WE‐G‐BRCD‐05: Evaluation of Localization Errors for CSA Delivery Using VMAT

P. Myers, Sotirios Stathakis, C. Esquivel, A. Gutierrez, P. Mavroidis, Nikos Papanikolaou

Research output: Contribution to journalArticle

Abstract

Purpose: To dosimetrically evaluate the effects of improper patient positioning in the junction area of a VMAT cranio‐spinal axis irradiation technique consisting of one superior and one inferior arc. Methods: Five (n=5) cranio‐spinal axis irradiation patients were planned with 2 arcs: one superior and one inferior. The plans were then recalculated with inferior isocenter shifted, in order to mimic patient setup errors, eight times: lmm, 2mm, 5mm, and 10mm superiorly, and 1mm, 2mm, 5mm, and 10mm inferiorly. Plans were then compared to the original, non‐shifted arc plan based on target metrics of conformity number and homogeneity index, as well as several normal structure mean doses. Results: Percent differences were calculated in order to compare each of the eight shifted plans to the original arc plan without shifts, which would be the ideal setup of patient without error. The conformity number was on average 0.87%, 2.74%, 5.75%, and 9.10% lower for the 1mm, 2mm, 5mm, and 10mm inferiorly‐ shifted plans and 0.41%, 0.82%, 2.75%, and 5.99% lower for the respective superiorly‐shifted plans. The homogeneity indices were, averaged among the five patients, 0.03%, 0.26%, 0.97%, and 2.84% for the inferior shifts and 0.23%, 1.17%, 6.31%, and 15.29% worse, or less homogenous for the superior shifts. Overall the mean doses to the organs at risk were less than 2% different for the 1mm, 2mm, and 5mm shifted plans. The 10mm shifted plans, however, showed percent differences from original plan of up to 5.6% on average. Conclusions: Setup errors when shifting isocenters should be minimized in order to provide the patient with the best treatment possible. Errors of 1 to 2mm can negatively affect patient treatment, most notably in the arc junction area, but are not as problematic as larger errors of 5 to 10mm.

Original languageEnglish (US)
Pages (from-to)3965
Number of pages1
JournalMedical Physics
Volume39
Issue number6
DOIs
StatePublished - 2012

Fingerprint

Craniospinal Irradiation
Organs at Risk
Patient Positioning
Therapeutics

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging

Cite this

WE‐G‐BRCD‐05 : Evaluation of Localization Errors for CSA Delivery Using VMAT. / Myers, P.; Stathakis, Sotirios; Esquivel, C.; Gutierrez, A.; Mavroidis, P.; Papanikolaou, Nikos.

In: Medical Physics, Vol. 39, No. 6, 2012, p. 3965.

Research output: Contribution to journalArticle

Myers, P, Stathakis, S, Esquivel, C, Gutierrez, A, Mavroidis, P & Papanikolaou, N 2012, 'WE‐G‐BRCD‐05: Evaluation of Localization Errors for CSA Delivery Using VMAT', Medical Physics, vol. 39, no. 6, pp. 3965. https://doi.org/10.1118/1.4736182
Myers, P. ; Stathakis, Sotirios ; Esquivel, C. ; Gutierrez, A. ; Mavroidis, P. ; Papanikolaou, Nikos. / WE‐G‐BRCD‐05 : Evaluation of Localization Errors for CSA Delivery Using VMAT. In: Medical Physics. 2012 ; Vol. 39, No. 6. pp. 3965.
@article{128c93d59f83461ea4a0725b5bf7200a,
title = "WE‐G‐BRCD‐05: Evaluation of Localization Errors for CSA Delivery Using VMAT",
abstract = "Purpose: To dosimetrically evaluate the effects of improper patient positioning in the junction area of a VMAT cranio‐spinal axis irradiation technique consisting of one superior and one inferior arc. Methods: Five (n=5) cranio‐spinal axis irradiation patients were planned with 2 arcs: one superior and one inferior. The plans were then recalculated with inferior isocenter shifted, in order to mimic patient setup errors, eight times: lmm, 2mm, 5mm, and 10mm superiorly, and 1mm, 2mm, 5mm, and 10mm inferiorly. Plans were then compared to the original, non‐shifted arc plan based on target metrics of conformity number and homogeneity index, as well as several normal structure mean doses. Results: Percent differences were calculated in order to compare each of the eight shifted plans to the original arc plan without shifts, which would be the ideal setup of patient without error. The conformity number was on average 0.87{\%}, 2.74{\%}, 5.75{\%}, and 9.10{\%} lower for the 1mm, 2mm, 5mm, and 10mm inferiorly‐ shifted plans and 0.41{\%}, 0.82{\%}, 2.75{\%}, and 5.99{\%} lower for the respective superiorly‐shifted plans. The homogeneity indices were, averaged among the five patients, 0.03{\%}, 0.26{\%}, 0.97{\%}, and 2.84{\%} for the inferior shifts and 0.23{\%}, 1.17{\%}, 6.31{\%}, and 15.29{\%} worse, or less homogenous for the superior shifts. Overall the mean doses to the organs at risk were less than 2{\%} different for the 1mm, 2mm, and 5mm shifted plans. The 10mm shifted plans, however, showed percent differences from original plan of up to 5.6{\%} on average. Conclusions: Setup errors when shifting isocenters should be minimized in order to provide the patient with the best treatment possible. Errors of 1 to 2mm can negatively affect patient treatment, most notably in the arc junction area, but are not as problematic as larger errors of 5 to 10mm.",
author = "P. Myers and Sotirios Stathakis and C. Esquivel and A. Gutierrez and P. Mavroidis and Nikos Papanikolaou",
year = "2012",
doi = "10.1118/1.4736182",
language = "English (US)",
volume = "39",
pages = "3965",
journal = "Medical Physics",
issn = "0094-2405",
publisher = "AAPM - American Association of Physicists in Medicine",
number = "6",

}

TY - JOUR

T1 - WE‐G‐BRCD‐05

T2 - Evaluation of Localization Errors for CSA Delivery Using VMAT

AU - Myers, P.

AU - Stathakis, Sotirios

AU - Esquivel, C.

AU - Gutierrez, A.

AU - Mavroidis, P.

AU - Papanikolaou, Nikos

PY - 2012

Y1 - 2012

N2 - Purpose: To dosimetrically evaluate the effects of improper patient positioning in the junction area of a VMAT cranio‐spinal axis irradiation technique consisting of one superior and one inferior arc. Methods: Five (n=5) cranio‐spinal axis irradiation patients were planned with 2 arcs: one superior and one inferior. The plans were then recalculated with inferior isocenter shifted, in order to mimic patient setup errors, eight times: lmm, 2mm, 5mm, and 10mm superiorly, and 1mm, 2mm, 5mm, and 10mm inferiorly. Plans were then compared to the original, non‐shifted arc plan based on target metrics of conformity number and homogeneity index, as well as several normal structure mean doses. Results: Percent differences were calculated in order to compare each of the eight shifted plans to the original arc plan without shifts, which would be the ideal setup of patient without error. The conformity number was on average 0.87%, 2.74%, 5.75%, and 9.10% lower for the 1mm, 2mm, 5mm, and 10mm inferiorly‐ shifted plans and 0.41%, 0.82%, 2.75%, and 5.99% lower for the respective superiorly‐shifted plans. The homogeneity indices were, averaged among the five patients, 0.03%, 0.26%, 0.97%, and 2.84% for the inferior shifts and 0.23%, 1.17%, 6.31%, and 15.29% worse, or less homogenous for the superior shifts. Overall the mean doses to the organs at risk were less than 2% different for the 1mm, 2mm, and 5mm shifted plans. The 10mm shifted plans, however, showed percent differences from original plan of up to 5.6% on average. Conclusions: Setup errors when shifting isocenters should be minimized in order to provide the patient with the best treatment possible. Errors of 1 to 2mm can negatively affect patient treatment, most notably in the arc junction area, but are not as problematic as larger errors of 5 to 10mm.

AB - Purpose: To dosimetrically evaluate the effects of improper patient positioning in the junction area of a VMAT cranio‐spinal axis irradiation technique consisting of one superior and one inferior arc. Methods: Five (n=5) cranio‐spinal axis irradiation patients were planned with 2 arcs: one superior and one inferior. The plans were then recalculated with inferior isocenter shifted, in order to mimic patient setup errors, eight times: lmm, 2mm, 5mm, and 10mm superiorly, and 1mm, 2mm, 5mm, and 10mm inferiorly. Plans were then compared to the original, non‐shifted arc plan based on target metrics of conformity number and homogeneity index, as well as several normal structure mean doses. Results: Percent differences were calculated in order to compare each of the eight shifted plans to the original arc plan without shifts, which would be the ideal setup of patient without error. The conformity number was on average 0.87%, 2.74%, 5.75%, and 9.10% lower for the 1mm, 2mm, 5mm, and 10mm inferiorly‐ shifted plans and 0.41%, 0.82%, 2.75%, and 5.99% lower for the respective superiorly‐shifted plans. The homogeneity indices were, averaged among the five patients, 0.03%, 0.26%, 0.97%, and 2.84% for the inferior shifts and 0.23%, 1.17%, 6.31%, and 15.29% worse, or less homogenous for the superior shifts. Overall the mean doses to the organs at risk were less than 2% different for the 1mm, 2mm, and 5mm shifted plans. The 10mm shifted plans, however, showed percent differences from original plan of up to 5.6% on average. Conclusions: Setup errors when shifting isocenters should be minimized in order to provide the patient with the best treatment possible. Errors of 1 to 2mm can negatively affect patient treatment, most notably in the arc junction area, but are not as problematic as larger errors of 5 to 10mm.

UR - http://www.scopus.com/inward/record.url?scp=85024784966&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85024784966&partnerID=8YFLogxK

U2 - 10.1118/1.4736182

DO - 10.1118/1.4736182

M3 - Article

AN - SCOPUS:85024784966

VL - 39

SP - 3965

JO - Medical Physics

JF - Medical Physics

SN - 0094-2405

IS - 6

ER -