Photon-counting CT via interleaved/gapped spectral channels: Feasibility and imaging performance

Area of Science:

• Medical Imaging
• Photon-Counting CT
• Spectral Imaging

Background:

• Photon-counting detectors enable spectral channelization in CT, allowing advanced data acquisition schemes.
• Energy integration methods in CT lack the spectral resolution for sophisticated channelization.

Purpose of the Study:

• To investigate and compare the performance of material decomposition spectral imaging using gapped and interleaved spectral channelization schemes in photon-counting CT.
• To evaluate these schemes against a benchmark and conventional methods.

Main Methods:

• A simulation study using an anthropomorphic head phantom was conducted for two-material decomposition in photon-counting CT.
• Four spectral channels were used to implement gapping and interleaving schemes, alongside benchmark and conventional schemes.
• Image quality was assessed using contrast-to-noise ratio for material-specific and virtual monochromatic imaging.

Main Results:

• Under ideal conditions, the (ch1, ch4) scheme showed superior material-specific imaging performance, while (ch1, ch4) + (ch2, ch3) excelled in virtual monochromatic imaging.
• The (ch1, ch4) scheme achieved comparable image quality with approximately half the X-ray dose.
• Realistic detector spectral responses reduced performance differences between schemes and highlighted the need to mitigate spectral distortions.

Conclusions:

• Different spectral channelization strategies are necessary for material-specific versus virtual monochromatic imaging.
• Mitigating spectral distortions from realistic detector responses is crucial for optimal performance in photon-counting CT spectral imaging.