Spectral performance for iodine quantification of a dual-source, dual-kV photon counting detector CT

Area of Science:

• Medical Imaging
• Radiological Physics
• Computed Tomography

Background:

• Multi-energy CT (MECT) uses multiple X-ray spectra for material concentration quantification.
• Photon counting detector (PCD)-CT, a MECT approach, can exhibit noise amplification due to spectral overlap.
• Dual-source (DS) techniques in energy-integrating detector (EID)-CT may enhance spectral separation and could be applied to PCD-CT.

Purpose of the Study:

• To evaluate the iodine quantification performance of a novel dual-source (DS)-PCD-CT scan mode.
• To compare DS-PCD-CT against single-source (SS)-PCD-CT and DS-EID-CT for iodine quantification.

Main Methods:

• A solid water phantom with iodine inserts was scanned using SS-PCD-CT, DS-PCD-CT (90/Sn150 kV), and DS-EID-CT (90/Sn150 kV).
• Scans were performed at full-dose (12 mGy) and half-dose; images were reconstructed using filtered back-projection.
• Modulation transfer function (MTF) was matched between single-source and dual-source acquisitions; iodine quantification accuracy and noise were assessed.

Main Results:

• DS-PCD-CT demonstrated the lowest iodine image noise, 39%-41% lower than DS-EID-CT.
• After MTF matching, SS-PCD-CT noise was 9%-22% lower than DS-EID-CT.
• Mean iodine quantification accuracy was within 5% for all modalities at full dose; only DS-PCD-CT achieved <5% accuracy at half-dose.

Conclusions:

• Single-source PCD-CT with two energy thresholds showed lower image noise than DS-EID-CT when spatial resolution was matched.
• DS-PCD-CT achieved the lowest noise, attributed to PCD technology and superior spectral separation from distinct X-ray spectra.
• DS-PCD-CT offers improved iodine quantification performance, particularly at reduced radiation doses.