【作者】 刘成林；

【导师】 张新夷；

【作者基本信息】 复旦大学 ， 凝聚态物理， 2006， 博士

【摘要】 肿瘤是危害人类健康和生命的重大疾病之一。目前，临床上常规的肿瘤诊断方法主要有组织病理学和影像学等。近年来，各种新的诊断技术不断进展，使肿瘤的诊断不断接近早期、准确、微创伤或无创伤性的目标。本文用衍射增强成像（DEI）、类同轴全息成像（位相衬度成像）和吸收成像等同步辐射X射线成像方法研究了各种类型的乳腺组织和子宫肌瘤的微结构；用同步辐射傅立叶变换红外光谱（SR-FTIR）研究了正常乳腺组织、良性乳腺肿瘤组织和乳腺癌组织的光谱特性；用同步辐射X射线荧光分析方法（SR-XRF）和X射线吸收精细结构（XAFS）方法分析了各种乳腺组织中微量元素的种类、相对含量和化学环境。同时，评价了同步辐射的X射线成像和谱学方法在辨别正常的、良性的和癌变的组织中的作用，并探讨同步辐射实验方法在医学应用中的价值。 首先，用X射线成像方法研究乳腺肿瘤和子宫肌瘤的微结构。在衍射增强成像原理的基础上，通过简单的实验模型分析了DEI成像的过程与特点。在摇摆曲线顶部记录的图像，即衍射图像有很好的衬度，可以直接用于观察物体的内部结构；在摇摆曲线半高宽处记录的图像也有一定的衬度，它们经过像素对像素的算法处理后可以得到表观吸收图像和折射图像。表观吸收图像的特点与传统X射线图像相似，但折射图像具有更好的边界衬度，能够分辨材料内部不同折射率的微结构。同时也发现，分析晶体的本底信号会影响DEI成像的质量，但对折射图像没有任何影响，不会引起折射图像与实际物体之间的偏差。因而，折射图像用于辨别正常组织与病变组织、工业检测等方面具有很好的可信度。 X射线衍射增强成像能够显示出正常乳腺组织、良性乳腺肿瘤组织和乳腺癌组织的内部结构以及它们的差异性，而且不需要大量繁琐的病理切片。尽管表观吸收图像与传统医学图像相类似，在分辨这些组织上不存在优势，但表观吸收图像的衬度高于同步辐射吸收图像的衬度。而折射图像能够很好地显示出各种乳腺组织的内部结构，如正常乳腺组织中的微小纤维、良性乳腺肿瘤组织中的纤维束和乳腺癌组织中的微小钙化等，这些微结构的尺度均在几十微米左右。同样，衍射图像的衬度也比吸收图像的衬度高，也能够直接用于观察乳腺组织的内部结构，特别是其用X射线胶片记录并经光学显微镜放大后，图像的清晰度得到了很好的改善，在辨别乳腺组织的类型上有更好的效果。对包含各种乳腺组织的摇摆曲线进行统计分析后可知：摇摆曲线的峰位和半高宽的变化并不明显，但它们的反射强度或积分强度的差异比较显著，能够反映出各种乳腺组织对X射线的吸收能力的不同。同时，对DEI图像衬度与入射X射线能量关系的研究发现：衍射图像和表观吸收图像的衬度随X射线能量的变化关系是相似的，说明衍射图像和表观吸收图像包含的主要衬度是相似的，即吸收衬度，而折射图像的衬度随X射线能量的增大总体上呈现下降趋势。综合来看，对于乳腺组织来说，DEI成像在低能量端有很好的衬度，反映了衍射增强成像更适合于对轻元素的成像。 我们对子宫肌瘤进行的同步辐射成像研究表明，光学显微镜只能观察子宫肌瘤的表面形貌，而无法显示出它的内部结构。而衍射增强成像可以显示子宫肌瘤的内部结构。尽管在子宫肌瘤的表观吸收图像中难以完整地辨别出肌瘤的内部结构，但衍射图像和折射图像都能够清晰地显示出肌瘤内部尺度在30μm左右的微结构，包括肌瘤的漩涡状结构、透明变性、囊状变性、红色变性以及因变性而产生的空洞。这些微结构有利于提示子宫肌瘤的恶化趋势。 将位相衬度成像用于乳腺肿瘤的结构研究后发现：正常乳腺组织的吸收图像的清晰度比较高，原因是正常乳腺组织比较致密，对于对X射线的吸收相对较强。而位相衬度成像在分辨肿瘤组织内部结构方面的优势是比较明显的，能够清晰地显示出乳腺组织中的一些精细结构，并可以反映出正常组织、良性肿瘤组织和癌变组织结构的特异性。在位相衬度成像中，图像的衬度是与样品到探测器的距离有关的，在不同样品到探测器的距离下，位相衬度成像的分辨率是不同的。根据衬度传递函数（CTF），可以估计出乳腺癌组织中的钙化尺度在30μm左右，与衍射增强成像的实验结果基本一致。 其次，利用同步辐射傅立叶变换红外光谱对各种类型的乳腺组织进行了研究。从SR-FTIR的结果中可以观察到不同类型乳腺组织红外吸收光谱结构上的显著差异。对900-3600cm^-1范围内的红外吸收光谱进行仔细分析，得到的明显印象是从正常组织到良性肿瘤组织，红外吸收的丰富光谱特征变为模糊；而病变组织在癌变过程中，比较平滑的光谱变得比较复杂。另外，SR-FTIR能够很好地分辨出比较接近的峰，如1464cm^-1和1474cm^-1变得比较清楚。在SR-FTIR中，也发现了一些特定的吸收峰，它们可以帮助诊断乳腺组织的类型。 最后，我们还用同步辐射X射线荧光分析（SR-XRF）和X射线吸收精细结构（XAFS）分析了正常乳腺组织、良性乳腺肿瘤组织和乳腺癌组织中微量元素的种类、相对含量和化学环境等。根据SR-XRF的结果，在正常乳腺组织、良性乳腺肿瘤组织和乳腺癌组织中微量元素的种类是相同的，但相对含量是不相同的，特别是正常组织和肿瘤组织中的Ca、Fe和Zn的差异相当明显。肿瘤组织中S、Cr、Mn、Ni、Cu和se的相对含量与正常组织中含量具有正相关性，即肿瘤组织的含量相对于正常组织是增加的，而K和Ca则是负相关性。P在正常乳腺组织和良性乳腺肿瘤组织中的含量基本不变，但在癌变组织中略有下降。恶性肿瘤中的Fe和Zn是正相关性，而在良性肿瘤中则是负相关性。对组织中Ca、Fe和Zn的XANES分析后发现：只有Fe出现了边前结构，而Ca和Zn没有；在边后，肿瘤组织中Ca和Zn的变化规律基本相似，与正常组织的不同，但是正常组织和癌变组织中Fe的边后规律是相似的，而良性组织中的规律存在特异性。各种组织中不同元素的径向分布函数（RDF）的差异是比较明显的，但它们的规律性不是很明确，说明在组织中Ca、Fe和Zn的存在环境是非常复杂的，而且轻元素的散射对实验结果的影响很大。 总之，正常组织和肿瘤组织在X射线图像和光谱上的差异性是显著的，各种方法得到的结论是基本一致的，它们可以互相印证、相互补充。因此，将同步辐射实验方法应用到肿瘤的早期诊断中具有一定的可行性。更多还原

【Abstract】 The cancer is one of the illnesses seriously harming human health and lift. At the present time, conventional clinic diagnoses of cancer are mainly the histopathology, imaging and so on. At recent years, many kinds of new diagnosing techniques are continually developed, and make the diagnosis of cancer to its early stage, more exact and precise or no hurting. In this paper, the X-ray imaging and several spectroscopy techniques based on synchrotron radiation are used to study the micro-structures of various breast tissues and uterine leiomyomas. The importance of these methods in distinguishing the normal, benign or cancerous tissues is evaluated, and the basis for medical applications of synchrotron radiation is also discussed.At first, the microstructures of breast tumors and uterine leiomyomas are studied by the X-ray imaging, such as diffraction enhanced imaging （DEI）. On the basis of the DEI’s principle, the processes and character of DEI are analyzed by a simple experimental model. The key point of the DEI setup is the analyzer which is a perfect crystal. X-rays from the synchrotron light source pass through a monochromator and are translated into monoenergetic lights. The monoenergetic X-rays traverse a sample and undergo diffraction by the analyzer crystal, and are finally recorded by the detector. When the X-rays traverse the sample, they are refracted by very small angles （around microradians） due to the tiny variation of refractive indexes in the sample. The analyzer crystal can almost eliminate the X-rays scattered within a large angle by the sample. The X-rays emerging from the sample and hitting the analyzer crystal will satisfy the conditions for Bragg diffraction only for a very narrow range of incident angles （typically on the order of a few microradians）. If the X-rays that have been refracted by the sample are within the angular acceptance range of the analyzer, they will be diffracted to the detector. Otherwise, if the X-rays that have been scattered by the sample will fall outside this angular acceptance range, they will not be reflected at all. The relationship of reflectivity on incident angle is called rocking curve. The rocking curve is usually a triangular-shaped one whose full width of half maximum （FWHM） is about several microradians. Since the resulting refraction contrast originates from the slope of either shoulder of the triangular-shaped rocking curve, it depends on its FWHM as well as the tuning angle. We can obtain various images at different positions of rocking curve with tuning the analyzer crystal. These pictures contain the absorption, therefraction and the extinction （that is to say, the small angle scattering is rejected） information. In the DEI experiment, three kinds of images can be obtained. One is recoded at the peak of rocking curve, which is usually called diffraction image because the analyzer is in Bragg angle position, the diffraction images have higher contrast than the absorption images and can show also micro-structures inside the breast tissues. Other two images can be obtained when the analyzer is tuned to the FWHM positions on either side of the rocking curve. These two images contain the same absorption information but the opposite refraction information. Consequently the different information from two images can be separated through pixel-by-pixel algorithm. When two images are added, we can obtain the apparent absorption image that has only absorption, no refraction effect, but with weak extinction. The apparent absorption image is similar to the conventional X-ray image. When two images are subtracted, we can obtain the refraction image in which the edge effect has been enhanced. The refraction image is extraordinarily sensitive to the change of the refractive index of the sample, and can clearly display edges of organic tissues having different refractive indexes. Furthermore, the background of the analyzer crystal shall affect the quality of the imaging, but does not affect the refraction image. There is aesthetically consistent relationship between the object and the refraction image. So, the refraction image has very good reliability in distinguishing normal or disease tissues, as well as for industry examining.We have also recorded the images by X-ray films and read by an optical microscope. In this case two different methods were used. One of them is to place the X-ray film about 1 cm behind the sample and no analyzer crystal will be used, then to record the image called absorption image, resembling the conventional mammography. For the another method the X-ray film is just placed behind the analyzer crystal which is in the top position of its rocking curve, then the so called diffraction images are obtained. These images can display more abundant microstructures of various tissues when they are read by the optical microscope, but its imaging process is not as convenient as use of CCD.The changes of rocking curves are also carefully studied as various breast tissues are inserted. The differences of the integrated intensity of rocking curves are also possible to distinguish the normal, benign or malignant breast tissues.The relations between the contrast of different DEI images and the X-ray energies are discussed. The results show that the contrasts of diffraction image or apparent absorption image keep unchanged when different X-ray energies are used. The contrast of refraction image trends to be weakened when the X-ray energy is increased. As a result, it seems the DEI method fits for imaging light elements.The uterine leiomyomas are imaged using synchrotron radiation. The results show the optical microscope can only observe the surface morphology of the sample, but not the inner structures. The DEI images can clearly show inside micro-structures of uterine leiomyomas, including the burble structure, hyaline degeneration and rupture of muscle fibers, red degeneration and cavum of myomatous in the inner of uterine leiomyomas. The inside hyaline degeneration and the cavum of liquefied uterine leiomyomas can be shown very clearly in the refraction image. And the burble structure of uterine leiomyomas, rupture of muscle fiber, conglomeration and cavum can be displayed in images which were recorded at the top of rocking curve. Therefore, the DEI is more valuable diagnoses method that we can directly observe the inside micro-structures of organs or soft tissues and the complexity of doing with a large number of pathology slices is avoid.The phase-contrast imaging （in-line holography） is used to study the structures of breast tissues, too. The absorption image of normal breast tissue has better definition than that of phase-contrast image because the normal breast tissues are compact, and the absorption of X-ray is very intensive. However, the superiority of phase-contrast imaging is obvious in the tissues of tumor. Some microstructures, which can reflect the differences of normal, benign and malignant breast tissues, are distinctly shown in phase-contrast images. The contrast of image, and the resolving power as well, are related to the distance from the sample to the detector in phase-contrast imaging. According to the contrast transfer function, the sizes of micro-calcifications are estimated to be approximately 30μm in breast cancer tissues. These results are consistent to the experimental results of DEI technique.In addition, various breast tissues are studied by synchrotron-based Fourier transform infrared spectrum （SR-FTIR）. In SR-FTIR absorption spectra, there are obvious differences of spectral structures among normal, benign and malignant breast tissues. Having analyzed carefully the whole IR absorption spectrum in energy range of 900-3600 cm^-1, we have a general impression: the IR absorption spectrum varies from to be featured abundantly to faint from normal breast tissue to benign tumors; while it develops from relatively smooth spectrum to much more complicated one in progression to cancer of the diseased tissue. On the other hand, the high resolving power of SR-FTIR can make closer peaks, such as the double peak at 1464 and 1474 cm^-1 be visible. Some specific absorption peaks are found by SR-FTIR method, which may help us distinguish the kinds of breast tissues.At last, the kinds, relative contents and chemical state of trace elements in normal breast tissues, benign breast tumor tissues and breast cancer tissues are studied by theX-ray fluorescence （SR-XRF） and X-ray absorption fine structure （XAFS） techniques. According to the results of SR-XRF, there are same kinds of trace elements in various breast tissues, but their relative contents are different in normal breast tissue, benign breast tumor tissue and breast cancer tissue. The differences of Ca, Fe and Zn are especially obvious between the normal breast tissues and the breast tumor tissues. Comparing the contents of elements in breast tumor tissue to normal tissue, S, Cr, Mn, Ni, Cu and Se is of positive relativity, i.e. their contents in tumor tissues are increased to ones in normal tissues, but negative to K and Ca element. The contents of P in normal breast tissues are as same as in benign tissues, but a little decreasing in malignant tissues. However, Fe and Zn are of positive relativity in malignant breast tumor tissues, and negative in benign tissues.The results of the X-rays absorption near edge structure of Ca, Fe and Zn in various breast tissues show there are pre-edge structures in Fe K-edge absorption spectrum, but not in that of Ca and Zn. The change rules of Ca and Zn behind their K-edge in tumor tissues are similar, but not as same as in normal tissues. The change rule of Fe behind their K-edge in normal breast tissues is similar to that in breast cancer tissue, but not in benign tissue. The differences of radial distribution function of three elements in the tissues are definite, but the rule is not specific. These results show the circumstances of Ca, Fe and Zn are very complex in tissues, the scattering of light elements affect experimental results especially.In summary, the differences of normal tissues and tumor tissues in X-ray imaging and spectroscopy are very distinct. The results obtained by various methods are basically coincident. They can confirm and reinforce each other. DEI images can show the inside micro-structures of various breast tissues but not need a large number of pathology slices, so the DEI method could be valuable in diagnosing the cancerous tissues in their early stage. Hence, the synchrotron-based methods have definite feasibility in early diagnosis of cancer.更多还原