CHARACTERIZATION OF A 2-DIMENSIONAL, THERMOLUMINESCENT, DOSE-MAPPING SYSTEM - UNIFORMITY, REPRODUCIBILITY, AND CALIBRATIONS

Initial testing of a new, commercially available, thermoluminescent do simetry system is reported. The radiation detectors consist of two-dim ensional arrays of 10(4) CaF2:Mn dosimeters, deposited on flexible pol yimide sheets. The spatial resolution is 3 mm, and the combined thickn ess of the dosimeters and the substrate is 185 mum. Exposed sheets are processed by laser heating. This system is compatible with intense, p ulsed Bremsstrahlung fields and electronics hardness testing. A two-st ep calibration procedure is described. In spatial uniformity tests at 66 Gy the detectors exhibited random fluctuations of 1%-3% superposed on broad spatial drifts of approximately +/- 5%. Reproducibility for s trips of 288 elements, cut from sheets and given absorbed doses of 100 Gy, was approximately 2%. For absorbed doses in the 10 Gy-1.5 kGy ran ge, response vs exposure curves show reasonable features of linearity, supralinearity, and saturation for CaF2:Mn phosphor. Small systematic effects (<7%) can be observed for sheets and strips stacked during ex posure; these effects are explained by radiation transport calculation s and impact the dosimetric technique.