Evaluation of ultra-sensitive leucomalachite dye derivatives for use in the PRESAGE® dosimeter

In this study we carry out a comparison between the commercially available leucomalachite green (LMG) dye and three newly synthesised derivatives (with either methoxy, chloro or bromo substituents) incorporated into the PRESAGE® dosimeter to determine their effect on the sensitivity and post-response photostability of the dosimeter. In addition, the influence of the new LMG derivatives on the basic radiological properties of the PRESAGE® dosimeter was also investigated. The dosimeters were prepared in spectrophotometric cuvettes, irradiated with a 6 MV X-ray beam, and the change in optical density of each dosimeter was measured using a spectrophotometer. For all of the new LMG derivatives investigated, the sensitivity of the resulting dosimeters to radiation dose increased significantly relative to the unmodified LMG dosimeter, and was dependent on the type of LMG derivative used, with the bromo substituted derivative showing the highest increase in sensitivity (450%), followed by chloro and methoxy substituted derivatives (340 and 200%, respectively). Overall, the new LMG derivatives had only a minimal influence on the radiological properties of the PRESAGE® dosimeter, with the exception of the bromo substituted LMG, which increased the effective atomic number (Zeff) of the dosimeter by 9%. All of the LMG dyes investigated showed similar post-response photostability characteristics, with the methoxy substituted LMG showing a slight improvement in post-response photoretention.