Y microspheres have been widely used for treatment of liver-dominant malignancies. There have been a few case reports of radiation dermatitis post-inadvertent falciform artery Y radioembolization and a few retrospective studies with prophylactic coiling or use of ice packs prior to radioembolization. Our patient had inadvertent falciform artery radioembolization, which was not predicted on pretherapy angiography or Tc-macroaggregated albumin SPECT/CT but was localized on posttherapy Y PET/CT and treated with topical betamethasone valerate 0.1% BD and ice packing immediately postprocedure. He subsequently developed a small area of periumbilical radiation dermatitis, which resolved after 4 weeks.