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Objective characterization of GE discovery CT750 HD scanner: gemstone spectral imaging mode.

Abstract：

PURPOSE:To objectively characterize the performance of the gemstone spectral imaging (GSI) mode of GE CT750 HD scanner from a user's perspective. METHODS:A regular scan protocol that approximates the adult abdomen scan protocol frequently used in the authors' institute was selected as the baseline, and a GSI protocol (preset 11) that is similar to the regular protocol and has a moderate dose level (CTDI(vol) = 26.27 mGy) was compared to the baseline protocol. The resolving power of both protocols was characterized in terms of modulation transfer functions and high contrast resolution bar readings. Their noise characteristics were studied through noise power spectra, and their low contrast detectability was compared via contrast-to-noise ratio. Material decomposition capability of GSI was evaluated by scanning iodine solutions of 9-24 mg/ml iodine concentration in a Gammex CT phantom and by examining the estimated iodine concentration. In addition, a formula describing the dependency of HU in iodine enhanced area on GSI monochromatic energies and iodine concentrations was provided and the theoretical values were compared with the measured results. RESULTS:The resolutions levels of 50%, 10%, and 5% MTF of GSI monochromatic images at 65 keV agree with those of the regular protocol within 0.1 1p/cm. GSI monochromatic images at 65 keV demonstrated the lowest noise level among GSI images of different monochromatic energies and showed very similar noise magnitude and noise power distribution as compared to the regular protocol images. The CNR of 60 and 65 keV GSI monoimages are approximately 100% of those of the regular protocol images. Estimated iodine concentration levels agreed with the actual values within 2% when the iodine solutions were placed at 3, 9, 12 o'clock positions of the phantom; when iodine solutions were placed at the phantom center and at 6 o'clock position, higher discrepancies of 2%-10% were observed. The observed dependency of HU on keV and iodine concentration levels agreed with the expectation from x-ray attenuations. CONCLUSIONS:Equivalent performances were observed in the comparison between GSI 65 keV monochromatic images and images from a regular abdomen scan protocol. This suggests the possibility of GSI to be employed in routine abdominal scans, which would potentially offer more information through its capabilities of material decomposition.

journal_name

Med Phys

journal_title

Medical physics

authors

Zhang D,Li X,Liu B

doi

10.1118/1.3551999

subject

Has Abstract

pub_date

2011-03-01 00:00:00

pages

1178-88

issue

eissn

0094-2405

issn

2473-4209

journal_volume

pub_type

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Objective characterization of GE discovery CT750 HD scanner: gemstone spectral imaging mode.