Characteristics of a new polymer gel for high-dose gradient dosimetry using a micro optical CT scanner

The properties of a new polymer gel with two sensitivities, made specifically for high-dose-gradient dosimetry, were investigated. The measurements were performed at NIST using a 1 cm×1 cm calibrated 60Co field, and a 1 cm active diameter 90Sr/90Y beta particle source. A high-resolution laser CT scanner was used to quantify the response. The results show that the high-sensitivity gel responds linearly to the absorbed dose for doses from 0.5 up to 15 Gy, while the low-sensitivity one is linear up to 225 Gy. For both radiation types, the gel response remains stable in time up to a month after the irradiation. The response of the gel was found to have no dose rate dependence for dose rates ranging from 3.7 to 15 mGy/s. Within the measurement uncertainty, the gel response is more sensitive for beta particles than high energy photons.