本文選題：HIFU + 經(jīng)顱聚焦�。� 參考：《天津醫(yī)科大學(xué)》2015年碩士論文

【摘要】：高強(qiáng)度聚焦超聲(High Intensity Focused Ultrasound,HIFU)技術(shù)已被應(yīng)用于臨床治療實(shí)體性肝腫瘤、子宮肌瘤等,因其具有的非侵入性和可重復(fù)治療性被引入經(jīng)顱腦腫瘤治療和經(jīng)顱藥物傳遞等。由于顱內(nèi)靶區(qū)被顱骨包圍,顱骨與腦組織的聲學(xué)參數(shù)存在巨大差異,使經(jīng)顱傳播的聲波發(fā)生相位和幅值畸變,導(dǎo)致經(jīng)顱骨聲波偏離設(shè)定焦點(diǎn)聚焦、對(duì)顱骨及周邊組織可能造成熱損傷等問(wèn)題的發(fā)生。研究精確有效的經(jīng)顱聚焦方法和降低對(duì)顱骨及周邊組織熱損傷的方法非常必要。研究目的由于HIFU經(jīng)非均質(zhì)顱骨傳播時(shí)發(fā)生相位失真、幅值畸變導(dǎo)致經(jīng)顱HIFU聲波在顱內(nèi)設(shè)定焦點(diǎn)處不能聚焦,對(duì)顱骨及其周邊組織造成熱損傷。本文通過(guò)對(duì)相控?fù)Q能器陣元激勵(lì)信號(hào)相位、幅值及消除顱骨內(nèi)高聲壓的信號(hào)相位和幅值的調(diào)控,調(diào)控經(jīng)顱聚焦形成的聲場(chǎng)及溫度場(chǎng),實(shí)現(xiàn)顱骨及周邊組織無(wú)傷的HIFU經(jīng)顱內(nèi)高效精確聚焦,為經(jīng)顱HIFU應(yīng)用于臨床治療提供理論參考。研究方法本研究以人體頭顱CT掃描數(shù)據(jù)的重建圖像為基礎(chǔ),結(jié)合小開(kāi)口64陣元球冠狀相控?fù)Q能器,建立三維HIFU經(jīng)顱數(shù)值仿真模型,以時(shí)域有限差分法(Finite Difference Time Domain,FDTD)數(shù)值解析Westervelt非線性聲波傳播方程和Pennes生物熱傳導(dǎo)方程,分析HIFU經(jīng)顱后形成的聲場(chǎng)及溫度場(chǎng)分布。應(yīng)用基于時(shí)間反轉(zhuǎn)的相位和幅值調(diào)制法獲得相控?fù)Q能器陣元的激勵(lì)信號(hào),根據(jù)這些激勵(lì)信號(hào)形成的聲場(chǎng)及溫度場(chǎng),分析與討論不同陣元激勵(lì)信號(hào)對(duì)其形成聲場(chǎng)及溫度場(chǎng)的影響及調(diào)控作用;利用溫度閾值和熱劑量法分析對(duì)正常組織可能存在的傷害和靶區(qū)內(nèi)形成的治療焦域體積;在對(duì)正常組織無(wú)傷害的前提下分析相控?fù)Q能器可實(shí)現(xiàn)的調(diào)控區(qū)域,并對(duì)形成的可治療焦域體積進(jìn)行調(diào)控。研究結(jié)果1.調(diào)控?fù)Q能器陣元激勵(lì)信號(hào)對(duì)經(jīng)顱聲波進(jìn)行相位校正聚焦時(shí),形成焦點(diǎn)在設(shè)定位置處,但顱骨內(nèi)可能存在高聲壓,顱骨處高聲壓與焦點(diǎn)聲壓比值(骨焦比)較大;再結(jié)合幅值校正后,焦點(diǎn)處聲壓較僅作相位校正時(shí)的聲壓有所升高,顱骨內(nèi)聲壓略有降低,骨焦比略降低;采用相位校正結(jié)合降低顱骨內(nèi)高聲壓后,骨焦比降低,顱骨內(nèi)高聲壓降低,但焦點(diǎn)處聲壓也降低;采用相位及幅值校正結(jié)合降低顱骨內(nèi)高聲壓調(diào)控法后,骨焦比和顱骨內(nèi)高聲壓繼續(xù)降低,焦點(diǎn)處聲壓相對(duì)于相位校正后的無(wú)變化。2.聲軸上聚焦時(shí),采用幅值校正后,焦點(diǎn)聲壓和可治療焦域體積比不做幅值校正時(shí)均有增大。3.基于時(shí)間反轉(zhuǎn)的數(shù)值擬合法與互相關(guān)法獲得的調(diào)控陣元激勵(lì)信號(hào)的相位信息,都可用于經(jīng)顱聲場(chǎng)的相位校正。4.對(duì)相控?fù)Q能器不同環(huán)上陣元激勵(lì)信號(hào)進(jìn)行相位和幅值調(diào)制,以調(diào)制換能器外環(huán)陣元信號(hào)的幅值作用較佳,這種調(diào)節(jié)模式既可使焦點(diǎn)達(dá)到可治療的溫度,也可使顱骨與水的臨界面溫度降低。5.經(jīng)顱聲波的非線性導(dǎo)致焦點(diǎn)處的聲壓、溫度和熱量沉積均大于線性。6.經(jīng)枕骨窗聚焦時(shí),在聚焦深度為25 mm的條件下,沿垂直于換能器聲軸的Y軸方向偏離距離小于等于5 mm的范圍內(nèi)可實(shí)現(xiàn)僅針對(duì)靶區(qū)組織且對(duì)非靶區(qū)組織不會(huì)造成傷害的聚焦,而不能在沿Z方向偏離聲軸實(shí)現(xiàn)安全聚焦。7.經(jīng)顱聲波調(diào)控后聚焦形成的焦域體積隨垂直偏離換能器聲軸距離增大而減小;當(dāng)偏離聲軸距離一定時(shí),焦域體積隨輸入聲強(qiáng)增大而呈近似線性關(guān)系增大;調(diào)控?fù)Q能器陣元的輸入聲強(qiáng),可調(diào)控偏離換能器聲軸聚焦時(shí)焦域體積的大小,使不同偏離距離下聚焦形成的焦域體積與在軸聚焦時(shí)體積相同。研究結(jié)論1.相控?fù)Q能器陣元激勵(lì)信號(hào)直接影響相控?fù)Q能器經(jīng)顱聚焦形成聲壓場(chǎng)和溫度場(chǎng),通過(guò)調(diào)制相控?fù)Q能器陣元激勵(lì)信號(hào)相位和幅值,可使經(jīng)顱聲波精確聚焦,提高焦點(diǎn)處最大聲壓和最高溫度,增大在焦點(diǎn)處的經(jīng)顱聲能量聚積。2.通過(guò)疊加降低顱骨內(nèi)高聲壓的激勵(lì)信號(hào),可使聲波在顱骨內(nèi)的能量沉積減小,避免聲波對(duì)顱骨造成熱損傷;也可針對(duì)換能器不同環(huán)陣元激勵(lì)信號(hào)的幅值進(jìn)行調(diào)控,尤其只對(duì)換能器外環(huán)陣元信號(hào)調(diào)控時(shí),可使顱骨與水的臨界面的溫度降低。3.經(jīng)顱聲波的非線性影響聚焦形成的聲壓場(chǎng)和溫度場(chǎng),經(jīng)顱HIFU治療時(shí)需要考慮其非線性。4.當(dāng)聲窗一定時(shí),存在聲波經(jīng)顱偏離換能器聲軸安全聚焦的距離,且隨垂直偏離聲軸距離的增大,聚焦形成的體積減小,但可根據(jù)垂直偏離聲軸的距離及聲強(qiáng)的線性關(guān)系,調(diào)節(jié)換能器陣元的輸入聲強(qiáng),使偏離聲軸聚焦時(shí)形成的焦域體積與在軸聚焦時(shí)一致。本研究通過(guò)數(shù)值仿真方法,研究調(diào)控經(jīng)顱聲波聚焦形成溫度場(chǎng)的方法,解決了經(jīng)顱聲波不能在設(shè)定焦點(diǎn)聚焦且對(duì)顱骨造成熱損傷的問(wèn)題,在完成顱內(nèi)精確聚焦且不熱損傷顱骨的同時(shí),通過(guò)調(diào)控聲波幅值的方法提升了焦點(diǎn)處的能量沉積,使聲波能量更加集中于需治療的焦域處。并通過(guò)調(diào)控聲強(qiáng)的方法,提供補(bǔ)償聲強(qiáng)及偏離聲軸聚焦的關(guān)系,對(duì)臨床聚焦治療劑量提供理論參考。
[Abstract]:High intensity focused ultrasound (High Intensity Focused Ultrasound, HIFU) technology has been applied to the clinical treatment of solid liver tumors, uterine leiomyoma, etc. because of its noninvasive and repeatable therapeutic effects that are introduced through Craniocerebral Tumor Therapy and transcranial drug delivery. The acoustic parameters of the skull and brain tissue are surrounded by skull targets. There is a huge difference in the distortion of the phase and amplitude of the acoustic wave transmitted by the cranium, which causes the deviation of the skull sound wave from the focus focus and may cause heat damage to the skull and the surrounding tissue. It is necessary to study the accurate and effective methods of transcranial focusing and to reduce the heat damage to the skull and the surrounding tissues. The phase distortion is caused by the transmission of HIFU through heterogeneous skull. The amplitude distortion leads to the inability of the cranial HIFU acoustic wave to focus at the set focal point and causes heat damage to the skull and its surrounding tissue. This paper regulates the phase and amplitude of the signal phase, amplitude and the high sound pressure in the skull to regulate the phase and amplitude of the phase controlled transducer array element. The sound field and temperature field formed by craniofacial focus can be used to provide a theoretical reference for the application of cranial and peripheral HIFU to the clinical treatment of HIFU. The research method based on the reconstruction image of the CT scan data of human head, combined with the small opening 64 array element ball coronal phase controlled transducer, to establish a three-dimensional HIFU Through the numerical simulation model of Finite Difference Time Domain (FDTD), the Westervelt nonlinear acoustic wave propagation equation and the Pennes biologic heat conduction equation are numerically analyzed, and the distribution of sound field and temperature field formed after HIFU's transcranial is analyzed. The phase and amplitude modulation method based on time reversal is applied to obtain the phased transducer array element. The excitation signal, based on the sound field and temperature field formed by these excitation signals, analyzes and discusses the influence and regulation effect of different array element excitation signals on its sound field and temperature field, and uses the temperature threshold and thermal dose to analyze the possible damage to normal tissues and the volume of the focal area formed in the target area; in the normal tissue, there is no injury to normal tissues. On the premise of damage, we analyze the control area that the phase controlled transducer can realize, and regulate the volume of the treatable focal region. Results 1., when the transducer array element excitation signal focuses on the phase correction of the transcranial acoustic wave, the focus is at the set position, but there may be high sound pressure in the skull, the high acoustic pressure and the focus pressure in the skull. The ratio (bone coke ratio) is larger, and the sound pressure in the focus is higher than that of phase correction, the sound pressure in the skull is slightly lower and the bone coke ratio decreases slightly. The bone coke ratio is reduced, the high sound pressure in the skull is reduced, but the sound pressure in the skull is reduced, and the phase and amplitude are also used. After correction and reduction of the high acoustic pressure control method in the skull, the bone coke ratio and the high acoustic pressure in the skull continue to decrease. When the sound pressure at the focal point is focused on the non changing.2. sound axis after the phase correction, the numerical fitting of the focal sound pressure and the therapeutic focal area volume ratio increases.3. based on the time reversal when the amplitude correction is adopted. The phase information of the modulated array element excitation signal obtained by the cross correlation method can be used in the phase and amplitude modulation of the array element excitation signal on the different loop of the phase controlled transducer by the phase correction.4. of the transcranial sound field. The amplitude of the outer ring element signal of the modulating transducer is better. The surface temperature of the skull and water can also be reduced by the nonlinearity of.5. through the acoustic wave of the cranium resulting in the sound pressure at the focal point. Both the temperature and the heat deposition are greater than the linear.6. focusing on the occipital window. Under the condition of the focusing depth of 25 mm, the deviation distance from the Y axis perpendicular to the transducer sound axis is less than equal to 5 mm, and the target area can be achieved only for the target area. The focus of non target tissue does not cause damage, but it can not achieve the focus volume formed by focusing.7. through the cranial sound wave in the direction of the Z direction. The focus volume decreases with the increase of the acoustic axis distance of the transducer perpendicular to the transducer, and the volume of the focal region is approximately linear when the distance from the acoustic axis is fixed. Increasing the input sound intensity of the transducer array element can regulate the size of the focal volume when the focus of the transducer is focused. The volume of focal region formed by focusing at different deviations is the same as that of the axis focusing on the axis. It is concluded that the excitation signal of the 1. phased transducer array element directly affects the acoustic pressure field and temperature of the phase controlled transducer through the transcranial focus. The field, by modulating the phase and amplitude of the excitation signal of the phased transducer array element, the transcranial acoustic wave can be focused accurately, and the maximum sound pressure and maximum temperature at the focal point can be increased, and the transcranial acoustic energy accumulation.2. at the focal point can reduce the energy deposition in the skull by superposition and reduce the high acoustic pressure in the skull, so that the acoustic wave can be reduced and the sound wave is avoided. The heat damage of the skull is caused by the skull, and the amplitude of the excitation signal of the transducer with different ring element can be regulated, especially when the outer ring element signal of the transducer is regulated, the temperature of the surface of the skull and water can be reduced by the nonlinear influence of the cranial acoustic wave on the acoustic pressure field and temperature field of the.3., and the nonlinearity of the transcranial magnetic field should be considered when the cranial HIFU is treated. .4. when the sound window is fixed, there is a distance between the sound axis and the sound axis of the transducer, and the volume of the focusing is reduced with the increase of the vertical deviation from the sound axis, but the input sound intensity of the transducer array element can be adjusted according to the vertical deviation of the sound axis and the linear relationship between the sound intensity. The focal volume formed when the acoustic axis is focused is formed. It is consistent with the axis focusing. In this study, the method of numerical simulation is used to study the method of regulating the temperature field of the transcranial acoustic focusing, which solves the problem that the transcranial acoustic wave can not focus on the focus and causes the heat damage to the skull. It is promoted by the method of regulating the amplitude of sound waves while completing the precise focus of the skull and without the heat damage of the skull. The energy deposition at the focal point makes the acoustic energy more concentrated in the focal region that needs to be treated. Through the method of regulating the sound intensity, the relationship between the compensation sound intensity and the deviation of the focus of the acoustic axis is provided, and the theoretical reference for the clinical focus treatment dose is provided.
【學(xué)位授予單位】：天津醫(yī)科大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：R454.3

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本文編號(hào)：1948091