Department of BIOMORF, University of Messina, Via Consolare Valeria, 98168 Messina, Italy.
School on Medical Physic, University of Messina, Via Consolare Valeria, 98168 Messina, Italy.
Int J Environ Res Public Health. 2018 Jun 21;15(7):1298. doi: 10.3390/ijerph15071298.
The Directive 2013/35/EU establishes standards for workers exposed to static and time varying magnetic fields. These limits are based on ICNIRP guidelines expressed in terms of the electric field induced in the body. The complexity of this measurement led to theoretical models being developed. In this study, the experimental evaluation included varying magnetic field exposures for two classes of MRI workers. The measurements are conducted on four different MRI Systems including one 0.35 T, two 1.5 T, and one 3.0 T. Pocket magnetic dosimeters were used and it was carried out during routine conditions, emergency conditions, and cold-head maintenance/substitution. The acquired data has been processed and the corresponding dB/dt curves have been computed as the first time derivative of the dataset. The weighted peak approach was also implemented for the compliance assessment with regulatory limits. The dB/dt peak values have been compared with the reference level (RL) proposed by ICNIRP. The results show that the RL always exceeds during measurements on the 3.0 T scanner and sometimes on 1.5 T. In light of the foregoing, the diffusion of ultra-high field MRI scanners involves the introduction of behavioral rules that could be more useful than a numerical action level.
指令 2013/35/EU 为接触静态和时变磁场的工人建立了标准。这些限值基于 ICNIRP 指南，以体内感应电场表示。这种测量的复杂性导致了理论模型的发展。在这项研究中，实验评估包括对两类 MRI 工作人员进行不同的磁场暴露。测量是在四个不同的 MRI 系统上进行的，包括一个 0.35 T、两个 1.5 T 和一个 3.0 T。使用了口袋式磁场剂量计，并在常规条件、紧急情况和冷头维护/更换期间进行了测量。所获得的数据已被处理，并计算了数据集的一阶导数作为相应的 dB/dt 曲线。还实施了加权峰值方法来评估与法规限值的符合性。dB/dt 峰值与 ICNIRP 提出的参考水平 (RL) 进行了比较。结果表明，在对 3.0 T 扫描仪进行测量时，RL 始终超过，有时在 1.5 T 扫描仪上也会超过。有鉴于此，超高磁场 MRI 扫描仪的普及涉及到引入行为规则，这些规则可能比数值行动水平更有用。
