Dual-Source Dual-Energy CT With Additional Tin Filtration: Dose and Image Quality Evaluation in Phantoms and In Vivo

Abstract

Purpose-To investigate the effect on radiation dose and image quality of the use of additional spectral filtration for dual-energy CT (DECT) imaging using dual-source CT (DSCT).Materials and Methods-A commercial DSCT scanner was modified by adding tin filtration to the high-kV tube, and radiation output and noise measured in water phantoms. Dose values for equivalent image noise were compared among DE-modes with and without tin filtration and singleenergy (SE) mode. To evaluate DECT material discrimination, the material-specific DE ratio for calcium and iodine were determined using images of anthropomorphic phantoms. Data were additionally acquired in 38 and 87 kg pigs, and noise for the linearly mixed and virtual non-contrast (VNC) images compared between DE-modes. Finally, abdominal DECT images from two patients of similar sizes undergoing clinically-indicated CT were compared.Results-Adding tin filtration to the high-kV tube improved the DE contrast between iodine and calcium as much as 290%. Pig data showed that the tin filtration had no effect on noise in the DECT mixed images, but decreased noise by as much as 30% in the VNC images. Patient VNC-images acquired using 100/140 kV with added tin filtration had improved image quality compared to those generated with 80/140 kV without tin filtration.Conclusion-Tin filtration of the high-kV tube of a DSCT scanner increases the ability of DECT to discriminate between calcium and iodine, without increasing dose relative to SECT. Furthermore, use of 100/140 kV tube potentials allows improved DECT imaging of large patients.

Comparison of image quality and radiation dose of different pulmonary CTA protocols on a 128-slice CT: high-pitch dual source CT, dual energy CT and conventional spiral CT

“…The most recent technical advances include the ability of performing highpitch acquisitions of the entire chest in less than 1 s. Our study confirms that this approach results in good diagnostic image quality when applied for pulmonary CTA. DECT has been shown to provide simultaneous information on the presence of endoluminal thrombus and lung perfusion impairment [10][11][12][13][14][15]. Our study indicates that all CTA approaches tested result in good diagnostic image quality thus extending previous data [11].…”

“…DECT uses two different tube energies (kV) and allows analyses of the chemical composition of tissues by means of dual-energy data acquisition according to the material decomposition theory [8,9]. Previous studies have shown the potential of pulmonary blood volume maps obtained by DECT for showing perfusion impairment [10][11][12][13][14][15].…”

CT Urography

“…This is due to subtraction of some stone signal from the stone periphery along with the iodine signal. In addition, the difference in collimation between dual-energy (1.2 mm) and single-energy (0.6 mm) acquisitions determines a relatively lower z-axis resolution that does not allow separation of the small stones and iodine in the urinary tract because of the volume averaging [41][42][43]. Similar results have been reported by reconstructing virtual unenhanced images from synchronous nephrographic/excretory enhancement (split-bolus CT urography technique) dualenergy CT images [44].…”

“…Due to an energy spectra overlap between 100 and 140 kVp, these scanners had to be operated at 80 and 140 kVp, resulting in the inability to be used in the abdomen due to a low penetration depth and beam-hardening artifact [40,41].…”

Numerical observer for atherosclerotic plaque classification in spectral computed tomography

“…8,54 For both DECT-DS and DECT-SW, the xray exposure from both tubes matched that of a single-source CT protocol, with the dose ratio of the low-and high-energy spectra was 19:1. By performing the experiment, this ratio was chosen empirically to maximize the discrimination performance of DECT.…”