What dose and fractionation regimen would you use for a patient with DCIS with multiple close margins unable to undergo re-excision, who has a history of photosensitivity (polymorphous light eruption)?

Generally, photosensitivity doesn't lead to higher photon reactions. That being said, I would get the pre-RT mammogram done to rule out residual calcification before RT and favor whole breast to 40 in 15 with higher 16 Gy equivalent boost dose.