Spatial Resolution Fidelity Comparison Between Energy Integrating and Deep Silicon Photon Counting CT: Implications...

Area of Science:

• Medical Imaging
• Detector Technology
• Computed Tomography

Background:

• Spatial resolution in computed tomography (CT) scanners can degrade as measurements move away from the isocenter.
• Traditional energy-integrating detector (EID) CT scanners face challenges in maintaining consistent spatial resolution across the field of view.
• Advancements in detector technology, such as photon-counting detectors (PCDs), are being explored to overcome limitations of existing CT systems.

Purpose of the Study:

• To evaluate the spatial resolution performance of a prototype deep silicon photon-counting detector (PCD) CT scanner.
• To compare the spatial resolution loss away from the isocenter of the PCD CT scanner with a clinical energy-integrating detector (EID) CT scanner.
• To assess the impact of high-definition (HD) EID CT mode on spatial resolution compared to standard EID CT and PCD CT.

Main Methods:

• Three CT acquisition modes were tested: 120 kV EID CT, 120 kV high-definition (HD) EID CT, and 120 kV PCD CT.
• Scans were performed on a wire phantom positioned at the isocenter and at distances of 6.7, 11.8, and 17.1 cm off-isocenter.
• Spatial resolution was quantified using the full width at half maximum (FWHM) of wire profiles in radial and azimuthal directions; changes were assessed by diameter ratio relative to isocenter.

Main Results:

• The deep silicon PCD CT demonstrated statistically significant (P <0.05) smaller changes in diameter ratio in both radial and azimuthal directions compared to regular and HD EID modes.
• Spatial resolution changes for PCD CT were not statistically different from unity (P <0.05), indicating minimal degradation.
• Maximum increases in FWHM relative to isocenter were 36% for regular EID, 12% for HD EID, and only 1% for deep silicon PCD.

Conclusions:

• The prototype deep silicon photon-counting detector (PCD) CT scanner exhibits superior spatial resolution maintenance compared to clinical energy-integrating detector (EID) CT.
• PCD CT technology offers improved consistency in spatial resolution across the field of view, reducing resolution loss away from the isocenter.
• These findings suggest PCD CT is a promising advancement for CT imaging, potentially enhancing diagnostic accuracy at extended off-isocenter positions.