Po-342 Measurements of an Electronic Brachytherapy Source With a Brachytherapy Dose Verification Phantom

Pike, T; DeWerd, Larry A.; Micka, J

doi:10.1016/s0167-8140(12)72308-3

Cited by 2 publications

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“…We are not the first to report difficulties with this chamber. Issues with modeling and performing measurements with the PTW 34013 in the context of electronic brachytherapy have been previously reported (Rivard et al 2006, Pike 2012, Fulkerson et al 2014. It is recommended that alternative soft x-ray ionization chambers with desirable qualities such as a more precise knowledge of dimensions, inclusion of a guard ring, and waterproof construction (i.e.…”

Section: Discussionmentioning

confidence: 99%

Determination of absorbed dose to water from a miniature kilovoltage x-ray source using a parallel-plate ionization chamber

Watson¹,

Popović²,

Seuntjens³

2017

Phys. Med. Biol.

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Electronic brachytherapy sources are widely accepted as alternatives to radionuclide-based systems. Yet, formal dosimetry standards for these devices to independently complement the dose protocol provided by the manufacturer are lacking. This article presents a formalism for calculating and independently verifying the absorbed dose to water from a kV x-ray source (The INTRABEAM System) measured in a water phantom with an ionization chamber calibrated in terms of air-kerma. This formalism uses a Monte Carlo (MC) calculated chamber conversion factor, [Formula: see text], to convert air-kerma in a reference beam to absorbed dose to water in the measurement beam. In this work [Formula: see text] was determined for a PTW 34013 parallel-plate ionization chamber. Our results show that [Formula: see text] was sensitive to the chamber plate separation tolerance, with differences of up to 15%. [Formula: see text] was also found to have a depth dependence which varied with chamber plate separation (0 to 10% variation for the smallest and largest cavity height, over 3 to 30 mm depth). However for all chamber dimensions investigated, [Formula: see text] was found to be significantly larger than the manufacturer reported value, suggesting that the manufacturer recommended method of dose calculation could be underestimating the dose to water.

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Section: Discussionmentioning

confidence: 99%

Determination of absorbed dose to water from a miniature kilovoltage x-ray source using a parallel-plate ionization chamber

Watson¹,

Popović²,

Seuntjens³

2017

Phys. Med. Biol.

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“…The use of each of these tallies for dose calculation has some advantages and drawbacks. However, considering the negligible range of secondary electrons in solid or liquid media at photon energies lower than 200 keV ( 38 ), and the presence of negligible radiative losses ( 39 ), and since total kerma has about the same magnitude as the collision kerma ( 38 ), the absorbed dose can be approximated by collision kerma ( 39 ) and therefore F6 tally was recognized as the best option for this calculation. This tally is known as the track length estimate of energy deposition, or as the heating or energy deposition tally, and is faster than other tallies of dose calculation.…”

Section: Methodsmentioning

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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Po-342 Measurements of an Electronic Brachytherapy Source With a Brachytherapy Dose Verification Phantom

Cited by 2 publications

References 0 publications

Determination of absorbed dose to water from a miniature kilovoltage x-ray source using a parallel-plate ionization chamber

Determination of absorbed dose to water from a miniature kilovoltage x-ray source using a parallel-plate ionization chamber

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

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