Accidental neutron exposure in a medical setting: a case study.

In May 2016, a new linear accelerator (Linac) was installed at a hospital oncology department. A team of individuals supervised the installation, including a Radiation Oncologist who acted as an independent observer to the installation, calibration, beam data collection and shielding measurements. In order to ensure the shielding was correct, a licensed representative of the Turkish Atomic Energy Authority carried out formal measurements of the gamma and neutron dose rates at a variety of locations in and around the Linac facility. At 18 MV, the maximum neutron dose rate was 172µSv h-1and the maximum gamma dose rate was approximately 2µSv h-1(ambient dose equivalent in both cases), significantly higher than the expected and local background doses. As the neutron dose rates in particular were so high, it was concluded that the shielding was not sufficient, potentially due to an inadequate design. In order to rule out overexposure during the installation, biological dosimetry was carried out for a number of the individuals involved. The estimated doses were closely aligned with the doses measured using commercially available neutron dosemeters and were also within the tolerance dose ranges estimated using Monte Carlo simulations, which also supported the investigation. The results underline the need for careful planning before and after installation of new radiation exposure facilities, especially high MV Linac operation for which photo-neutrons might need to be mitigated. The results clearly indicate the importance of such checks, in addition to demonstrating the relevance of biological dosimetry supported by modelling strategies complex or unclear exposure scenarios.

Heavy metal pollution in surface sediment and mussel samples in the Gulf of Gemlik.

Sediment quality data provide essential information for evaluating ambient environmental quality conditions. An evaluation is presented of heavy metal pollution, on the basis of statistical analysis of metal concentrations from the sediments of the Gulf of Gemlik, southeastern Marmara Sea, Turkey, which has been subject to high levels of pollution. The ranges for heavy metal concentrations (Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) at the <63 microm grain size were higher when compared with those obtained from >63 microm fractions. Not only large industrialized seaports but also resort areas throughout the Gulf are flagged as hotspots for elevated concentrations, generally higher compared to those from the other Turkish marine environment. The highest concentrations of Cr, Pb and Ni were measured in the outer part of the Gulf, while the highest concentrations of Cu were documented offshore the main rivers. While the concentrations of Cr, Fe, Mn and Ni in some stations approach the severe effect level given in various sediment quality guidelines, the concentrations of the most human-related metals (Cd and Zn) in the mussels collected from the Port Mudanya were higher than the acceptable values for human consumption set by various healthy organizations.

Heavy metal levels in biota and sediments in the northern coast of the Marmara Sea.

Concentration of Cd, Co, Cr, Ni, Zn, Fe, Mn, Pb and Cu were determined in biota and sediment samples collected from the Marmara Sea in Turkey. The levels of Zn, Fe, Mn, Pb and Cu in the macroalgae are higher than previous studies in the Marmara Sea. Moreover, Cu and Zn concentrations at the present study are significantly high than Bosphorus and Black Sea algae. The order heavy metal concentrations in the mussel samples was: Fe > Zn > Ni > Mn > Cu > Pb > Cr > Cd > Co. The metal concentrations are generally lower when compared with the Black Sea mussels except Pb. At the same time, concentrations of Pb, Cu and Zn in the mussel species are lower when compared with the results in the Aegean Sea. The ranges of Mn and Cu in the tested fish samples are higher than Black Sea fish. On the other hand, Cd, Co, Cr, Zn and Pb concentrations are lower. The northern coast of the Marmara Sea having the highest metal concentrations in sediments as follows: Co, Cr, Ni, Fe at Sarköy; Pb, Cu at M. Eregli; Cd, Zn, Mn at Menekse. The heavy metal levels in the sediment samples are lower than other areas in the Marmara Sea.