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. Author manuscript; available in PMC: 2013 Jul 15.
Published in final edited form as: Int J Radiat Oncol Biol Phys. 2011 Dec 29;83(4):e487–e493. doi: 10.1016/j.ijrobp.2011.10.021

Fig. 2.

Fig. 2

Dose–volume histogram for hippocampal avoidance during whole-brain radiotherapy using (A) helical tomotherapy and (B) linear accelerator–based LINAC-based IMRT. Modified from (6) to include equivalent dose in 2-Gy fractions (assuming α/β = 2 Gy) (EQD2) along the X axis. EQD2 to 40% (D40%) of the bilateral hippocampi is 4.6 to 5.4 Gy by use of helical tomotherapy and 7.1 to 7.5 Gy by use of LINAC-based IMRT. These values do not significantly exceed the D40% threshold associated with long-term memory impairment on this study. PTV = whole brain planned target volume.