Exploratory study of the association of volumetric modulated arc therapy (VMAT) plan robustness with local failure in head and neck cancer

Wei Liu, Samir H. Patel, Daniel P. Harrington, Yanle Hu, Xiaoning Ding, Jiajian Shen, Michele Y. Halyard, Steven E. Schild, William W. Wong, Gary E. Ezzell, Martin Bues

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

This work is to show which is more relevant to cause local failures (LFs) due to patient setup uncertainty between the planning target volume (PTV) underdosage and the potential target underdosage subject to patient setup uncertainties in head and neck (H&N) cancer treated with volumetric-modulated arc therapy (VMAT). Thirteen LFs in 10 H&N patients treated by VMAT were analyzed. Measures have been taken to minimize the chances of insufficient target delineation for these patients and the patients were clinically determined to have LF based on the PET/CT scan results by an experienced radiologist and then reviewed by a second experienced radiation oncologist. Two methods were used to identify the possible locations of LF due to underdosage: (a) examining the standard VMAT plan, in which the underdosed volume in the nominal dose distribution (UVN) was generated by subtracting the volumes receiving the prescription doses from PTVs, and (b) plan robustness analysis, in which in addition to the nominal dose distribution, six perturbed dose distributions were created by translating the CT iso-center in three cardinal directions by the PTV margin. The coldest dose distribution was represented by the minimum of the seven doses in each voxel. The underdosed volume in the coldest dose distribution (UVC) was generated by subtracting the volumes receiving the prescription doses in the coldest dose distribution from the volumes receiving the prescription doses in the nominal dose distribution. UVN and UVC were subsequently examined for spatial association with the locations of LF. The association was tested using the binominal distribution and the Fisher's exact test of independence. We found that of 13 LFs, 11 were associated with UVCs (P = 0.011), while three were associated with UVNs (P = 0.99). We concluded that the possible target underdosage due to patient setup uncertainties appeared to be a more relevant factor associated with LF in VMAT for H&N cancer than the compromised PTV coverage at least for the patients included in this study.

Original languageEnglish (US)
Pages (from-to)76-83
Number of pages8
JournalJournal of Applied Clinical Medical Physics
Volume18
Issue number4
DOIs
StatePublished - Jul 1 2017

Fingerprint

Intensity-Modulated Radiotherapy
Head and Neck Neoplasms
therapy
arcs
cancer
Planning
dosage
Computerized tomography
Uncertainty
Prescriptions
planning
Radiation
Neoplasms
Neck
translating
delineation
Head
margins

Keywords

  • Head and neck cancer
  • Local failure
  • Plan robustness
  • Uncertainty
  • VMAT

ASJC Scopus subject areas

  • Radiation
  • Instrumentation
  • Radiology Nuclear Medicine and imaging

Cite this

Exploratory study of the association of volumetric modulated arc therapy (VMAT) plan robustness with local failure in head and neck cancer. / Liu, Wei; Patel, Samir H.; Harrington, Daniel P.; Hu, Yanle; Ding, Xiaoning; Shen, Jiajian; Halyard, Michele Y.; Schild, Steven E.; Wong, William W.; Ezzell, Gary E.; Bues, Martin.

In: Journal of Applied Clinical Medical Physics, Vol. 18, No. 4, 01.07.2017, p. 76-83.

Research output: Contribution to journalArticle

Liu, W, Patel, SH, Harrington, DP, Hu, Y, Ding, X, Shen, J, Halyard, MY, Schild, SE, Wong, WW, Ezzell, GE & Bues, M 2017, 'Exploratory study of the association of volumetric modulated arc therapy (VMAT) plan robustness with local failure in head and neck cancer', Journal of Applied Clinical Medical Physics, vol. 18, no. 4, pp. 76-83. https://doi.org/10.1002/acm2.12099
Liu, Wei ; Patel, Samir H. ; Harrington, Daniel P. ; Hu, Yanle ; Ding, Xiaoning ; Shen, Jiajian ; Halyard, Michele Y. ; Schild, Steven E. ; Wong, William W. ; Ezzell, Gary E. ; Bues, Martin. / Exploratory study of the association of volumetric modulated arc therapy (VMAT) plan robustness with local failure in head and neck cancer. In: Journal of Applied Clinical Medical Physics. 2017 ; Vol. 18, No. 4. pp. 76-83.
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