Raman scattering for dosimetry using GAFCHROMIC EBT3 radiochromic dosimetry film

Raman scattering spectra can be thought of as the "fingerprints" of the investigated material. The purpose of this work was to link the absorbed doses of irradiated radiochromic film at the micrometer level with changes in their Raman spectra.

Raman spectra of irradiated GAFCHROMIC EBT3 film with doses ranging from 0 to 40 Gy were acquired. The excitation wavelengths used in the experiments (457.9 and 647.1 nm) coincided with electronic transitions of the active layer of the film. The effect of resonance Raman scattering enhanced Raman peaks in the resonance region. Spectra were taken in the range of room temperature to around the temperature of liquid nitrogen (-190°C).

The Raman peak intensity redistribution is shown for films with different absorbed doses. The ratio of intensities of the 1445 cm^-1 band with respect to the 1330 cm^-1 band increases with the increase in absorbed dose. This allows building a dose calibration curve for the film.

The dose distribution of the irradiated film can be identified based on the intensity ratio of the 1445 and 1330 cm^-1 bands by means of Raman mapping. This is a noninvasive and computerized readout method which provides micrometer resolution results for the film surface. This is beneficial in the use of radiochromic films as dosimeters for high-precision radiotherapies.