Background: The primary objective of this study was to investigate the coupling effect of the thermal wave and the pulsating blood flow in thermally significant blood vessels on the distributions of temperature and thermal dose during thermal therapy.

Methods: Due to the rhythmic nature of the beating heart, the blood pressure gradient along the blood vessels was assumed as sinusoidal changes. The pulsatile blood flow was described by a time-periodic change in the velocity profiles. The temperature field in tissues was solved by incorporating the modified wave bioheat transfer transport equation in the cylindrical coordinates. The thermal dose distribution was calculated by the formulation proposed by Sapareto and Dewey.

Results: Numerical results show that under the same total absorbed energy deposition 100 J/cm³ the peak temperature calculated by the wave bioheat transfer equation, which considers the finite propagation speed in tissue, is always higher than that by the classical Pennes’ bioheat transfer equation. Figure 1 demonstrates that the thermal relaxation time ( s) affects the thermal lesion regions for the three different heating schemes. The thermal region induced by the rapid heating (i.e., = 50 W/cm³, and the heating duration t = 2 s) is significantly larger than that by the slow heating (i.e., = 2 W/cm³, and the heating duration t = 50 s), as shown in Fig. 1.

Conclusions: The difference of the estimated thermal distributions between the conventional Pennes’ bioheat transfer equation and the wave bioheat transfer equation becomes smaller for a slow heating process. The wave bioheat transfer equation would provide an adequate approach for describing the thermal dose distribution and the thermal lesion dimension during rapid thermal therapies.