The Effect of Tissue Physiological Variability on Transurethral Ultrasound Therapy of the Prostate

Therapeutic ultrasound is an investigational modality which could potentially be used for minimally invasive treatment of prostate cancer. Computational simulations were used to study the effect of natural physiological variations in tissue parameters on the efficacy of therapeutic ultrasound treatment in the prostate. The simulations were conducted on a clinical ultrasound therapy system using patient computed tomography (CT) data. The values of attenuation, perfusion, specific heat capacity and thermal conductivity were changed within their biological ranges to determine their effect on peak temperature andthermal dose volume. Increased attenuation was found to have the biggest effect on peak temperature with a 6.9%rise. The smallest effect was seen with perfusion with ±0.2% variation in peak temperature. Thermal dose was mostly affected by specific heat capacity which showed a 20.7% increase in volume with reduced heat capacity. Thermal conductivity had the smallest effect on thermal dose with up to 2.1% increase in the volume with reduced thermal conductivity. These results can be used to estimate the interpatient variation during the therapeutic ultrasound treatment of the prostate.