Li Faqi, Zhang Qiang, Du Yonghong, Xu Guihua, Wen Shuang, Bai Jin, Wu Feng, Wang Zhilong, Wang Zhibiao, Feng Ruo
Institute of Ultrasonic Engineering in Medicine, Chongqing University of Medical Sciences, Chongqing 400016.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi. 2003 Sep;20(3):466-71.
Based on the well-known Pennes' bioheat equation, we analyzed theoretically the temperature rise in tissue during high intensity focused ultrasound(HIFU) irradiation, and measured the focal temperature rise induced by HIFU in the treatment of freshly excised cow liver with different acoustic intensity and exposure time. The results showed that a threshold exposure time always existed under a certain acoustic intensity. Temperature rise was slow when exposure time exceeded the threshold exposure time. The greater the acoustic intensity was, the earlier the threshold time appeared. The focal temperature rise and the relative cumulative thermal dose (RCTD) increased with the increase of acoustic intensity and exposure time. For a certain therapeutic dose, the effects of acoustic intensity on focal temperature rise were more distinct than the effects of exposure time on focal temperature rise. Therefore, the optimal HIFU therapeutic dose should meet the need, i.e. moderate acoustic intensity, and the exposure time be the threshold exposure time under this acoustic intensity.
基于著名的彭尼斯生物热方程，我们从理论上分析了高强度聚焦超声（HIFU）辐照期间组织中的温度升高，并测量了在不同声强和暴露时间下HIFU治疗新鲜切除的牛肝时引起的焦点温度升高。结果表明，在一定声强下总是存在一个阈值暴露时间。当暴露时间超过阈值暴露时间时，温度升高缓慢。声强越大，阈值时间出现得越早。焦点温度升高和相对累积热剂量（RCTD）随声强和暴露时间的增加而增加。对于一定的治疗剂量，声强对焦点温度升高的影响比暴露时间对焦点温度升高的影响更明显。因此，最佳的HIFU治疗剂量应满足以下需求，即适中的声强，且暴露时间为该声强下的阈值暴露时间。
