Synchrotron Multi-mode X-ray Imaging And Its Application In Archaeology And Oncology

Since the significant and rapid growth of X-ray techniques,the third generation synchrotron radiation X-ray light source has played a paramount role in modern scientific research and applications.Compared with visible light and electron beam.X-rays can be used nondestructively to achieve three-dimensional and high-resolution imaging because of its short wavelength and strong penetrating ability.Based on the complicated interaction between X-rays and substance,various X-ray imaging methods have been developed,such as absorption contrast imaging,phase contrast imaging and X-ray fluorescence imaging.These imaging methods based on synchrotron radiation X-ray have successfully applied to material science,biological science and so on.However,there are some limitations in theory and application of single mode synchrotron radiation X-ray imaging especially in the interdisciplinary research areas,such as the scientific archaeology and oncology.For example,the structural and compositional analysis of ancient samples;the structural and functional study of the cancer cells.Therefore,current synchrotron radiation imaging methods need to be developed both in methods and in technological aspects.There is a need of multi-mode synchrotron radiation imaging methods to resolve the specific scientific issues.The scientific archaeology and oncology are the typical interdisciplinary regions studied by synchrotron radiation imaging.That synchrotron radiation X-ray imaging applied to scientific and technical archaeology and oncology not only could solve the specific scientific question but also could complete the methodology of synchrotron radiation imaging.In this thesis,we have investigated a multiple imaging methodology based on synchrotron radiation X-rays.Also we have applied a nondestructive technique to obtain the three-dimensional and high-resolution images thereby probe the archaeological samples,such as ancient soybeans,casting mold,and biological samples such as blood capillaries and the cancer cells.The outcome of the research results is presented as follows.(1)Application study and investigation of ancient soybean origin and domestication by synchrotron radiation X-ray imaging.Due to the brittleness of ancient charred soybeans,conventional archaeological techniques only give morphological information and investigation of the core level structural information remains a problem.By considering the advantage of the nondestructive and high resolution imaging technique,we have studied a series of ancient soybeans obtained from with different ages from the middle and lower Yellow River using a synchrotron radiation computed tomography.The radiocarbon dating results indicated that these ancient soybeans spanned an age of 1.000-7,500 B.P.and more suitable to study the soybean origin and domestication.Combined with the synchrotoron radiation in-line phase contrast imaging technology and,boundary contrast in the charred soybeans had enhanced significantly and could improve the experimental data.A model was proposed to identify the relationship between the structure and composition of the ancient charred soybeans.The soybean origin and domestication were revealed in a new perspective.A kind of hole structure was discovered through the comparative experiments with modern soybeans and other crops.The factors such as soybean composition.water and carbonization temperature affected the hole structure of modern and ancient soybeans.Based on the results and analyses of three-dimensional reconstruction and statistics,the analysis method that links structure of charred soybean and composition was established:1)a higher content of the oil facilitates generation of small holes,while a higher content of protein leads for the generation of the large holes;2)The water and high temperature decreased the number of small holes.Both the protein and oil content of the series of ancient soybeans have increased as time proceeded when we applied the above analysis method to them,but the oil content increased much more.The results concluded that:1)The Chinese ancestors were aware of selection and cultivation of soybeans in 7,500 B.P.2)Domestication could be obviously identified from their wild counterparts after 3,000 years,during which soybean cultivation proceeded.Different from the conventional genetics study in domestication,three-dimensional structural studv of chared soybean using synchrotron radiation X-ray imaging revealed soybean origin and domestication.This study made a breakthrough on the analysis method of the synchrotron radiation imaging and archaeological domestication study.(2)Synchrotron radiation X-ray structural and chemical imaging of a Shang dynasty casting mold sherd.The Shang dynasty casting molds were rarely excavated in other bronze casting site except the Yin ruins,while the Daxinzhuang site was located in the east of Shang state,excavations of casting molds and other castings are of attracting significant interest to analyze the settlements development and power expansion in the Shang dynasty.Using the synchrotron radiation X-ray computed tomography,we studied the inner structure of the decorations and the sherd matrix.Furthermore,we performed chemical(elemental)imaging analysis for the traces of metals brought by casting,especially copper and iron.Through the three-dimensional computed tomography,we analyzed one part of the casting mold sherd,which includes decorations to identify the compositional difference and boundary issue between the decorations and matrix.We found that there were no boundaries between them and the decorations might be carved out of the mold matrix.There were hardly copper or iron in the mold matrix.It indicated that this mold had been used for bronze casting and iron on the surface,which should be contaminated by the local surroundings.Finally,to confirm the elemental information of the mold matrix and surface,we performed XPS.ICP-AES and other analyses to identify the qualitative and quantitative distribution of elements.With synchrotron radiation X-ray structural and chemical imaging,we had confirmed that the casting mold was carefully designed and had been used for bronze casting.The decorations on the surface were carved out of the mold but not pasting.(3)Microstructure study of blood capillaries of mouse using synchrotron radiation hard X-ray full field microscopy and soft X-ray scanning transmission microscopy.Cancer therapy materials pass through the blood capillaries before they enter into the tumor tissues to treat the cancer cells.The study of micro-structure of blood capillaries would widen our understanding of the microcosmic mechanism in the drug delivery process.It will also give a guide for designing the therapy materials.Firstly,we studied the three-dimensional structure of the mouse blood capillaries at sub-micrometer level by synchrotron radiation hard X-ray full field microscopy.Secondly,we achieved two-dimensional high resolution imaging of the capillaries at 50 nm level through synchrotron radiation soft X-ray scanning transmission microscopy.A kind of "bamboo" structure was discovered under these two imaging modes.Based on the high resolution imaging results,a structural model of blood capillary was suggested and then the relevant biological effect was analyzed.The"bamboo" structure can improve the substance exchange rate of 17.2%between blood and tissues.However,the "bamboo" structure also decreases the section of the blood channel,which will increase the risk of some diseases,such as thrombus.The synchrotron radiation X-ray imaging technique enchanced our understanding to the micro-structure of blood capillaries,also this study realized the methodology exploration by using soft X-ray scanning transmission microcopy studied some biological large sized samples.(4)Low dose,three-dimensional and high resolution imaging methodology based on synchrotron radiation X-rays and its application in cancer cells.We have performed the simulation experiment of equally sloped three-dimensional reconstruction algorithm(Equally Sloped Tomography,EST)to adherent the cancer cells.The simulation results showed that EST has great advantages compared with conventional filtered back-projection(FBP)method.The EST could achieve high quality reconstruction with fewer projections than the FBP.The combined synchrotron radiation soft X-ray scanning transmission microscopy with the EST.we conducted a high resolution three-dimensional imaging study for the human cervical adenocarcinoma cells(Hela)and internal tumor therapy drug(Cisplatin).During the three-dimensional reconstruction,the data processing was improved and artifacts or noises were removed.The reconstructed results suggested that cisplatin mainly distributed on one side around the cell and preliminarily verifies cisplatin which might suppress or stop the DNA replicating to treat the cancer cells.In addition.to further test the low dose imaging quality of the EST,we performed soft X-ray scanning transmission imaging for eiythroleukemia cells(HEL).By using only 30 projections,we achieved three reconstructions of the HEL cell.The reconstructed results indicatedthat the biological functional materials(Au-Gd nanoparticles)mainly distributed on the cell membranes.This result was in accordance with the mechanism that Au-Gd nanoparticles could specifically identify integrin protein on the cell membranes.