Alanine/EPR dosimetry system is well known for being robust, precise and having low measurement uncertainty for absorbed dose to water measurements, all, whilst covering a broad dose range (few Gy up to more than 100 kGy). In addition, the alanine/EPR dosimetry system is widely used by NMIs as well as SSDLs as a transfer standard dosimetry system for calibration of other systems.

Many influence quantities can change a dosimeter’s response. For alanine, literature shows that the dosimeter’s response can suffer from a combined dose/dose rate influence, where for dose levels higher than 5 kGy, at dose rates smaller than 2 Gy/s. This could pose a problem during the creation of reference alanine dosimeters by metrology labs, where often ⁶⁰Co sources are used and such sources could have dose rates less than 2 Gy/s. From the user’s side, alanine dosimeters could have been calibrated at high dose rates but irradiated at low dose rates in attenuated radiation fields (gamma or low to medium power X-rays), where dose rates could get far below the 2 Gy/s limit.

In this study, an investigation is carried out to characterize the alanine response change with respect to absorbed dose, at different dose rates (0.05 up to 50 Gy/s). Dose rates are calibrated using an ion chamber dosimetry system. 7 MV X-rays are used to irradiate all alanine dosimeters at the different dose levels.

Preliminary results show that, for an absorbed dose of 100 Gy, the response of alanine drops by 12% at a dose rate of 0.05 Gy/s, yet it is stable for dose rates ranging from 0.5 Gy/s up to 50 Gy/s, within 0.8% variation. Further irradiations will be carried out at different dose levels, for multiple dose rates in order to better characterize the influence of absorbed dose/dose rate on the dosimeter’s response.