高强度超声聚焦焦域大小的剂量学研究

Study on the dosimetry of high intensity focused ultrasoundon to produce the biological focal region

目的:体外体模辐照实验研究高强度聚焦超声(HIFU)不同辐照剂量下焦域形成规律,为临床提供参考。方法:运用PRO2008型聚焦超声子宫肌瘤治疗系统,超声换能器频率为1.3MHz、焦距130mm,设置声强5×103W/cm^2、辐照深度19mm,采用脉冲波辐照仿组织体模,通过改变辐照功率及时间,测量焦域的长短轴,同时,在辐照功率恒定时,改变单点打击时间和次数,测量焦域长短轴。结果:随辐照功率和时间的增加,HIFU形成的焦域长轴和短轴长度均增加,但其比值减小,当辐照功率恒定时,HIFU生物学焦域的长轴和短轴长度均随单点打击时间和打击次数增加而增加。结论:辐照剂量影响HIFU焦域形态,HIFU辐照体模所形成的焦域大小呈剂量依赖型。

Objective：To explore the dosimetry effect on the size of biological focal region （BFR） of high intensity focused ultrasound （HIFU） and provide clue to clinical use.Methods：PRO2008 Focused Ultrasound uterine fibroids Therapeutic System （transducer：1.6 MHz,focal length： 130 mm） was used in this study. Pulsed focused ultrasound was used to irradiate freshly made transparent tissue-mimicking phantom at a fixed ultrasound intensity of 5000W/cm2 and a fixed depth of 19mm.By changing the output power and irradiation time, different dosage were used to irradiate the phantom. After the exposure, the long and short axes of the biological focused region（BFR） was measured.Results：With the increase of acoustic intensity and exposure time, the length and width of BFR increased, but the ratio of length/width of BRF decreased. When the intensity was constant, the length and width of the BFR increased with the increase of impulse time.Conclusion：The exposure dose has influence on the size of a BFR of HIFU and the size of BFR dependent on the dose of HIFU irradiation which has provided evidence for the study of dosimetry of HIFU.