Effect of dosimeter’s position on occupational radiation extremity dose measurement for nuclear medicine workers during 18F-FDG preparation for PET/CT

BACKGROUND The recent spread of positron emission tomography-computed tomography (PET/CT) poses extremity dosimetry challenges. The question arose whether the radiation dose measured by the ring thermoluminescent dosimeter usually worn on the proximal phalanx (P1) of the index finger measures doses that are representative of the true doses received by the upper extremities of the operators. A prospective individual dosimetry study was performed in which the personal equivalent dose Hp (0.07) received during a specific 2-[(18)F]fluoro-2-deoxy-D-glucose ((18)F-FDG) manual dose-dispensing procedure was measured in a paired design by two operational personal electronic dosimeters fitted on the palm side of the index finger, namely in the P1 and distal phalanx (P3) positions. The study participants were ten nuclear medicine technologists working in two nuclear medicine departments. The personal equivalent radiation doses received by the palm side of the proximal phalanx of the index finger [Hp (0.07)P1] and that received by the distal phalanx [Hp (0.07)P3] were compared. RESULTS The median Hp (0.07)P3/Hp (0.07)P1 ratio per participant varied between 1.0 and 2.5 (based on 23 to 31 measurements per participant). The 271 paired measurements revealed a crude Hp (0.07)P3/Hp (0.07)P1 ratio of 1.67, significantly different from 1 (p = 0.0004, 95 % CI [1.35-2.07]). When adjusted on participant's gender and mother vial activity, the ratio was similar (1.53, p = 0.003, 95 % CI [1.22-1.92]). CONCLUSIONS The study demonstrated a significant disparity that may exist between the radiation doses measured in the P1 and P3 positions of operators during (18)F-FDG manipulation. These findings emphasize the importance of performing workplace dosimetry studies adapted to each radiopharmaceutical and manipulation thereof, aiming to guarantee optimal workers' dosimetry monitoring schemes. TRIAL REGISTRATION Hospital Nursing and Paramedical Research Program (PHRIP, 2011-2013) from the French Ministry of Health (DGOS), http://social-sante.gouv.fr/IMG/pdf/Resultats_PHRIP_2011.pdf.