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[{"key": "dc.contributor.advisor", "value": "Kataja, Markku", "language": null, "element": "contributor", "qualifier": "advisor", "schema": "dc"}, {"key": "dc.contributor.author", "value": "Laitinen, Jussi", "language": null, "element": "contributor", "qualifier": "author", "schema": "dc"}, {"key": "dc.date.accessioned", "value": "2018-05-16T09:05:56Z", "language": null, "element": "date", "qualifier": "accessioned", "schema": "dc"}, {"key": "dc.date.available", "value": "2018-05-16T09:05:56Z", "language": null, "element": "date", "qualifier": "available", "schema": "dc"}, {"key": "dc.date.issued", "value": "2018", "language": null, "element": "date", "qualifier": "issued", "schema": "dc"}, {"key": "dc.identifier.uri", "value": "https://jyx.jyu.fi/handle/123456789/57984", "language": null, "element": "identifier", "qualifier": "uri", "schema": "dc"}, {"key": "dc.description.abstract", "value": "R\u00f6ntgentomografia on kuvantamismenetelm\u00e4, jonka avulla kappaleesta pystyt\u00e4\u00e4n\nmuodostamaan kolmiulotteinen rekonstruktio ilman kappaleen rikkomista. Tutkittavasta\nn\u00e4ytteest\u00e4 otetaan useasta eri suunnasta varjokuvia, joista lasketaan kappaleen\nrakenteen paljastavia poikkileikekuvia. Jyv\u00e4skyl\u00e4n yliopiston fysiikan laitoksella\ntutkitaan heterogeenisia materiaaleja r\u00f6ntgenmikrotomografialla, joka mahdollistaa\nmikrometrien kokoluokkaa olevan erotuskyvyn saavuttamisen.\n\nTavanomaisia rekonstruktioalgoritmeja k\u00e4ytett\u00e4ess\u00e4 on t\u00e4rke\u00e4\u00e4, ett\u00e4 tutkittava kappale\nmahtuu kokonaisuudessaan jokaiseen otettuun varjokuvaan. Muuten rekonstruktiossa\nvoi esiinty\u00e4 sen kvantitatiivista analysointia vaikeuttavia artefakteja.\nT\u00e4m\u00e4n ty\u00f6n tavoitteena on toteuttaa kaksi r\u00f6ntgenmikrotomografiakuvaukseen sopivaa\nmenetelm\u00e4\u00e4 varjokuvien korjaamiseen siten, ett\u00e4 virheett\u00f6m\u00e4n rekonstruktion\ntekeminen kappaleen sis\u00e4isest\u00e4 tarkastelutilavuudesta (engl. region of interest, ROI)\non mahdollista, sek\u00e4 arvioida toteutettujen menetelmien k\u00e4ytt\u00f6kelpoisuutta. Toteutetut\nmenetelm\u00e4t perustuvat varjokuvien korjaamiseen hy\u00f6dynt\u00e4en koko kappaleen\nrekonstruktion uudelleenprojisointia. Korjauksen tekemist\u00e4 varten tulee suorittaa\nkaksi kuvausta tutkittavalle n\u00e4ytteelle, yksi koko kappaleelle ja toinen kiinnostuksen\nkohteena olevalle pienemm\u00e4lle tarkastelutilavuudelle kappaleen sis\u00e4ll\u00e4.\n\nMenetelmist\u00e4 tehtiin kaksiulotteiset toteutukset Matlab-ohjelmointikielell\u00e4, mink\u00e4\nj\u00e4lkeen niit\u00e4 testattiin t\u00e4ysin simuloidulla tomografiakuvauksella. Simulaatiot osoittivat\nmenetelmien toimivan ideaalisessa tilanteessa todella hyvin. T\u00e4m\u00e4n j\u00e4lkeen\nmenetelmien toimivuutta kokeiltiin oikeissa tomografiakuvauksissa puukorkki- ja\nkivin\u00e4ytteelle. Menetelm\u00e4t toimivat kohtalaisen hyvin tilanteissa, joissa n\u00e4ytteen\npaikka pysyi suunnilleen muuttumattomana pystysuunnassa ensimm\u00e4isen ja toisen\nkuvauksen v\u00e4lill\u00e4. Korjausten tekeminen ei kuitenkaan tuottanut merkitt\u00e4v\u00e4\u00e4 parannusta\nrekonstruktioiden laatuun varsinkaan puukorkin tapauksessa. Syyn\u00e4 t\u00e4h\u00e4n\nvoi olla puukorkin tasalaatuinen rakenne. Menetelmien hy\u00f6dyt tulevat luultavasti\nparemmin esiin silloin, kun tarkasteltava sis\u00e4inen tilavuus on pienempi n\u00e4ytteen kokoon\nverrattuna ja n\u00e4ytteen rakenne on heterogeenisempi. Seuraavat kehitysaskeleet\novat hyv\u00e4n kuvanrekister\u00f6intialgoritmin toteuttaminen, algoritmien laajentaminen\nkolmiulotteisiksi ja suorituskyvyn parantaminen.", "language": "fi", "element": "description", "qualifier": "abstract", "schema": "dc"}, {"key": "dc.description.abstract", "value": "X-ray tomography is a non-destructive imaging method, which makes it possible to\nreconstruct three-dimensional structure of the sample. Multiple X-ray projections\nof the sample are acquired from different directions from which two-dimensional\ncross-sectional slices of the sample can be calculated. A technique called X-ray\nmicrotomography, which allows spatial resolution order of micrometre, is utilized in\nPhysics Department of University of Jyv\u00e4skyl\u00e4 to study various kinds of heterogeneous\nmaterials.\n\nOrdinarily used reconstruction algorithms require that a whole sample must fit in each\ntaken projection image. Otherwise a reconstruction can suffer from artefacts, which\nmake quantitative image analysis difficult. The purpose of this work is to implement\ntwo methods to reconstruct a subvolume (or region of interest, ROI) of the sample\nwithout artefacts and evaluate usefulness of the implemented methods. The methods\nare based on utilizing a forward projection of the whole sample reconstruction. Thus,\nmethods require two scans, one for the whole sample and another for the region of\ninterest inside the sample.\n\nTwo-dimensional versions of the methods were implemented with Matlab and they\nwere tested in the simulated tomography scans. Simulations showed that the methods\nwork well in ideal situation. After simulations methods were tested in real scans for\ncork and stone samples. Methods worked quite well when the vertical movement of\nthe sample was not remarkable between the whole body and region of interest scans.\nHowever, methods did not enhance the quality of the reconstruction remarkably\nespecially in the case of cork sample, a structure of which is quite homogeneous.\nBenefits of the corrections would probably be more remarkable when the region\nof interest is smaller compared to a sample and a material of a sample is more\nheterogeneous. Next steps are to develop a good image registration algorithm, make\nthree dimensional versions of the algorithms and make them more efficient.", "language": "en", "element": "description", "qualifier": "abstract", "schema": "dc"}, {"key": "dc.description.provenance", "value": "Submitted using Plone Publishing form by Jussi Laitinen (jumalait) on 2018-05-16 09:05:54.095104. Form: Pro gradu -lomake (https://kirjasto.jyu.fi/julkaisut/julkaisulomakkeet/pro-gradu-lomake). JyX data: [jyx_publishing-allowed (fi) =True]", "language": "en", "element": "description", "qualifier": "provenance", "schema": "dc"}, {"key": "dc.description.provenance", "value": "Submitted by jyx lomake-julkaisija (jyx-julkaisija.group@korppi.jyu.fi) on 2018-05-16T09:05:56Z\nNo. of bitstreams: 2\nURN:NBN:fi:jyu-201805162626.pdf: 16636692 bytes, checksum: 7685f86be485e6843db6832af9112088 (MD5)\nlicense.html: 4835 bytes, checksum: fa9b7527933ba506b9eaaa20bf9a3678 (MD5)", "language": "en", "element": "description", "qualifier": "provenance", "schema": "dc"}, {"key": "dc.description.provenance", "value": "Made available in DSpace on 2018-05-16T09:05:56Z (GMT). No. of bitstreams: 2\nURN:NBN:fi:jyu-201805162626.pdf: 16636692 bytes, checksum: 7685f86be485e6843db6832af9112088 (MD5)\nlicense.html: 4835 bytes, checksum: fa9b7527933ba506b9eaaa20bf9a3678 (MD5)\n Previous issue date: 2018", "language": "en", "element": "description", "qualifier": "provenance", "schema": "dc"}, {"key": "dc.format.extent", "value": "41", "language": "", "element": "format", "qualifier": "extent", "schema": "dc"}, {"key": "dc.format.mimetype", "value": "application/pdf", "language": null, "element": "format", "qualifier": "mimetype", "schema": "dc"}, {"key": "dc.language.iso", "value": "fin", "language": null, "element": "language", "qualifier": "iso", "schema": "dc"}, {"key": "dc.rights", "value": "In Copyright", "language": "en", "element": "rights", "qualifier": null, "schema": "dc"}, {"key": "dc.subject.other", "value": "r\u00f6ntgentomografia", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "sis\u00e4isen tarkastelutilavuuden rekonstruointi", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "rekonstruktion uudelleenprojisointi", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.title", "value": "Kappaleen sis\u00e4isen tarkastelutilavuuden rekonstruointi r\u00f6ntgentomografiassa", "language": "", "element": "title", "qualifier": null, "schema": "dc"}, {"key": "dc.type", "value": "master thesis", "language": null, "element": "type", "qualifier": null, "schema": "dc"}, {"key": "dc.identifier.urn", "value": "URN:NBN:fi:jyu-201805162626", "language": null, "element": "identifier", "qualifier": "urn", "schema": "dc"}, {"key": "dc.type.ontasot", "value": "Master\u2019s thesis", "language": "en", "element": "type", "qualifier": "ontasot", "schema": "dc"}, {"key": "dc.type.ontasot", "value": "Pro gradu -tutkielma", "language": "fi", "element": "type", "qualifier": "ontasot", "schema": "dc"}, {"key": "dc.contributor.faculty", "value": "Matemaattis-luonnontieteellinen tiedekunta", "language": "fi", "element": "contributor", "qualifier": "faculty", "schema": "dc"}, {"key": "dc.contributor.department", "value": "Fysiikan laitos", "language": "fi", "element": "contributor", "qualifier": "department", "schema": "dc"}, {"key": "dc.contributor.organization", "value": "University of Jyv\u00e4skyl\u00e4", "language": "en", "element": "contributor", "qualifier": "organization", "schema": "dc"}, {"key": "dc.contributor.organization", "value": "Jyv\u00e4skyl\u00e4n yliopisto", "language": "fi", "element": "contributor", "qualifier": "organization", "schema": "dc"}, {"key": "dc.subject.discipline", "value": "Applied Physics", "language": "en", "element": "subject", "qualifier": "discipline", "schema": "dc"}, {"key": "dc.subject.discipline", "value": "Soveltava fysiikka", "language": "fi", "element": "subject", "qualifier": "discipline", "schema": "dc"}, {"key": "dc.date.updated", "value": "2018-05-16T09:05:56Z", "language": null, "element": "date", "qualifier": "updated", "schema": "dc"}, {"key": "yvv.contractresearch.funding", "value": "0", "language": null, "element": "contractresearch", "qualifier": "funding", "schema": "yvv"}, {"key": "dc.type.coar", "value": "http://purl.org/coar/resource_type/c_bdcc", "language": null, "element": "type", "qualifier": "coar", "schema": "dc"}, {"key": "dc.rights.accesslevel", "value": "openAccess", "language": "fi", "element": "rights", "qualifier": "accesslevel", "schema": "dc"}, {"key": "dc.type.publication", "value": "masterThesis", "language": null, "element": "type", "qualifier": "publication", "schema": "dc"}, {"key": "dc.subject.oppiainekoodi", "value": "4023", "language": "", "element": "subject", "qualifier": "oppiainekoodi", "schema": "dc"}, {"key": "dc.format.content", "value": "fulltext", "language": null, "element": "format", "qualifier": "content", "schema": "dc"}, {"key": "dc.rights.url", "value": "https://rightsstatements.org/page/InC/1.0/", "language": null, "element": "rights", "qualifier": "url", "schema": "dc"}, {"key": "dc.type.okm", "value": "G2", "language": null, "element": "type", "qualifier": "okm", "schema": "dc"}]
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