Confidence limit variation for a single IMRT system following the TG119 protocol

J. D. Gordon, S. P. Krafft, S. Jang, L. Smith-Raymond, M. Y. Stevie, Russell J Hamilton

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Purpose: To evaluate the robustness of TG119-based quality assurance metrics for an IMRT system. Methods: Four planners constructed treatment plans for the five IMRT test cases described in TG119. All plans were delivered to a 30 cm×30 cm×15 cm solid water phantom in one treatment session in order to minimize session-dependent variation from phantom setup, film quality, machine performance, etc. Composite measurements utilized film and an ionization chamber. Per-field measurements were collected using a diode array device at an effective depth of 5 cm. All data collected were analyzed using the TG119 specifications to determine the confidence limit values for each planner separately and then compared. Results: The mean variance of ion chamber measurements for each planner was within 1.7% of the planned dose. The resulting confidence limits were 3.13%, 1.98%, 3.65%, and 4.39%. Confidence limit values determined by composite film analysis were 8.06%, 13.4%, 9.30%, and 16.5%. Confidence limits from per-field measurements were 1.55%, 0.00%, 0.00%, and 2.89%. Conclusions: For a single IMRT system, the accuracy assessment provided by TG119-based quality assurance metrics showed significant variations in the confidence limits between planners across all composite and per-field evaluations. This observed variation is likely due to the different levels of modulation between each planner's set of plans. Performing the TG119 evaluation using plans produced by a single planner may not provide an adequate estimation of IMRT system accuracy.

Original languageEnglish (US)
Pages (from-to)1641-1648
Number of pages8
JournalMedical Physics
Volume38
Issue number3
DOIs
StatePublished - Mar 2011

Fingerprint

Metric System
Ions
Equipment and Supplies
Water

Keywords

  • commissioning
  • IMRT
  • quality assurance

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging

Cite this

Gordon, J. D., Krafft, S. P., Jang, S., Smith-Raymond, L., Stevie, M. Y., & Hamilton, R. J. (2011). Confidence limit variation for a single IMRT system following the TG119 protocol. Medical Physics, 38(3), 1641-1648. https://doi.org/10.1118/1.3555298

Confidence limit variation for a single IMRT system following the TG119 protocol. / Gordon, J. D.; Krafft, S. P.; Jang, S.; Smith-Raymond, L.; Stevie, M. Y.; Hamilton, Russell J.

In: Medical Physics, Vol. 38, No. 3, 03.2011, p. 1641-1648.

Research output: Contribution to journalArticle

Gordon, JD, Krafft, SP, Jang, S, Smith-Raymond, L, Stevie, MY & Hamilton, RJ 2011, 'Confidence limit variation for a single IMRT system following the TG119 protocol', Medical Physics, vol. 38, no. 3, pp. 1641-1648. https://doi.org/10.1118/1.3555298
Gordon, J. D. ; Krafft, S. P. ; Jang, S. ; Smith-Raymond, L. ; Stevie, M. Y. ; Hamilton, Russell J. / Confidence limit variation for a single IMRT system following the TG119 protocol. In: Medical Physics. 2011 ; Vol. 38, No. 3. pp. 1641-1648.
@article{ba8813f336fa4b0f8090550643eab7c8,
title = "Confidence limit variation for a single IMRT system following the TG119 protocol",
abstract = "Purpose: To evaluate the robustness of TG119-based quality assurance metrics for an IMRT system. Methods: Four planners constructed treatment plans for the five IMRT test cases described in TG119. All plans were delivered to a 30 cm×30 cm×15 cm solid water phantom in one treatment session in order to minimize session-dependent variation from phantom setup, film quality, machine performance, etc. Composite measurements utilized film and an ionization chamber. Per-field measurements were collected using a diode array device at an effective depth of 5 cm. All data collected were analyzed using the TG119 specifications to determine the confidence limit values for each planner separately and then compared. Results: The mean variance of ion chamber measurements for each planner was within 1.7{\%} of the planned dose. The resulting confidence limits were 3.13{\%}, 1.98{\%}, 3.65{\%}, and 4.39{\%}. Confidence limit values determined by composite film analysis were 8.06{\%}, 13.4{\%}, 9.30{\%}, and 16.5{\%}. Confidence limits from per-field measurements were 1.55{\%}, 0.00{\%}, 0.00{\%}, and 2.89{\%}. Conclusions: For a single IMRT system, the accuracy assessment provided by TG119-based quality assurance metrics showed significant variations in the confidence limits between planners across all composite and per-field evaluations. This observed variation is likely due to the different levels of modulation between each planner's set of plans. Performing the TG119 evaluation using plans produced by a single planner may not provide an adequate estimation of IMRT system accuracy.",
keywords = "commissioning, IMRT, quality assurance",
author = "Gordon, {J. D.} and Krafft, {S. P.} and S. Jang and L. Smith-Raymond and Stevie, {M. Y.} and Hamilton, {Russell J}",
year = "2011",
month = "3",
doi = "10.1118/1.3555298",
language = "English (US)",
volume = "38",
pages = "1641--1648",
journal = "Medical Physics",
issn = "0094-2405",
publisher = "AAPM - American Association of Physicists in Medicine",
number = "3",

}

TY - JOUR

T1 - Confidence limit variation for a single IMRT system following the TG119 protocol

AU - Gordon, J. D.

AU - Krafft, S. P.

AU - Jang, S.

AU - Smith-Raymond, L.

AU - Stevie, M. Y.

AU - Hamilton, Russell J

PY - 2011/3

Y1 - 2011/3

N2 - Purpose: To evaluate the robustness of TG119-based quality assurance metrics for an IMRT system. Methods: Four planners constructed treatment plans for the five IMRT test cases described in TG119. All plans were delivered to a 30 cm×30 cm×15 cm solid water phantom in one treatment session in order to minimize session-dependent variation from phantom setup, film quality, machine performance, etc. Composite measurements utilized film and an ionization chamber. Per-field measurements were collected using a diode array device at an effective depth of 5 cm. All data collected were analyzed using the TG119 specifications to determine the confidence limit values for each planner separately and then compared. Results: The mean variance of ion chamber measurements for each planner was within 1.7% of the planned dose. The resulting confidence limits were 3.13%, 1.98%, 3.65%, and 4.39%. Confidence limit values determined by composite film analysis were 8.06%, 13.4%, 9.30%, and 16.5%. Confidence limits from per-field measurements were 1.55%, 0.00%, 0.00%, and 2.89%. Conclusions: For a single IMRT system, the accuracy assessment provided by TG119-based quality assurance metrics showed significant variations in the confidence limits between planners across all composite and per-field evaluations. This observed variation is likely due to the different levels of modulation between each planner's set of plans. Performing the TG119 evaluation using plans produced by a single planner may not provide an adequate estimation of IMRT system accuracy.

AB - Purpose: To evaluate the robustness of TG119-based quality assurance metrics for an IMRT system. Methods: Four planners constructed treatment plans for the five IMRT test cases described in TG119. All plans were delivered to a 30 cm×30 cm×15 cm solid water phantom in one treatment session in order to minimize session-dependent variation from phantom setup, film quality, machine performance, etc. Composite measurements utilized film and an ionization chamber. Per-field measurements were collected using a diode array device at an effective depth of 5 cm. All data collected were analyzed using the TG119 specifications to determine the confidence limit values for each planner separately and then compared. Results: The mean variance of ion chamber measurements for each planner was within 1.7% of the planned dose. The resulting confidence limits were 3.13%, 1.98%, 3.65%, and 4.39%. Confidence limit values determined by composite film analysis were 8.06%, 13.4%, 9.30%, and 16.5%. Confidence limits from per-field measurements were 1.55%, 0.00%, 0.00%, and 2.89%. Conclusions: For a single IMRT system, the accuracy assessment provided by TG119-based quality assurance metrics showed significant variations in the confidence limits between planners across all composite and per-field evaluations. This observed variation is likely due to the different levels of modulation between each planner's set of plans. Performing the TG119 evaluation using plans produced by a single planner may not provide an adequate estimation of IMRT system accuracy.

KW - commissioning

KW - IMRT

KW - quality assurance

UR - http://www.scopus.com/inward/record.url?scp=79952139734&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=79952139734&partnerID=8YFLogxK

U2 - 10.1118/1.3555298

DO - 10.1118/1.3555298

M3 - Article

C2 - 21520877

AN - SCOPUS:79952139734

VL - 38

SP - 1641

EP - 1648

JO - Medical Physics

JF - Medical Physics

SN - 0094-2405

IS - 3

ER -