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Reconstruction Approach for Partially Truncated CT Data
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
2018 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesisAlternative title
Tillvägagångssätt för rekonstruktion av delvis trunkerad CT data (Swedish)
Abstract [en]

For various reasons it might be required to scan an object that partially

lies outside the field of view(FOV) of a CT scanner. The parts of

the object that lie outside the FOV will not contribute to the line integrals

measured by the detector which will cause image artifacts that

affect the final image quality. In this paper, I suggest a novel reconstruction

approach that estimates the attenuation by the object outside

the FOV using a priori knowledge about the outline of the object. It is

shown that, knowing the object’s outline, it is possible to determine

whether the attenuation along a given line is truncated. The total attenuation

for a truncated projection is then estimated by interpolating

the data between the consistent projections. The method therefore

requires some of the projections to be consistent. This estimate,

along with the knowledge of the distance traversed by the X-Ray inside

the object is then used to determine the average attenuation. The

method was tested on both numerical and physical phantoms. The results

are satisfactory even when up to 80% of the projections are truncated.

Structural Similarity Index (SSIM) was compared for the complete

reconstructed images,and regions of truncations before and after

the algorithm was applied. Reconstructed images from completely

consistent projections served as ground truth. The results indicate that

the algorithm can be used to reconstruct partially truncated CT data,

which was tested on numerical and physical phantoms (of semicircular

cross section). There is scope for further testing of the algorithm on

irregularly shaped objects.

Place, publisher, year, edition, pages
2018. , p. 48
Series
TRITA-CBH-GRU ; 2018:71
Keywords [en]
partially truncated, partial CT reconstruction
National Category
Medical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-231159OAI: oai:DiVA.org:kth-231159DiVA, id: diva2:1222951
Subject / course
Medical Engineering
Educational program
Master of Science - Medical Engineering
Presentation
2018-06-07, Hälsovägen 11 C, Huddinge, 15:00 (English)
Supervisors
Examiners
Projects
TechnologyAvailable from: 2018-06-25 Created: 2018-06-24 Last updated: 2018-06-25Bibliographically approved

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