{"created":"2023-06-20T13:21:08.351709+00:00","id":1244,"links":{},"metadata":{"_buckets":{"deposit":"edbee60f-2dbe-4141-9c8d-85dd4e0f8ff9"},"_deposit":{"created_by":1,"id":"1244","owners":[1],"pid":{"revision_id":0,"type":"depid","value":"1244"},"status":"published"},"_oai":{"id":"oai:ir.soken.ac.jp:00001244","sets":["2:431:24"]},"author_link":["3759","3757","3758"],"item_1_creator_2":{"attribute_name":"著者名","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"Maksimenko, Anton"}],"nameIdentifiers":[{}]}]},"item_1_creator_3":{"attribute_name":"フリガナ","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"マクシメンコ, アントン"}],"nameIdentifiers":[{}]}]},"item_1_date_granted_11":{"attribute_name":"学位授与年月日","attribute_value_mlt":[{"subitem_dategranted":"2004-09-30"}]},"item_1_degree_grantor_5":{"attribute_name":"学位授与機関","attribute_value_mlt":[{"subitem_degreegrantor":[{"subitem_degreegrantor_name":"総合研究大学院大学"}]}]},"item_1_degree_name_6":{"attribute_name":"学位名","attribute_value_mlt":[{"subitem_degreename":"博士（学術）"}]},"item_1_description_12":{"attribute_name":"要旨","attribute_value_mlt":[{"subitem_description":"Computed tomography (CT) is the general process of creating cross-sectional or tomographic image from projections (line integrals) of the object at multiple angles and using a computer for image reconstruction. If unmodified, the term CT generally implies images made from projections measured by transmission of X rays (X-ray computed tomography). <br /><br />The mathematical foundation of computed tomography was initially derived by Radon and published in 1917. However, it was not until the development of modern computers that the technique was at all viable. The first commercial CT scanner based on the prototype developed by Godfrey Hounsfield consisted of an X-ray source and two detectors, with a third, reference, detector near the X-ray source. <br /><br />In the last years alternative x-ray imaging techniques, other than the conventional absorption contrast were rapidly developing by various group of scientists in many working laboratories all over the world. Growing availability of the synchrotron light sources for wide range of users accelerated the development of the x-ray imaging techniques abruptly. Besides attenuation, x-ray refraction and shift of the electromagnetic wave phase occurs in an x-ray beam passing through an object. The widely used imaging techniques is based on the angular resolved (or refraction) contrast on which we concentrate in this work. As it follows from the definition it arises when an x-ray penetrated through an object deflects certain angle. In other words this contrast is proportional to the deviation angle which x-ray beam accumulates when it penetrates through an object and refracts on its boundaries. <br /><br />The emerging x-rays present characteristic angular deflections, which are on the microradian scale. Different refraction directions can be resolved by using an angular analyzer, for instance a perfect crystal, which can then be revealed by a detector placed behind it. By varying the alignment of the analyzer with regard to the incoming x-ray beam, the unrefracted x-rays can either be recorded on a detector or rejected thus, either contributing or not contributing to the image contrast. The x-ray refraction contrast can greatly exceed the absorption contrast for instance in imaging low Z materials, where the potentialities of the technique have been exploited from the beginning. An analyzer-based imaging technique has been presented in various versions also assuming different names. An important variation based on an algorithm that differentiates the separation of the refraction contrast from the absorption contrast in an image, has been introduced with the name 'diffraction enhanced imaging' (DEI). The interest in the potential medical application of the diffraction imaging technique has given origin to many projects utilizing analyzer-based refraction imaging. Initiated with conventional x-ray generators, it has been rapidly developed in synchrotron radiation sites thanks to the highly intense collimated beams available that permit fast projection and tomographic imaging. <br /><br />Thus this work is the attempt to accumulate the information on the different implementations of the refraction contrast and prepare the CT-reconstruction of the refraction index field inside an object. Due to the success in this field I can state that it is the first known presentation of the complete solution of the problem. The CT-reconstruction performed from the refraction contrast promises the same advantages over the one based on the absorption contrast that the refraction contrast provides in comparison to other contrasts. The main of these advantages are i )possibility to observe the materials with low Z in higher energies, for example the soft tissue of the human body and ii) visualization of a tiny inclusions which are unobservable in the conventional absorption or phase-shift contracts, for example the cracks and defects in materials. The advantages automatically suggest to the ranges of applicability of this new method varying from medical applications of the synchrotron radiation up to material structure science. <br /><br />Once this work trying to cover all aspects of the problem of the 3D reconstruction of the object inner structure from the refraction contrast it consists of three main parts: the theoretical consideration of the question, experimental implementation and finally the discussion of the results acquired in the experiment and processed in accordance with the theory. All three parts are structured trough and logically connected to each other in order to make the understanding easier and smoother to the reader. <br /><br />We can state that the goal was achieved. The model of penetration of the x-ray was assumed and the theory for the computed tomography reconstruction was built on the base of the model. The algorithm for the reconstruction was implemented in the accordance with the theoretical model. The software which utilizes the algorithm was written and debugged. The problem of the information about the deflection angle distribution from the distribution of the intensity at the detector was considered from different points of view. Several types of the analyzing devices that can provide the intensity distribution were considered. The devices were tested in experiment in order to judge about their applicability for the particular problem. After the test the judgment was done and the chosen device was studied in deep details which resulted into development of new method of extraction the information about the deflection of the x-ray. Actually, the method is modernization and generalization of the previously used one. However it allows to overcome the limits of the present method and makes the limitations on the sensitivity approximately 4 times wider. This great advantage allows us to state that the method developed is principally new. The theoretical base for the new method was built. It was tested in the experiment ad proved its usability. Then the experiment on the data acquisition for the CT-reconstruction which utilized the newly developed method of the refraction angle extraction was performed. The resulted of the experiment were processed by the software prepared for the CT-reconstruction from the refraction contrast. The results of the reconstruction are presented and discussed. The result allows us to conclude that the physical model chosen for the theoretical calculation is applicable and fits the problem. The proves of great advantage of the CT-reconstruction from the refraction contrast over the other types of contrasts developed by the current moment were provided and presented.","subitem_description_type":"Other"}]},"item_1_description_7":{"attribute_name":"学位記番号","attribute_value_mlt":[{"subitem_description":"総研大甲第822号","subitem_description_type":"Other"}]},"item_1_select_14":{"attribute_name":"所蔵","attribute_value_mlt":[{"subitem_select_item":"有"}]},"item_1_select_8":{"attribute_name":"研究科","attribute_value_mlt":[{"subitem_select_item":"先導科学研究科"}]},"item_1_select_9":{"attribute_name":"専攻","attribute_value_mlt":[{"subitem_select_item":"22 光科学専攻"}]},"item_1_text_10":{"attribute_name":"学位授与年度","attribute_value_mlt":[{"subitem_text_value":"2004"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"MAKSIMENKO, Anton","creatorNameLang":"en"}],"nameIdentifiers":[{}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2016-02-17"}],"displaytype":"simple","filename":"甲822_要旨.pdf","filesize":[{"value":"515.9 kB"}],"format":"application/pdf","licensetype":"license_11","mimetype":"application/pdf","url":{"label":"要旨・審査要旨 / Abstract, Screening Result","url":"https://ir.soken.ac.jp/record/1244/files/甲822_要旨.pdf"},"version_id":"b235932b-0466-4acb-92d8-e5876bea1d83"},{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2016-02-17"}],"displaytype":"simple","filename":"甲822_本文.pdf","filesize":[{"value":"92.4 MB"}],"format":"application/pdf","licensetype":"license_11","mimetype":"application/pdf","url":{"label":"本文","url":"https://ir.soken.ac.jp/record/1244/files/甲822_本文.pdf"},"version_id":"8e71a834-97d9-4ca2-8d2a-16b60da27116"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"eng"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"thesis","resourceuri":"http://purl.org/coar/resource_type/c_46ec"}]},"item_title":"CT Reconstruction on the Base of the Refraction Contrast Theory, Experiment and Results","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"CT Reconstruction on the Base of the Refraction Contrast Theory, Experiment and Results"},{"subitem_title":"CT Reconstruction on the Base of the Refraction Contrast Theory, Experiment and Results","subitem_title_language":"en"}]},"item_type_id":"1","owner":"1","path":["24"],"pubdate":{"attribute_name":"公開日","attribute_value":"2010-02-22"},"publish_date":"2010-02-22","publish_status":"0","recid":"1244","relation_version_is_last":true,"title":["CT Reconstruction on the Base of the Refraction Contrast Theory, Experiment and Results"],"weko_creator_id":"1","weko_shared_id":1},"updated":"2023-06-20T14:39:51.075300+00:00"}