Temperature distribution analysis for high intensity focused ultrasound breast cancer treatment by numerical simulation

Breast cancer incidence is dramatically increasing in Japan and remaining high over the world. High intensity focused ultrasound (HIFU) is a low-invasive treatment method for breast cancer. It could produce irreversible tissue thermal coagulation in focus position. Direct reason for coagulation is temperature-rise. This study tried to numerically analyze temperature-rise distribution for HIFU breast cancer treatment. The breast model is constructed from MRI images of real patient, and a total of 4 patient cases were studied. Temporal study indicates that temperature rises with irradiation time, and possible unexpected burn could be anticipated outside of targeted focus due to heterogeneous breast tissue. Spatial observation reveals noticeable temperature-rise positions outside of focus. Temperature-rise ratio was calculated and quantitative influence of high temperature-rise positions outside of focus was shown. To avoid unexpected burns, focus control turns to be necessary.