Estimation of Whole Body Radiation Exposure to Nuclear Medicine Personnel During Synthesis of 177Lutetium-labeled Radiopharmaceuticals

Radiation Exposure to the Nuclear Medicine Personnel During Preparation and Handling of 213Bi-Radiopharmaceuticals

Because of the excellent ability of α-particles to transfer a high amount of energy over a short tissue range, targeted α-therapy has been attracting rising numbers of nuclear medicine centers. In this study, we estimated the radiation exposure to the occupational workers with pocket dosimeters during handling of the α-emitter ²¹³Bi, used for targeted α-therapy of neuroendocrine tumor and castration-resistant prostate cancer patients. The dose rates from patients at different distances and time points after injection of the therapy were also evaluated. Methods: This prospective study was done in the Department of Nuclear Medicine at Fortis Memorial Research Institute, Gurgaon, India. Twelve patients with neuroendocrine tumors or castration-resistant prostate cancer were enrolled to receive ²¹³Bi-DOTATOC or ²¹³Bi-prostate-specific membrane antigen therapy, respectively. Each patient received 2-3 intravenous injections of ²¹³Bi-peptide, 266-362 MBq (7.2-9.8 mCi) in a single cycle over 2-3 d. The radiation exposure to nuclear medicine personnel at the chest and extremity levels was assessed for tasks such as elution, dispensing, injecting, and collecting blood samples. Radiation levels were measured at distances of 1 cm and 1 m from patients immediately after, and at 1, 2, and 4 h after, the administration of ²¹³Bi-peptide. Results: The external dose incurred at the chest level by radiopharmacists during synthesis, by physicians during injection, by technologists during imaging, and by nurses during sample collection was 2-7 μSv/procedure. The extremity dose was 1-14 μSv/procedure. The dose rate at 1 m from patients immediately after ²¹³Bi-radiopharmaceutical injection was 0.02-0.03 μSv/MBq⋅h. Conclusion: The external radiation doses received by occupational workers involved in various procedures were far below the limit prescribed by the regulatory authority (20 mSv/y).

Radiation Dose to the Occupational Worker during the Synthesis of 188Re-labeled Radiopharmaceuticals in the Nuclear Medicine Department

Aim:

The aim of this study is to estimate whole-body radiation dose to the radiopharmacist involved in labeling of three different ¹⁸⁸Re-labeled compounds, namely, ¹⁸⁸Re-Lipiodol, ¹⁸⁸Re-tin colloid, and ¹⁸⁸Re-hydroxyl-ethylidene-diphosphonate (HEDP) and to compare the occupational burden with the dose limits recommended by Atomic Energy Regulatory Board, India.

Materials and Methods:

The Department of Nuclear Medicine at Fortis Memorial Research Institute currently synthesizes three different Rhenium-188 labeled compounds, namely, ¹⁸⁸Re-Lipiodol, ¹⁸⁸Re-HEDP, and ¹⁸⁸Re-tin colloid. To estimate the radiation exposure to the radiopharmacist involved in the synthesis, a survey meter was used to measure radiation level before the start of labeling procedure in the radiopharmacy by keeping it at the location where the radiopharmacist normally stands during preparation. Data were collected for 6 syntheses of each ¹⁸⁸Re-Lipiodol, 4 for ¹⁸⁸Re-HEDP, and 3 for ¹⁸⁸Re-tin colloid followed by the quality control. The pocket dosimeter was used by the radiopharmacistat chest level, performing the labeling of ¹⁸⁸Re-labeled compounds. All radiopharmaceuticals were synthesized by a single radiopharmacist.

Results:

1850 MBq (50 mCi) ¹⁸⁸W-¹⁸⁸Re generator was eluted before the preparation of each radiopharmaceutical. The amount of ¹⁸⁸ReO4^- used for labeling with lipiodol/4-hexadecyl-1,2,9,9-tetramethyl-4,7-diaza-1,10-decanethiol, HEDP, and Tin colloid was in the range of 3182–4440 MBq (86–120 mCi), 2812–3774 MBq (76–102 mCi), and 962–1295 MBq (26–35 mCi), respectively. Meantime required to complete the synthesis was 95, 40, and 131.5 min, respectively. Mean whole-body effective dose received was 0.052, 0.009, and 0.004 mSv, respectively, as measured by using the pocket dosimeter.

Conclusion:

From this small study, we observed that the whole-body radiation dose to the radiopharmacist in radiolabeling and quality control of ¹⁸⁸Re-labeled radiopharmaceuticals is within prescribed limits at the current synthesis frequency.