Numerical Study on a Focus-Control Method Using Breast Model With Intentionally Assigned High-Absorbing Layer Near Skin for High-Intensity Focused Ultrasound Treatment.

To prevent undesirable skin burns that occur in high-intensity focused ultrasound (HIFU) treatment, we numerically study focus-control methods, such as phase compensation (PC) and amplitude adaptation (AA). We intentionally assign a high-absorbing layer (HAL) near the part of the skin, where heat generation and tissue ablation are observed, because of high energy loss in the interface between water and breast skin. Results show that PC improves the effectiveness of focusing by enhancing the focal peak and reducing the focal deviation; however, PC does not suppress skin burn.

Numerical study on sector-vortex phased irradiation method using annular array transducer in High-Intensity Focused Ultrasound treatment.

Sector-vortex phased irradiation from annular array transducer was numerically studied with breast model constructed from MRI data of real patient. Phase compensation (PC) based on time reversal pre-computation was applied in order to handle phase delay caused by heterogeneity of breast tissues, and results showed great effectiveness on single-focus case, insignificant effectiveness on multi-focus cases with 4 and 8 phase-sectors, but ineffectiveness on multi-focus case with 12 phase-sectors, where enormous undesired outer ablation occurred. For single-focus case, phase compensation not only produced real focus very close to targeted site (0.

Effects of breast structure on high-intensity focused ultrasound focal error.

Background: The development of imaging technologies and breast cancer screening allowed early detection of breast cancers. High-intensity focused ultrasound (HIFU) is a non-invasive cancer treatment, but the success of HIFU ablation was depending on the system type, imaging technique, ablation protocol, and patient selection. Therefore, we aimed to determine the relationship between breast tissue structure and focal error during breast cancer HIFU treatment.

Temperature distributions measurement of high intensity focused ultrasound using a thin-film thermocouple array and estimation of thermal error caused by viscous heating.

To improve the throughput of high intensity focused ultrasound (HIFU) treatment, we have considered a focus switching method at two points. For this method, it is necessary to evaluate the thermal distribution under exposure to ultrasound. The thermal distribution was measured using a prototype thin-film thermocouple array, which has the advantage of minimizing the influence of the thermocouple on the acoustic and temperature fields.