When using short course fractionation for an elderly patient with glioblastoma (40 Gy in 15 fractions), what are appropriate dose constraints for chiasm, brainstem, optic nerves?

Dose constraints for normal tissues were not published in the randomized trial by Roa et al. of 40 Gy in 15 fractions vs. 60 Gy in 30 fractions for elderly patients with glioblastoma (Journal of Clinical Oncology, 2004). Given the apparent similar efficacy and tolerability of the hypofractionated an...

I agree with @Dr. First Last in that when treating with a 3 week course of radiation for GBM risks are relatively low even with>105% hot spots. However, I tend to be a bit more conservative. I generally use 37.5 Gy as an optic apparatus maximum dose (which is a commonly used WBRT dose - 2.5 x 15). W...