Please use this identifier to cite or link to this item: http://archive.cmb.ac.lk:8080/xmlui/handle/70130/1411
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dc.contributor.authorSumanaweera, T.S
dc.date.accessioned2011-12-13T08:44:34Z
dc.date.available2011-12-13T08:44:34Z
dc.date.issued1992
dc.identifier.citationPh.D – Stamford Universityen_US
dc.identifier.urihttp://archive.cmb.ac.lk:8080/xmlui/handle/70130/1411-
dc.description.abstractNew in vivo method is presented to correct the non -linear, object shape-dependent spatial distoration in MR images caused by magnetic susceptibility variation. This distoration across the air/tissue interface before and after the correction is qualified using a phantom.The results are compared to the "distortion -free" CT images of the same phantom by fusing CT and MR images using fiducials, with registration accuracy of better than a millimeter.Magnetic susceptibility of cortical bone is measured using a SQUID magnetometer and found to be -8.86 ppm (with respect to air) which is quite similar to that of tissue (-9 ppm). A new method to estimate magnetic suspceptibility of materials from MR images is also presented.Geometric distortion in MR images caused by gradient field non-linearity is quantified accurately using a 3D phantom before and after a commercial correction scheme.This correction scheme improves the accuracy of MR images from about 4 mm to better than 1 mm everywhere within a 200*200*200 mm3 cubic volume of interest centered at the gradient isocenter.This volume corresponds to the typical size of a human head.A computer vision techniques is used to automate the distortion quantification process.
dc.language.isoenen_US
dc.titleSegmentation and distortion correction in medical imagingen_US
dc.typeResearch abstracten_US
Appears in Collections:Masters Theses - Postgraduate Institute of Medicine

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