Simulations of MAPA and APA heating using a whole body thermal model

Simulations of hyperthermia treatments to the extremities and the pelvis with miniannular phased array (MAPA) and annular phased array (APA) applicators have been conducted using a whole-body thermal model of man. The model is an enhanced version of a simpler model and accounts for gross spatial variations in arterial and venous blood temperatures throughout the body during a hyperthermia treatment. Included in the modified model are constitutive relations governing the local thermoregulatory changes in skin and muscle blood flow and sweating during local heating. Results of these simulations reveal that systemic heating is not significant during extremity heating with a MAPA due to the lack of aberrant energy deposition outside of the treated area. A nonthermoregulated tumor can be preferentially heated to therapeutic levels by the MAPA if it is positioned within the central region of the applicator. Simulations of APA treatments show that systemic heating is quite significant when aberrant electromagnetic energy deposition is taken into account. Comparison of simulated results to clinical data indicates that the modified model can predict the deep body temperatures and cardiac output changes in a more realistic manner than the original model.