Back to Search
Start Over
Slice NEQ and system DQE to assess CT imaging performance
- Source :
- Physics in medicine and biology, vol. 65, no. 10, pp. 105009
- Publication Year :
- 2020
-
Abstract
- The standard Fourier metrics used for assessing image quality in computed tomography (CT) use a planar (2D) formulation of the noise equivalent quanta (NEQ) without a specific concept to manage the influence of longitudinal resolution variations, thus create a bias in the comparison of image quality for different reconstructed slice thicknesses. For this work, we designed a ‘slice NEQ’ that takes the longitudinal resolution into account and provides a volumetric indication of the scanner imaging performance. We also developed a specific formulation for the system DQE at the CT isocentre. A cylindrical water phantom with three different inserts for three contrast levels (−100, 120 and 1000 HU) was used for the task-based transfer functions (TTF) and noise power spectra (NPS) measurements. The longitudinal TTF was measured using the point source of the Catphan® 600 phantom. Images of the phantoms were acquired on two scanners (GE Discovery 750 HD and Siemens SOMATOM Force) and reconstructed using different slice thicknesses between 1 and 5 mm and algorithms (FBP for both systems, ASIR 50 and ASIR-V 50 for the GE). The slice NEQ correctly compared the imaging performance for different longitudinal resolutions whereas the 2D NEQ increased proportionally with the reconstructed slice thickness. The system DQE peaked at 0.70 (at 0.1 mm−1) for the Siemens and at 0.50 (at 0.1 mm−1) for the GE for FBP reconstructions. The validity of these Fourier-based metrics was restricted to a limited range of contrast due to nonlinearities introduced when dealing with iterative reconstructions (IR).
- Subjects :
- Scanner
Image quality
Signal-To-Noise Ratio
Radiation Dosage
Noise (electronics)
Imaging phantom
030218 nuclear medicine & medical imaging
Detective quantum efficiency
03 medical and health sciences
0302 clinical medicine
Optics
Humans
Radiology, Nuclear Medicine and imaging
computed tomography
detective quantum efficiency
image quality
noise equivalent quanta
quality controls
Physics
Radiological and Ultrasound Technology
business.industry
Phantoms, Imaging
Resolution (electron density)
Water
Signal-to-noise ratio (imaging)
030220 oncology & carcinogenesis
Tomography
business
Tomography, X-Ray Computed
Algorithms
Subjects
Details
- ISSN :
- 13616560
- Volume :
- 65
- Issue :
- 10
- Database :
- OpenAIRE
- Journal :
- Physics in medicine and biology
- Accession number :
- edsair.doi.dedup.....eaef64d07ec7cef85427c24ce4f1edef