Gafchromic HD-V2 investigations using MeV ion beams in vacuum

Gafchromic HD-V2 films are employed to study the response to light ions useful in radiotherapy, such as protons, helium and car- bon beams. The effects induced by the ions at an energy within about 300 keV and 16 MeV were investigated in terms of optical absorbance measurements in the irradiated active region of the film. The employed ion doses range between 0.4 Gy and 12kGy. The results show that the net optical density increases almost exponen- tially with the absorbed dose and that it becomes saturated after pro- longed dose higher than 1 kGy. The optical density produced in the film was measured by light transmission measurements at 700 nm wavelength, at which is observed the highest gafchromic sensitiv- ity. Calibration curves of optical density versus exposure dose and type of ion are given. The dependence on the ion stopping power was presented and discussed.