First-generation clinical dual-source photon-counting CT: ultra-low-dose quantitative spectral imaging

• Published in: European radiology Vol. 32; no. 12; pp. 8579 - 8587
• Main Authors: Liu, Leening P., Shapira, Nadav, Chen, Andrew A., Shinohara, Russell T., Sahbaee, Pooyan, Schnall, Mitchell, Litt, Harold I., Noël, Peter B.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-12-2022; Springer Nature B.V
• Subjects: Background noise; Computed Tomography; Diagnostic Radiology; Exposure; Humans; Imaging; Inserts; Internal Medicine; Interventional Radiology; Medical diagnosis; Medical imaging; Medicine; Medicine & Public Health; Neuroradiology; Noise reduction; Phantoms, Imaging; Photons; Radiation; Radiation Dosage; Radiation effects; Radiology; Scanners; Tomography, X-Ray Computed - methods; Ultrasound; X-ray computed tomography; Diagnostic imaging; Radiation dosage
• ISSN: 1432-1084; 0938-7994; 1432-1084
• DOI: 10.1007/s00330-022-08933-x

Objective
Evaluation of image characteristics at ultra-low radiation dose levels of a first-generation dual-source photon-counting computed tomography (PCCT) compared to a dual-source dual-energy CT (DECT) scanner.
Methods
A multi-energy CT phantom was imaged with and without an extension ring on both scanners over a range of radiation dose levels (CTDI
vol
0.4–15.0 mGy). Scans were performed in different modes of acquisition for PCCT with 120 kVp and DECT with 70/Sn150 kVp and 100/Sn150 kVp. Various tissue inserts were used to characterize the precision and repeatability of Hounsfield units (HUs) on virtual mono-energetic images between 40 and 190 keV. Image noise was additionally investigated at an ultra-low radiation dose to illustrate PCCT’s ability to remove electronic background noise.
Results
Our results demonstrate the high precision of HU measurements for a wide range of inserts and radiation exposure levels with PCCT. We report high performance for both scanners across a wide range of radiation exposure levels, with PCCT outperforming at low exposures compared to DECT. PCCT scans at the lowest radiation exposures illustrate significant reduction in electronic background noise, with a mean percent reduction of 74% (
p
value ~ 10
−8
) compared to DECT 70/Sn150 kVp and 60% (
p
value ~ 10
−6
) compared to DECT 100/Sn150 kVp.
Conclusions
This paper reports the first experiences with a clinical dual-source PCCT. PCCT provides reliable HUs without disruption from electronic background noise for a wide range of dose values. Diagnostic benefits are not only for quantification at an ultra-low dose but also for imaging of obese patients.
Key Points
PCCT scanners provide precise and reliable Hounsfield units at ultra-low dose levels.
The influence of electronic background noise can be removed at ultra-low-dose acquisitions with PCCT.
Both spectral platforms have high performance along a wide range of radiation exposure levels, with PCCT outperforming at low radiation exposures.