Distance between exposed object and exposure source
The Radial Transmission Line (RTL) irradiator and the shielded and temperature-controlled facility housing nine RTLs have been described and comprehensively characterised previously [Moros et al., 1999]. Each RTL was formed by two parallel metal plates, 4.3 cm apart, with a lightweight composite top plate hinged to the bottom aluminium plate (1/4" thick) providing mechanical support and equalising the temperatures of the flasks. The TEM waves travelling radially from the central conical antenna (10.2 cm radius) were terminated by an annulus of MW-absorbing foam backed by a perforated aluminium lamina. The radius of the entire parallel region from the antenna's center to the lamina was 53.3 cm.
Sixteen sealed T-75 flasks, each containing 40 ml of culture medium, were positioned in the region around the antenna at a mean radial position of 29.2 cm, for a total of 1200 cm² of culture area per RTL, and maintained at 37.0 ± 0.3°C.
Average SAR values over the cell layer were measured using both thermometric and thermographic techniques and agreed reasonably with two-dimensional FD 7-layer model calculations [Pickard et al., 2000].