Complex magnetic field exposure system for in vitro experiments at intermediate frequencies

Abstract

In occupational environments, an increasing number of electromagnetic sources emitting complex magnetic field waveforms in the range of intermediate frequencies is present, requiring an accurate exposure risk assessment with both in vitro and in vivo experiments. In this article, an in vitro exposure system able to generate complex magnetic flux density B-fields, reproducing signals from actual intermediate frequency sources such as magnetic resonance imaging (MRI) scanners, for instance, is developed and validated. The system consists of a magnetic field generation system and an exposure apparatus realized with a couple of square coils. A wide homogeneity (99.9%) volume of 210 × 210 × 110 mm(3) was obtained within the coils, with the possibility of simultaneous exposure of a large number of standard Petri dishes. The system is able to process any numerical input sequence through a filtering technique aimed at compensating the coils' impedance effect. The B-field, measured in proximity to a 1.5 T MRI bore during a typical examination, was excellently reproduced (cross-correlation index of 0.99). Thus, it confirms the ability of the proposed setup to accurately simulate complex waveforms in the intermediate frequency band. Suitable field levels were also attained. Moreover, a dosimetry index based on the weighted-peak method was evaluated considering the induced E-field on a Petri dish exposed to the reproduced complex B-field. The weighted-peak index was equal to 0.028 for the induced E-field, indicating an exposure level compliant with the basic restrictions of the International Commission on Non-Ionizing Radiation Protection. Bioelectromagnetics 34:211-219, 2013. © 2012 Wiley Periodicals, Inc.

Effects of exposure to gradient magnetic fields emitted by nuclear magnetic resonance devices on clonogenic potential and proliferation of human hematopoietic stem cells

“…To investigate the effects of occupational exposure to GMFs emitted by MRI scanners, an exposure system able to reproduce gradient signals actually used during MRI exams was designed and realized. GMFs, produced by gradient coils, were firstly acquired through field measurements [Andreuccetti et al, ]; then a procedure to reproduce measured signals by means of a system of coils was set up as in Lodato et al [].…”

“…In vitro exposure was carried out using a device previously described [Lodato et al, ]. Briefly, a couple of square coils (side 32 cm) were designed with a mutual distance of 15 cm, in order to achieve a 270 × 270 × 136 mm 3 nominal volume, suitable for simultaneous in vitro exposure of a large number of samples to a B‐field in horizontal direction.…”

Controlled release from magnetoliposomes aqueous suspensions exposed to a low intensity magnetic field

“…The exposure system used was one already available in our laboratory (Fig. a) and designed for experiments where large volumes (>10 dm 3 ) are required [Lodato et al, ]. It consists of two coaxial magnetic coils of square shape with a length of 21 cm and placed 11 cm apart; coil section is square with a side of 2 cm and is composed of 25 cable turns.…”

Uncertainty quantification in the assessment of human exposure to pulsed or multi-frequency fields

“…Each standard and guideline addresses this problem differently proposing solutions that depends on the shape of the waveform (ICNIRP 2003, 2010, Bailey et al 2019. The literature includes several papers using these methods to analyze specific exposure scenarios (Lodato et al 2012, Andreuccetti et al 2013, Fiocchi et al 2015, Canova et al 2016, Paffi et al 2016, Tang et al 2022 and other papers pointing out issues and performances of these methods (De Santis et al 2013, Schmid and Hirtl 2016, Keller 2017, Schmid et al 2019. Most of these methods move the problem from the time domain to the frequency domain by means of the Fourier decomposition of the waveform.…”