Optimizing extremity dosimetry: an investigation of thermoluminescence dosemeter ring orientation when handling radioactive sources

Accurate extremity dosimetry is essential in nuclear medicine due to finger exposure being one of the major radiation protection concerns. Instinctive ring wearing habits, such as facing decorative elements outwards or 'diamond-up', frequently leads to incorrectly orientated thermoluminescence dosemeter (TLD) ring placement. This study investigated how the orientation of TLD rings can affect recorded extremity dose when handling 99mTc. A two-part method was undertaken involving a physical experiment using a constructed finger phantom followed by a Geant4 Monte Carlo simulation to validate the findings. The results highlighted that doses were significantly reduced by a ratio of 19:1 (-95%) when TLD dosemeter rings were orientated outward when compared to inward, primarily due to the additional attenuation introduced by the finger. Greater awareness on the influence of ring orientation is essential for improving the accuracy of extremity dosimetry, addressing a simple yet often overlooked aspect of radiation protection.