Comparisons of the standards for air kerma of the GUM and the BIPM for<sup>60</sup>Co and<sup>137</sup>Cs gamma radiation

Allisy-Roberts, P J; Kessler, C; Burns, D T; Derlaciński, M; Kokocinski, J.

doi:10.1088/0026-1394/48/1a/06015

Cited by 5 publications

(2 citation statements)

References 13 publications

(34 reference statements)

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“…This air-filled graphite-walled Bragg-Gray chamber, which is usually denoted by PTB-HRK2, is described, e.g. in the publications by Allisy et al (2005) or by Büermann and Burns (2009). The model of the chamber used in the MC calculation is based on detailed information found in the original engineering drawings available at PTB.…”

Section: Monte Carlo Simulation Of the Benchmark Experimentsmentioning

confidence: 99%

Uncertainties in Monte Carlo-based absorbed dose calculations for an experimental benchmark

Renner

Wulff

et al. 2015

Phys. Med. Biol.

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There is a need to verify the accuracy of general purpose Monte Carlo codes like EGSnrc, which are commonly employed for investigations of dosimetric problems in radiation therapy. A number of experimental benchmarks have been published to compare calculated values of absorbed dose to experimentally determined values. However, there is a lack of absolute benchmarks, i.e. benchmarks without involved normalization which may cause some quantities to be cancelled. Therefore, at the Physikalisch-Technische Bundesanstalt a benchmark experiment was performed, which aimed at the absolute verification of radiation transport calculations for dosimetry in radiation therapy. A thimble-type ionization chamber in a solid phantom was irradiated by high-energy bremsstrahlung and the mean absorbed dose in the sensitive volume was measured per incident electron of the target. The characteristics of the accelerator and experimental setup were precisely determined and the results of a corresponding Monte Carlo simulation with EGSnrc are presented within this study. For a meaningful comparison, an analysis of the uncertainty of the Monte Carlo simulation is necessary. In this study uncertainties with regard to the simulation geometry, the radiation source, transport options of the Monte Carlo code and specific interaction cross sections are investigated, applying the general methodology of the Guide to the expression of uncertainty in measurement. Besides studying the general influence of changes in transport options of the EGSnrc code, uncertainties are analyzed by estimating the sensitivity coefficients of various input quantities in a first step. Secondly, standard uncertainties are assigned to each quantity which are known from the experiment, e.g. uncertainties for geometric dimensions. Data for more fundamental quantities such as photon cross sections and the I-value of electron stopping powers are taken from literature. The significant uncertainty contributions are identified as the energy of the radiation source and the underlying photon cross sections as well as the I-value of media involved in the simulation. The combined standard uncertainty of the Monte Carlo calculation yields 0.78% as a conservative estimation. The result of the calculation is close to the experimental result and with each combined standard uncertainty <1%, the accuracy of EGSnrc is confirmed. The setup and methodology of this study can be employed to benchmark other Monte Carlo codes for the calculation of absorbed dose in radiotherapy.

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Section: Monte Carlo Simulation Of the Benchmark Experimentsmentioning

confidence: 99%

Uncertainties in Monte Carlo-based absorbed dose calculations for an experimental benchmark

Renner

Wulff

et al. 2015

Phys. Med. Biol.

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“…Table 2 presents example values for the physical constants and correction factors and their uncertainties. These are taken from the BIPM.RI(I)-K1 comparison report [90] for the PTB parallel-plate (HRK-3) cavity standard used in the BIPM reference 60 Co beam.…”

Section: Typical Uncertainty Budget For a Cavity Chamber For 60 Comentioning

confidence: 99%

Air-kerma cavity standards

Büermann

Burns

2009

Metrologia

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This paper reviews the current status of air-kerma cavity standards for gamma rays from 60Co, 137Cs and 192Ir sources. It describes the basic principles and the theories to determine the air-kerma rate from the ionization current of graphite-walled cavity ionization chambers. A typical design of a cavity chamber is shown and described. The various correction factors to be applied to the standards and their determination by experimental and Monte Carlo methods are discussed. A typical uncertainty budget for a cavity standard is presented and the results of comparisons between primary standards are summarized and discussed. Finally, conclusions are drawn and proposals made for topics to be addressed in future studies.

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Simulation of gamma minitype reference radiation for calibration of personal dosimeter

et al. 2020

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Comparisons of the standards for air kerma of the GUM and the BIPM for⁶⁰Co and¹³⁷Cs gamma radiation

Cited by 5 publications

References 13 publications

Uncertainties in Monte Carlo-based absorbed dose calculations for an experimental benchmark

Uncertainties in Monte Carlo-based absorbed dose calculations for an experimental benchmark

Air-kerma cavity standards

Simulation of gamma minitype reference radiation for calibration of personal dosimeter

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Comparisons of the standards for air kerma of the GUM and the BIPM for60Co and137Cs gamma radiation

Cited by 5 publications

References 13 publications

Uncertainties in Monte Carlo-based absorbed dose calculations for an experimental benchmark

Uncertainties in Monte Carlo-based absorbed dose calculations for an experimental benchmark

Air-kerma cavity standards

Simulation of gamma minitype reference radiation for calibration of personal dosimeter

Contact Info

Product

Resources

About

Comparisons of the standards for air kerma of the GUM and the BIPM for⁶⁰Co and¹³⁷Cs gamma radiation