Abstract
A specially designed phantom consisting of a 3D array of 427 accurately manufactured spheres together with a point-based registration algorithm was used to detect distortion described by polynomial orders 1-4. More than thirty 3D gradient echo (GRE) and multi-slice spin echo (SE) phantom scans were acquired with a Philips 1.5T Gyroscan ACS2. Distortion was measured as a function of: readout gradient strength (0.72 0.93). There was a significantly higher (p <0.01) sagittal shear for 5 SE scans compared with 5 FFE ones with the same G, possibly because of slice selection. Different shim settings produced only linear distortion change: up to 2 % scale kand 1 degree shear. There was negligible distortion change over time: scale <0.1%, shear 0.9, n = 3), 75% of the distortion was either first or second order.
Original language | English |
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Pages (from-to) | 69 - 78 |
Number of pages | 10 |
Journal | PROCEEDINGS- SPIE THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING |
Volume | 2 |
Issue number | 27 |
Publication status | Published - 2001 |
Event | Medical Imaging 2001 Conference - SAN DIEGO, CALIFORNIA Duration: 1 Jan 2001 → … |