Accuracy of the electron transport in mcnp5 and its suitability for ionization chamber response simulations

A comparison with the egsnrc and penelope codes

Hanna Koivunoro (Corresponding Author), Teemu Siiskonen, Petri Kotiluoto, Iiro Auterinen, Eero Hippeläinen, Sauli Savolainen

Research output: Contribution to journalReview ArticleScientificpeer-review

10 Citations (Scopus)

Abstract

Purpose: In this work, accuracy of the mcnp5 code in the electron transport calculations and its suitability for ionization chamber (IC) response simulations in photon beams are studied in comparison to egsnrc and penelope codes. Methods: The electron transport is studied by comparing the depth dose distributions in a water phantom subdivided into thin layers using incident energies (0.05, 0.1, 1, and 10 MeV) for the broad parallel electron beams. The IC response simulations are studied in water phantom in three dosimetric gas materials (air, argon, and methane based tissue equivalent gas) for photon beams (60Co source, 6 MV linear medical accelerator, and mono-energetic 2 MeV photon source). Two optional electron transport models of mcnp5 are evaluated: the ITS-based electron energy indexing (mcnp5ITS) and the new detailed electron energy-loss straggling logic (mcnp5new). The electron substep length (ESTEP parameter) dependency in mcnp5 is investigated as well. Results: For the electron beam studies, large discrepancies (>3) are observed between the mcnp5 dose distributions and the reference codes at 1 MeV and lower energies. The discrepancy is especially notable for 0.1 and 0.05 MeV electron beams. The boundary crossing artifacts, which are well known for the mcnp5ITS, are observed for the mcnp5new only at 0.1 and 0.05 MeV beam energies. If the excessive boundary crossing is eliminated by using single scoring cells, the mcnp5ITS provides dose distributions that agree better with the reference codes than mcnp5new. The mcnp5 dose estimates for the gas cavity agree within 1 with the reference codes, if the mcnp5ITS is applied or electron substep length is set adequately for the gas in the cavity using the mcnp5new. The mcnp5new results are found highly dependent on the chosen electron substep length and might lead up to 15 underestimation of the absorbed dose. Conclusions: Since the mcnp5 electron transport calculations are not accurate at all energies and in every medium by general clinical standards, caution is needed, if mcnp5 is used with the current electron transport models for dosimetric applications.

Original languageEnglish
Pages (from-to)1335-1344
Number of pages10
JournalMedical Physics
Volume39
Issue number3
DOIs
Publication statusPublished - 1 Jan 2012
MoE publication typeA2 Review article in a scientific journal

Fingerprint

Electron Transport
Electrons
Gases
Photons
Particle Accelerators
Water
Argon
Methane
Artifacts
Air

Keywords

  • dosimetry
  • EGSNRC
  • MCNP
  • Monte Carlo
  • PENELOPE

Cite this

@article{cd1d03416b6840b184bb28b490239f1b,
title = "Accuracy of the electron transport in mcnp5 and its suitability for ionization chamber response simulations: A comparison with the egsnrc and penelope codes",
abstract = "Purpose: In this work, accuracy of the mcnp5 code in the electron transport calculations and its suitability for ionization chamber (IC) response simulations in photon beams are studied in comparison to egsnrc and penelope codes. Methods: The electron transport is studied by comparing the depth dose distributions in a water phantom subdivided into thin layers using incident energies (0.05, 0.1, 1, and 10 MeV) for the broad parallel electron beams. The IC response simulations are studied in water phantom in three dosimetric gas materials (air, argon, and methane based tissue equivalent gas) for photon beams (60Co source, 6 MV linear medical accelerator, and mono-energetic 2 MeV photon source). Two optional electron transport models of mcnp5 are evaluated: the ITS-based electron energy indexing (mcnp5ITS) and the new detailed electron energy-loss straggling logic (mcnp5new). The electron substep length (ESTEP parameter) dependency in mcnp5 is investigated as well. Results: For the electron beam studies, large discrepancies (>3) are observed between the mcnp5 dose distributions and the reference codes at 1 MeV and lower energies. The discrepancy is especially notable for 0.1 and 0.05 MeV electron beams. The boundary crossing artifacts, which are well known for the mcnp5ITS, are observed for the mcnp5new only at 0.1 and 0.05 MeV beam energies. If the excessive boundary crossing is eliminated by using single scoring cells, the mcnp5ITS provides dose distributions that agree better with the reference codes than mcnp5new. The mcnp5 dose estimates for the gas cavity agree within 1 with the reference codes, if the mcnp5ITS is applied or electron substep length is set adequately for the gas in the cavity using the mcnp5new. The mcnp5new results are found highly dependent on the chosen electron substep length and might lead up to 15 underestimation of the absorbed dose. Conclusions: Since the mcnp5 electron transport calculations are not accurate at all energies and in every medium by general clinical standards, caution is needed, if mcnp5 is used with the current electron transport models for dosimetric applications.",
keywords = "dosimetry, EGSNRC, MCNP, Monte Carlo, PENELOPE",
author = "Hanna Koivunoro and Teemu Siiskonen and Petri Kotiluoto and Iiro Auterinen and Eero Hippel{\"a}inen and Sauli Savolainen",
year = "2012",
month = "1",
day = "1",
doi = "10.1118/1.3685446",
language = "English",
volume = "39",
pages = "1335--1344",
journal = "Medical Physics",
issn = "0094-2405",
number = "3",

}

Accuracy of the electron transport in mcnp5 and its suitability for ionization chamber response simulations : A comparison with the egsnrc and penelope codes. / Koivunoro, Hanna (Corresponding Author); Siiskonen, Teemu; Kotiluoto, Petri; Auterinen, Iiro; Hippeläinen, Eero; Savolainen, Sauli.

In: Medical Physics, Vol. 39, No. 3, 01.01.2012, p. 1335-1344.

Research output: Contribution to journalReview ArticleScientificpeer-review

TY - JOUR

T1 - Accuracy of the electron transport in mcnp5 and its suitability for ionization chamber response simulations

T2 - A comparison with the egsnrc and penelope codes

AU - Koivunoro, Hanna

AU - Siiskonen, Teemu

AU - Kotiluoto, Petri

AU - Auterinen, Iiro

AU - Hippeläinen, Eero

AU - Savolainen, Sauli

PY - 2012/1/1

Y1 - 2012/1/1

N2 - Purpose: In this work, accuracy of the mcnp5 code in the electron transport calculations and its suitability for ionization chamber (IC) response simulations in photon beams are studied in comparison to egsnrc and penelope codes. Methods: The electron transport is studied by comparing the depth dose distributions in a water phantom subdivided into thin layers using incident energies (0.05, 0.1, 1, and 10 MeV) for the broad parallel electron beams. The IC response simulations are studied in water phantom in three dosimetric gas materials (air, argon, and methane based tissue equivalent gas) for photon beams (60Co source, 6 MV linear medical accelerator, and mono-energetic 2 MeV photon source). Two optional electron transport models of mcnp5 are evaluated: the ITS-based electron energy indexing (mcnp5ITS) and the new detailed electron energy-loss straggling logic (mcnp5new). The electron substep length (ESTEP parameter) dependency in mcnp5 is investigated as well. Results: For the electron beam studies, large discrepancies (>3) are observed between the mcnp5 dose distributions and the reference codes at 1 MeV and lower energies. The discrepancy is especially notable for 0.1 and 0.05 MeV electron beams. The boundary crossing artifacts, which are well known for the mcnp5ITS, are observed for the mcnp5new only at 0.1 and 0.05 MeV beam energies. If the excessive boundary crossing is eliminated by using single scoring cells, the mcnp5ITS provides dose distributions that agree better with the reference codes than mcnp5new. The mcnp5 dose estimates for the gas cavity agree within 1 with the reference codes, if the mcnp5ITS is applied or electron substep length is set adequately for the gas in the cavity using the mcnp5new. The mcnp5new results are found highly dependent on the chosen electron substep length and might lead up to 15 underestimation of the absorbed dose. Conclusions: Since the mcnp5 electron transport calculations are not accurate at all energies and in every medium by general clinical standards, caution is needed, if mcnp5 is used with the current electron transport models for dosimetric applications.

AB - Purpose: In this work, accuracy of the mcnp5 code in the electron transport calculations and its suitability for ionization chamber (IC) response simulations in photon beams are studied in comparison to egsnrc and penelope codes. Methods: The electron transport is studied by comparing the depth dose distributions in a water phantom subdivided into thin layers using incident energies (0.05, 0.1, 1, and 10 MeV) for the broad parallel electron beams. The IC response simulations are studied in water phantom in three dosimetric gas materials (air, argon, and methane based tissue equivalent gas) for photon beams (60Co source, 6 MV linear medical accelerator, and mono-energetic 2 MeV photon source). Two optional electron transport models of mcnp5 are evaluated: the ITS-based electron energy indexing (mcnp5ITS) and the new detailed electron energy-loss straggling logic (mcnp5new). The electron substep length (ESTEP parameter) dependency in mcnp5 is investigated as well. Results: For the electron beam studies, large discrepancies (>3) are observed between the mcnp5 dose distributions and the reference codes at 1 MeV and lower energies. The discrepancy is especially notable for 0.1 and 0.05 MeV electron beams. The boundary crossing artifacts, which are well known for the mcnp5ITS, are observed for the mcnp5new only at 0.1 and 0.05 MeV beam energies. If the excessive boundary crossing is eliminated by using single scoring cells, the mcnp5ITS provides dose distributions that agree better with the reference codes than mcnp5new. The mcnp5 dose estimates for the gas cavity agree within 1 with the reference codes, if the mcnp5ITS is applied or electron substep length is set adequately for the gas in the cavity using the mcnp5new. The mcnp5new results are found highly dependent on the chosen electron substep length and might lead up to 15 underestimation of the absorbed dose. Conclusions: Since the mcnp5 electron transport calculations are not accurate at all energies and in every medium by general clinical standards, caution is needed, if mcnp5 is used with the current electron transport models for dosimetric applications.

KW - dosimetry

KW - EGSNRC

KW - MCNP

KW - Monte Carlo

KW - PENELOPE

U2 - 10.1118/1.3685446

DO - 10.1118/1.3685446

M3 - Review Article

VL - 39

SP - 1335

EP - 1344

JO - Medical Physics

JF - Medical Physics

SN - 0094-2405

IS - 3

ER -