Finite Element Method

et al. 2017

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Radiochromic films change color upon exposures to radiation doses as a result of solid-state polymerization (SSP). Commercially available radiochromic films are primarily designed for, and have become widely used in, clinical X-ray dosimetry. However, many intriguing properties of radiochromic films are not yet fully understood. The present work aimed at developing a theoretical model at both atomic and macroscopic scales to provide a platform for future works to understand these intriguing properties. Despite the fact that radiochromic films were primarily designed for clinical X-ray dosimetry, dose-response curves for the Gafchromic EBT3 film obtained for ultraviolet (UV) radiation were employed to develop our model in order to avoid complications of ionization, non-uniform energy deposition, as well as dispersed doses caused by secondary electrons set in motion by the indirectly ionizing X-ray photons, which might introduce added uncertainties to the model and overshadow the basic SSP processes. The active layer in the EBT3 film consisted of diacetylene (DA) pentacosa-10,12-diynoate monomers, which were modelled using molecular dynamics (MD). The degrees of SSP in the atomic scale upon different UV exposures were obtained to determine the absorption coefficients of the active layer, which were then input into the finite element method (FEM). The classical steady-state Helmholtz equation was engaged to model the reflection from the active layer using the FEM technique. The multifrontal massively parallel sparse direct solver (MUMPS) was employed to solve the present numerical problem. Very good agreement between experimentally and theoretically obtained coloration in terms of net reflective optical density was achieved for different UV exposures. In particular, for UV exposures larger than~40 J/cm 2 , the reflected light intensity decreased at a lower rate when compared to other UV exposure values, which was explained by the densely cross-linked structure under near-complete polymerization, and thus the lower efficiency for further bond formation between DA monomer strands.

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Conversion coefficients for determination of dispersed photon dose during radiotherapy: NRUrad input code for MCNP

Cited by 13 publications

References 19 publications

Radiation Dosimetry of Inhaled Radioactive Aerosols: CFPD and MCNP Transport Simulations of Radionuclides in the Lung

Radiation Dosimetry of Inhaled Radioactive Aerosols: CFPD and MCNP Transport Simulations of Radionuclides in the Lung

Modeling kV X-ray-Induced Coloration in Radiochromic Films

Modeling Coloration of a Radiochromic Film with Molecular Dynamics-Coupled Finite Element Method

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