A numerical study of rapid heating for high temperature radio frequency hyperthermia

Hyperthermia is a promising adjuvant cancer treatment modality. However, unresolved engineering problems with the production and regulation of temperature distributions within tissues in vivo have frustrated repeated efforts to implement clinical hyperthermia protocols. A major technical problem with hyperthermia production in vivo is the cooling effect caused by circulating blood in larger vessels. Larger blood vessels, when located in heated tumors, can prevent achievement of sufficiently high temperatures, resulting in loss of therapeutic effect. One possible way of circumventing this problem is the delivery of a critical heat dose during a short-term, high-temperature treatment episode to minimize cooling from blood flow. We investigated the concept of such rapid, high-temperature heating of tissue in a two-dimensional finite element numerical model. The model demonstrates the feasibility of interstitial radiofrequency delivery of a therapeutic heat dose, equivalent to 30 min at 43 degrees C, to a 1 cm3 tumor during a 60-s period. The model assumes circulation of cooling fluid through hollow electrodes. A post processor has been designed to display a 3-D image of the temperature distribution, electric field, and thermal dose delivered to a unit volume within the heated tissue.