Influences of spherical phantom heterogeneities on dosimetric charactristics of miniature electronic brachytherapy X-ray sources: Monte Carlo study

Jashni, H Karimi; Safigholi, Habib; Meigooni, Ali S.

doi:10.1016/j.apradiso.2014.10.014

Cited by 10 publications

(4 citation statements)

References 19 publications

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“…All three, the Zeiss Intrabeam system (Carl Zeiss, Oberkochen, Germany), the Axxent system (Xoft, Fremont, CA) and the Esteya Electronic Brachytherapy System (Elekta AB-Nucletron, Stockholm, Sweden) mentioned above, use particular photon emitting sources, for which Task Group-186 of the American Association of Physicists in Medicine (AAPM) have developed a number of guidelines (17). The AAPM has also provided exact definitions for the Miniature Electronic Brachytherapy X-ray Sources (MEBXS) emitting a spectrum of bremsstrahlung and characteristic X-ray photons (18). The work of Task Group 152 of AAPM has resulted in a model regulation for electronic brachytherapy, where the term “electronic brachytherapy” has been defined as “a method of radiation therapy using electrically generated x-rays to deliver a radiation dose at a distance of up to a few centimeters by intracavitary, intraluminal, or interstitial application, or by applications with the source in contact with the body surface or very close to the body surface” (19).…”

Section: Introductionmentioning

confidence: 99%

Assessment of two hemispherical and hemispherical-conical miniature sources used in electronic brachytherapy using Monte Carlo Simulation

et al. 2017

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IntroductionSince the heart of the electronic brachytherapy system is a tube of a miniature x-ray and due to the increasing use of electronic brachytherapy, there is an urgent need for acquiring knowledge about the X-ray spectrum produced, and distribution of x-ray dose. This study aimed to assess the optimal target thickness (TT), the X-ray source spectrum, and the absorbed dose of two miniature sources of hemispherical and hemispherical-conical used in electronic brachytherapy systems, through a Monte Carlo simulation.MethodsConsidering the advantages of MCNPX Code (2.6.0), two input files corresponding to the characteristics of the investigated miniature sources were prepared for this code and then were used for simulation. The optimal thickness (OT) of gold and tungsten targets was determined for the energy levels of 40, 45, and 50 kilo-electron-volts.ResultsIn this study, the values of the size of the optimal thickness of 0.92, 1.01 and 1.06 μ for gold target and values of 0.99, 1.08 and 1.34 μ for tungsten target were obtained for energies 40, 45 and 50 keV that using these values, the optimum thickness of 0.92, X-ray spectrum within and outside targets, axial and radial doses for the used energy were calculated for two miniature sources.ConclusionIt was found that the energy of incident electron, target shape, cross-sectional area of the produced bremsstrahlung, atomic number of materials constituting of the target and output window are the factors with the greatest impacts on the produced X-ray spectrum and the absorbed dose.

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Section: Introductionmentioning

confidence: 99%

Assessment of two hemispherical and hemispherical-conical miniature sources used in electronic brachytherapy using Monte Carlo Simulation

et al. 2017

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“…The heart of the MEBXS is a miniature X-ray tube which is very small in dimensions (a small accelerator). Using electrically generated X-rays a radiation dose is delivered at a distance of up to a few centimeters by intracavitary, intraluminal or interstitial application, or by applications with the source in contact with the body surface or very close to the body surface [1] , [2] , [3] , [4] . The initial theory of electronic X-ray source is based on the electron bombardment of transmission-type target in a small vacuum tube with low energy electrons and bremsstrahlung photons production.…”

Section: Introductionmentioning

confidence: 99%

“…Since the source is a miniature accelerator, with changing voltage (30–60 keV) and currents, it can give desired dose rate to the cancerous tissue. Because low voltages and currents are used, minimal shielding is required and radiation exposure to the staff can be reduced [2] , [3] , [4] .…”

Section: Introductionmentioning

confidence: 99%

“…The source is outside the patient. In the Carl Zeiss mobile source, electrons are produced by an electron gun outside patient and accelerated to a very fine tube which is in turn attached to a hemisphere gold target at tube tip [2] , [3] , [4] , [5] . A thin thickness of beryllium covers the outside surface of target as a thermal buffer.…”

Section: Introductionmentioning

confidence: 99%

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Anode optimization for miniature electronic brachytherapy X-ray sources using Monte Carlo and computational fluid dynamic codes

Masoud

Safigholi

2016

Journal of Advanced Research

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A miniature X-ray source has been optimized for electronic brachytherapy. The cooling fluid for this device is water. Unlike the radionuclide brachytherapy sources, this source is able to operate at variable voltages and currents to match the dose with the tumor depth. First, Monte Carlo (MC) optimization was performed on the tungsten target-buffer thickness layers versus energy such that the minimum X-ray attenuation occurred. Second optimization was done on the selection of the anode shape based on the Monte Carlo in water TG-43U1 anisotropy function. This optimization was carried out to get the dose anisotropy functions closer to unity at any angle from 0° to 170°. Three anode shapes including cylindrical, spherical, and conical were considered. Moreover, by Computational Fluid Dynamic (CFD) code the optimal target-buffer shape and different nozzle shapes for electronic brachytherapy were evaluated. The characterization criteria of the CFD were the minimum temperature on the anode shape, cooling water, and pressure loss from inlet to outlet. The optimal anode was conical in shape with a conical nozzle. Finally, the TG-43U1 parameters of the optimal source were compared with the literature.

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HDR brachytherapy in vivo source position verification using a 2D diode array: A Monte Carlo study

Poder

Cutajar

Guatelli

et al. 2018

J Applied Clin Med Phys

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PurposeThis study aims to assess the accuracy of source position verification during high‐dose rate (HDR) prostate brachytherapy using a novel, in‐house developed two‐dimensional (2D) diode array (the Magic Plate), embedded exactly below the patient within a carbon fiber couch. The effect of tissue inhomogeneities on source localization accuracy is examined.MethodMonte Carlo (MC) simulations of 12 source positions from a HDR prostate brachytherapy treatment were performed using the Geant4 toolkit. An Ir‐192 Flexisource (Isodose Control, Veenendaal, the Netherlands) was simulated inside a voxelized patient geometry, and the dose deposited in each detector of the Magic Plate evaluated. The dose deposited in each detector was then used to localize the source position using a proprietary reconstruction algorithm.ResultsThe accuracy of source position verification using the Magic Plate embedded in the patient couch was found to be affected by the tissue inhomogeneities within the patient, with an average difference of 2.1 ± 0.8 mm (k = 1) between the Magic Plate predicted and known source positions. Recalculation of the simulations with all voxels assigned a density of water improved this verification accuracy to within 1 mm.ConclusionSource position verification using the Magic Plate during a HDR prostate brachytherapy treatment was examined using MC simulations. In a homogenous geometry (water), the Magic Plate was able to localize the source to within 1 mm, however, the verification accuracy was negatively affected by inhomogeneities; this can be corrected for by using density information obtained from CT, making the proposed tool attractive for use as a real‐time in vivo quality assurance (QA) device in HDR brachytherapy for prostate cancer.

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Influences of spherical phantom heterogeneities on dosimetric charactristics of miniature electronic brachytherapy X-ray sources: Monte Carlo study

Cited by 10 publications

References 19 publications

Assessment of two hemispherical and hemispherical-conical miniature sources used in electronic brachytherapy using Monte Carlo Simulation

Assessment of two hemispherical and hemispherical-conical miniature sources used in electronic brachytherapy using Monte Carlo Simulation

Anode optimization for miniature electronic brachytherapy X-ray sources using Monte Carlo and computational fluid dynamic codes

HDR brachytherapy in vivo source position verification using a 2D diode array: A Monte Carlo study

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