Filippou Antria, Damianou Christakis
Department of Electrical Engineering, Computer Engineering and Informatics, Cyprus University of Technology, Limassol, Cyprus.
J Med Phys. 2024 Jul-Sep;49(3):343-355. doi: 10.4103/jmp.jmp_52_24. Epub 2024 Sep 21.
Phantoms are often utilized for the preclinical evaluation of novel high-intensity focused ultrasound (HIFU) systems, serving as valuable tools for validating efficacy. In the present study, the feasibility of a homogeneous agar-based breast-shaped phantom as a tool for the preclinical evaluation of HIFU systems dedicated to breast cancer was assessed. Specifically, the effect of the increased phantom curvature on temperature increase was examined through sonications executed on two sides having varied curvatures.
Assessment was performed utilizing a 1.1 MHz focused transducer. Sonications on the two phantom sides were executed at varied acoustical power in both a laboratory setting and inside a 1.5 T magnetic resonance imaging scanner. Sonications were independently performed on two identical phantoms for repeatability purposes.
Temperature changes between 7.1°C-34.3°C and 5.1°C-21.5°C were recorded within the decreased and increased curvature sides, respectively, for acoustical power of 3.75-10 W. High-power sonications created lesions which were approximately symmetrically formed around the focal point at the decreased curvature side, while they were shifted away from the focal point at the increased curvature side.
The present findings indicate that increased curvature of the breast phantom results in deformed focal shapes and decreased temperatures induced at the focal area, thus suggesting treatment correction requirements in the form of focus control or accurate robotic movement. The developed breast-shaped phantom can be utilized as an evaluation tool of HIFU systems dedicated to breast cancer since it can visually verify the efficacy of any system.
体模常用于新型高强度聚焦超声（HIFU）系统的临床前评估，是验证疗效的重要工具。在本研究中，评估了基于琼脂的均匀乳房形状体模作为用于乳腺癌的HIFU系统临床前评估工具的可行性。具体而言，通过在具有不同曲率的两侧进行超声处理，研究了体模曲率增加对温度升高的影响。
使用1.1MHz聚焦换能器进行评估。在实验室环境和1.5T磁共振成像扫描仪内，在体模的两侧以不同的声功率进行超声处理。为了保证可重复性，在两个相同的体模上独立进行超声处理。
对于3.75 - 10W的声功率，在曲率减小侧和曲率增加侧分别记录到7.1°C - 34.3°C和5.1°C - 21.5°C的温度变化。高功率超声处理产生的损伤在曲率减小侧围绕焦点大致对称形成，而在曲率增加侧则偏离焦点。
本研究结果表明，乳房体模曲率增加会导致焦点形状变形以及焦点区域温度降低，因此提示需要通过焦点控制或精确的机器人运动等形式进行治疗校正。所开发的乳房形状体模可作为用于乳腺癌的HIFU系统的评估工具，因为它可以直观地验证任何系统的疗效。
