Dosimetry evaluation of EBT3 radiochromic film based on scanning method for radiation therapy

EBT3 radiochromics film is a dosimeter commonly used in radiation oncology because it has properties equivalent to tissue or water, high spatial resolution, low dependence on energy and dose. Consequently, the accuracy and precision during the dose reading procedure of the EBT3 must be excellent accomplished during radiation therapy treatment. The objective was to evaluate the dosimetry of the EBT3 radiochromic using the transmission and reflection mode scanning method for radiation therapy. This study used an EBT3 radiochromic film with a size of 2.5×3 cm² and irradiated with 6 MV photons and 6, 8, 10, 12, and 15 MeV electrons. The EBT3 film irradiation process used a surface axis distance (SAD) of 100 cm, solid water phantom for the scattering medium, and an irradiation field of 10×10 cm². Each EBT3 film was irradiated using prescribed energy at doses of 0, 100, 200, 300, 400, 500, 600, and 700 cGy. The digitalization process of EBT3 film used an Epson V850 Pro flatbed with a resolution of 72 dpi, 48-bit RGB, no correction color, using reflection and transmission modes. The pixel value reading of the EBT3 film used Image-J to obtain a calibrating curve for EBT3 film in each photon and electron energy range. The results showed that the transmission mode had a higher accuracy than the reflection mode for all dose and energy ranges, while the reflection mode had a higher sensitivity than the transmission mode.