NUMERICAL AND EXPERIMENTAL DOSIMETRY OF PETRI DISH EXPOSURE SETUPS

Crawford TEM cells are often used to expose cell cultures or small ani mals in order to study the effects caused by high-frequency fields. Th ey are self-contained, easy-to-use setups that provide a rather homoge neous field distribution in a large area around its center, correspond ing approximately to far-field conditions. However, a number of condit ions must be met if such TEM cells are intended to be used for in vitr o experiments. For instance, poor interaction with the incident field must be maintained to avoid significant field disturbances in the TEM cell. This is best achieved with E-polarization, i.e., when the E-fiel d vector is normal to the investigated cell layer lining the bottom of a synthetic Petri dish. In addition, E-polarization provides the most homogeneous field distribution of all polarizations within the entire layer of cells. In this paper, we present a detailed dosimetric asses sment for 60 and 100 mm Petri dishes as well as for a 48-well titer pl ate at 835 MHz. The dosimetry was performed by using numerical computa tions. The modeling and the simplifications are validated by a second numerical technique and by experimental measurements. For thin liquid layers, an approximation formula is provided with which the induced fi eld strength for many other experiments conducted in Petri dishes can be assessed reliably. (C) 1996 Wiley-Liss, Inc.