Cells that are in the late anaphase or telophase stages of cell division arevulnerable to damage by AC electric fields that have specific frequency andfield strength characteristics. The selective destruction of rapidly dividingcells can therefore be accomplished by imposing an AC electric field in atarget region for extended periods of time. Some of the cells that dividewhile the field is applied will be damaged, but the cells that do not dividewill not be harmed. This selectively damages rapidly dividing cells like tumorcells, but does not harm normal cells that are not dividing. Since thevulnerability of the dividing cells is strongly related to the alignmentbetween the long axis of the dividing cells and the lines of force of theelectric field, improved results are obtained when the field is sequentiallyimposed in different directions. The field may also be rotated through 360~ byapplying AC waveforms with different phases to the electrodes.
