Evaluation of skin absorbed doses during manipulation of radioactive sources: a comparison between the VARSKIN code and Monte Carlo simulations
The evaluation of skin doses during manipulation of radioactive sources can be a critical issue for which the most accurate calculation strategies available should be used. The aim of this work was to compare the results of the analytical approach used in VARSKIN with the simulation of radiation transport and interaction by Monte Carlo calculations in GAMOS (GEANT4-based Architecture for Medicine-Oriented Simulations), and to provide an accurate and versatile tool for the evaluation of skin doses from radionuclide sources of any realistic shape (e.g. cylindrical, parallelepiped), even in the presence of multiple interposed absorber layers. A set of 20 radionuclides (pure β, β–γ, Auger and γ emitters) from among the most frequently employed in nuclear medicine and laboratory practices were selected for comparison. We studied a point-like and a cylindrical source, in the presence of varying thicknesses of absorbing layers. We found a general agreement for most nuclides when the source was directly in contact with skin or in the presence of a thin layer of absorbing material. However, when the thickness of the absorber increased, significant differences were found for several nuclides. In these cases, the proposed method based on a dedicated Monte Carlo simulation could give more accurate results in a reasonable time, which could optimise accuracy when assessing skin doses in routine as well as incidental exposure scenarios.
A Collaborative Experience: Implementation of an Optimized Tc-99m Generator Assembly Process

 Technetium-99m (Tc-99m) has a 6-hr half-life making customer transportation times a challenge. Australian Nuclear Science and Technology Organization (ANSTO) health products group has overcome this by delivering the parent isotope molybdenum-99 (Mo-99), which has a half-life of 66 hr, in shielded GENTECH™ generators. As part of ANSTO's questioning attitude, an augmented risk assessment was undertaken to identify any potential exposure risks of the GENTECH™ assembly process. The evaluation identified potential areas of improvement in contamination control for the manual handling of the generator leads. Upon further analysis, contamination events from the generator leads had the potential for skin doses above the threshold for skin tissue reactions. Additional substitution and administrative controls were designed to mitigate the risks identified. The effectiveness of the new controls was assessed for efficiency in the manufacturing process through mock trials and fitness for use in a pharmaceutical cleanroom environment. The implemented controls were monitored, and data from each run were gathered. These data included changes in radiological conditions and dosimetry results. Upon implementation, there was an observable decrease in glove contamination. The decrease verified that there was a reduction in the risk of skin contamination events. The data analysis was used to model the dose averted, which revealed a reduction in potential extremity dose to production workers. This paper aims to show the optimization within an approved process through the implementation of engineering and administrative controls, resulting in a dose reduction to workers.
Protecting Marine Biodiversity on the Continental Shelf Beyond 200 Nautical Miles
States are expending significant effort to chart the extent of their continental shelves where these extend beyond 200 nautical miles. As more is understood about marine biodiversity on the outer continental shelf, states may wish to regulate the use of biodiversity for the purposes of conservation or for future exploitation. This article identifies potential threats to marine biodiversity on the continental shelf, explores whether conservation is a legitimate purpose for exercising coastal state rights over the outer continental shelf under the Law of the Sea Convention, and considers the various legal rules that coastal states may use to protect marine biodiversity. The article concludes that the continental shelf regime is undesirably vague in some instances but that coastal states have a legal basis for taking action to regulate activities that impact the marine biodiversity of the outer continental shelf.