Measuring the temperature dependence of refractive index in water phantom for precise monitoring of the absorbed dose by radiation therapy techniques

In this paper, an experimental setup is used to measure the temperature dependence of the refractive index of a water phantom. In radiation calorimetry by laser beams and interferometric systems, the amount of change induced by radiation within the phantom can be accurately measured. Absorption of dose and the resulted change in temperature changes the refractive index within the material. In order to be able to measure the small amount of the absorbed dose within the phantom, the temperature dependence of the refractive index of the material must be precisely known. The measurement results of temperature dependence to the refractive index of water indicate the decrease of its refractive index by increasing the temperature.