Development of a 2D dosimeter using the optically stimulated luminescence of NaMgF3:Eu with CCD camera readout

A two-dimensional (2D) dosimeter has been developed using tissue-equivalent NaMgF3:Eu as a radiation-sensing material. The bulk compound shows optically stimulated luminescence (OSL) after irradiation in the form of 359 nm Eu2+ emission and where the OSL stimulation occurs at wavelengths above 400 nm. The OSL integrated intensity is shown to be linear up to at least 100 Gy when stimulated with 445 nm light. When the OSL is detected using a thermoelectrically cooled CCD camera, 2D X-ray images can be obtained and the measured intensity is proportional to the total radiation dose. NaMgF3:Eu can be incorporated into epoxy to produce imaging films and both the bulk compound and a film are characterised using the 2D setup. The noise equivalent dose in 2D for the bulk is determined to be 14 mGy. The modulation transfer function (MTF) is determined and the spatial resolution at MTF = 0.2 is 2.9 lp/mm for the bulk material and 1.25 lp/mm for the film. Our results show that NaMgF3:Eu has potential in the field of 2D dosimetry, where the response to radiation is linear to high doses, sensitive to low doses, and doses can be resolved with a spatial resolution below 1 mm.