The photon energy response of six thermoluminescent detector types (6LiF:Mg,Ti, 7LiF:Mg,Ti, natLiF:Mg,Ti, 6LiF:Mg,Cu,P, 7LiF:Mg,Cu,P and natLiF:Mg,Cu,P) was studied in the energy range 12–1250 keV by means of irradiations with different γ-ray sources and X-rays. As expected, for both LiF:Mg,Ti and LiF:Mg,Cu,P detectors, no significant differences were found between the results of detectors with same dopant concentrations but different lithium isotopic enrichment. On the other hand, the type and concentration of dopants influence the photon energy response of the detectors up to 50%. The obtained results were compared with experimental data from literature showing good agreement. In addition, the recently developed Microdosimetric d(z) Model was employed to assess the photon response of these detectors. For microdosimetric calculations performed in the optimal site size of 40 nm (determined in previous investigations with charged particles), a very good agreement was observed between results of the model and the experimental data with an average relative deviation of 3% and 4% for LiF:Mg,Ti and LiF:Mg,Cu,P detectors respectively.