What is a safe and efficacious fractionation to use when re-irradiating a recurrent GBM?

One of the approaches for patents not suitable for radiosurgery salvage is 35 Gy in 10 fractions treating only the GTV (as published from Jefferson) showing reasonable palliation even in patients with short interval recurrence after primary treatment.

I am a fan of 6x5 to the T1post and 5x5 to the local FLAIR; this is extrapolating from MSK experience of 6x5 to the post-op cavity for resected brain mets.