Abstract
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Objectives This study, based on a large UK single-centre experience, considers a range of scientific aspects which ensure safe delivery of 177Lu-dotatate therapy.
Methods 156 177Lu-dotatate therapies were administered over a 3 year period. Activity was measured using radionuclide calibrators traceable to a national standard. Treatments were infused via a 3-way tap/PVC extension tubing using a shielded syringe driver. All staff involved (physicists, clinicians, nurses) wore electronic personal dosemeters (EPDs) measuring depth/skin dose. Additionally, physicists wore automatic, real-time fingertip EPDs to isolate specific tasks contributing to extremity exposure. Post-administration, radiation dose rate (DR) from patients was measured regularly until hospital discharge 24 hours subsequently. Patients were advised regarding appropriate behaviour/travel restrictions.
Results All calibrators measured 177Lu accurately (Mean[SD] difference was -2.0[0.6] %). Container geometry (filling volume) had minimal effect (<3%) on calibrator relative response over the range 5-30ml. Mean[SD] therapeutic administered/residual activity were 7497[372] and167[86] MBq respectively. All staff doses were reassuringly low. The greatest proportion of operator extremity dose (42%) arose from connection of therapeutic syringe to tubing. Mean[SD] patient DR immediately after infusion (anterior/posterior combined) at 2m distance was 9.5[1.7] μSv/hour. Subsequent DR measurements at 60, 90 and 120 minutes gave mean[SD] % excretion of 13[8], 18[11] and 20[12] % respectively. Mean[SD] patient DR measured upon hospital discharge were 2.6[1.4] and 7.8[4.0] μSv/hour at 2m and 1m (range: 0.9-12.6 and 2.9-22.0 μSv/hour) respectively. Estimated public doses from contact with discharged patients travelling on public transport were all <0.3mSv constraint. Maximum patient journey time was 6.5 hours.
Conclusions Appropriate shielding, radiation monitoring equipment and staff training ensure that 177Lu-dotatate therapy is an effective, safe treatment with minimal radiation exposure to staff, patient’s family and members of the public.