Hi everyone, I’d like to calculate Hp(0.07) for photons from an F-18 source placed about 30 cm away from a soft-tissue slab phantom (30×30×15 cm³), and I’m not sure what’s the best way to set up the detector and physics parameters. Since Hp(0.07) is defined at 70 µm depth and averaged over 1 cm², should I create a 1×1 cm² scoring volume that’s only a few microns thick (like 5–10 µm)? Or is it better to make it thicker for better statistics? What’s a good choice of physics list for this (Livermore, Penelope, or something else) and what production cuts would make sense for such a thin layer? Also, since the detector is small and far from the source, I assume I’ll need some variance reduction — maybe importance splitting or weight windows, but I’ve never done that for surface dose before. Any tips or examples on how to properly model the geometry, cuts, and VR settings to get a reliable Hp(0.07) estimate would be really appreciated!