SU‐E‐T‐267: Construction and Evaluation of a Neutron Wall to Shield a 15 MV Linac in a Low‐Energy Vault

M. Speiser, F. Hager, R. Foster, T. Solberg

Research output: Contribution to journalArticle

Abstract

Purpose: To design and quantify the shielding efficacy of an inner Borated Polyethylene (BPE)wall for a 15 MV linac in a low energy vault. Methods: A Varian TrueBeam linac with a maximum photon energy of 15 MV was installed in asmaller, preexisting vault. This vault originally housed a low‐energy machine and did not havesufficient maze length recommended for neutron attenuation. Effective dose rate calculationswere performed using the Modified Kersey's Method as detailed in NCRP Report No. 151 andfound to be unacceptably high. An initial survey following the machine installation confirmedthese calculations. Rather than restrict the linac beam energy to 10 MV, BPE was investigatedas a neutron moderating addition. An inner wall and door were planned and constructed using4′×8′×1″ thick 5% BPE sheets. The resulting door and wall had 2″ of BPE; conduits and ductwork were also redesigned and shielded. A survey was conducted following construction of thewall. Results: The vault modification reduced the expected effective dose at the vault door from 36.23to 0.010 mSv/week. Conclusion: As specific guidelines for vault modification are lacking, this project quantitativelydemonstrates the potential use of BPE for vault modification. Such modifications may provide alow‐cost shielding solution to allow for the use of high energy modes in smaller treatment vaults.

Original languageEnglish (US)
Pages (from-to)3764-3765
Number of pages2
JournalMedical Physics
Volume39
Issue number6
DOIs
StatePublished - 2012

Fingerprint

Neutrons
Polyethylene
Photons
Guidelines
Surveys and Questionnaires

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging

Cite this

SU‐E‐T‐267 : Construction and Evaluation of a Neutron Wall to Shield a 15 MV Linac in a Low‐Energy Vault. / Speiser, M.; Hager, F.; Foster, R.; Solberg, T.

In: Medical Physics, Vol. 39, No. 6, 2012, p. 3764-3765.

Research output: Contribution to journalArticle

Speiser, M. ; Hager, F. ; Foster, R. ; Solberg, T. / SU‐E‐T‐267 : Construction and Evaluation of a Neutron Wall to Shield a 15 MV Linac in a Low‐Energy Vault. In: Medical Physics. 2012 ; Vol. 39, No. 6. pp. 3764-3765.
@article{4c0331aedc4e454aa18098a28022087a,
title = "SU‐E‐T‐267: Construction and Evaluation of a Neutron Wall to Shield a 15 MV Linac in a Low‐Energy Vault",
abstract = "Purpose: To design and quantify the shielding efficacy of an inner Borated Polyethylene (BPE)wall for a 15 MV linac in a low energy vault. Methods: A Varian TrueBeam linac with a maximum photon energy of 15 MV was installed in asmaller, preexisting vault. This vault originally housed a low‐energy machine and did not havesufficient maze length recommended for neutron attenuation. Effective dose rate calculationswere performed using the Modified Kersey's Method as detailed in NCRP Report No. 151 andfound to be unacceptably high. An initial survey following the machine installation confirmedthese calculations. Rather than restrict the linac beam energy to 10 MV, BPE was investigatedas a neutron moderating addition. An inner wall and door were planned and constructed using4′×8′×1″ thick 5{\%} BPE sheets. The resulting door and wall had 2″ of BPE; conduits and ductwork were also redesigned and shielded. A survey was conducted following construction of thewall. Results: The vault modification reduced the expected effective dose at the vault door from 36.23to 0.010 mSv/week. Conclusion: As specific guidelines for vault modification are lacking, this project quantitativelydemonstrates the potential use of BPE for vault modification. Such modifications may provide alow‐cost shielding solution to allow for the use of high energy modes in smaller treatment vaults.",
author = "M. Speiser and F. Hager and R. Foster and T. Solberg",
year = "2012",
doi = "10.1118/1.4735334",
language = "English (US)",
volume = "39",
pages = "3764--3765",
journal = "Medical Physics",
issn = "0094-2405",
publisher = "AAPM - American Association of Physicists in Medicine",
number = "6",

}

TY - JOUR

T1 - SU‐E‐T‐267

T2 - Construction and Evaluation of a Neutron Wall to Shield a 15 MV Linac in a Low‐Energy Vault

AU - Speiser, M.

AU - Hager, F.

AU - Foster, R.

AU - Solberg, T.

PY - 2012

Y1 - 2012

N2 - Purpose: To design and quantify the shielding efficacy of an inner Borated Polyethylene (BPE)wall for a 15 MV linac in a low energy vault. Methods: A Varian TrueBeam linac with a maximum photon energy of 15 MV was installed in asmaller, preexisting vault. This vault originally housed a low‐energy machine and did not havesufficient maze length recommended for neutron attenuation. Effective dose rate calculationswere performed using the Modified Kersey's Method as detailed in NCRP Report No. 151 andfound to be unacceptably high. An initial survey following the machine installation confirmedthese calculations. Rather than restrict the linac beam energy to 10 MV, BPE was investigatedas a neutron moderating addition. An inner wall and door were planned and constructed using4′×8′×1″ thick 5% BPE sheets. The resulting door and wall had 2″ of BPE; conduits and ductwork were also redesigned and shielded. A survey was conducted following construction of thewall. Results: The vault modification reduced the expected effective dose at the vault door from 36.23to 0.010 mSv/week. Conclusion: As specific guidelines for vault modification are lacking, this project quantitativelydemonstrates the potential use of BPE for vault modification. Such modifications may provide alow‐cost shielding solution to allow for the use of high energy modes in smaller treatment vaults.

AB - Purpose: To design and quantify the shielding efficacy of an inner Borated Polyethylene (BPE)wall for a 15 MV linac in a low energy vault. Methods: A Varian TrueBeam linac with a maximum photon energy of 15 MV was installed in asmaller, preexisting vault. This vault originally housed a low‐energy machine and did not havesufficient maze length recommended for neutron attenuation. Effective dose rate calculationswere performed using the Modified Kersey's Method as detailed in NCRP Report No. 151 andfound to be unacceptably high. An initial survey following the machine installation confirmedthese calculations. Rather than restrict the linac beam energy to 10 MV, BPE was investigatedas a neutron moderating addition. An inner wall and door were planned and constructed using4′×8′×1″ thick 5% BPE sheets. The resulting door and wall had 2″ of BPE; conduits and ductwork were also redesigned and shielded. A survey was conducted following construction of thewall. Results: The vault modification reduced the expected effective dose at the vault door from 36.23to 0.010 mSv/week. Conclusion: As specific guidelines for vault modification are lacking, this project quantitativelydemonstrates the potential use of BPE for vault modification. Such modifications may provide alow‐cost shielding solution to allow for the use of high energy modes in smaller treatment vaults.

UR - http://www.scopus.com/inward/record.url?scp=85024814929&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85024814929&partnerID=8YFLogxK

U2 - 10.1118/1.4735334

DO - 10.1118/1.4735334

M3 - Article

C2 - 28517270

AN - SCOPUS:85024814929

VL - 39

SP - 3764

EP - 3765

JO - Medical Physics

JF - Medical Physics

SN - 0094-2405

IS - 6

ER -