What is an acceptable maximum "bridging" dose between SRS/SRT targeted brain metastases in close proximity to one another?

Hi @Dr. First Last, hello from your neighbor in Flint, I hope this helps:

I use "Brain Minus GTV" as my normal brain OAR, and to reduce the risk of radiation necrosis/edema, I try to keep it under:

• V12 at 5 cc or less for single fraction SRS; above that I will fractionate
• V28.8 at 7 cc or less when using 30 Gy in 5 fractions - slowest and safest regimen I know
• occ need to go down to 25 or 27.5 Gy in 5 fx when inside the brainstem, max Brainstem minus GTV dose 31 Gy to 0.03 cc and 23 Gy to 0.5 cc
• V26 at 7 cc or less when giving 27 Gy in 3 fractions (scaled down from the V28.8)

These aren't absolutes, I've gone up to 10 cc before instead of 7. When in doubt, or facing down large volumes or numbers of mets, fractionation is your friend.

Our do...

Until we have data, I think 300x10 is adequate.