Scintillation compositions comprising a gadolinium compound and a scintillation compound in a polymer matrix precursor. The scintillation compound comprises strontium diiodide, fac-tris(2-phenylpyridine)iridium (Ir(ppy)3), a quinine compound, or combinations thereof, or 2-(4-biphenylyl)-5 phenyl-1,3,4-oxadiazole (PBD), 2-(4-tert-butylphenyl)-5-(4-phenylphenyl)-1,3,4-oxadiazole (b-PBD), 2,5-diphenyl oxazole (PPO), 1,4-bis(5-phenyloxazol-2-yl) benzene (POPOP), or combinations thereof. Hydrogels comprising the gadolinium compound and scintillation compound in a polymer matrix are also disclosed, as are related systems and methods.