RDNA-17. POWER DENSITY LOSS CAN BE USED TO DEFINED TUMOR TREATING FIELDS DOSE

Abstract

Tumor Treating Fields (TTFields) are alternating electric at 200 kHz approved for the treatment of Glioblastoma Multiforme. Historically, TTFields dose has been quantified using the magnitude of the electric field, indicative of the force that the field applies on charged objects. However, when considering TTFields dose, it is important to consider the amount of energy transferred from the electric fields to the tissue. This energy quantifies the extent to which the field alters the state of the objects on which it operates. Since power loss density quantifies the energy transferred by an electric field to tissue, we analyzed the power loss density distributions when TTFields is delivered to the brain. The analysis was performed by numerically simulating delivery of TTFields to computational models of glioblastoma patient. The simulations showed that TTFields magnitude tends to be higher in regions of low conductivity and tends to decrease in regions of high conductivity such as the ventricles and resection cavities. On the other hand, power loss density tends to increase in regions of higher conductivity. Within the highly conductive ventricles and resection cavity, it can take on values comparable to those observed in other tissue types. The total power loss of TTFields within the simulated cases was between 20–40 Watts, which is equivalent to 412–825 Kcalories per day, on-par with the resting metabolic rate of the brain (about 20% of the body’s resting metabolic rate). This analysis shows that power loss density is a viable measure for quantifying TTFields dose. The observation that the power delivered by TTFields to cells is comparable to the metabolic rate of the cells could lead to new insights into the mechanism of action of TTFields.