Monte Carlo analysis of energy dependent anisotropy of bremsstrahlung x‐ray spectra

Kákonyi, Róbert; Erdélyi, Miklós; Szabó, Gábor

doi:10.1118/1.3176954

Cited by 2 publications

(5 citation statements)

References 16 publications

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“…Although the models above have been shown to be adequate for certain applications, their validity for off‐axis emissions has been challenged. Kákonyi et al 14 concluded that the emission angles predicted by Birch and Marshall, 7 and Poludniowski 8 disagree with MC predictions due to an inaccurate representation of the intrinsic bremsstrahlung angular distribution. A persistent assumption of x‐ray spectrum models has been that the angular distribution of bremsstrahlung production is uniform.…”

Section: Introductionmentioning

confidence: 99%

A model for the energy and angular distribution of x rays emitted from an x‐ray tube. Part II. Validation of x‐ray spectra from 20 to 300 kV

2020

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To present and validate a complete x-ray emission model (bremsstrahlung and characteristic x-ray emission) for the energy range 20-300 kV. Methods: An analytical x-ray spectrum model that combines the bremsstrahlung emission model developed in Part I with a previously developed characteristic x-ray emission model is validated by comparison with Monte Carlo calculations, published measured spectra, and models developed by other authors. Furthermore, the assumptions and limitations of previous spectrum models are summarized, and their predictions are compared with results obtained by Monte Carlo simulations of x rays emitted from tungsten and molybdenum targets. Results: The model is able to reproduce narrow-beam Monte Carlo calculations to within 0.5% in terms of the first and second aluminum half-value layer thickness (HVL). Compared with measured spectra, the difference in HVL is < 2% for typical diagnostic and therapeutic beam qualities available at primary standard laboratories. Compared with previous spectrum models, the present model performs especially well for low kilovoltage x-ray beams (below 50 kV), and is reliable for a wider range of takeoff angles, that is, the angle between the target surface and the direction of emission. The difference in model and Monte Carlo predictions of the energy-fluence weighted air kerma (i.e., the photon energy absorption in air) is < 0.5% using the present model, while previous spectrum models can differ by more than 10%. Conclusions: The x-ray emission model developed in this work has been validated against Monte Carlo calculations and measured results. The model provides an efficient alternative to comprehensive Monte Carlo simulations and is an improvement over previous models. The model can be used to predict both central-and off-axis spectra, as well as off-axis effects such as the (anode) heel effect.

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Section: Introductionmentioning

confidence: 99%

A model for the energy and angular distribution of x rays emitted from an x‐ray tube. Part II. Validation of x‐ray spectra from 20 to 300 kV

2020

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“…The physical background of the maximum in the spectral photon flux was discussed in our previous paper. 5 The position of the maximum of the spectral photon flux was shifted to higher emission angles with increased anode surface roughness in all energy ranges. The reduction of spectral photon flux due to anode surface roughness is higher at low emission angles.…”

Section: Iiib the Changes In The Spectra Shapementioning

confidence: 89%

“…The measured angular dependency of the detected intensity values also confirms the cylindrical symmetry of the x-ray beam. 5 The energy and angular distributions of the excited photons were recorded with resolutions of 0.5 keV and 1°, respectively, by means of transmitted image on cylinder ͑TIC͒ tally. 5 During simulations, no other variance reduction processes were applied; the default parametrization of MCNPX was used with the integrated TIGER series electron transport method.…”

Section: Iia Mcnpx Input Geometry and Parametrizationmentioning

confidence: 99%

“…5 The energy and angular distributions of the excited photons were recorded with resolutions of 0.5 keV and 1°, respectively, by means of transmitted image on cylinder ͑TIC͒ tally. 5 During simulations, no other variance reduction processes were applied; the default parametrization of MCNPX was used with the integrated TIGER series electron transport method. The proper cross-sections for all photon and elec-tron interactions are taken from the ENDF library.…”

Section: Iia Mcnpx Input Geometry and Parametrizationmentioning

confidence: 99%

“…3 However, the applied model did not take into consideration the angular dependency of the bremsstrahlung radiation, which limits the applicability of the model. 5 The aim of this paper is to study the spectral and spatial distribution of the x-ray beam generated on a rough anode surface and to analyze the validity of modeling the effect of anode surface roughness by simple filters. The range of the analyzed anode surface roughness was extended into relatively high roughness values.…”

Section: Introductionmentioning

confidence: 99%

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Monte Carlo simulation of the effects of anode surface roughness on x‐ray spectra

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Monte Carlo analysis of energy dependent anisotropy of bremsstrahlung x‐ray spectra

Cited by 2 publications

References 16 publications

A model for the energy and angular distribution of x rays emitted from an x‐ray tube. Part II. Validation of x‐ray spectra from 20 to 300 kV

A model for the energy and angular distribution of x rays emitted from an x‐ray tube. Part II. Validation of x‐ray spectra from 20 to 300 kV

Monte Carlo simulation of the effects of anode surface roughness on x‐ray spectra

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