Variations in temperature distribution and tissue lesion formation induced by tissue inhomogeneity for therapeutic ultrasound.
Tissue inhomogeneity might have an important effect on the treatment accuracy of therapeutic ultrasound. Both computer simulation and measurement were performed to study the influence of tissue inhomogeneity on the temperature distribution and tissue lesion formation induced by focused ultrasound. The inhomogeneous tissue is considered a combination of a homogeneous medium and a phase aberration screen in this article. Temperature distributions and lesion dimensions were predicted using the combination of acoustic non-linear and bio-heat transfer equations. To verify the theoretical predictions, polyethylene plates with phase distributions of different correlation lengths and standard deviations were made to mimic inhomogeneous tissues such as human abdominal tissue, and a series of experiments were performed, including acoustic and thermal measurements. The results indicate that the tissue inhomogeneity caused phase aberration of the ultrasound beam. With increasing standard deviation and correlation length of phase aberration, the scattering level of the acoustic field increased, while ultrasound-induced peak temperature and lesion size decreased. This study provides a theoretical and experimental basis for future development of accurate treatment plans for high-intensity focused ultrasound.
Key Laboratory of Modern Acoustics (Nanjing University), Ministry of Education, Nanjing, China; Nanjing Normal University, Nanjing, China.
Zhenbo
Z
Liu
Key Laboratory of Modern Acoustics (Nanjing University), Ministry of Education, Nanjing, China.
Xiasheng
X
Guo
Key Laboratory of Modern Acoustics (Nanjing University), Ministry of Education, Nanjing, China. Electronic address: juantu@nju.edu.cn.
Juan
J
Tu
Key Laboratory of Modern Acoustics (Nanjing University), Ministry of Education, Nanjing, China; State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing, China. Electronic address: dzhang@nju.edu.cn.
Dong
D
Zhang
D003198:Computer Simulation; D004735:Energy Transfer / Q000502:physiology*; D057086:High-Intensity Focused Ultrasound Ablation / Q000379:methods*; D006358:Hot Temperature; D008954:Models, Biological; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D014018:Tissue Distribution
High-intensity focused ultrasound; Phase aberration; Temperature field; Tissue inhomogeneity