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Calculation of Stopping-Power Ratio from Multiple CT Numbers Using Photon-Counting CT System: Two- and Three-Parameter-Fitting Method
- Source :
- Sensors, Vol 21, Iss 1215, p 1215 (2021), Sensors (Basel, Switzerland), Sensors, Volume 21, Issue 4
- Publication Year :
- 2021
- Publisher :
- MDPI AG, 2021.
-
Abstract
- The two-parameter-fitting method (PFM) is commonly used to calculate the stopping-power ratio (SPR). This study proposes a new formalism: a three-PFM, which can be used in multiple spectral computed tomography (CT). Using a photon-counting CT system, seven rod-shaped samples of aluminium, graphite, and poly(methyl methacrylate) (PMMA), and four types of biological phantom materials were placed in a water-filled sample holder. The X-ray tube voltage and current were set at 150 kV and 40 μμA respectively, and four CT images were obtained at four threshold settings. A semi-empirical correction method that corrects the difference between the CT values from the photon-counting CT images and theoretical values in each spectral region was also introduced. Both the two- and three-PFMs were used to calculate the effective atomic number and electron density from multiple CT numbers. The mean excitation energy was calculated via parameterisation with the effective atomic number, and the SPR was then calculated from the calculated electron density and mean excitation energy. Then, the SPRs from both methods were compared with the theoretical values. To estimate the noise level of the CT numbers obtained from the photon-counting CT, CT numbers, including noise, were simulated to evaluate the robustness of the aforementioned PFMs. For the aluminium and graphite, the maximum relative errors for the SPRs calculated using the two-PFM and three-PFM were 17.1% and 7.1%, respectively. For the PMMA and biological phantom materials, the maximum relative errors for the SPRs calculated using the two-PFM and three-PFM were 5.5% and 2.0%, respectively. It was concluded that the three-PFM, compared with the two-PFM, can yield SPRs that are closer to the theoretical values and is less affected by noise.
- Subjects :
- Electron density
Materials science
Stopping power
photon-counting CT
lcsh:Chemical technology
Biochemistry
Noise (electronics)
Article
Imaging phantom
030218 nuclear medicine & medical imaging
Analytical Chemistry
03 medical and health sciences
0302 clinical medicine
Hounsfield scale
lcsh:TP1-1185
electron density
Electrical and Electronic Engineering
Instrumentation
stopping-power ratio
effective atomic number
mean excitation energy
Atomic and Molecular Physics, and Optics
Photon counting
Computational physics
030220 oncology & carcinogenesis
Effective atomic number
Excitation
Subjects
Details
- ISSN :
- 14248220
- Volume :
- 21
- Database :
- OpenAIRE
- Journal :
- Sensors
- Accession number :
- edsair.doi.dedup.....da2c4cdc841d453cdb12d15cb1a0cd5a
- Full Text :
- https://doi.org/10.3390/s21041215