TY - JOUR
T1 - Hippocampal-sparing whole-brain radiotherapy
T2 - A "how-to" technique using helical tomotherapy and linear accelerator-based intensity-modulated radiotherapy
AU - Gondi, Vinai
AU - Tolakanahalli, Ranjini
AU - Mehta, Minesh P.
AU - Tewatia, Dinesh
AU - Rowley, Howard
AU - Kuo, John S.
AU - Khuntia, Deepak
AU - Tomé, Wolfgang A.
N1 - Funding Information:
Supported by a grant from the National Institute of Health R01-CA109656 .
PY - 2010/11/4
Y1 - 2010/11/4
N2 - 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 cm3, 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 Gy2 using helical tomotherapy and by 81% to 0.73 Gy2 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.
AB - 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 cm3, 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 Gy2 using helical tomotherapy and by 81% to 0.73 Gy2 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.
KW - Helical tomotherapy
KW - Radiation Therapy Oncology Group (RTOG) 0933
KW - hippocampal avoidance
KW - neurocognitive function
KW - whole-brain radiotherapy
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U2 - 10.1016/j.ijrobp.2010.01.039
DO - 10.1016/j.ijrobp.2010.01.039
M3 - Article
C2 - 20598457
AN - SCOPUS:77958472320
SN - 0360-3016
VL - 78
SP - 1244
EP - 1252
JO - International Journal of Radiation Oncology Biology Physics
JF - International Journal of Radiation Oncology Biology Physics
IS - 4
ER -