Thermoluminescent responses of LiF: Mg,Cu,P and co-polymer of tetrafluoroethylene and ethylene (ETFE) dosimeters exposed to low-energy X-rays from 0.6 to 8.1keV are compared with responses of TLD-700H. Thickness of a front dead layer of ETFE, which screens the LiF: Mg,Cu,P grains, is estimated with the use of a narrow band of 1.1-keV radiation emitted from Xe/He plasma generated with a laser beam. Absorption properties of the polymer–LiF: Mg,Cu,P dosimeters are measured with 5.9-keV radiation. A large area polymer–LiF: Mg,Cu,P dosimeter is presented as a recording full cross-section of a beam of Cu-Kα radiation (8050eV) from a copper rotating anode. The surface roughness of polymer–LiF: Mg,Cu,P dosimeters is compared with the roughness of TLD chips.