本文選題：高強度聚焦超聲　切入點：超聲空化碎石　出處：《清華大學(xué)》2014年碩士論文

【摘要】：腎結(jié)石病是一種常見病，在我國發(fā)病規(guī)模逐年增大。目前腎結(jié)石病的治療方式如外科手術(shù)、體外沖擊波碎石術(shù)等都存在副作用大、治療效果差等弊端。隨著超聲空化現(xiàn)象的深入研究，越來越多的研究者開始致力于將超聲空化運用于腎結(jié)石病的體外治療。 高強度聚焦超聲(HIFU-High Intensity Focused Ultrasound)在液體中可以誘發(fā)強烈的空化現(xiàn)象，這種空化現(xiàn)象以空化云的形式出現(xiàn)。當這些空化云作用于腎結(jié)石時，空化泡破碎產(chǎn)生的高溫高壓以及微射流將會快速磨蝕腎結(jié)石，粉末可達微米級大小，足以快速排出體外�？紤]到結(jié)石的不規(guī)則形狀，本文通過改變由結(jié)石作用面曲率定義的參數(shù)ξ（ξ越大曲率越�。沪�=1時，結(jié)石作用面為平面）研究不同形狀結(jié)石的碎石過程，，并通過高速攝影和聲致發(fā)光的方法觀察和測量空化云的行為。 具體來說，本文建立了一套完整的超聲空化碎石試驗臺，使用高強度聚焦超聲換能器以及其配套設(shè)施產(chǎn)生聚焦空化場，制作不同曲率仿天然結(jié)石進行碎石試驗，并通過3D掃描研究其體積損失隨時間的變化。在除氣NaCl溶液中，利用高強度脈沖激光誘發(fā)空化核定位空化云位置，使用高速攝像機記錄空化云在聚焦超聲場中的運動。在配置的魯米諾溶液中，利用單反相機和光電倍增管觀察、測量空化云造成的聲致發(fā)光分布。主要研究結(jié)論如下： （1）超聲空化碎石過程分兩個階段，第一階段結(jié)石磨蝕由邊緣開始，隨后向中心靠攏。結(jié)石截面積逐漸增加，當達到空化云作用面面積（超聲聲場焦域截面積）時，外緣將不會被磨蝕進入第二階段。在碎石開始階段（0-30s），曲率更大（ξ更�。┑慕Y(jié)石模型獲得了更快的碎石速度，隨著曲率增加（ξ減少），體積損失越來越大，但在0.5后，體積損失的變化不再明顯。 （2）超聲波在障礙物處反彈形成駐波，使空化云的上升過程出現(xiàn)脈動現(xiàn)象，在接觸曲率壁面后，由于聲流和壁面頂端的分流作用，空化云的振動區(qū)域在頂端附近形成環(huán)形區(qū)域。障礙物曲率的變化將會對空化云上升的速度有所影響，曲率更大（ξ更�。┑谋诿鎸�(yīng)的空化云上升速度更快，反之則速度更慢。 （3）加入結(jié)石模型后整體空化強度提高，結(jié)石周圍形成回流，導(dǎo)致結(jié)石模型下方出現(xiàn)阻滯區(qū)域。這種情況隨著ξ的逐步增大（曲率減小）越來越明顯。結(jié)石模型的處于焦域中心偏上位置空化強度最高。
[Abstract]:Kidney stone disease is a common disease, in our country the scale of disease increases year by year.At present, the treatment of renal calculi, such as surgery, extracorporeal shock wave lithotripsy, has many disadvantages.With the in-depth study of ultrasound cavitation, more and more researchers begin to apply ultrasound cavitation to the treatment of renal calculi in vitro.HIFU-High Intensity Focused ultrasound (HIFU-High Intensity Focused ultrasound) can induce strong cavitation in liquid, which appears in the form of cavitation cloud.When these clouds act on the kidney stones, the high temperature and high pressure produced by the cavitation bubble breakup and the micro-jet will erode the kidney stone rapidly, and the powder can be as large as micron size, which is enough to be discharged from the body quickly.Considering the irregular shape of stone, this paper studies the lithotriptic process of stone with different shapes by changing the parameter 尉 defined by curvature of the action surface of stone, which is defined by curvature of stone action surface, which is smaller and bigger curvature; 尉 = 1, stone action surface is plane.The behavior of cavitation cloud was observed and measured by high-speed photography and sonoluminescence.Specifically, a complete set of ultrasonic cavitation gravel test bench is established, which uses high intensity focused ultrasonic transducer and its supporting facilities to produce focused cavitation field, and makes lithotripsy test with different curvature imitating natural stones.The change of volume loss with time was studied by 3D scanning.High intensity pulsed laser induced cavitation nuclei were used to locate the position of cavitation cloud in NaCl solution, and high-speed cameras were used to record the motion of cavitation cloud in focused ultrasound field.The sonoluminescence distribution caused by cavitation cloud was measured by using a SLR camera and a photomultiplier tube in the collocated Lumino solution.The main findings are as follows:Ultrasonic cavitation lithotripsy process is divided into two stages, the first stage of stone erosion from the edge, and then close to the center.The cross section area of stone increases gradually, and when the area of cavitation cloud action surface (focal area of ultrasonic sound field) is reached, the external edge will not be eroded into the second stage.In the initial stage of lithotripsy, the stone model with larger curvature (尉 smaller) obtains faster gravel velocity. With the increase of curvature (尉 decreases), the volume loss becomes larger and larger, but after 0.5, the change of volume loss is not obvious.2) the ultrasonic wave bounces back at the obstacle to form standing wave, which makes the rising process of cavitation cloud appear pulsating phenomenon. After contacting the curvature wall, the vibration region of the cavitation cloud forms a ring area near the top because of the flow of sound and the shunt of the top of the wall.The change of obstacle curvature will affect the rising speed of cavitation cloud, and the cavitation cloud with larger curvature (尉 smaller) will rise faster, otherwise it will be slower.3) after the stone model was added, the overall cavitation intensity increased and the reflux formed around the stone, which led to the block area under the stone model.This situation becomes more and more obvious with the gradual increase (curvature decrease) of 尉.The cavitation intensity of stone model is the highest in the center of focal region.
【學(xué)位授予單位】：清華大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：R692.4

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