Suitability of the BPY-12 photodiode for beta dosimetry

A common photodiode (BPY-12, Siemens) was tested for use as a dosimeter for beta radiation. Measurements were performed with a specially designed integrating electrometer. Parameters evaluated included the variation of its response with beta dose, reproducibility, stability of response, and energy dependence. The results showed that there is a linear relationship between the current produced in the photodiode and the applied dose (r2=0.99991 for a 90Sr/90Y source). As far as stability and reproducibility of response are concerned, the results indicated that the BPY-12 presents a stable response as a function of time, and that the coefficient of variation of the reproducibility of its response is less than 1%. Based on these findings, depth-dose measurements were built for the 90Sr/90Y source, which agree with those obtained with conventional extrapolation chambers. The results obtained show that the PBY-12 photodiode is adequate for use as a beta dosimeter. (orig.)