高强聚焦超声(HIFU)无创外科─21世纪治疗肿瘤的新技术

本文从简要回顾超声治疗的发展历史开始,重点介绍了９０年代初在国际上兴起的ＨＩＦＵ无创外科技术及我国在该领域中的成就．文章继而对ＨＩＦＵ“切除”肿瘤的机理,治疗质量及其及发展前景做了讨论．     

“首届高强度聚焦超声(HIFU)技术在医学中应用国际学术研讨会”在重庆召开

ＨＩＦＵ技术被誉为２１世纪治疗肿瘤的新技术,是当今国际医学超声领域发展的一个突出的研究热点．我国在这一研究领域取得了国际公认的领先地位． 由中国有关单位主办,英国、美国有关单位协办,重庆医科大学承办的“首届高强度聚焦超声（ＨＩＦＵ）技术在医学中应用国际研讨会”（Ｆｉｒｓｔ ＩｎｔｅｒｎａｔｉｏｎａｌＷｏｒｋｓｈｏｐ ｏｎ ｔｈｅ Ａｐｐｌｉｃａｔｉｏｎ ｏｆＨｉｇｈＩｎｔｅｎｓｉｔｙＦｏｃｕｓｅｄ Ｕｌｔｒａｓｏｕｎｄ ｉｎ Ｍｅｄｉｃｉｎｅ） 于 ２００１年 ５月１０－１３日在重庆市成功召开．会议计收到论…     

UCFC晶体场理论方法（I）——UCFC方法基本概念与d^4组态空间标准基

作为以ｄ４／ｄ６离子为例系统地介绍“ＵＣＦＣ（统一晶场偶合）图象晶体场理论方法”（简称ＵＣＦＣ方法）的系列论文的第一篇，首先介绍了ＵＣＦＣ方法的基本概念，然后介绍了ｄ４／ｄ６离子ＵＣＦＣ方法基本内容的第一部分：ｄ４离子全组态空间标准基链的构造方法。第二篇将介绍如何在标准基链中建造能量矩阵链。第三篇将介绍ｄ４／ｄ６离子ＵＣＦＣ方法的ＥＰＲ理论部分。ＵＣＦＣ方法不仅是一种考虑ｄ电子组态全部多重态的完全计算方法，而且是一种统一的、规范化的、简洁的理论方法体系。它克服了强场、弱场等传统逐次对角化方法的局限性，不须区分晶体场的强弱，因而原则上可通用于任意过渡金属络合物。     

基于扩散速度方法粘性流场的离散涡数值模拟

基于扩散速度方法粘性流场的离散涡数值模拟吴文权，李春，卜千里（上海机械学院上海２０００９３）关键词：扩散速度模型，粘性流场，离散涡方法。ＮＵＭＥＲＩＣＡＬＳＩＭＵＬＡＴＩＯＮＯＦＶＩＳＣＯＵＳＦＬＯＷＦＩＥＬＤＳＵＳＩＮＧＤＩＦＦＵＳＩＯＮＶＥＬＯＣ...     

q变形带电Fermion相干态和q’变形的SU（3）电荷、超荷Fermion相干态

利用ｑ变形的Ｆｅｒｍｉｏｎ振子代数讨论了ｑ变形的带电Ｆｅｒｍｉｏｎ相干态和ｑ变形的ＳＵ（３）电荷、超荷Ｆｅｒｍｉｏｎ相干态．利用ｑ－ＦｅｒｍｉｏｎＦｏｃｋ空间中的基失的完闭性，得到上述两种相干态的具体表现形式．将ｑ变形的结果与普通结果比较发现：在变形参数ｑ＝１时，ｑ变形的带电Ｆｅｒｍｉｏｎ相干态和ＳＵ（３）电荷、超荷Ｆｅｒｍｉｏｎ相干态自然回到普通的带电Ｆｅｒｍｉｏｎ相干态和ＳＵ（３）电荷、超荷Ｆｅｒｍｉｏｎ相干态．     

圆阵波束输出的高分辨方位估计

在研究波束域高分辨ＭＵＳＩＣ算法的基础上,本文把阵元域ＷＳＦ算法推广到波束域中。这两种算法对阵列的形式没有限制,可以应用于水声系统中常见的均匀圆阵波束输出,计算机仿真结果表明,对于圆阵波束输出,波束域ＭＵＳＩＣ算法估计目标方位的性能优于阵元域ＭＵＳＩＣ算法,而波束域ＷＳＦ算法测保持了阵元域ＷＳＦ算法的最佳方位估计性能。     

聚变实验增殖堆FEB-E放射性废物处置指标的计算

应用中子输运程序ＢＩＳＯＮ３．０、增殖堆放射性计算程序ＦＤＫＲ、剂量率计算程序ＤＯＳＥ完成了聚变实验增殖堆ＦＥＢ－Ｅ的放射性、核废物特性及废物处置额定容量（ＷＤＲ）的计算。结果表明,在停堆以后几周内,ＦＥＢ－Ｅ设计的经一壁和包层结构材料满足１０ＣＦＲ６１Ｃ级核废物处置额定容量的要求。对包层中的重要锕系元素＾２３２Ｕ、＾２３７Ｎｐ的含量也作了计算分析。     

非致冷焦平面热成像技术

简要介绍了三种非致冷红外探测器的技术途径和发展现状。从系统原理提出ＵＦＰＡ热像仪的设计概念以及必须解决的几个关键技术。分析ＵＦＰＱ的性能极限和系统的性能水平,并与第一代轻型热像仪的ＭＲＴＤ曲线进行比较。     

紫外-可见多功能光谱电化学池的研制

利用研制的紫外－可见多功能光谱电化学池，以ＵＶ－Ｖｉｓ长光程薄层和光透支光谱电化学法的分别测定了Ｆｅ（ＣＮ）６＾３－／Ｆｅ（ＣＮ）６＾４－电对的反应电数ｎ；燕以ＵＶ－Ｖｉｓ光透半无限扩散和平行人射式光谱电学法分别测定了Ｆｅ（ＣＮ）６＾３－的扩散系数Ｄ。实验的结果均与文献值相近，从而表明了这种ＵＶ－Ｖｉｓ多功能光谱电化学池的可靠性。     

离心叶栅内气固两相流动的数值模拟

离心叶栅内气固两相流动的数值模拟蔡体菁，王文琪，郁斌（东南大学动力工程系南京２１００１８）关键词：离心叶栅，粒子轨迹，龙格－库塔方法。ＮＵＭＥＲＩＣＡＬＭＯＤＥＬＩＮＧＦＯＲＧＡＳ－ＳＯＬＩＤＳＦＬＯＷＳＴＨＲＯＵＧＨＡＣＥＮＴＲＩＦＵＧＡＬＣＡＳＣ...     

Pulse compression technique for simultaneous HIFU surgery and ultrasonic imaging: a preliminary study

In an ultrasound image-guided High Intensity Focused Ultrasound (HIFU) surgery, reflected HIFU waves received by an imaging transducer should be suppressed for real-time simultaneous imaging and therapy. In this paper, we investigate the feasibility of pulse compression scheme combined with notch filtering in order to minimize these HIFU interference signals. A chirp signal modulated by the Dolph-Chebyshev window with 3-9 MHz frequency sweep range is used for B-mode imaging and 4 MHz continuous wave is used for HIFU. The second order infinite impulse response notch filters are employed to suppress reflected HIFU waves whose center frequencies are 4 MHz and 8 MHz. The prototype integrated HIFU/imaging transducer that composed of three rectangular elements with a spherically con-focused aperture was fabricated. The center element has the ability to transmit and receive 6 MHz imaging signals and two outer elements are only used for transmitting 4 MHz continuous HIFU wave. When the chirp signal and 4 MHz HIFU wave are simultaneously transmitted to the target, the reflected chirp signals mixed with 4 MHz and 8 MHz HIFU waves are detected by the imaging transducer. After the application of notch filtering with pulse compression process, HIFU interference waves in this mixed signal are significantly reduced while maintaining original imaging signal. In the single scanline test using a strong reflector, the amplitude of the reflected HIFU wave is reduced to −45 dB. In vitro test, with a sliced porcine muscle shows that the speckle pattern of the restored B-mode image is close to that of the original image. These preliminary results demonstrate the potential for the pulse compression scheme with notch filtering to achieve real-time ultrasound image-guided HIFU surgery.     

New Techniques and Designs of Focusing Piezoelectric Transducers for Ultrasonic Diagnostics and Therapy

New techniques of forming high intensity focused ultrasound (HIFU) fields using dynamic focusing and harmonic multifrequency excitation are developed for ultrasonic diagnostics and therapy. New designs of HIFU transducers based on high-performance composite materials are developed and studied. Finite-element and finite-difference simulations of HIFU transducers and processes of ultrasonic wave propagation in biological tissues are performed. The parameters of piezoceramic materials, piezoelements, and the acoustic fields of focusing ultrasonic transducers are measured. Experiments are performed on biological tissues ex vivo that confirm the efficiency, selectivity, and safety of the developed HIFU transducers and techniques of forming acoustic fields.     

A novel method for estimating the focal size of two confocal high-intensity focused ultrasound transducers

Estimating the focal size and position of a high-intensity focused ultrasound (HIFU) transducer remains a challenge since traditional methods, such as hydrophone scanning or schlieren imaging, cannot tolerate high pressures, are directional, or provide low resolution. The difficulties increase when dealing with the complex beam pattern of a multielement HIFU transducer array, e.g., two transducers facing each other. In the present study we show a novel approach to the visualization of the HIFU focus by using shockwave-generated bubbles and a diagnostic B-mode scanner. Bubbles were generated and pushed by shock waves toward the HIFU beam, and were trapped in its pressure valleys. These trapped bubbles moved along the pressure valleys and thereby delineated the shape and size of the HIFU beam. The main and sidelobes of 1.1- and 3.5 MHz HIFU beams were clearly visible, and could be measured with a millimeter resolution. The combined foci could also be visualized by observing the generation of sustained inertial cavitation and enhanced scattering. The results of this study further demonstrate the possibility of reducing the inertial cavitation threshold by the local introduction of shock wave-generated bubbles, which might be useful when bubble generation and cavitation-related bioeffects are intended within a small region in vivo.     

高强聚焦超声(HIFU)无创外科─21世纪治疗肿瘤的新技术

本文从简要回顾超声治疗的发展历史开始,重要介绍了90年代初在国际上兴起的HIFU无创外科技术及我国在该领域中的成就。文章继而对HIFU“切除”肿瘤的机理,治疗质量及其发展前景做了讨论。     

高强聚焦超声(HIFU)无创外科

本文从简要回顾超声治疗的发展历史开始,重点介绍了90年代初在国际上兴起的HIFU无创外科技术及我国在该领域中的成就.文章继而对HIFU“切除”肿瘤的机理,治疗质量及其及发展前景做了讨论。     

HIFU治疗中换能器驱动电功率变化机制及规律*

高强度聚焦超声(HIFU)治疗中的驱动电功率对治疗效率起着非常关键的作用,驱动电功率控制的精准性势必会影响治疗的效率和安全性。前期研究表明：HIFU治疗过程中焦域瞬态物理特性的变化会导致换能器的负载阻抗发生变化,进而影响HIFU驱动电功率,但驱动电功率与焦域瞬态物理特性之间的影响关系及规律尚不明确。该文基于电压、电流传感器、空化检测探头和温度传感器等器件,构建了一种HIFU治疗中驱动电功率实时监测及焦域声空化、温度检测系统。基于该实验研究系统,以离体牛心组织作为HIFU辐照对象,分别研究了HIFU焦域温度变化、声空化及组织损伤与驱动电功率之间的变化关系及规律。研究结果表明：当焦域温度升高时,驱动电功率缓慢上升,驱动电功率与温度变化有良好的相关性;当空化产生时,驱动电功率出现明显的波动;当组织出现损伤时,驱动电功率呈陡然下降的变化。三种情景下,驱动电功率变化有明显区别,这有望为区分HIFU治疗过程中焦域处发生损伤和空化以及实时监测靶组织损伤程度提供一种新的解决方案。     

High-speed observation of cavitation bubble cloud structures in the focal region of a 1.2 MHz high-intensity focused ultrasound transducer

Cavitation bubble clouds in the focal region of HIFU play important roles in therapeutic applications of HIFU. Temporal evolution and spatial distribution of cavitation bubble clouds generated in the focal region of a 1.2 MHz single element concave HIFU transducer in water are investigated by high-speed photography. It is found that during the initial 600 micro s insonation cavitation bubble clouds organize to the "screw-like structure" or "cap-like structure". The screw-like structure is characterized by a nearly fixed tip at the geometrical focus of the HIFU transducer, and the cap-like structure is marked by a dent formed in the direction of ultrasound transmission. After 600 micro s, another two structures are recorded - "streamer structure" and "cluster structure". The streamer structure is also featured by a nearly fixed bottom position at the focus, while the cluster structure is distinguished by agglomerations of bubbles around the focus.     

基于回波平移序列的快速三维磁共振温度成像方法

高强度聚焦超声（HIFU）是一种无创的热消融疗法，为保证其安全性和有效性，需要一种精度高、速度快的测温方法在其治疗过程中对温度进行监控.基于质子共振频率位移（PRFS）的磁共振温度成像（MRT）对温度具有较高的灵敏度，且与温度具有良好的线性关系，因此常被用于引导HIFU治疗.然而在实际应用中，HIFU治疗的最大隐患在于可能造成表皮灼伤，并且灼伤区域可能与焦点区域相隔较远.因此MRT的监控范围十分重要.本文基于三维回波平移成像序列，结合可控混叠的空间并行成像技术，实现了时间分辨率为3 s的快速三维温度成像.为了验证该方法的精度，本文首先设计了仿体降温实验，利用光纤温度计验证回波平移序列测温的准确度和精确度.然后在室温条件下扫描离体猪肉组织，对比加速前后的MRT的测温精确度.在HIFU加热条件下扫描离体猪肉组织，对比加速前后的MRT的测温准确度.结果显示，本文提出的方法可以在3 s内完成三维温度精准测量，对于HIFU治疗的安全监控具有重要意义.     

多阵元高强度聚焦超声多目标控制方法研究

对多阵元高强度聚焦超声非侵入外科治疗采用多目标控制方法可望取得好的温度控制性能.提出和构造了闭环控制的模糊控制器,从而得到好的温度特性 为得到理想的能量空间分布,专门形成了优化声场的模式控制 另外,重要参量辨识和开关模式控制技术是十分有效的控制方法.考虑非线性效应的仿真结果显示出优越的控制性能.随后的活体实验结果显示出好的温度响应特性,同时证实了多目标控制方法的可行性 关键词： 高强度聚焦超声 多目标 模糊逻辑