title: Acoustic power measurement of high intensity focused ultrasound in medicine based on radiation force.
abstract: How to measure the acoustic power of HIFU is one of the most important tasks in its medical application. In the paper a whole series of formula for calculating the radiation force related to the acoustic power radiated by a single element focusing transducer and by the focusing transducer array were given. Various system of radiation force balance (RFB) to measure the acoustic power of HIFU in medicine were designed and applied in China. In high power experiments, the dependence of radiation force acting the absorbing target on the target position at the beam axis of focusing transducer was fined. There is a peak value of "radiation force" acting the absorbing target in the focal region when the acoustic power through the focal plane exceeds some threshold. In order to avoid this big measurement error caused by the 'peak effect' in focal region, the distance between the absorbing target of RFB and the focusing transducer or transducer array was defined to be equal to or less than 0.7 times of the focal length in the National Standard of China for the measurements of acoustic power and field characteristics of HIFU. More than six different therapeutic equipments of HIFU have been examined by RFB for measuring the acoustic power since 1998. These results show that RFB with the absorbing target is valid in the acoustic power range up to 500W with good linearity for the drive voltage squared of focusing transducer or array. The uncertainty of measurement is within +/-15%.
authors.affiliation: Department of Biomedical Engineering, Shanghai JiaoTong University, Shanghai 200030, China. wdshou@sjtu.edu.cn <wdshou@sjtu.edu.cn>
authors.forename: Wende
authors.initials: W
authors.lastname: Shou
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Huang
authors.forename: Shimei
authors.initials: S
authors.lastname: Duan
authors.forename: Rongmin
authors.initials: R
authors.lastname: Xia
authors.forename: Zhonglong
authors.initials: Z
authors.lastname: Shi
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Geng
authors.forename: Faqi
authors.initials: F
authors.lastname: Li
mesh_terms: D000162:Acoustics / Q000295:instrumentation; D019544:Equipment Failure Analysis / Q000295:instrumentation* / Q000379:methods*; D011829:Radiation Dosage; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical; D014159:Transducers; D014464:Ultrasonic Therapy / Q000295:instrumentation* / Q000379:methods*