Christopher Ted
IEEE Trans Ultrason Ferroelectr Freq Control. 2005 Sep;52(9):1523-33. doi: 10.1109/tuffc.2005.1516025.
A measure of focusing efficiency is introduced for high-intensity, focused ultrasound (HIFU). The measure consists of the fraction of the total acoustic power emitted that linearly propagates through a circle located at the focus. The medium is absorption-free water, and power is computed using pressure and the normal component of velocity. 3 MHz phased-array designs involving different element layouts and curvatures are placed in square apertures of length 2.2 cm. The acoustic fields of these devices then are propagated to on-axis foci. The resulting focal efficiencies then are calculated using a two wavelength (0.1 cm) radius circle. Among these array designs, an annular array with 27 wavelength-wide rings then is extended to be the basis of a twin phased-array device for prostate hyperthermia treatment. The two annular arrays are attached to door-like hinges to allow for joint two-dimensional focusing. The focusing efficiency of this device then is compared to rectangular element-array devices with the same 5.4 by 2.2 cm source extent. With the addition of absorption and finite-amplitude distortion, the heating rate and temperature rise produced by the twin annular device in prostate tissue is considered. As a final look at the potential of annular array-based designs, three larger 2 MHz devices are briefly considered for abdominal treatment.
针对高强度聚焦超声（HIFU）引入了一种聚焦效率测量方法。该测量方法由通过位于焦点处的一个圆线性传播的发射总声功率的分数组成。介质为无吸收水，功率通过压力和速度的法向分量计算得出。涉及不同元件布局和曲率的3兆赫相控阵设计被放置在边长为2.2厘米的方形孔径中。然后将这些设备的声场传播到轴上焦点。接着使用半径为两个波长（0.1厘米）的圆计算得到的聚焦效率。在这些阵列设计中，具有27个波长宽度环的环形阵列随后被扩展成为用于前列腺热疗的双相控阵设备的基础。两个环形阵列连接到类似门的铰链上，以实现联合二维聚焦。然后将该设备的聚焦效率与具有相同5.4×2.2厘米源范围的矩形元件阵列设备进行比较。考虑到吸收和有限振幅畸变的影响，研究了双环形设备在前列腺组织中产生的加热速率和温度上升。作为对基于环形阵列设计潜力的最后审视，简要考虑了三种更大的2兆赫设备用于腹部治疗。
