The standardized exposure device has been described in [Sannino et al., 2006 and Calabrese et al., 2006]. Two identical waveguides, one for RF and one for sham exposure, were housed in a commercial incubator at 37°C with 95% air and 5% CO2.
A total of eight 35-mm Petri dishes were inoculated with lymphocytes from each donor. Four dishes, each filled with 3 ml of cell suspension, were held by a plastic stand in each waveguide. The distance between the samples allowed simultaneous exposure at two different SARs. The induced electric field was essentially parallel to the sample surface.
The feeding end was a coaxial waveguide adapter, the other end terminated with a fixed short circuit. The center of the samples was at a distance of 0.5 λ from the short circuit in order to achieve the best trade-off between efficiency and SAR uniformity.
Two of the dishes in each waveguide were given 4 Gy of X rays immediately before RF or sham exposure (one dish per SAR). The X rays were produced by a Thomson tube (250 kVp, 0.8 Gy/min) and filtered by 1-mm thick copper foil.
Mess- und Berechnungsdetails
Incident and reflected powers were measured using a bidirectional power sensor connected to a computer continuously adjusting the power level of the signal generator to the required SAR. Measurements of local SAR and power efficiency showed good agreement with the calculated values. The ratio between the SAR standard deviation and the average SAR was 0.33 in all four samples. The measured increase in temperature during the RF exposure at 2 W/kg was 0.2 ± 0.1°C, which was considered sufficiently low to exclude damage induced by thermal processes.
Sannino A et al.
Evaluation of Cytotoxic and Genotoxic Effects in Human Peripheral Blood Leukocytes Following Exposure to 1950-MHz Modulated Signal