Voxelwise characterization of noise for a clinical photon-counting CT scanner with a model-based iterative reconstruction algorithm

Abstract Background Photon-counting detector (PCD) technology has the potential to reduce noise in computed tomography (CT). This study aimed to carry out a voxelwise noise characterization for a clinical PCD-CT scanner with a model-based iterative reconstruction algorithm (QIR). Methods Forty repea...

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Main Authors: Luigi Masturzo, Patrizio Barca, Luca De Masi, Daniela Marfisi, Antonio Traino, Filippo Cademartiri, Marco Giannelli
Format: Article
Language:English
Published: SpringerOpen 2025-01-01
Series:European Radiology Experimental
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Online Access:https://doi.org/10.1186/s41747-024-00541-2
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author Luigi Masturzo
Patrizio Barca
Luca De Masi
Daniela Marfisi
Antonio Traino
Filippo Cademartiri
Marco Giannelli
author_facet Luigi Masturzo
Patrizio Barca
Luca De Masi
Daniela Marfisi
Antonio Traino
Filippo Cademartiri
Marco Giannelli
author_sort Luigi Masturzo
collection DOAJ
description Abstract Background Photon-counting detector (PCD) technology has the potential to reduce noise in computed tomography (CT). This study aimed to carry out a voxelwise noise characterization for a clinical PCD-CT scanner with a model-based iterative reconstruction algorithm (QIR). Methods Forty repeated axial acquisitions (tube voltage 120 kV, tube load 200 mAs, slice thickness 0.4 mm) of a homogeneous water phantom and CTP404 module (Catphan-504) were performed. Water phantom acquisitions were also performed on a conventional energy-integrating detector (EID) scanner with a sinogram/image-based iterative reconstruction algorithm, using similar acquisition/reconstruction parameters. For smooth/sharp kernels, filtered back projection (FBP)- and iterative-reconstructed images were obtained. Noise maps, non-uniformity index (NUI) of noise maps, image noise histograms, and noise power spectrum (NPS) curves were computed. Results For FBP-reconstructed images of water phantom, mean noise was (smooth/sharp kernel) 11.7 HU/51.1 HU and 18.3 HU/80.1 HU for PCD-scanner and EID-scanner, respectively, with NUI values for PCD-scanner less than half those for EID-scanner. Percentage noise reduction increased with increasing iterative power, up to (smooth/sharp kernel) 57.7%/72.5% and 56.3%/70.1% for PCD-scanner and EID-scanner, respectively. For PCD-scanner, FBP- and QIR-reconstructed images featured an almost Gaussian distribution of noise values, whose shape did not appreciably vary with iterative power. Noise maps of CTP404 module showed increased NUI values with increasing iterative power, up to (smooth/sharp kernel) 15.7%/9.2%. QIR-reconstructed images showed limited low-frequency shift of NPS peak frequency. Conclusion PCD-CT allowed appreciably reducing image noise while improving its spatial uniformity. QIR algorithm decreases image noise without modifying its histogram distribution shape, and partly preserving noise texture. Relevance statement This phantom study corroborates the capability of photon-counting detector technology in appreciably reducing CT imaging noise and improving spatial uniformity of noise values, yielding a potential reduction of radiation exposure, though this needs to be assessed in more detail. Key Points First voxelwise characterization of noise for a clinical CT scanner with photon-counting detector technology. Photon-counting detector technology has the capability to appreciably reduce CT imaging noise and improve spatial uniformity of noise values. In photon-counting CT, a model-based iterative reconstruction algorithm (QIR) allows decreasing effectively image noise. This is done without modifying noise histogram distribution shape, while limiting the low-frequency shift of noise power spectrum peak frequency. Graphical Abstract
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spelling doaj-art-7118850553484f1c84e8f3a4984a89792025-01-05T12:08:11ZengSpringerOpenEuropean Radiology Experimental2509-92802025-01-019111310.1186/s41747-024-00541-2Voxelwise characterization of noise for a clinical photon-counting CT scanner with a model-based iterative reconstruction algorithmLuigi Masturzo0Patrizio Barca1Luca De Masi2Daniela Marfisi3Antonio Traino4Filippo Cademartiri5Marco Giannelli6Unit of Medical Physics, Pisa University Hospital “Azienda Ospedaliero-Universitaria Pisana”Unit of Medical Physics, Pisa University Hospital “Azienda Ospedaliero-Universitaria Pisana”Siemens Healthcare s.r.l.Medical Physics Department, Udine University Hospital “Azienda Sanitaria Universitaria Friuli Centrale”Unit of Medical Physics, Pisa University Hospital “Azienda Ospedaliero-Universitaria Pisana”Department of Radiology, Fondazione MonasterioUnit of Medical Physics, Pisa University Hospital “Azienda Ospedaliero-Universitaria Pisana”Abstract Background Photon-counting detector (PCD) technology has the potential to reduce noise in computed tomography (CT). This study aimed to carry out a voxelwise noise characterization for a clinical PCD-CT scanner with a model-based iterative reconstruction algorithm (QIR). Methods Forty repeated axial acquisitions (tube voltage 120 kV, tube load 200 mAs, slice thickness 0.4 mm) of a homogeneous water phantom and CTP404 module (Catphan-504) were performed. Water phantom acquisitions were also performed on a conventional energy-integrating detector (EID) scanner with a sinogram/image-based iterative reconstruction algorithm, using similar acquisition/reconstruction parameters. For smooth/sharp kernels, filtered back projection (FBP)- and iterative-reconstructed images were obtained. Noise maps, non-uniformity index (NUI) of noise maps, image noise histograms, and noise power spectrum (NPS) curves were computed. Results For FBP-reconstructed images of water phantom, mean noise was (smooth/sharp kernel) 11.7 HU/51.1 HU and 18.3 HU/80.1 HU for PCD-scanner and EID-scanner, respectively, with NUI values for PCD-scanner less than half those for EID-scanner. Percentage noise reduction increased with increasing iterative power, up to (smooth/sharp kernel) 57.7%/72.5% and 56.3%/70.1% for PCD-scanner and EID-scanner, respectively. For PCD-scanner, FBP- and QIR-reconstructed images featured an almost Gaussian distribution of noise values, whose shape did not appreciably vary with iterative power. Noise maps of CTP404 module showed increased NUI values with increasing iterative power, up to (smooth/sharp kernel) 15.7%/9.2%. QIR-reconstructed images showed limited low-frequency shift of NPS peak frequency. Conclusion PCD-CT allowed appreciably reducing image noise while improving its spatial uniformity. QIR algorithm decreases image noise without modifying its histogram distribution shape, and partly preserving noise texture. Relevance statement This phantom study corroborates the capability of photon-counting detector technology in appreciably reducing CT imaging noise and improving spatial uniformity of noise values, yielding a potential reduction of radiation exposure, though this needs to be assessed in more detail. Key Points First voxelwise characterization of noise for a clinical CT scanner with photon-counting detector technology. Photon-counting detector technology has the capability to appreciably reduce CT imaging noise and improve spatial uniformity of noise values. In photon-counting CT, a model-based iterative reconstruction algorithm (QIR) allows decreasing effectively image noise. This is done without modifying noise histogram distribution shape, while limiting the low-frequency shift of noise power spectrum peak frequency. Graphical Abstracthttps://doi.org/10.1186/s41747-024-00541-2AlgorithmsImage processing (computer-assisted)Radiation exposureTomography (x-ray computed)Tomography scanners (x-ray computed)
spellingShingle Luigi Masturzo
Patrizio Barca
Luca De Masi
Daniela Marfisi
Antonio Traino
Filippo Cademartiri
Marco Giannelli
Voxelwise characterization of noise for a clinical photon-counting CT scanner with a model-based iterative reconstruction algorithm
European Radiology Experimental
Algorithms
Image processing (computer-assisted)
Radiation exposure
Tomography (x-ray computed)
Tomography scanners (x-ray computed)
title Voxelwise characterization of noise for a clinical photon-counting CT scanner with a model-based iterative reconstruction algorithm
title_full Voxelwise characterization of noise for a clinical photon-counting CT scanner with a model-based iterative reconstruction algorithm
title_fullStr Voxelwise characterization of noise for a clinical photon-counting CT scanner with a model-based iterative reconstruction algorithm
title_full_unstemmed Voxelwise characterization of noise for a clinical photon-counting CT scanner with a model-based iterative reconstruction algorithm
title_short Voxelwise characterization of noise for a clinical photon-counting CT scanner with a model-based iterative reconstruction algorithm
title_sort voxelwise characterization of noise for a clinical photon counting ct scanner with a model based iterative reconstruction algorithm
topic Algorithms
Image processing (computer-assisted)
Radiation exposure
Tomography (x-ray computed)
Tomography scanners (x-ray computed)
url https://doi.org/10.1186/s41747-024-00541-2
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