Please use this identifier to cite or link to this item:
http://archive.cmb.ac.lk:8080/xmlui/handle/70130/1411
Full metadata record
DC Field | Value | Language |
---|---|---|
dc.contributor.author | Sumanaweera, T.S | |
dc.date.accessioned | 2011-12-13T08:44:34Z | |
dc.date.available | 2011-12-13T08:44:34Z | |
dc.date.issued | 1992 | |
dc.identifier.citation | Ph.D – Stamford University | en_US |
dc.identifier.uri | http://archive.cmb.ac.lk:8080/xmlui/handle/70130/1411 | - |
dc.description.abstract | New 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.iso | en | en_US |
dc.title | Segmentation and distortion correction in medical imaging | en_US |
dc.type | Research abstract | en_US |
Appears in Collections: | Masters Theses - Postgraduate Institute of Medicine |
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.