高强度聚焦超声辐照剂量与生物学效应研究

Study on Therapeutic Dosimetry and Biologic Effect of High Intensity Focused Ultrasound

研究高强度聚焦超声体外致凝固性坏死的辐照剂量及其对应产生的生物学效应。将新鲜离体牛肝组织(屠宰后6 h内),浸泡于0.9%NS中,常规脱气25 min后作为实验材料备用。实验设备为JC型高强度聚焦超声肿瘤治疗系统。治疗头频率1.6 MHz。采用定点点打方式辐照牛肝组织。固定辐照深度为20 mm。辐照声功率为65.44～196.32 W,分为8级,每级相差16.44 W,对应每级声功率,辐照时间分别为1～20 s。声功率与辐照时间的乘积即为辐照剂量。相同剂量下重复实验3次。取靶区灰白色区域与正常组织交界处组织送病理检查(HE染色),光镜下观察靶区和靶区边缘是否发生凝固性坏死。实验发现辐照所采用的声功率越大,达到凝固性坏死所需辐照时间越短,当声功率达到一定水平(超过179.96 W)只需1s就能致凝固性坏死;不同辐照剂量,生物学焦域形态不同,生物学焦域面积大小亦不同,生物学焦域面积与辐照剂量之间存在正相关(y=0.0164x1.0591,R2=0.9238,P<0.05)。因此,研究高强度聚焦超声辐照剂量与生物学效应关系,有助于临床治疗过程中辐照剂量的选择。

This study was aimed at exploring the high intensity focused ultrasound（HIFU） therapeutic dosimetry and its biologic effect. In-vitro, bovine liver was immersed into 0.9% NS and degassed for application. The JC Model-focused ultrasound tumor therapeutic system was used in the experiment. The HIFU parameters were： frequency 1.6 MHz,depth 20 mm, acoustic power from 16.44 W to 196.32W. Under each power, at radiating times from ls to 20 s, bioptic specimens were obtained from all samples. The results showed when the acoustic power was equal to or higher than 179.96 W, only ls of radiating is adequate to induce eoagulative necrosis, and when the acoustic power was lower than 65.44 W, the radiating time to produce coagulative necrosis was about 7 s. In the range of 65.44-179.96 W, at each time when the acoustic power was set up with an increment of 16.36 W, the time to produce coagulative necrosis was 1-2 s shorter. The form of biological focal region（BFR） varied with the acoustic power and HIFU irradiation time. The size of BFR increased with the increase of HIFU irradiation dosage （a- coustic power）〈 exposure time）. There is positive correlation between the size of BFR and the dosage of HIFU irradi- ation（y=0.0164x1.0591,R2=0.9238,P〈O.05）.