Issue |
Acta Acust.
Volume 6, 2022
|
|
---|---|---|
Article Number | 41 | |
Number of page(s) | 8 | |
Section | Ultrasonics | |
DOI | https://doi.org/10.1051/aacus/2022036 | |
Published online | 23 September 2022 |
Technical & Applied Article
Formation process of thermal damage in a target area of high intensity focused ultrasound and effectiveness analysis of B-ultrasound real-time monitoring
1
College of Optoelectronic Engineering, Changchun University of Science and Technology, Changchun 130013, China
2
College of Metrology and Measurement Engineering, China Jiliang University, Hangzhou 310018, Zhejiang, China
3
Department of Medical Oncology, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310009, Zhejiang, China
* Corresponding author: wuyanqi@cjlu.edu.cn
Received:
2
June
2022
Accepted:
24
August
2022
High intensity of focused ultrasound (HIFU) is an effective tumor therapy, taking advantage of the thermal effect and cavitation effect to generate thermal damage to the target tissue. However, inaccurate ultrasonic dose control may result in ineffective or excessive treatment. Thus, real-time monitoring of the thermal damage formation process is critical. To evaluate the effectiveness of real-time monitoring of B-ultrasound, ex-vivo bovine livers were irradiated by 1.155 MHz focused ultrasound with emission time T1 of 200 ms and interval time T2 of 200 ms. For orthogonal experiments, ultrasound was irradiated at sound power of 100 W, 125 W, and 150 W for 10 s, 20 s, and 40 s, respectively. B-ultrasound image sequences are collected using a 7.5 MHz linear array and compared with backscattered echo signals and thermal damage slices, respectively, to build relationships between B-mode ultrasound monitoring and thermal effect or cavitation effect. The experimental results demonstrated that the tissue ablation process caused by thermal effect cannot be effectively monitored using B-ultrasound, but the process caused by the cavitation effect can. The analysis revealed a strong temporal correlation between the appearance of bright spots in B-ultrasound images and the sudden increase of the scattered echo power spectrum, which were caused by a large number of micro-bubbles from cavitation. The damaged cavity structure of the slices and the development trend of micro-bubbles showed a strong spatial correlation. Furthermore, the sudden increase in the scattered echo signal shows the potential of early warning of cavitation, as it is 1.2–2.0 s ahead of the bright spot in the B-ultrasound image, laying the experimental basis for improving the effectiveness of B-ultrasound monitoring in clinical HIFU surgery.
Key words: High intensity focused ultrasound / Thermal damage / Cavitation / B-ultrasound imaging / Real-time monitoring
© The Author(s), published by EDP Sciences, 2022
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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