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. 2019 Dec 13;64(24):245003.
doi: 10.1088/1361-6560/ab55bf.

Radiation dose efficiency of multi-energy photon-counting-detector CT for dual-contrast imaging

Liqiang Ren  1 , Kishore Rajendran  1 , Cynthia H McCollough  1 , Lifeng Yu  1   2
Affiliations

Radiation dose efficiency of multi-energy photon-counting-detector CT for dual-contrast imaging

Liqiang Ren et al. Phys Med Biol. .

Abstract

Compared to traditional multi-scan single-energy CT (SECT), one potential advantage of single-scan multi-energy CT (MECT) proposed for simultaneous imaging of multiple contrast agents is the radiation dose reduction. This phantom study aims to rigorously evaluate whether the radiation dose can truly be reduced in a single-scan MECT protocol (MECT_1s) in biphasic liver imaging with iodine and gadolinium, and small bowel imaging with iodine and bismuth, compared to traditional two-scan SECT protocols (SECT_2s). For MECT_1s, mixed iodine/gadolinium samples were prepared corresponding to late arterial/portal-venous phase for biphasic liver imaging. Mixed iodine/bismuth samples were prepared representing the arterial/enteric enhancement for small bowel imaging. For SECT_2s, separate contrast samples were prepared to mimic separate scans in arterial/venous phase and arterial/enteric enhancement. Samples were placed in a 35 cm wide water phantom and scanned by a research whole-body photon-counting-detector-CT (PCD-CT) system ('chess' mode). MECT images were acquired with optimized kV/threshold settings for each imaging task, and SECT images were acquired at 120 kV. Total CTDIvol was matched for the two protocols. Image-based three-material decomposition was employed in MECT_1s to determine the basis material concentration values, which were converted to CT numbers at 120 kV (i.e. virtual SECT images) to compare with the SECT images directly acquired with SECT_2s. The noise difference between the SECT and the virtual SECT images was compared to evaluate the dose efficiency of MECT_1s. Compared to SECT_2s, MECT_1s was not dose efficient for both imaging tasks. The amount of noise increase is highly task dependent, with noise increased by 203%/278% and 110%/82% in virtual SECT images for iodine/gadolinium and iodine/bismuth quantifications, respectively, corresponding to dose increase by 819%/1328% and 340%/230% in MECT_1s to achieve the same image noise level. MECT with the current PCD-CT technique requires higher radiation dose than SECT to achieve the same image quality.

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Figures

Figure 1.
Figure 1.
Scan protocols for biphasic liver imaging with (a) two SECT scans for iodine imaging and (b) one MECT scan for simultaneous iodine and gadolinium imaging; the total radiation dose is matched for comparison.
Figure 2.
Figure 2.
Scan protocols for small bowel imaging with (a) one SECT scan for iodine imaging, (b) one SECT scan for bismuth imaging, and (c) one MECT scan for simultaneous imaging of both iodine and bismuth; the total radiation dose is matched for comparison.
Figure 3.
Figure 3.
Phantom layouts for testing the two tasks: biphasic liver imaging (a)–(c) and small bowel imaging (d)–(f). (a) Iodine samples mimicking contrast enhancement at late arterial phase in SECT_2s, (b) iodine samples mimicking contrast enhancement at portal-venous phase in SECT_2s, and (c) mixed iodine and gadolinium samples for contrast enhancement at the two phases in MECT_1s; (d) iodine samples mimicking arterial enhancement in SECT_2s, (e) bismuth samples mimicking enteric enhancement in SECT_2s, and (f) mixed iodine and bismuth samples for both arterial and enteric enhancements in MECT_1s (phantom lateral dimension: 35 cm).
Figure 4.
Figure 4.
PCD-CT x-ray spectra for (a) biphasic liver imaging with iodine and gadolinium and (b) small bowel imaging with iodine and bismuth; the linear attenuation curves (LACs) derived from pure iodine, gadolinium, and bismuth were also plotted.
Figure 5.
Figure 5.
Biphasic liver imaging using MECT scan with three-material decomposition algorithm: (a) iodine-specific image, (b) gadolinium-specific image, and (c) water image; linearity analysis between measured and nominal concentrations: (d) iodine samples and (e) gadolinium samples.
Figure 6.
Figure 6.
(a) SECT images (1st column) acquired from SECT_2s and vSECT images (2nd column) generated from MECT_1s for biphasic liver imaging; (b) noise level comparison between SECT and vSECT images.
Figure 7.
Figure 7.
Small bowel imaging using MECT scan with three-material decomposition algorithm: (a) iodine-specific image, (b) bismuth-specific image, and (c) water image; linearity analysis between measured and nominal concentrations: (d) iodine samples and (e) bismuth samples.
Figure 8.
Figure 8.
(a) SECT images (1st column) and vSECT images (2nd column) for small bowel imaging; (b) noise level comparison between SECT and vSECT images.
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References

    1. Anderson NG et al. 2010. Spectroscopic (multi-energy) CT distinguishes iodine and barium contrast material in MICE Eur. Radiol 20 2126–34 - PubMed
    1. Cormode DP. et al. Multicolor spectral photon-counting computed tomography: in vivo dual contrast imaging with a high count rate scanner. Sci. Rep. 2017;7:4784. - PMC - PubMed
    1. Dangelmaier J et al. 2018. Experimental feasibility of spectral photon-counting computed tomography with two contrast agents for the detection of endoleaks following endovascular aortic repair Eur. Radiol 28 3318–25 - PMC - PubMed
    1. Faby S et al. 2015. Performance of today’s dual energy CT and future multi energy CT in virtual non-contrast imaging and in iodine quantification: a simulation study Med. Phys 42 4349–66 - PubMed
    1. Gutjahr R et al. 2016. Human imaging with photon counting–based computed tomography at clinical dose levels: contrast-to-noise ratio and cadaver studies Investi. Radiol 51 421–9 - PMC - PubMed

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