Organic　scintillators,　materials　with　the　ability　to　exhibit　luminescence　when　exposed　to　X-rays,　have　aroused　increasing　interest　in　recent　years.　However,　the　enhancement　of　radioluminescence　and　improving　X-ray　absorption　of　organic　scintillators　lie　in　the　inherent　dilemma,　due　to　the　waste　of　triplet　excitons　and　weak　X-ray　absorption　during　scintillation.　Here,　we　employ　halogenated　thermally　activated　delayed　fluorescence　materials　to　improve　the　triplet　exciton　utilization　and　X-ray　absorption　simultaneously,　generating　efficient　scintillation　with　a　low　detection　limit,　which　is　one　order　of　magnitude　lower　than　the　dosage　for　X-ray　medical　diagnostics.　Through　experimental　study　and　theoretical　calculation,　we　reveal　the　positive　role　of　X-ray　absorption,　quantum　yields　of　prompt　fluorescence,　and　intersystem　crossing　in　promoting　the　radioluminescence　intensity.　This　finding　offers　an　opportunity　to　design　diverse　types　of　organic　scintillators　and　expands　the　applications　of　thermally　activated　delayed　fluorescence.　©　2023　Xiao　Wang　et　al.