Dosimetry of ionizing radiation using an iodide/iodate aqueous solution

Details of a new aqueous chemical dosimeter consisting of a mixture of KI (0.6 M) and the electron scavenger KIO3 (0.1 M) in 0.01 M borate buffer (pH 9.25) are presented. Exposure was either to gamma sources (137Cs, 60Co) or to linear accelerator (LINAC) radiations (18-MeV electrons, bremsstrahlung X-ray spectrum). G values were obtained for the formation of triiodide; the absorbance at its maximum was then measured at 352 nm. The dose response was linear up to 6000 Gy, the lower limit of detection being approximately 0.25 Gy. G values calculated from the initial slopes of the dose-response curves were 14.1±0.8 for 137Cs radiations and 13.8±0.4 and 13.9±0.8 for the NIST and AFRRI 60Co radiations, respectively. G values obtained for the electron and bremsstrahlung radiations were 12.2±1.9 and 11.9±1.8, respectively. The iodide/iodate dosimeter extends the range of detection an order of magnitude both above and below the accepted detection limits of the Fricke dosimeter.