Measuring solar ultraviolet exposure dose on EBT3 film through the application of visible absorbance spectroscopy

Abstract

External Beam Therapy 3 (EBT3) film is the latest model of the EBT film that has been designed to overcome Newton’s Rings artifact and the orientation problem of film during scanned process that occur in radiotherapy procedure. The original colour of the film (light green) will become darken (dark green) depending on the cumulative energy received on the film. This paper examined the applicability of EBT3 film in measuring solar ultraviolet (UV) exposure dose. The solar UV energy obtained through conventional UV meter was correlated with the colour changes of EBT3 film. The colour changes of the films were analyzed using visible absorbance spectroscopy technique. The 5 best wavelengths (A506.77 nm, A604.68 nm, A658.17 nm, A692.99 nm, A699.83 nm) in the experiment produce calibration result with R2= 98.5 % and RMSEC = 301.59 mJ/cm2; and predicted result with R2= 98.3 % and RMSEP = 381.92 mJ/cm2, which mean high correlation between UV irradiance with colour changes of EBT3 film. The EBT3 film gave a good response toward UV dose with the increases in the absorbance of the film with the exposed dose. This means that the measurement of UV dose can be performed using EBT3 film.