Photon-Counting Detector CT Versus Conventional CT for Low-Dose Chest Imaging: A Reader Preference Study

Photon-counting detector CT (PCD-CT) is a technology that directly counts individual photons and their energy, compared to conventional energy-integrating detector CT (EID-CT) which measures the total deposited X-ray energy without distinguishing photon energies. PCD-CT promises to provide higher quality images at equal or reduced radiation doses. We aimed to compare the objective and subjective image quality of PCD-CT to EID-CT for low-dose chest CT.

Asbestos-exposed participants from the Western Australian Asbestos Review Program underwent paired EID-CT (2023-2024) and PCD-CT (2024-2025) at a reduced radiation dose. Three independent chest radiologists rated relative image quality on a 5-point Likert scale, with higher scores indicating better quality on the right-hand image. Quantitative image noise was measured in the descending thoracic aorta. Interobserver agreement was assessed using κ statistics, intraclass correlation coefficients (ICC), and near-agreement (±1 category).

Fifty subjects (median age 77 IQR 10.25 years; 40 men) were included. Across 150 ratings, 88% fell in categories 'somewhat higher' (4) or 'much higher' (5), favouring PCD-CT. The pooled mean score was 4.2. Individual reader mean scores ranged from 3.6 to 4.7. Interobserver agreement was modest by exact κ statistics, but near-agreement (±1 category) was high (80%-98%) and intraclass correlation coefficients demonstrated strong reader consistency. Quantitative analysis showed similar image quality despite approximately 40% reduced radiation dose for PCD-CT.

PCD-CT provides superior subjective image quality to EID-CT for low-dose chest CT, at a substantially reduced radiation dose.

Clinical trial number: ACTRN12621001627842; https://www.anzctr.org.au/.