本文選題：高強(qiáng)度聚焦超聲 + 損傷��； 參考：《重慶醫(yī)科大學(xué)》2015年碩士論文

【摘要】：背景高強(qiáng)度聚焦超聲(HIFU)作為一種無創(chuàng)治療方法,已用于子宮肌瘤、前列腺癌、肝癌、胰腺癌、乳腺癌等良惡性腫瘤的臨床治療,并展示良好的安全性和有效性。HIFU輻照所致?lián)p傷是超聲非線性傳播、熱效應(yīng)、空化和沸騰泡作用的結(jié)果。氣泡溶解率、氣泡動力學(xué)和沸騰溫度被認(rèn)為是壓力的函數(shù),已經(jīng)證實,過壓能夠通過溶解氣泡、限制氣泡振蕩和提高沸點的方式最小化氣泡和氣泡的活動,即過壓能提高空化閾值從而抑制空化的發(fā)生和程度。因而,過壓提供了一種研究HIFU治療機(jī)制的手段,不同研究者對過壓下HIFU所致?lián)p傷的變化持有不同的觀點,為進(jìn)一步研究不同環(huán)境壓力下HIFU對組織損傷的影響,并探討其作用機(jī)理,本實驗采用兩個不同的HIFU輻照強(qiáng)度在梯度環(huán)境壓力下進(jìn)行離體牛肝組織實驗,并通過只考慮非線性作用的KZK方程進(jìn)行理論仿真,比較了不同環(huán)境壓力下,空化對牛肝組織損傷的影響。與過壓相比,由于負(fù)壓能進(jìn)一步降低介質(zhì)水溶氧量,負(fù)壓對HIFU治療的影響尚未有研究報道。目的探討不同環(huán)境壓力和溶氧量對HIFU所致?lián)p傷的影響,以期認(rèn)識過壓、負(fù)壓/不同溶氧量下非線性傳播、空化和沸騰對HIFU所致?lián)p傷的作用。方法1.過壓對等劑量下不同HIFU聲強(qiáng)所致離體牛肝組織損傷的影響實驗分為理論仿真和組織實驗兩部分。理論部分基于KZK方程計算了常壓下空間平均聲強(qiáng)3,900W/cm2和6,240W/cm2的非線性波形畸變和諧波滋生,并對相同輻照劑量3,900W/cm2×8s和6,240W/cm2×5s的熱劑量(CEM43℃)范圍進(jìn)行了比較,說明非線性傳播對損傷的貢獻(xiàn)；實驗部分采用1MHz的HIFU換能器在常壓、0.5MPa、1.0MPa、 1.5MPa、2.0MPa、2.5MPa和3.OMPa七個環(huán)境壓力兩個輻照劑量下對離體牛肝組織分別進(jìn)行輻照,比較損傷的形態(tài)、大小、程度并且PCD檢測常壓下的空化信號(有空化組和無空化組)。2.負(fù)壓(-0.09MPa)和不同溶氧量(2. Omg/L、1.5mg/L、1.0mg/L)對HIFU所致?lián)p傷的影響及焦域處回聲和空化信號的變化用新鮮離體牛肝組織作為實驗材料,在上述不同環(huán)境條件下,使用頻率1.OMHz,輻照強(qiáng)度為11,700W/cm2×2s,輻照過程中分別采用被動空化檢測系統(tǒng)(PCD)和超聲(US)對輻照焦域處的氣泡和回聲進(jìn)行監(jiān)控。結(jié)果1.基于KZK方程仿真計算的6,240W/cm2下的反映非線性傳播的P+/P-、諧波與基波的比值均大于3,900W/cm2,但相同輻照劑量3,900W/cm2×8s和6,240W/cm2×5s的熱劑量范圍差別不大。2.常壓下高聲強(qiáng)6,240W/cm2×5s輻照過程有明顯寬帶噪聲信號,表明有空化參與,而低聲強(qiáng)3,900W/cm2×8s輻照時沒有。3.3,900W/cm2×8s輻照后,損傷未隨環(huán)境壓力發(fā)生顯著改變(p0.05),與未考慮空化的理論計算結(jié)果基本一致。而6,240W/cm2×5s輻照后,常壓下比低聲強(qiáng)輻照的損傷偏大且有明顯變形,明顯大于未考慮空化的KZK方程仿真結(jié)果。4.6,240W/cm2×5s輻照后,0.5MPa, 1.0MPa下?lián)p傷較常壓下增大(p0.05),出現(xiàn)對稱碳化壞死。5.6,240W/cm2×5s輻照后,隨著壓力增大至1.5MPa、2.0MPa、 2.5MPa和3.OMPa,損傷基本一致(p0.05),但都比常壓下?lián)p傷偏小(p0.05),這與未考慮空化的KZK方程仿真結(jié)果和低聲強(qiáng)輻照的損傷基本一致(p0.05)。6.無論是常壓還是負(fù)壓條件下,輻照參數(shù)為11,700W/cm2×2s,溶氧量分別為2. Omg/L、1.5 mg/L、1.0 mg/L,隨著溶氧量的降低,損傷減小,且趨于橢球形對稱分布；相同溶氧量時,負(fù)壓條件下的損傷明顯小于常壓下的損傷(p0.05),且負(fù)壓下、溶氧量1.0 mg/L時甚至未形成損傷。7.無論是常壓還是負(fù)壓條件下,輻照參數(shù)為11,700W/cm2×2s,溶氧量分別為2. Omg/L、1.5 mg/L、1.0 mg/L,輻照后B超圖像上焦域處強(qiáng)回聲水平隨溶氧量的降低而減��；相同溶氧量時,負(fù)壓條件下輻照后B超圖像上焦域處強(qiáng)回聲水平明顯小于常壓下的強(qiáng)回聲水平,且負(fù)壓下、溶氧量為1.0 mg/L時未出現(xiàn)肉眼可見的回聲增強(qiáng),甚至未形成損傷。8.常壓下,輻照參數(shù)為11,700W/cm2×2s,溶氧量分別為2. Omg/L、1.5mg/L、1.0 mg/L,隨著溶氧量的降低,HIFU輻照過程中3-7MHz寬帶噪聲水平減弱。溶氧量為2.Omg/L,與常壓相比,負(fù)壓下HIFU輻照過程中的寬帶噪聲水平減弱。結(jié)論1.常壓下,對等劑量的兩組輻照參數(shù)6,240W/cm2×5s和3900W/cm2×8s,前者有空化發(fā)生,后者未發(fā)生空化,而基于KZK方程仿真計算的兩組熱劑量范圍差別不大；但輻照參數(shù)6,240W/cm2×5s在離體牛肝組織中形成的損傷大于3900W/cm2×8s,也遠(yuǎn)大于仿真結(jié)果,且形態(tài)不對稱,說明瞬態(tài)空化是HIFU所致?lián)p傷增大的主要原因。2.對常壓下未發(fā)生空化的輻照參數(shù)3,900W/cm2×8s,環(huán)境壓力為常壓、0.5MPa, 1.0MPa、1.5MPa、2.0MPa、2.5MPa和3.OMPa時,隨環(huán)境壓力升高,HIFU所致?lián)p傷大小、形態(tài)、程度均未發(fā)生顯著變化,說明環(huán)境壓力升高引起的組織聲參數(shù)的變化對損傷的變化基本沒有影響。3.對常壓下發(fā)生空化的輻照參數(shù)6,240W/cm2×5s,當(dāng)環(huán)境壓力增加至0.5MPa、1.0MPa時,HIFU輻照后的離體牛肝組織損傷較常壓下有顯著增加(p0.05),形狀由水滴狀變?yōu)闄E球狀,并在焦域處出現(xiàn)了邊界明顯的碳化性壞死。4.對常壓下發(fā)生空化的輻照參數(shù)6,240W/cm2×5s,當(dāng)環(huán)境壓力繼續(xù)增加至1.5MPa、2.0MPa、2.5MPa和3.OMPa時,損傷范圍基本一致,且小于常壓下的損傷范圍；同時損傷范圍和理論仿真結(jié)果,以及不同環(huán)境壓力下輻照參數(shù)3,900W/cm2×8s的損傷范圍基本一致。說明此時空化已被完全抑制,只有超聲非線性傳播的作用,空化對損傷的作用遠(yuǎn)大于非線性傳播。5.無論是常壓還是負(fù)壓下,輻照參數(shù)為11,700W/cm2×2s下的損傷隨著溶氧量的降低而減小,且相同溶氧量下,負(fù)壓下的損傷明顯小于常壓下的損傷,從被動空化檢測和B超圖像上回聲監(jiān)控得到其原因與負(fù)壓和降低介質(zhì)水中溶氧量能不同程度抑制空化作用有關(guān)。
[Abstract]:Background High intensity focused ultrasound ( HIFU ) has been used as a noninvasive method to treat benign and malignant tumors , such as uterine fibroids , prostate cancer , liver cancer , pancreatic cancer and breast cancer .
The experimental parts were irradiated with a 1MHz HIFU transducer at normal pressure , 0.5MPa , 1.0MPa , 1.5MPa , 2.0MPa , 2.5MPa and 3.OMPa at two irradiation doses . The morphology , size and degree of damage were compared , and the cavitation signal at normal pressure was detected by PCD ( cavitation group and cavitation group ) . 2 . Negative pressure ( - 0.09MPa ) and different dissolved oxygen ( 2 ) . The effects of Omg / L , 1.5mg / L , 1.0 mg / L on HIFU - induced damage and the change of echo and cavitation signals in focal area were monitored . Results 1 . The results showed that the ratio of harmonic to fundamental wave was more than 3 , 900 W / cm ~ 2 at normal pressure . Omg / L , 1.5 mg / L , 1.0 mg / L , decreased with the decrease of dissolved oxygen , and tended to be ellipsoidal symmetric distribution ;
Under the condition of atmospheric pressure or negative pressure , the irradiation parameters were 11,700 W / cm2 脳 2s and the dissolved oxygen content was 2 . Omg / L , 1.5 mg / L , 1.0 mg / L , the strong echo level at the focal region of B - ultrasonic image after irradiation decreased with the decrease of dissolved oxygen ;
At the same dissolved oxygen level , the strong echo level at the upper focal region of B - ultrasonic image after irradiation under negative pressure was significantly lower than that at atmospheric pressure , and no visible echo enhancement occurred at 1.0 mg / L under negative pressure , even without damage . 8 . Under normal pressure , the irradiation parameters were 11,700 W / cm2 脳 2s and the dissolved oxygen content was 2 . Conclusion 1 . Under normal pressure , two groups of irradiation parameters 6 , 240 W / cm 2 脳 5 s and 3900W / cm 2 脳 8 s , the former has cavitation , and the difference between the two groups is not large .
The damage size , shape and extent of HIFU induced by HIFU were more than 3900W / cm ~ 2 脳 8 s , which was more than 3900W / cm ~ 2 脳 8 s .
At the same time , the damage range and the theoretical simulation result , and the irradiation parameters 3 , 900 W / cm 2 脳 8 s in different ambient pressure are basically consistent . The results show that the cavitation has been completely suppressed , and only the effect of ultrasonic nonlinear propagation is more than that of non - linear propagation . 5 . Under normal pressure or negative pressure , the damage of cavitation damage is much larger than that of non - linear propagation . Under the same oxygen dissolved oxygen , the damage under negative pressure is obviously lower than that under normal pressure . The reason is related to the negative pressure and the decrease of dissolved oxygen content in the medium water .

【學(xué)位授予單位】：重慶醫(yī)科大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：R454.3

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