Hippocampus-sparing whole-brain radiotherapy: Dosimetric comparison between non-coplanar and coplanar planning

Li Jhen Chen, Ming Hsien Li, Hao Wen Cheng, Chun Yuan Kuo, Wei Lun Sun, Jo Ting Tsai

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Background: To compare non-coplanar and coplanar volumetric-modulated arc therapy (VMAT) for hippocampal avoidance during whole-brain radiotherapy (HA-WBRT) using the Elekta Synergy and Pinnacle treatment planning system (TPS) according to the suggested criteria of the radiation therapy oncology group (RTOG) 0933 trial. Methods: Nine patients who underwent WBRT were selected for this retrospective study. The hippocampus was contoured, and the hippocampal avoidance regions were created using a 5-mm volumetric expansion around the hippocampus for each patient. Non-coplanar and coplanar VMAT plans were generated for each patient. All treatment plans were generated for a prescribed dose (PD) of 30 Gy in 10 fractions. Results: The average volumes of the hippocampus and hippocampal avoidance region were 2.8±0.38 and 27±2.48 cm3, respectively. For coplanar and non-coplanar VMAT plans, the average D100% of the hippocampus was 8.60 Gy (range, 8.30-8.80 Gy) and 8.56 Gy (range, 8.30-8.90 Gy), respectively, and the average Dmax of the hippocampus was 15.29 Gy (range, 14.35-15.92 Gy) and 14.99 Gy (range, 13.80-15.83 Gy), respectively. The non-coplanar VMAT plans showed a significantly lower average Dmax of the lens (4.23 Gy) than did the coplanar VMAT plans (4.77 Gy). The average gamma passing rate for non-coplanar and coplanar VMAT quality assurance (QA) with criteria of 3%/3 mm were 95.4%±2.6% and 95.6%±1.6%, indicating good agreement between the calculated plan dose and the measured dose. Conclusions: We showed that the suggested criteria of the RTOG 0933 trial for the hippocampal dose can be achieved in both coplanar and non-planar VMAT plans. We performed VMAT QA for each treatment plan to verify the clinical feasibility.

Original languageEnglish
Article number1
JournalTherapeutic Radiology and Oncology
Issue numberMarch
Publication statusPublished - Mar 2021


  • Hippocampus
  • Radiation therapy
  • RTOG 0933
  • Volumetric-modulated arc therapy (VMAT)
  • Whole brain

ASJC Scopus subject areas

  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Oncology(nursing)
  • Radiological and Ultrasound Technology


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