Exposure assessment of electromagnetic fields near electrosurgical units.

Electrosurgical units (ESU) are widely used in medical health services. By applying sinusoidal or pulsed voltage in the frequency range of 0.3-5 MHz to the electrode tip, the desired mixture of coagulation and cutting are achieved. Due to the high voltage and current in the cable, strong electromagnetic fields appear near the ESU. The surgeon and others inside the operating room such as nurses, anesthesiologists, etc., will be highly exposed to these fields. The stray fields surrounding the ESU have previously been measured, but now a deeper analysis has been made of the curve shape of the field and the implication of this when assessing exposure from a commonly used ESU in accordance with the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines. The result showed that for some of the modes, especially those using high-pulsed voltage with only a few sinusoidal periods, the E-field close to the cable could reach linear spatially averaged values of 20 kV/m compared to the 2.1 kV/m stated in ICNIRP guidelines. Assessing the E- and B-field from ESU is not straightforward since in this frequency range, both induced current density and specific absorption rate are restricted by the ICNIRP guidelines. Nevertheless, work needs to be done to reduce the stray fields from ESU.