本文選題：超聲熱療 + 生物熱傳導方程　； 參考：《陜西師范大學》2007年碩士論文

【摘要】： 根據(jù)WHO預測：惡性腫瘤將成為21世紀危害人類健康的頭號殺手。但就目前情況而言，對于一些腫瘤特別是中晚期腫瘤，任何一種常規(guī)治療(手術切除、化學療法或放射療法)均不能單獨成為一種根治腫瘤的手段。腫瘤溫熱治療是通過超聲加熱腫瘤組織而促進腫瘤細胞的死亡。高強度聚焦超聲技術則是近幾年快速發(fā)展的先進熱療技術，它能將超聲波聚焦于深部腫瘤組織，通過高熱效應使腫瘤組織在短時間內(nèi)凝固壞死，而對超聲波所穿過的組織和靶區(qū)周圍的正常組織沒有損傷。高強度聚焦超聲技術作為一種有效的和非侵入性的腫瘤治療方法已開始引起腫瘤熱療領域的關注。 然而，，隨著對高強度聚焦超聲技術研究的不斷深入，發(fā)現(xiàn)在超聲熱療的過程中，關于如何提高超聲熱療的治愈成功率和治療效率的相關理論還不成熟。這方面的問題涉及：治療靶區(qū)解剖位置和幾何形狀的確定、治療熱劑量的確定、最佳聲焦點分布或最佳掃描路線和掃描速度選取、治療區(qū)域溫度分布計算、熱區(qū)計算結果與預定加熱指標的比較和加熱方法的優(yōu)化。因此，要完善超聲加熱治療的理論，還需做大量的研究、探索工作。 本文通過數(shù)值模擬的方法，探討了超聲熱療時，影響生物軟組織內(nèi)熱源與溫度分布的因素。主要工作和相關結論如下所示： (1)闡述了超聲熱療技術的基本原理，以高強度聚焦超聲技術為例，詳細介紹了聚焦超聲對處于其聲場中的物質(zhì)的作用機理，并歸納總結了幾種常見的醫(yī)用聚焦聲場； (2)對比了幾種生物熱傳導模型，得出Pennes生物熱傳導模型是目前比較理想的模型。并以該模型為基礎，運用Matlab數(shù)學工具，討論了對于同一生物軟組織，在被聚焦超聲加熱時，其內(nèi)部的熱源分布由下列參數(shù)決定：聲源頻率f、換能器曲率半徑R及孔徑半徑a。數(shù)值模擬結果顯示：聚焦聲場中的生物組織內(nèi)熱源的分布區(qū)域隨著超聲頻率的增高、換能器孔徑半徑的增加、換能器曲率半徑的減小而不斷變小。 (3)分析了聲源參數(shù)和生物組織參數(shù)對組織溫度分布的影響。運用Matlab的pdetool工具，求解了Pennes生物熱傳導方程，得到的結論是： a．聲源參數(shù)對生物組織溫升的影響 換能器曲率半徑越小、孔徑半徑越大、超聲頻率越高時，組織內(nèi)溫度上升越快、越多。幾何焦距及換能器半徑對升溫快慢及大小的影響很突出；超聲頻率越高時，因為衰減作用，聲焦點處的升溫快慢及大小隨頻率變化較小。 b．生物組織特性參數(shù)對組織溫升的影響 衰減系數(shù)越大、熱傳導系數(shù)越小時，組織內(nèi)溫度上升越快。當衰減系數(shù)較大時，衰減系數(shù)的變化對聲焦點處溫升快慢和大小的影響相對較��；熱傳導系數(shù)較大時，溫度上升較小，但達到穩(wěn)態(tài)溫度所需的加熱時間也越短。
[Abstract]:According to WHO forecast: malignant tumor will become the first killer of human health in the 21 st century. However, as far as the present situation is concerned, no conventional therapy (surgical resection, chemotherapy or radiotherapy) can be used to cure the tumor alone for some tumors, especially in the middle and late stage. Tumor hyperthermia therapy promotes tumor cell death by ultrasound heating of tumor tissue. High intensity focused ultrasound (HIFU) is an advanced hyperthermia technique developed rapidly in recent years. It can focus ultrasound on deep tumor tissue and make tumor tissue coagulate and necrosis in a short time by high heat effect. There was no damage to the tissue through which the ultrasound went and the normal tissue around the target area. As an effective and non-invasive tumor therapy, high intensity focused ultrasound (HIFU) has attracted more and more attention in the field of hyperthermia. However, with the development of high intensity focused ultrasound (HIFU), it is found that in the process of ultrasonic hyperthermia, the theory on how to improve the cure success rate and therapeutic efficiency of ultrasonic hyperthermia is not mature. The problems related to the determination of the anatomical position and geometric shape of the therapeutic target, the determination of the therapeutic heat dose, the optimal acoustic focus distribution or the optimal scanning route and scanning speed, the calculation of the temperature distribution in the treatment area, The comparison between the calculated results of the hot zone and the predetermined heating index and the optimization of the heating method. Therefore, in order to perfect the theory of ultrasonic heating, a lot of research and exploration are needed. In this paper, the factors that influence the distribution of heat source and temperature in biological soft tissue during ultrasonic hyperthermia are discussed by numerical simulation. The main work and related conclusions are as follows: (1) the basic principle of ultrasonic hyperthermia is expounded. In this paper, the mechanism of focused ultrasound on substances in its sound field is introduced in detail, and several common medical focused sound fields are summarized. (2) several biological heat conduction models are compared. Pennes biological heat conduction model is an ideal model at present. On the basis of this model, the distribution of internal heat source is determined by the following parameters: the frequency of sound source f, the radius of curvature of transducer R and the radius of aperture a for the same biological soft tissue by using Matlab mathematical tools. The distribution of heat source is determined by the following parameters: the frequency of sound source f, the radius of curvature of transducer R and the radius of aperture a. The numerical simulation results show that the distribution of heat source in the biological tissue in the focused sound field increases with the increase of ultrasonic frequency, and the aperture radius of the transducer increases. The curvature radius of transducer becomes smaller and smaller. (3) the influence of sound source parameters and biological tissue parameters on tissue temperature distribution is analyzed. The Pennes biothermic conduction equation is solved by using the pdetool tool of Matlab. The results are as follows: a. The influence of sound source parameters on temperature rise of biological tissue. The smaller the curvature radius of transducer, the larger the aperture radius. The higher the frequency of ultrasound, the faster and more the temperature in the tissue rises. The effect of geometric focal length and transducer radius on the speed and size of temperature rise is very prominent; the higher the ultrasonic frequency, the more attenuation, The rate and magnitude of the temperature rise at the acoustic focus are smaller with the frequency. B. the larger the attenuation coefficient of the effect of biological tissue characteristic parameters on the temperature rise of the tissue, The smaller the heat conductivity is, the faster the temperature in the tissue rises. When the attenuation coefficient is larger, the change of attenuation coefficient has a relatively small effect on the temperature rise rate and magnitude at the acoustic focal point, and when the heat conduction coefficient is larger, the temperature rise is smaller, but the heating time required to reach the steady state temperature is also shorter.
【學位授予單位】：陜西師范大學
【學位級別】：碩士
【學位授予年份】：2007
【分類號】：R312

【引證文獻】

相關碩士學位論文 前1條

1 羅環(huán)千;超聲空化阻斷兔正常肝臟血流對超聲熱療的促進作用[D];廣州醫(yī)學院;2010年

本文編號：2080640