Li Faqi, Wang Zhibiao, Du Yonghong, Ma Ping, Bai Jin, Wu Feng, Feng Ruo
Department of Biomedical Engineering, Institute of Ultrasonic Engineering in Medicine, Chongqing University of Medical Sciences, Chongqing 400016, China.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi. 2006 Aug;23(4):839-43.
It is a difficult problem in high intensity focused ultrasound (HIFU) therapeutic dosimetry that how to use a BFR to ablate a mass in tissue and to determine the energy-efficiency relation, that is, the scale of biological effects of HIFU. A mass lesion was realized in this study according to a treatment principle of damaging tissue from BFRs to fascicle lesions, slice lesions and a mass lesion. A 1.6 MHz transducer, 150 mm in diameter and with a focal length of 120 mm, was used. The focal intensities (I(SATA)) were 0-27 000 W/cm2 and the scanning speeds were 1-4 mm/s. The distance between every fascicle lesion was 5-10 mm and the distance between two slice lesions was 10-20 mm. Different irradiation depths of fascicle slice and mass lesion were observed after HIFU procedures in this study. The dosage of HIFU required for tissue coagulated necrosis was evaluated with energy of HIFU (J) per cubic millimeter (mm3), i.e., J/mm3 which was defined as energy-efficiency factor (EEF). Results showed that EEF needed for producing fascicle lesions increased with the increase of irradiation depth. EEF required for inducing various lesions in biological tissue was different. Generally, it followed the law: EEF(mase)< EEF(slice)<EEF(fascicle). EEF for slice lesion was not simply a summation of EEFs for fascicle lesions at different irradiation depths, although the slice lesion was assembled with fascicle lesions at different irradiation depths in the same treatment slice. In the same way, EEF for a mass lesion was not simple summation of EEFs for slice lesions at different layers. So HIFU therapeutic dosimetry can be carried on investigation by using EEF, Factors of affecting EEF of HIFU include acoustic power, exposure time, irradiation depth, tissue structure, and tissue functional status. Besides, another important factor is the change of the acoustic environment in tissue during the HIFU procedure.
在高强度聚焦超声（HIFU）治疗剂量学中，一个难题是如何利用声束辐射（BFR）消融组织中的肿块并确定能量效率关系，即HIFU的生物效应规模。本研究根据从声束辐射损伤组织到束状损伤、片状损伤和肿块损伤的治疗原则实现了肿块病变。使用了一个直径150毫米、焦距120毫米的1.6兆赫换能器。焦点强度（I(SATA)）为0至27000瓦/平方厘米，扫描速度为1至4毫米/秒。每个束状损伤之间的距离为5至10毫米，两个片状损伤之间的距离为10至20毫米。本研究在HIFU治疗后观察了束状、片状和肿块损伤的不同照射深度。用每立方毫米（mm3）的HIFU能量（J）评估组织凝固性坏死所需的HIFU剂量，即J/mm3，其被定义为能量效率因子（EEF）。结果表明，产生束状损伤所需的EEF随照射深度的增加而增加。诱导生物组织中各种损伤所需的EEF不同。一般来说，遵循以下规律：EEF(肿块) < EEF(片状) < EEF(束状)。片状损伤的EEF并非不同照射深度下束状损伤EEF的简单总和，尽管片状损伤是在同一治疗切片中由不同照射深度的束状损伤组合而成。同样，肿块损伤的EEF也不是不同层面片状损伤EEF的简单总和。因此，可以通过使用EEF进行HIFU治疗剂量学研究。影响HIFU的EEF的因素包括声功率、暴露时间、照射深度、组织结构和组织功能状态。此外，另一个重要因素是HIFU治疗过程中组织内声环境的变化。
