Radiochromic film dosimeters

Radiochromic film dosimeters. Many polymer-based film dosimeters have been developed containing various types of dyes, whose color or depth of color changes during irradiation. Certain leucocyanides or leucomethoxides of triphenylmethane dyes are widely applied in the dose range of 10 -10 Gy (McLaughlin 1974,1977, 1985, ISO/ASTM 51275). 

Essentially, a calorimeter measures absorbed dose in terms of the radiation-induced temperature rise in the calorimeter core connected electrically to the outside. The dose to the dosimeter being calibrated is related to the associated calorimeter reading of the net temperature rise. These calorimeters are used as reference dosimeters for high-energy electron beams (2-12 MeV) and also for small references and routine dosimeters (pellets and radiochromic films). 

Dosimeters that are sufficiently small, such as thin radiochromic films and alanine pellets, can readily be calibrated against the calorimeter, by irradiating in tandem (with a suitable radiation monitor) while encased in a phantom material that is identical in size, shape and substance to the calorimetric absorber. The main appreciable correction that is required is the ratio of mass energy-absorption coefficients of the two materials (in the case of photon irradiations) or the ratio of mass collision stopping powers of the two materials (in the case of electron beam irradiations) (McLaughlin et al., 1989). 

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