Calculation of x‐ray spectra emerging from an x‐ray tube. Part I. Electron penetration characteristics in x‐ray targets

Poludniowski, Gavin; Evans, Philip

doi:10.1118/1.2734725

Cited by 212 publications

(159 citation statements)

References 30 publications

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“…In order to predict the imaging performance of different solute choices for the brine, calculate the x-ray spectrum of the incident x-rays [29][30][31] . Include the impact of the core-holder, core assembly and confining fluids on x-ray spectrum.…”

Section: Imaging Strategy Designmentioning

confidence: 99%

Reservoir Condition Pore-scale Imaging of Multiple Fluid Phases Using X-ray Microtomography

Andrew

Bijeljic

Blunt

2015

JoVE

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X-ray microtomography was used to image, at a resolution of 6.6 µm, the pore-scale arrangement of residual carbon dioxide ganglia in the pore-space of a carbonate rock at pressures and temperatures representative of typical formations used for CO 2 storage. Chemical equilibrium between the CO 2 , brine and rock phases was maintained using a high pressure high temperature reactor, replicating conditions far away from the injection site. Fluid flow was controlled using high pressure high temperature syringe pumps. To maintain representative in-situ conditions within the micro-CT scanner a carbon fiber high pressure micro-CT coreholder was used. Diffusive CO 2 exchange across the confining sleeve from the pore-space of the rock to the confining fluid was prevented by surrounding the core with a triple wrap of aluminum foil. Reconstructed brine contrast was modeled using a polychromatic x-ray source, and brine composition was chosen to maximize the three phase contrast between the two fluids and the rock. Flexible flow lines were used to reduce forces on the sample during image acquisition, potentially causing unwanted sample motion, a major shortcoming in previous techniques. An internal thermocouple, placed directly adjacent to the rock core, coupled with an external flexible heating wrap and a PID controller was used to maintain a constant temperature within the flow cell. Substantial amounts of CO 2 were trapped, with a residual saturation of 0.203 ± 0.013, and the sizes of larger volume ganglia obey power law distributions, consistent with percolation theory.

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Section: Imaging Strategy Designmentioning

confidence: 99%

Reservoir Condition Pore-scale Imaging of Multiple Fluid Phases Using X-ray Microtomography

Andrew

Bijeljic

Blunt

2015

JoVE

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“…The measurement time of the spectrometer was set to 1000 s. The measured (raw) spectrum was de-convoluted using a Monte Carlo calculated response of the detector. The Penelope2008 Monte Carlo code [20] and the SpekCalc software [22][23][24] were also used to obtain theoretical spectra to be compared with the measured ones. Penelope2008 is a MC code, which reliability and performance have been widely tested [25].…”

Section: Spectral Evaluationmentioning

confidence: 99%

Dosimetric Characteristics of a New Unit for Electronic Skin Brachytherapy

et al. 2014

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Purpose: Brachytherapy with radioactive high dose rate (HDR) 192 Ir source is applied to small skin cancer lesions, using surface applicators, i.e. Leipzig or Valencia type. New developments in the field of radiotherapy for skin cancer include electronic brachytherapy. This technique involves the placement of an HDR X-ray source close to the skin, therefore combining the benefits of brachytherapy with the reduced shielding requirements and targeted energy of low energy X-rays. Recently, the Esteya ® Electronic Brachytherapy System (Esteya EBS, Elekta AB-Nucletron, Stockholm, Sweden) has been developed specifically for HDR brachytherapy treatment of surface lesions. The system provides radionuclide free HDR brachytherapy by means of a small 69.5 kV X-ray source. The purpose of this study is to obtain the dosimetric characterization required for clinical implementation, providing the detailed methodology to perform the commissioning.Material and methods: Flatness, symmetry and penumbra, percentage of depth dose (PDD), kV stability, HVL, output, spectrum, linearity, and leakage have been evaluated for a set of applicators (from 10 mm to 30 mm in diameter).Results: Flatness and symmetry resulted better than 5% with around 1 mm of penumbra. The depth dose gradient is about 7%/mm. A kV value of 68.4 ± 1.0 kV (k = 1) was obtained, in good agreement with manufacturer data (69.5 kV). HVL was 1.85 mm Al. Dose rate for a typical 6 Gy to 7 Gy prescription resulted about 3.3 Gy/min and the leakage value was < 100 µGy/min. Conclusions:The new Esteya ® Electronic Brachytherapy System presents excellent flatness and penumbra as with the Valencia applicator case, combined with an improved PDD, allowing treatment of lesions of up to a depth of 5 mm in combination with reduced treatment duration. The Esteya unit allows HDR brachytherapy superficial treatment within a minimally shielded environment due its low energy.

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“…Other packages have been oriented toward teaching in radiotherapy: RadSim [21] can be used to simulate the main particle interactions of interest in radiotherapy. SpekCalc [15], an x-ray spectrum calculation tool based on a verified model [16,17], simulates x-ray production from tungsten targets in the radiology and superficial or orthovoltage therapy energy ranges. This paper describes a novel educational tool for teaching or self-learning the basics of the x-ray imaging process, ImaSim, consisting of a teaching software package based on a simulation environment.…”

Section: Introductionmentioning

confidence: 99%

ImaSim, a software tool for basic education of medical x-ray imaging in radiotherapy and radiology

2013

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Introduction: X-ray imaging is an important part of medicine and plays a crucial role in radiotherapy. Education in this field is mostly limited to textbook teaching due to equipment restrictions. A novel simulation tool, ImaSim, for teaching the fundamentals of the x-ray imaging process based on ray-tracing is presented in this work. ImaSim is used interactively via a graphical user interface (GUI). Materials and methods:The software package covers the main x-ray based medical modalities: planar kilovoltage (kV), planar (portal) megavoltage (MV), fan beam computed tomography (CT), and cone beam CT (CBCT) imaging. The user can modify the photon source, object to be imaged and imaging setup with three-dimensional editors. Objects are currently obtained by combining blocks with variable shapes. The imaging of three-dimensional voxelized geometries is currently not implemented, but can be added in a later release. The program follows a ray-tracing approach, ignoring photon scatter in its current implementation. Simulations of a phantom CT scan were generated in ImaSim and were compared to measured data in terms of CT number accuracy. Spatial variations in the photon fluence and mean energy from an x-ray tube caused by the heel effect were estimated from ImaSim and Monte Carlo simulations and compared.Results: In this paper we describe ImaSim and provide two examples of its capabilities. CT numbers were found to agree within 36 Hounsfield Units (HU) for bone, which corresponds to a 2% attenuation coefficient difference. ImaSim reproduced the heel effect reasonably well when compared to Monte Carlo simulations.Discussion: An x-ray imaging simulation tool is made available for teaching and research purposes. ImaSim provides a means to facilitate the teaching of medical x-ray imaging.

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Calculation of x‐ray spectra emerging from an x‐ray tube. Part I. Electron penetration characteristics in x‐ray targets

Abstract: 5The penetration characteristics of electron beams into x-ray targets are investigated for incident electron kinetic energies in the range 50 to 150 keV.

Cited by 212 publications

References 30 publications

Reservoir Condition Pore-scale Imaging of Multiple Fluid Phases Using X-ray Microtomography

Reservoir Condition Pore-scale Imaging of Multiple Fluid Phases Using X-ray Microtomography

Dosimetric Characteristics of a New Unit for Electronic Skin Brachytherapy

ImaSim, a software tool for basic education of medical x-ray imaging in radiotherapy and radiology

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