“…Photoelectric absorption in the elements of relatively high atomic number contained in the emulsion causes the ratio of photographic effect to exposure to be up to 30 and more times higher for 40-kev photons than for 1-Mev photons. For dosimetry in the photon energy ranges up to about 200 kev, suitable arrangements of metallic filters aid in reducing this energy dependence, and facilitate the determination of the particular radiation energy (Langendorff, et al, 1952). For higher energies, film response roughly parallels exposure, provided that electronic equilibrium is established at the film in air-equivalent materials.…”