共查询到17条相似文献,搜索用时 156 毫秒
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超声治癌与无损测温研究 总被引:6,自引:0,他引:6
至今已有很多关于超声治癌的研究。热疗已上升为治疗癌肿的主要方法之一。文中简述了热疗的历史发展,生物物理学基础和超声热疗的技术面貌,报道了对肿瘤或前列腺烧疗的高强度相控聚焦超声技术,它可在10s以内使肿瘤内升温超过70℃。 相似文献
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欲了解皮肤深层的状况,使用三维医学影像技术实属必要,作者提出(组织识别成像术)的新技术,以减低扫描光源对组织之侵入性.先建立皮肤内各种不同组织如黑色素、胶原蛋白、血红素的反射光谱以组成组织数据库;于实际扫描待测皮肤时.依序读出样本组织深层中各空间点的反射光谱,将各点的反射光谱与组织数据库中各种组织的反射光谱做交叉相关程度之运算.可侦测出扫描的各点属于肌肤中的何种组织.其次,再于成像程序中依序给予各点以各对应组织的颜色,即可产生彩色的肌肤衫深层显像.组织识别成像术具有系统简单、成本低廉、彩色成像等优点,且对组织达到真正的非侵入性,将可将之微小化成为个人式、可携式的肌肤检测仪,对于美容市场极具潜力. 相似文献
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Susceptibility artifacts from magnetic resonance (MR)-compatible cryoprobes can distort MR images of iceballs. In this work, we investigate the ability of view angle tilting (VAT) to correct susceptibility induced distortions in MR images of cryosurgery. The efficacy of VAT was tested in an ex vivo bovine liver model of cryosurgery using MR-compatible cryoprobes. Artifacts on high bandwidth fast spin echo images of freezing obtained with and without VAT were compared with photographs of the actual iceball shape and size. In vivo imaging with VAT was demonstrated during percutaneous MR-guided cryosurgery of pig liver and brain. VAT was most successful in reducing probe and iceball distortions when the imaging plane was normal to the cryoprobe, and the cryoprobe was perpendicular to the main magnetic field of the scanner. VAT had the greatest benefit when used to correct MR images of freezing when the surface of the iceball was relatively near to the cryoprobe. For large iceballs, the artifact was small so the VAT correction was less important. We conclude that VAT significantly reduced distortions in the shape of the signal void corresponding to the extent of freezing visualized during MR-guided cryosurgery. This improved ability to visualize the exact location of the cryoprobe, as well as the precise shape of the iceball, particularly during initial freezing when the iceball is small, has potential to significantly improve the accuracy of MR-guided cryosurgery of small lesions, and the accuracy of MR-assisted temperature calculations that are based on precise imaging of the probe location, and boundary geometry of the iceball. 相似文献
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The heating effect of urethral warming during cryosurgery has been investigated theoretically, via heat transfer simulations. Two warmer configurations have been considered: (i). the clinically available urethral warmer, which has a configuration of a counter flow fluid heat exchanger; (ii). a newly designed urethral warmer, based on a temperature controlled electrical heater, termed a "cryoheater". A dramatic effect of thermal resistance to heat transfer through the heat exchanger wall has been identified, which is absent in the cryoheater. It follows that the cryoheater is expected to be more efficient in generating an unfrozen region around the urethra. It is shown that the conventional heat exchanger may fail to prevent freezing around the urethra in a significant number of prostate cases, depending on the layout of cryoprobes around the urethra. On the other hand, clinical reports exist which suggest that the heat exchanger improves in many cases the outcome of cryosurgery, in terms of long term complications. It is speculated in the current report that the cryoheater can further improve the outcome of cryosurgery, by providing protection from freezing in a wider range of cases. It is suggested that a future study be conducted to examine the correlation between the layout of cryoprobes and surgical outcome. 相似文献
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J.C. Gilbert B. Rubinsky M.S. Roos S.T.S. Wong K.M. Brennan 《Magnetic resonance imaging》1993,11(8):1155-1164
The inability to observe the transient, irregular shape of the frozen region that develops during cryosurgery has inhibited the application of this surgical technique to the treatment of tumors in the brain and deep in visceral organs. We used proton NMR spin-echo and spoiled gradient-echo imaging to monitor the development of frozen lesions during cryosurgery in the rabbit brain and the resulting postervosurgical changes up to 4 hr after freezing. Spoiled gradient-echo images (TE = 14 ms; TR = 50 ms) were acquired during freezing and thawing at a rate of 15 s/slice. Although the frozen region itself is invisible in MR images, its presence is distinguished easily from the surrounding unfrozen soft tissue because of the large contrast difference between frozen and unfrozen regions. T2-weighted spin-echo images (TE = 100 ms, TR = 2 s) obtained after thawing suggest that edema forms first at the margin of the region that was frozen (cryolesion) and then moves into the region's core. Histological examination showed complete necrosis in the cryolesion and a sharp transition to undamaged tissue at the margin of the lesion and its image. Blood-brain barrier (BBB) damage was investigated using gadolinium-DTPA. The region of edema in the T2-weighted spin-echo images was coincident with the area of BBB damage in the Gd-DTPA-enhanced T1-weighted spin-echo images (TE = 33 ms, TR = 400 ms) and both were distinguishable as areas of high signal relative to the surrounding normal tissue. The results of these experiments indicate that MR can both effectively monitor the cryosurgical freezing and thawing cycle and characterize the postcryosurgical changes in tissue during follow-up. 相似文献
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Y. Pu 《Optics Communications》2009,282(21):4308-1322
Time-resolved polarization-dependent kinetics of near infrared (NIR) spectral wing (SW) emission from human cancerous and normal prostate tissues was investigated. The differences between the temporal profiles, intensities and polarization properties of SW emission from cancerous and normal prostate tissues were observed. The intensity of SW emission from cancerous prostate tissue at peak position was found ∼2 times stronger than the normal prostate tissue indicating changes of fluorophores contained in the cancerous tissue compared with normal tissue. The decay time of anisotropy of SW emission from cancerous tissue was found ∼1.4 times longer than that of normal tissue reflecting changes of the micro-environment of fluorophores in the cancerous tissue as compared with the normal tissue. The stronger intensity of SW emission from cancerous tissue was used to image and identify cancerous areas surrounded by normal tissue. 相似文献
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Time-resolved polarization-dependent fluorescence of Cybesin in solution and in cancerous and normal prostate tissues were measured. The polarization preservation property of Cybesin in tissue was observed. The fluorescence intensity emitted from a Cybesin-stained cancerous tissue area was found to be much stronger than that from a Cybesin-stained normal tissue area indicating that cancerous prostate tissue takes-up more Cybesin than normal tissue. The polarization anisotropy of Cybesin contained in cancerous prostate tissue was found to be larger than that of Cybesin in normal prostate tissue indicating that a larger degree of polarization was preserved in the Cybesin-stained cancerous tissue due to structures. A static anisotropy component from the emission of cell-bonded Cybesin molecules in tissue and a time-dependent anisotropy component from the emission of un-bonded Cybesin molecules were determined and discussed. The static anisotropy value of Cybesin in stained cancerous tissue was found to be much larger than that in stained normal tissue. The fluorescence polarization difference imaging technique based on the polarization preservation of Cybesin was used to enhance the image contrast between cancerous and normal prostate tissue areas. 相似文献
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Both the experimental and the analytical studies of the freezing/thawing process around a cryosurgical cylinder probes in a simulative biological tissue are presented in this paper. The enthalpy method and the finite element scheme are applied to solve the multidimensional phase change problems in cryosurgery. A very good agreement is found between the computed solutions and the experimental results. The influences of different cooling-warming schemes of the probe on the ice ball development, the temperature variation, the axial and the radial temperature gradients inside the tissues, and the requirement of cooling power are analyzed 相似文献
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A multidimensional, finite element analysis (FEA) for the freezing, holding, rewarming and heating processes of biological tissues during the cryosurgery process of the new Combined Cryosurgery/Hyperthermia System is presented to theoretically test its validity. The tissues are treated as nonideal materials freezing over a temperature range, and the thermophysical properties of which are temperature dependent. The enthalpy method is applied to solve the highly nonlinear problem. It was found that when the same boundary condition and the same target tissue presented, the novel Cryosurgery/Hyperthermia System could supply the target tissue an approximative cooling rate, a much lower minimal temperature, a much greater warming rate, and a much greater thermal gradients compared with that of the simplified Endocare system. The numerical simulation indicates that the novel combined cryosurgery and hyperthermia system can provide an excellent curative effect in the corresponding cryotherapy. And the most attractive feature of this FEA framework is that it can be easily mastered by the surgeon without in-depth theory of heat transfer to analyze the cryosurgery process beforehand due to the friendly GUI (graphical user interface) of Ansys software. 相似文献