Since its inception in 2012, the Nuclear Medicine Global Initiative (NMGI) of the Society of Nuclear Medicine and Molecular Imaging has played an important role in addressing significant challenges in the field of nuclear medicine and molecular imaging. The first 3 projects were dedicated to standardizing pediatric nuclear medicine practices, addressing the global challenges of radionuclide access and availability, and assessing the educational and training initiatives on theranostics across the globe. These efforts aimed to advance human health, foster worldwide educational collaboration, and standardize procedural guidelines to enhance quality and safety in nuclear medicine practice. In its latest project, NMGI aimed to develop a unified nomenclature for systemic radionuclide therapy in nuclear medicine, addressing the diverse terminology currently used. An online survey was distributed to NMGI member organizations, drawing participation from various geographical locations and disciplines. The survey anonymously collected responses from physicians, physicists, scientists, radiopharmacists, radiopharmaceutical scientists, dosimetrists, technologists, and nurse managers, totaling 240 responses from 30 countries. Findings revealed a prevailing use of the term targeted radionuclide therapy for radionuclide therapy, with 52% of respondents expressing a preference for this term. In contrast, approximately 37% favored "radiopharmaceutical therapy," whereas 11% favored "molecular radionuclide therapy." Other key terms under the umbrella of targeted radionuclide therapy were also discussed to achieve a consensus on terminology. NMGI efforts to standardize terminology in this dynamic and fluid field should improve communication within the field, better reflect the technology used, enable comparison of results, and ultimately lead to improved patient outcomes.

Objective: To calculate depth-weighted doses for 223Ra, 212Pb and 225Ac for the skin sites of trunk, arms/legs, face, wrist, back of hand, fingertip, back and side of fingers using VARSKIN+v1.2. Methods: Published depth distribution histograms of the basal cells were used with dose averaging in VARSKIN+v1.2. A density correction factor was applied for the 1 g/cc within VARSKIN. Results were compared to the regulatory 70 µm depth and to average depth values for the skin sites. Results: 223Ra has no alpha component at the regulatory 70 µm. This dose is exceeded by the depth-weighted dose rates for all sites (except the fingertip) with factors ×74 (back of finger) to x3600 (trunk). 212Pb and 225Ac have alpha contributions at 70 µm. . For 212Pb, this dose value is greater by over ×2 than the depth-weighted dose rate for the wrist, back of hand, and finger sites, and underestimates dose rates for the other sites. For 225Ac, the 70µm dose rate is exceeded by the depth-weighted dose rates for the trunk, face, arms/legs by factors of ×4-10. Using fixed depth values, the depth-weighted dose rates are larger for all sites except the fingertip. The skin dose is also calculated for biological half-lives of 1, 3 and 6 h. Using the depth-weighted dose rates and a 3 h biological half-life, the activity for 500 mSv is in the range 9-177 Bq for the trunk, face, arms/legs, wrist and hand for all three radionuclides. Conclusion: For alpha-emitting radionuclides a depth-weighted calculation gives more representative dose values. The very low activity values for 500 mSv skin dose to be exceeded have implications for appropriate staff PPE and training.

Aim: VARSKIN provides a convenient way of calculating skin dose from predefined geometries but the models are limited to concentric shapes such as discs, cylinders and point sources. The aim of this article is to use the Geant4 Monte Carlo code to independently compare the cylindrical geometries available in VARSKIN to more realistic droplet models obtained from photography. It may then be possible to recommend an appropriate cylinder model that can be used to represent a droplet within acceptable accuracy. Method: Geant4 Monte Carlo code was used to model various droplets of radioactive liquid on the skin based on photographs. The dose rates were then calculated to the sensitive basal layer 70 µm beneath the surface for three droplet volumes (10, 30 and 50 µl) and 26 radionuclides. The dose rates from the cylinder models were then compared against the dose rates from the 'true' droplet models. Results: The table gives the optimum cylinder dimensions that best approximate a true droplet shape for each volume. The mean bias and 95% confidence interval (CI) from the true droplet model are also quoted. Conclusion: The evidence from the Monte Carlo data suggests that different droplet volumes require different cylinder aspect ratios to approximate the true droplet shape. Using the cylinder dimensions in the table in software packages such as VARSKIN, dose rates from radioactive skin contamination are expected to be within ± 7.4% of a 'true' droplet model at 95% CI.