The use of different types of thermoluminescent dosimeters to measure extremity doses in nuclear medicine

Abstract Depth–dose curves in LiF detectors of different effective thicknesses, together with their responses, were calculated for typical nuclear medicine radiation fields with 99m Tc, 18 F and 90 Y sources. Responses were analysed in function of the radionuclide, detector effective thickness and irradiation geometry. On the other hand the results of the nuclear medicine measurement campaign of the ORAMED project were presented focussing on the dose distribution across the hand and on the appropriate position to wear the dosimeter. According to the results, thin LiF detectors provide better responses in all cases. Its use is essential for 18 F, since thick dosimeters can underestimate H p (0.07) up to a 50% because of the very inhomogeneous dose deposition on the active layer. The preliminary results of the measurement campaign showed that the index tip of the non-dominant hand is usually the most exposed position among the 22 monitored positions. It was also found that, in average, wrist dosimeters are likely to underestimate the maximum skin dose by a factor of the order of 20. This factor is reduced to around 6 for a ring dosimeter worn on the base of the index of the non-dominant hand. Thus, for typical nuclear medicine procedures, the base of the index of the non-dominant hand is recommended as the best monitoring option.