What PTV margins do you use for definitive prostate radiation?

I tend to follow the RTOG/NRG trials' guidelines for each clinical situation when deciding on margins from CTV to PTV (which use progressively tighter margins based on whether one is doing standard, moderate hypo-, or extreme hypo-fractionation):

For conventional fractionation, RTOG 0924 states 0.5-1.5cm margins, and RTOG 0815 states 0.5-1.0cm margins. I tend to use 0.8cm in all directions except for 0.6cm posterior in this setting.

For moderate hypofractionation, RTOG 0415 states 0.4-1.0cm marg...

In my opinion, the PTV should always be tailored to the situation and the steps that have been taken to minimize intra-fractional motion assuming daily imaging

In our department for modest hypofractionation and standard fractionation for an intact prostate, we sim with a 3 mm slice CT , intra-prostatic fiducials, daily imaging kv imaging, and PTV margins of 6 mm isotropically except 4 mm posteriorly and we try to keep the treatment to less than 4 minutes without re-imaging. Total treatment time ...