Node-positive left-sided breast cancer: does VMAT improve treatment plan quality with respect to IMRT?

Linksseitiges Mammakarzinom inklusive Lymphabfluss: Verbessert VMAT die Planqualität gegenüber IMRT?

Abstract

Purpose

The aim of the present work was to explore plan quality and dosimetric accuracy of intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) for lymph node-positive left-sided breast cancer.

Methods

VMAT and IMRT plans were generated with the Pinnacle3 V9.0 treatment planning system for 10 lymph node-positive left-sided breast cancer patients. VMAT plans were created using a single arc and IMRT was performed with 4 beams using 6, 10, and 15 MV photon energy, respectively. Plans were evaluated both manually and automatically using ArtiView™. Dosimetric plan verification was performed with a 2D ionization chamber array placed in a full scatter phantom.

Results

Photon energy had no significant influence on plan quality for both VMAT and IMRT. Large variability in low doses to the heart was found due to patient anatomy (range V5 Gy 26.5–95 %). Slightly more normal tissue dose was found for VMAT (e.g., VTissue30% = 22 %) than in IMRT (VTissue30% = 18 %). The manual and ArtiView™ plan evaluation coincided very accurately for most dose metrics (difference < 1 %). In VMAT, 96.7 % of detector points passed the 3 %/3 mm gamma criterion; marginally better accuracy was found in IMRT (98.3 %).

Conclusion

VMAT for node-positive left-sided breast cancer retains target homogeneity and coverage when compared to IMRT and allows maximum doses to organs at risk to be reduced. ArtiView™ enables fast and accurate plan evaluation.

Zusammenfassung

Ziel

Ziel der Studie war die Evaluierung der Planqualität und der dosimetrischen Genauigkeit von intensitätsmodulierter Strahlentherapie (IMRT) und volumetrisch modulierter Rotationstherapie (VMAT) für Patientinnen mit lymphknotenpositivem linksseitigem Mammakarzinom.

Methodik

VMAT- und IMRT-Pläne wurden mit dem Pinnacle3-Bestrahlungsplanungssystem (V9.0) für 10 Patientinnen mit lymphknotenpositivem linksseitigem Mammakarzinom generiert. VMAT-Pläne wurden mit einer Rotation, IMRT-Pläne mit 4 Feldern mit jeweils 6, 10 und 15 MV erstellt. Die Planauswertung erfolgte sowohl manuell als auch automatisch mittels ArtiView™. Die Planverifikation wurde mit einer 2-D-Ionisationskammer-Matrix in einem Festkörperphantom durchgeführt.

Ergebnisse

Die Photonenenergie hat keinen signifikanten Einfluss auf die VMAT- und IMRT-Planqualität. Es wurden aufgrund unterschiedlicher Anatomien große Variationen im Niedrigdosisvolumen des Herzens festgestellt (V5 Gy 26,5–95 %). In VMAT-Plänen wurde ein geringfügig höheres Niedrigdosisvolumen (z. B. VTissue30% = 22 %) als in IMRT-Plänen (VTissue30% = 18 %) ermittelt. Manuelle und automatische Auswertung stimmten für die meisten Parameter sehr genau überein (Abweichung < 1 %). VMAT-Pläne erreichten einen Gamma-Index < 1 (3 mm Abstand und 3 % Dosis) für 96,7 % der Detektorpunkte, geringfügig bessere Präzision erzielten die IMRT-Pläne mit 98,3 %.

Schlussfolgerung

VMAT liefert eine ähnliche Dosishomogenität und -abdeckung der Zielvolumina wie IMRT und ermöglicht eine Reduktion der Risikoorgan- und Maximaldosen. Mittels ArtiView™ können Bestrahlungspläne schnell und genau evaluiert werden.

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Conflict of interest statement

On behalf of all authors, the corresponding author states that there are no conflicts of interest.

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Correspondence to M. Pasler.

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Pasler, M., Georg, D., Bartelt, S. et al. Node-positive left-sided breast cancer: does VMAT improve treatment plan quality with respect to IMRT?. Strahlenther Onkol 189, 380–386 (2013). https://doi.org/10.1007/s00066-012-0281-2

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Keywords

  • Volumetric modulated arc therapy
  • Intensity-modulated radiotherapy
  • Breast neoplasms
  • Lymph nodes

Schlüsselwörter

  • Volumenmodulierte Arc-Therapie
  • Intensitätsmodulierte Strahlentherapie
  • Brustneoplasien
  • Lymphknoten