Sparing of normal tissues with volumetric arc radiation therapy for glioblastoma: Single institution clinical experience

Tina Marie Briere, Mary Frances McAleer, Lawrence B. Levy, James N. Yang

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

Background: Patients with glioblastoma multiforme (GBM) require radiotherapy as part of definitive management. Our institution has adopted the use of volumetric arc therapy (VMAT) due to superior sparing of the adjacent organs at risk (OARs) compared to intensity modulated radiation therapy (IMRT). Here we report our clinical experience by analyzing target coverage and sparing of OARs for 90 clinical treatment plans. Methods: VMAT and IMRT patient cohorts comprising 45 patients each were included in this study. For all patients, the planning target volume (PTV) received 50Gy in 30 fractions, and the simultaneous integrated boost PTV received 60Gy. The characteristics of the two patient cohorts were examined for similarity. The doses to target volumes and OARs, including brain, brainstem, hippocampi, optic nerves, eyes, and cochleae were then compared using statistical analysis. Target coverage and normal tissue sparing for six patients with both clinical IMRT and VMAT plans were analyzed. Results: PTV coverage of at least 95% was achieved for all plans, and the median mean dose to the boost PTV differed by only 0.1Gy between the IMRT and VMAT plans. Superior sparing of the brainstem was found with VMAT, with a median difference in mean dose being 9.4Gy. The ipsilateral cochlear mean dose was lower by 19.7Gy, and the contralateral cochlea was lower by 9.5Gy. The total treatment time was reduced by 5min. The difference in the ipsilateral hippocampal D100% was 12Gy, though this is not statistically significant (P=0.03). Conclusions: VMAT for GBM patients can provide similar target coverage, superior sparing of the brainstem and cochleae, and be delivered in a shorter period of time compared with IMRT. The shorter treatment time may improve clinical efficiency and the quality of the treatment experience. Based on institutional clinical experience, use of VMAT for the treatment of GBMs appears to offer no inferiority in comparison to IMRT and may offer distinct advantages, especially for patients who may require re-irradiation.

Original languageEnglish (US)
Article number79
JournalRadiation Oncology
Volume12
Issue number1
DOIs
StatePublished - May 2 2017

Keywords

  • Glioblastoma multiforme
  • IMRT
  • Radiation therapy
  • VMAT

ASJC Scopus subject areas

  • Oncology
  • Radiology Nuclear Medicine and imaging

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