Use of real-time electronic Silicon diode extremity dose detectors; towards optimising monitoring and radiopharmacy technique

Extremity radiation doses are typically monitored using ring dosimeters worn at the base of the palmar side of the index finger. This measurement does not represent the maximum extremity doses received; however, fingertip dose can be estimated by multiplying by a factor of 3, as recommended by ICRP. Indeed, the literature reports a considerable factor range, between 1.5 and 7 and, furthermore, there is debate as to whether the non-dominant or dominant index finger should be monitored. Ring dosimeters provide monthly dose information but do not provide shorter term data which may inform on radiopharmacy technique optimisation. Accordingly, using ED3 Si diode Hp(0.07) electronic dosimeters, this study sought to establish optimum ring dosimeter placement, operator specific maximum extremity dose correction factors and to examine radiopharmacy operator technique towards optimising extremity dose. Si diode detectors were attached to the index fingertips of radiopharmacy operators, recording real-time dosimetry data at 2 s intervals. After an initial session, an educational discussion was carried out, reviewing dosimetry data and identifying potential areas for technique improvement. A subsequent radiopharmacy session was then monitored. After educational sessions we demonstrated a 35% and 48% reduction, respectively, in dose per unit activity for bone radiopharmaceutical kit and injection preparation, which together accounted for 60% of extremity doses received. This work will discuss the technique optimisation employed. Further, simultaneous dose measurement of fingertip and base of non-dominant index finger, together with ring dosimeter data, allowed for more accurate estimation of the maximum extremity dose received for each operator.