Clement GT, Hynynen K
Brigham & Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
J Acoust Soc Am. 2000 Jul;108(1):441-6. doi: 10.1121/1.429477.
Spatial planar projection techniques propagate field measurements from a single plane in front of a transmitter to arbitrary new planes closer to or further away from the source. A linear wave vector frequency-domain projection algorithm is applied to the acoustic fields measured from several focused transducer arrays designed for ultrasound therapy. A polyvinylidene difluoride hydrophone is first scanned in a water tank over a plane using a three-dimensional positioning system to measure the complex pressure field as a function of position. The field is then projected to a series of new planes using the algorithm. Results of the projected fields are compared with direct measurements taken at corresponding distances. Excellent correlation is found between the projected and measured data. The method is shown to be accurate for use with phase-controlled field patterns, providing a rapid and accurate method for obtaining field information over a large spatial volume. This method can significantly simplify the characterization procedure required for phased-array application used for therapy. Most significantly, the wavefront propagated back to a phased array can be used to predict the field produced by different phase and amplitude settings of the array elements. A field back-projected to the source could be used as an improved source function in acoustic modeling.
空间平面投影技术将场测量从发射器前方的单个平面传播到更靠近或远离源的任意新平面。一种线性波矢频域投影算法应用于从为超声治疗设计的多个聚焦换能器阵列测量的声场。首先使用三维定位系统在水箱中的一个平面上扫描聚偏二氟乙烯水听器，以测量作为位置函数的复压力场。然后使用该算法将该场投影到一系列新平面。将投影场的结果与在相应距离处进行的直接测量进行比较。在投影数据和测量数据之间发现了极好的相关性。结果表明该方法适用于相控场模式，为在大空间体积上获取场信息提供了一种快速准确的方法。该方法可以显著简化用于治疗的相控阵应用所需的表征过程。最重要的是，传播回相控阵的波前可用于预测阵列元件不同相位和幅度设置所产生的场。反向投影到源的场可在声学建模中用作改进的源函数。
