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Proceedings Paper

Low kV rotational 3D x-ray imaging for improved CNR of iodine contrast agent
Author(s): Dirk Schäfer; Martin Ahrens; Peter Eshuis; Michael Grass
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Paper Abstract

The contrast of iodine to soft tissue (water) decreases with higher tube voltage in reconstructed 3D X-ray images. Improved acquisition protocols with a tube voltage of about 80 kV for imaging iodine have been proposed earlier for diagnostic CT imaging. We investigate the contrast-to-noise ratio (CNR) and the CNR-to-dose ratio (CDR) for different concentrations of iodinated contrast agent inserts in water background. The tube voltage of the protocol is lowered from 123 kV to 83 kV in 10 kV steps. Measurements with 16 different settings of tube voltage, current and Copper (Cu) filter settings are investigated. The weighted computed tomography dose index (CTDIW) for the new protocol settings is measured. Four protocols with tube voltages between 83 kV and 103 kV and similar X-ray dose are compared to the original protocol. An iodine-water contrast phantom, containing a water filled cylinder with 5 tubes of different mixtures of iodine contrast agent inside a 32 cm PMMA ring, is imaged with each protocol. Increased contrast of the iodine filled tubes to the water background is clearly visible in the reconstructed volumes for lower tube voltage and less copper filtering. The CNR increased by about 100% for the 83 kV protocols compared to 123 kV and the dose utility in terms of the CDR even by 350%. The best results are obtained with the (83 kV, 561 mA, 0.4 mm Cu) - protocol. This protocol may improve iodine contrast agent visibility in various 3D imaging applications. For large patients a higher tube voltage, e.g. the (103 kV, 325 mA, 0.4 mm Cu) - protocol, may be used to avoid tube power limitations at 83 kV. This protocol still has improved iodine contrast compared to the 123 kV protocol and a larger tube power reserve.

Paper Details

Date Published: 3 March 2012
PDF: 6 pages
Proc. SPIE 8313, Medical Imaging 2012: Physics of Medical Imaging, 83132V (3 March 2012); doi: 10.1117/12.909909
Show Author Affiliations
Dirk Schäfer, Philips Research (Germany)
Martin Ahrens, Philips Research (Germany)
Peter Eshuis, Philips Healthcare (Netherlands)
Michael Grass, Philips Research (Germany)

Published in SPIE Proceedings Vol. 8313:
Medical Imaging 2012: Physics of Medical Imaging
Norbert J. Pelc; Robert M. Nishikawa; Bruce R. Whiting, Editor(s)

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