Menikou Georgios, Damianou Christakis
Research Centre for Biomedical Engineering, City, University of London, London, UK.
Electrical Engineering Department, Cyprus University of Technology, Limassol, Cyprus.
J Ther Ultrasound. 2017 Jun 1;5:14. doi: 10.1186/s40349-017-0093-z. eCollection 2017.
This study describes a series of experimental work completed towards characterizing candidate materials for fabricating brain and muscle tissue mimicking phantoms.
The acoustic speed, attenuation, impedance, thermal diffusivity, specific heat and thermal conductivity were measured.
The resulting brain (2% w/v agar-1.2% w/v Silica Dioxide-25%v/v evaporated milk) and muscle tissue recipe (2% w/v agar-2% w/v Silica Dioxide-40%v/v evaporated milk) introduced a total attenuation coefficient of 0.59 dB/cm-MHz and 0.99 dB/cm-MHz respectively. Acrylonitrile Butadiene Styrene (ABS) possessed an attenuation coefficient of 16 dB/cm at 1 MHz which was found within the very wide range of attenuation coefficient values of human bones in literature. The thermal conductivity of the brain tissue phantom was estimated at 0.52 W/m°C and at 0.57 W/m.°Cfor the muscle. These values demonstrated that the proposed recipes conducted heat similar to the majority of most soft tissues found from bibliography. The soft tissue phantoms were also evaluated for their thermal repeatability after treating them repeatedly at different locations with the same sonication protocol and configuration. The average coefficient of variation of the maximum temperature at focus between the different locations was 2.6% for the brain phantom and 2.8% for the muscle phantom.
The proposed phantom closely matched the acoustic and thermal properties of tissues. Experiments using MR thermometry demonstrated the usefulness of this phantom to evaluate ultrasonic exposures.
本研究描述了一系列为表征用于制造模拟脑和肌肉组织的体模的候选材料而完成的实验工作。
测量了声速、衰减、声阻抗、热扩散率、比热容和热导率。
所得的脑（2% w/v琼脂-1.2% w/v二氧化硅-25% v/v脱脂乳）和肌肉组织配方（2% w/v琼脂-2% w/v二氧化硅-40% v/v脱脂乳）的总衰减系数分别为0.59 dB/cm-MHz和0.99 dB/cm-MHz。丙烯腈-丁二烯-苯乙烯共聚物（ABS）在1 MHz时的衰减系数为16 dB/cm，这一数值在文献中报道的人体骨骼衰减系数的很宽范围内。脑组织体模的热导率估计为0.52 W/m°C，肌肉组织体模的热导率为0.57 W/m°C。这些数值表明，所提出的配方传导热量的方式与文献中大多数软组织相似。还通过在不同位置以相同的超声处理方案和配置对软组织体模进行反复处理，评估了它们的热重复性。脑体模不同位置焦点处最高温度的平均变异系数为2.6%，肌肉体模为2.8%。
所提出的体模与组织的声学和热学特性紧密匹配。使用磁共振温度测量法进行的实验证明了该体模在评估超声暴露方面的实用性。
