diplomsko delo
Kim Golavšek (Author), Nejc Mekiš (Reviewer), Erna Huskić (Mentor), Aleš Kaučič (Co-mentor)

Abstract

Uvod: Kovinski artefakti so pogost klinični izziv pri ocenjevanju CT slik bolnikov s kovinskimi vsadki. Kovinski vsadki namreč izrazito poslabšajo kakovost slike zaradi prevelikega slabljenja snopa rentgenske svetlobe. Dejavniki, ki vplivajo na stopnjo kovinskih artefaktov so kovinska sestava kovinskega vsadka, parametri zajema, rekonstrukcija slike in algoritem rekonstrukcije slike. Namen: Namen diplomske naloge je primerjava učinkovitosti različnih algoritmov za odpravljanje artefaktov na CT slikah, katerih vzrok je prisotnost kovine v področju slikanja. Primerjali bomo kako se zmanjša prisotnost artefaktov pri virtualnih monoenergijskih rekonstrukcijah in kako pri rekonstrukcijah, kjer se uporabi MAR algoritem. Metode dela: Iz baze SyngoVia programa Zdravstvene fakultete v Ljubljani, smo izbrali štiri primere, na katerih so bili hrbtenica, kolk, koleno in gleženj z vstavljenimi različnimi kovinskimi ploščami in vijaki, ki na CT slikah predstavljajo artefakte. Nato smo ustvarili VME rekonstrukcije, z različnimi kerneli in kombinacijami različnih filtrov, v rangu 40 – 190 keV ter tri klasične rekonstrukcije, ki se vsakodnevno uporabljajo v kliničnem okolju. Pet ocenjevalcev je najprej pregledalo vse VME rekonstrukcije in med vsemi izbralo najljubše. Nato smo tem izbranim serijam dodali še klasične rekonstrukcije in ocenjevali so izbrali končno najljubšo oziroma najbolj primerno za klinično uporabo. Rezultati: Ugotovili smo, da je za oceno tako kostnih struktur kot tudi mehkih tkiv, najbolj optimalna kombinacija VME rekonstrukcij in MAR algoritma s kernelom za kosti Br59 oziroma za mehka tkiva Br36 in razponom energij med 140 in 160 keV. Razprava in zaključek: Skupaj z že narejenimi raziskavami se strinjamo, da je kombinacija VME in MAR rekonstrukcij v kombinacijami z višjimi energijami, najbolj optimalna za zmanjševanje kovinskih artefaktov in uporabo v diagnostične namene.

Keywords

diplomska dela;radiološka tehnologija;računalniška tomografija;MAR;VME;dvospektralno slikanje;CT;rekonstrukcije;iterativni MAR algoritem;kovinski artefakti;CT artefakti;odpravljanje artefaktov;iMAR;

Data

Language: Slovenian
Year of publishing:
Typology: 2.11 - Undergraduate Thesis
Organization: UL ZF - University College of Health Studies
Publisher: [K. Golavšek]
UDC: 616-07
COBISS: 169195267 Link will open in a new window
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Downloads: 8
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Other data

Secondary language: English
Secondary title: Comparison of virtual monoenergy reconstructions with iterative metal artefact reduction algorithm for eliminating metal artefacts on computed tomography scans
Secondary abstract: Introduction: Metal artefacts are a common clinical challenge when assessing CT images of patients with metal implants. This is because metallic implants markedly degrade image quality due to excessive attenuation of the X-ray beam. Factors influencing the level of metal artefacts are the metal composition of the metal implant, the acquisition parameters, the image reconstruction and the image reconstruction algorithm. Purpose: The purpose of this thesis is to compare the performance of different algorithms for the removal of artefacts in CT images caused by the presence of metal in the scan region. We will compare how the presence of artefacts is reduced in virtual monoenergy reconstructions and how it is reduced in reconstructions where the MAR algorithm is used. Methods: From the PACS database of the Faculty of Health Sciences in Ljubljana, we selected four cases showing the spine, hip, knee and ankle with various metal plates and screws implanted which represent artefacts on the CT images. We then created VME reconstructions, with different kernels and combinations of different filters, in the range of 40-190 keV and three classical reconstructions that are used on a daily basis in the clinical setting. Five evaluators first looked at all the VME reconstructions and chose their favourites among all of them. Then, the classical reconstructions were added to these selected series and the evaluators chose the final favourite or the most suitable for clinical use. Results: We found that the combination of VME reconstructions and the MAR algorithm with Br59 kernel for bone and Br36 for soft tissue and a range of energies between 140 and 160 keV, is the most optimal for the assessment of both bone and soft tissue structures. Discussion and conclusion: Together with the studies already done, we agree that the combination of VME and MAR reconstructions in combinations with higher energies is the most optimal for metal artefact reduction and diagnostic use.
Secondary keywords: diploma theses;radiologic technology;computed tomography;MAR;VME;virtual monoenergy;CT;reconstructions;iterative MAR algorithm;metal artefacts;CT artefacts;eliminating artefacts;iMAR;
Type (COBISS): Bachelor thesis/paper
Study programme: 0
Thesis comment: Univ. v Ljubljani, Zdravstvena fak., Oddelek za radiološko tehnologijo
Pages: 39 str., [13] str. pril.
ID: 20386063