Abstract
ObjectiveEvaluation of quantitative image parameters of a dual-energy CT (DE-CT) scanner compared to a photon counting detector CT (PCD-CT) with different scan parameters.
Background
Despite intensive research with DE-CT, the application areas of quantitative imaging are still rarely integrated into the daily clinical workflow. However, this could now change with the help of PCD-CT. The exact effect of various protocol parameters such as dose modulation, tube voltage settings and the reconstruction methods used on quantitative evaluation have hardly been considered in previous studies. However, suitable settings could allow more precise statements to be made about the various materials.
Methods
Imaging of a multi-energy CT phantom with different rods integrated into it. These scans are performed with various tube voltages, and for every tube voltage, a scan with and without dose modulation is acquired. Furthermore, the scans are reconstructed using various reconstruction algorithms. An evaluation is created to determine the deviation of the measured values and compare them to each other. The focus of the evaluation is iodine concentrations and rho values. Additionally, we measure the dose, which is used per scan.
Results
On average, the dose at tube voltages for EID-CT with a tin filter is 50% lower than for a scan without a filter. The dose modulation does not lead to a dose reduction of the phantom but to lower deviations from the reference iodine concentrations. The best result for the iodine concentration was achieved with 100kVp & Sn150kVp. In the PCD-CT measurement setup, dose modulation also leads to a lower deviation from the reference iodine concentration. The best result was achieved here with 140kVp. If both measurement methods are compared with each other, the PCD-CT measurement is more accurate on average. However, the smallest deviation was achieved at 100kVp and Sn150kVp with the EID-CT measurement setup.
Conclusions
Both a PCD-CT and an EID-CT are ideally suited for the quantification of iodine concentrations. Switching on dose modulation offers more precise quantification. In contrast to the selected tube voltage, reconstruction algorithms have no influence on the quantification. A higher tube voltage is recommended for areas of the abdomen or obese patients. For PCD-CT, a tube voltage of 140kVp is preferable. For EID-CT, 100kV and Sn150kV seems to be the tube voltage with the best results.
| Date of Award | Jun 2024 |
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| Original language | German (Austria) |
| Awarding Institution |
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| Supervisor | Mario Scheweder (Supervisor) |