锯齿波信号激励增强超声造影剂的次谐波信号  

Enhancement of sub-harmonic emission from ultrasound contrast agent using sawtooth signal excitation

作　　者：郗晓宇[1] 章东[1] 龚秀芬[1] 龚燕君[1] 刘政[2] 

机构地区：[1]南京大学声学研究所近代声学教育部重点实验室(南京大学),南京210093 [2]第三军医大学新桥医院超声科,重庆400037

出　　处：《声学学报》2007年第5期442-446,共5页Acta Acustica

基　　金：教育部新世纪优秀人才计划(06-0450);国家自然科学基金(30470468);江苏省自然科学基金(BK2004081)资助项目

摘　　要：提出了一种利用锯齿波激励以增强超声造影剂微气泡激发的次谐波信噪比的方法。基于修正的Church方程,采用数值计算分析了锯齿波激励下微气泡产生的次谐波的声压阈值及变化特性,并与正弦波激励进行了比较。实验中采用声压相等的基频为2 MHz的锯齿波及正弦波激发一种自制的包膜微气泡造影剂,测量了产生次谐波的激励声压阈值及与激励声压的关系。结果表明,锯齿波信号激励可以增强次谐波信号的强度,相对于正弦波激励增强约13 dB,并且激发声压阈值较低。实验结果与数值计算结果相符。A method to improve the signal-noise-ratio of the sub-harmonics generated from Ultrasound Contrast Agents （UCA） by using a sawtooth signal excitation was proposed. Based on the modified Church equation, the threshold and sound pressure dependence for the sawtooth excitation were numerically calculated, and a comparison with the case＇ of sine excitation was made. In the measurement, a sawtooth wave and a sine wave at fundamental frequency 2 MHz and with equal sound pressure were used to drive a kind of self-developed UCA containing microbubbles, respectively. The threshold of sub-harmonic emission and the sound pressure dependence were measured. Results demonstrated that the sawtooth wave excitation can effectively enhance the sub-harmonic emission. Compared with the sine wave excitation the amplitude of sub-harmonics was improved by 13 dB, and the threshold value was decreased. The measured results were in agreement with the theoretical predictions.

关 键 词：超声造影剂 谐波信号 锯齿波 激励 数值计算分析 次谐波 微气泡 正弦波 

分 类 号：O426.2[理学—声学]