HU DONG - School of Information Science and Engineering, Changsha Normal University, Changsha ۴۱۰۱۰۰, China
GANG LIU - School of Information Science and Engineering, Changsha Normal University, Changsha ۴۱۰۱۰۰, China School of Physics and Electronics, Central South University
ZHENZHONG MA - School of Information Science and Engineering, Changsha Normal University
GAOFENG PENG - School of Information Science and Engineering, Changsha Normal University
PING PAN - School of Information Science and Engineering, Changsha Normal University

Introduction: High-intensity Focused Ultrasound (HIFU) treatment is a non-invasive technology. The purpose of this study was to explore the effects of different treatment depths, tissue types and treatment interval on biological tissue thermal lesions under continuous and intermittent treatment modes.Material and Methods: A simulation model of biological tissue irradiated by HIFU was established by finite difference time domain (FDTD). The thermal lesion of biological tissue irradiated by HIFU was calculated using the spherical beam equation (SBE) and Pennes biological heat transfer equation (PBHTE). Parameters such as treatment depth, tissue type, and treatment interval were varied to explore their effects on the thermal lesion to biological tissues in both continuous and intermittent treatment modes.Results: For the same biological tissue or treatment depth, with the increase of HIFU irradiation time, the focal temperature under continuous treatment was higher than that under intermittent treatment, and the thermal lesion area under continuous treatment was greater than that under intermittent treatment. Whether continuous or intermittent treatment, with the increase of treatment depth, the temperature rise rate of deep tissue was slower than that of superficial tissue, and the thermal lesion area decreased gradually. Moreover, in the intermittent treatment mode with a long single treatment time and short treatment interval, the focal temperature rase quickly and the thermal lesion area was large.Conclusion: For the same tissue type, treatment depth, or any treatment interval, the focal temperature and thermal lesion area corresponding to continuous treatment were greater than those corresponding to intermittent treatment.

High, intensity Focused Ultrasound Treatment Interval Lesion Area Intermittent Treatment