Feasibility study on a micro-size dosimeter using an optical fiber probe based on a photostimulable phosphorescence

We propose a novel micro-size dosimeter using an optical fiber probe based on the PSL from the BaFBr:Eu²⁺. Through basic experiments using the prototype dosimeter, the feasibility of the proposed dose monitoring method has been confirmed. We confirm that increasing the stimulus laser power is effective to improve the signal to noise ratio. The lower limit of detectable dose of the prototype dosimeter probe having sensitive region with the diameter of 200 μm is preliminarily estimated to be 11 mGy for a Co-60 gamma-rays. This value is much smaller than the typical irradiation dose (a few Gy per treatment) in the radiotherapy. We can measure the dose in a few hundred subdivisions during a treatment. We, therefore, conclude that the proposed micro-size dosimeter can be a promising candidate of in-vivo and on-line dose monitor in the radiotherapy.