Energy dependence of GafChromic LD-V1 film dose response to X-ray photons in the 60 to 180 kV range

Abstract

Abstract Introduction Radiochromic film (RCF) is suitable for use as a dosimeter because of its inherently superior spatial resolution and near water-equivalence. A new model of RCF recommended for measuring imaging dose in the kV nominal energy range was recently introduced onto the market. In this study, we investigate the dependence on beam quality of GafChromic LD-V1 film's radiation dose response. Material and methods Pieces of LD-V1 film were irradiated to air kerma ranging from 0 to 570 mGy in X-ray photons with beam qualities of 60 kV (HVL = 1.32 mm Al), 100 kV (HVL = 2.83 mm Al), 120 kV (HVL = 5.11 mm Al), 150 kV (HVL = 6.23 mm Al), and 180 kV (HVL = 0.54 mm Cu). The net reflectance from each film was obtained from a color flatbed scanner. For each beam quality, an analytical power function was fitted to the net reflectance - air kerma relationship and tested for differences. Results We have found that for the beam qualities investigated, the response of Gafchromic LD-V1 film was not significantly dependent on energy, and a single dose - net reflectance calibration curve could be used to model the response at all beam qualities. The total relative uncertainty and absolute error reached maxima of 18% and 80%, respectively for air kerma values less than 50 mGy, but remained below 10% for air kerma in the range 50 mGy to 570 mGy. Conclusions The results of our investigation revealed that the response of Gafchromic LD-V1 film is not significantly dependent on beam quality. A minimum air kerma irradiation of 50 mGy is recommended to minimise uncertainty.