Computed tomography with a full FOV photon-counting detector in a clinical setting, the first experience

Ferda, Jiří; Vendiš, Tomáš; Flohr, Thomas; Schmidt, Bernhard; Henning, André; Ulzheimer, Stefan; Pecen, Ladislav; Ferdová, Eva; Baxa, Jan; Mírka, Hynek

doi:10.1016/j.ejrad.2021.109614

Cited by 46 publications

(35 citation statements)

References 22 publications

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“…QIR has four strength levels and is specifically tailored to PCD CT. In addition, given the multienergy capabilities of PCD CT, the routine reconstruction of virtual monoenergetic images as the reference standard for diagnostic readouts was defined (18,19).…”

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confidence: 99%

Quantum Iterative Reconstruction for Abdominal Photon-counting Detector CT Improves Image Quality

et al. 2022

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Background: An iterative reconstruction (IR) algorithm was introduced for clinical photon-counting detector (PCD) CT.Purpose: To investigate the image quality and the optimal strength level of a quantum IR algorithm (QIR; Siemens Healthcare) for virtual monoenergetic images and polychromatic images (T3D) in a phantom and in patients undergoing portal venous abdominal PCD CT. Materials and Methods:In this retrospective study, noise power spectrum (NPS) was measured in a water-filled phantom. Consecutive oncologic patients who underwent portal venous abdominal PCD CT between March and April 2021 were included. Virtual monoenergetic images at 60 keV and T3D were reconstructed without QIR (QIR-off; reference standard) and with QIR at four levels (QIR 1-4; index tests). Global noise index, contrast-to-noise ratio (CNR), and voxel-wise CT attenuation differences were measured. Noise and texture, artifacts, diagnostic confidence, and overall quality were assessed qualitatively. Conspicuity of hypodense liver lesions was rated by four readers. Parametric (analyses of variance, paired t tests) and nonparametric tests (Friedman, post hoc Wilcoxon signed-rank tests) were used to compare quantitative and qualitative image quality among reconstructions. Results:In the phantom, NPS showed unchanged noise texture across reconstructions with maximum spatial frequency differences of 0.01 per millimeter. Fifty patients (mean age, 59 years 6 16 [standard deviation]; 31 women) were included. Global noise index was reduced from QIR-off to QIR-4 by 45% for 60 keV and by 44% for T3D (both, P , .001). CNR of the liver improved from QIR-off to QIR-4 by 74% for 60 keV and by 69% for T3D (both, P , .001). No evidence of difference was found in mean attenuation of fat and liver (P = .79-.84) and on a voxel-wise basis among reconstructions. Qualitatively, QIR-4 outperformed all reconstructions in every category for 60 keV and T3D (P value range, ,.001 to .01). All four readers rated QIR-4 superior to other strengths for lesion conspicuity (P value range, ,.001 to .04). Conclusion:In portal venous abdominal photon-counting detector CT, an iterative reconstruction algorithm (QIR; Siemens Healthcare) at high strength levels improved image quality by reducing noise and improving contrast-to-noise ratio and lesion conspicuity without compromising image texture or CT attenuation values.

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confidence: 99%

Quantum Iterative Reconstruction for Abdominal Photon-counting Detector CT Improves Image Quality

et al. 2022

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“…38 The system is capable of patient scanning using typical clinical scan protocols. 48 A key benefit of photon-counting CT is improved spatial resolution. The achievable image quality with a photon-counting detector in high-resolution chest CT is demonstrated in Fig.…”

Section: Photon Counting Ctmentioning

confidence: 99%

Computed tomography recent history and future perspectives

Hsieh¹,

Flohr

2021

J. Med. Imag.

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Purpose: We provide a review of the key computed tomography (CT) technologies developed since the late 1980s and offer an overview of one of the future technologies under development. The focus of this review is mainly on the hardware and system development. The topics on the historical event linked to the early days of CT development and other innovations that contributed to the CT development, such as advanced image reconstruction techniques, are covered by companion papers in this special issue.Approach: The review is divided into five major sections, each linked to a key innovation in CT: helical spiral data acquisition, multi-slice CT, wide-cone CT, dual-source CT, and spectral CT. Given the limited scope of this review, only one of the future technologies, photon-counting CT, is discussed in detail. Whenever possible, both theory of operation and clinical examples are provided.Results: Theoretical analyses, phantom results, and clinical examples clearly demonstrate the efficacy and clinical relevancy of five historical technology developments and one future technology in CT. These technologies have improved and will continue to improve CT performance in terms of isotropic volume coverage, improved temporal resolution, and material differentiation and characterization capabilities.Conclusions: Over the past 30 years, technological developments of CT have contributed to the success of CT in many clinical applications such as trauma, oncology, cardiac imaging, and stroke. Advanced clinical applications have and will continue to demand more advanced technology development.

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“…The subsequent major loss of efficiency with respect to exposure limits the size of EID to 0.5 mm at iso-center in normal resolution for most of the current clinical system. PCD pixel pitch is not technically limited and can reach 0.19-0.225 mm at the iso-center in the latest full-body prototypes [9][10][11][12].…”

Section: Spatial Resolutionmentioning

confidence: 99%

“…According to the number of available thresholds (between 3 and 8 according to PCD manufacturer), several measurement bins can be defined (Figure 2) [9,11,12]. The first threshold is set just above the electronic noise level and suppresses it from the final counts, which cannot be done for EIDs, and therefore, electronic noise is added to the integrated energy.…”

Section: Reduction Of Electronic Noisementioning

confidence: 99%

“…In an attempt to evaluate the feasibility of PCD-CT in interstitial lung diseases, a recent study conducted by Ferda et al [12], with a clinical prototype large FOV PCD-CT system, identified a few cases in a cohort of 60 patients addressed for various reasons. They investigated the diagnostic quality of PCD-CT lung imaging using a standard and a low-dose protocol by subjectively assessing critical structures, such as bronchi and bronchial walls.…”

Section: Interstitial Lung Disease Imagingmentioning

confidence: 99%

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Spectral Photon-Counting CT Technology in Chest Imaging

Si‐Mohamed

Miailhes

Rodesch

et al. 2021

JCM

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The X-ray imaging field is currently undergoing a period of rapid technological innovation in diagnostic imaging equipment. An important recent development is the advent of new X-ray detectors, i.e., photon-counting detectors (PCD), which have been introduced in recent clinical prototype systems, called PCD computed tomography (PCD-CT) or photon-counting CT (PCCT) or spectral photon-counting CT (SPCCT) systems. PCD allows a pixel up to 200 microns pixels at iso-center, which is much smaller than that can be obtained with conventional energy integrating detectors (EID). PCDs have also a higher dose efficiency than EID mainly because of electronic noise suppression. In addition, the energy-resolving capabilities of these detectors allow generating spectral basis imaging, such as the mono-energetic images or the water/iodine material images as well as the K-edge imaging of a contrast agent based on atoms of high atomic number. In recent years, studies have therefore been conducted to determine the potential of PCD-CT as an alternative to conventional CT for chest imaging.

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Computed tomography with a full FOV photon-counting detector in a clinical setting, the first experience

Cited by 46 publications

References 22 publications

Quantum Iterative Reconstruction for Abdominal Photon-counting Detector CT Improves Image Quality

Quantum Iterative Reconstruction for Abdominal Photon-counting Detector CT Improves Image Quality

Computed tomography recent history and future perspectives

Spectral Photon-Counting CT Technology in Chest Imaging

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