Hippocampal-sparing whole-brain radiotherapy: a "how-to" technique using helical tomotherapy and linear accelerator-based intensity-modulated radiotherapy

Int J Radiat Oncol Biol Phys. 2010 Nov 15;78(4):1244-52. doi: 10.1016/j.ijrobp.2010.01.039.


Purpose: Sparing the hippocampus during cranial irradiation poses important technical challenges with respect to contouring and treatment planning. Herein we report our preliminary experience with whole-brain radiotherapy using hippocampal sparing for patients with brain metastases.

Methods and materials: Five anonymous patients previously treated with whole-brain radiotherapy with hippocampal sparing were reviewed. The hippocampus was contoured, and hippocampal avoidance regions were created using a 5-mm volumetric expansion around the hippocampus. Helical tomotherapy and linear accelerator (LINAC)-based intensity-modulated radiotherapy (IMRT) treatment plans were generated for a prescription dose of 30 Gy in 10 fractions.

Results: On average, the hippocampal avoidance volume was 3.3 cm(3), occupying 2.1% of the whole-brain planned target volume. Helical tomotherapy spared the hippocampus, with a median dose of 5.5 Gy and maximum dose of 12.8 Gy. LINAC-based IMRT spared the hippocampus, with a median dose of 7.8 Gy and maximum dose of 15.3 Gy. On a per-fraction basis, mean dose to the hippocampus (normalized to 2-Gy fractions) was reduced by 87% to 0.49 Gy(2) using helical tomotherapy and by 81% to 0.73 Gy(2) using LINAC-based IMRT. Target coverage and homogeneity was acceptable with both IMRT modalities, with differences largely attributed to more rapid dose fall-off with helical tomotherapy.

Conclusion: Modern IMRT techniques allow for sparing of the hippocampus with acceptable target coverage and homogeneity. Based on compelling preclinical evidence, a Phase II cooperative group trial has been developed to test the postulated neurocognitive benefit.

Publication types

  • Clinical Trial, Phase II
  • Research Support, N.I.H., Extramural

MeSH terms

  • Amygdala / diagnostic imaging
  • Brain Neoplasms / radiotherapy
  • Brain Neoplasms / secondary
  • Cognition Disorders / prevention & control*
  • Cranial Irradiation / methods*
  • Hippocampus / cytology
  • Hippocampus / diagnostic imaging
  • Hippocampus / radiation effects*
  • Humans
  • Particle Accelerators
  • Radiation Injuries / prevention & control*
  • Radiotherapy Dosage
  • Radiotherapy Planning, Computer-Assisted / methods*
  • Radiotherapy, Intensity-Modulated / methods*
  • Stem Cells / cytology
  • Stem Cells / radiation effects
  • Tomography, Spiral Computed / methods*