Photon-counting CT versus Energy-integrating Detector CT in Imaging Lung Cancer

Background Although energy-integrating detector (EID) CT remains the standard in diagnosing and monitoring lung cancer, it has limitations compared with photon-counting CT (PCCT). However, the role of low-dose PCCT in evaluating lung cancer remains unexplored. Purpose To compare the diagnostic quality of chest CT images from PCCT with a low radiation dose and a low injection rate, volume, and concentration of contrast agent (hereafter, a "quadruple-low protocol") with that of EID CT in patients with lung cancer. Materials and Methods This retrospective study included patients with lung cancer undergoing PCCT or EID CT between July 2024 and September 2024. Patients underwent PCCT with the low radiation dose plus reduced contrast agent protocol (quadruple-low protocol: 2.0 mL/sec injection rate, 1.0 mL/kg of 320 mg of iodine per milliliter) and EID CT with a conventional protocol. Two radiologists independently evaluated the subjective image quality and lesion imaging features. Lesion and parenchymal metrics (attenuation, signal-to-noise ratio [SNR], and contrast-to-noise ratio [CNR]) were also assessed. Data were compared using the Student <i>t</i> test, Mann-Whitney <i>U</i> test, or multivariable regression. Sensitivity analysis was performed using propensity score matching. Results Among 425 participants (mean age, 61 years ± 9.5 [SD]; 273 men), PCCT reduced radiation dose by 55% (mean effective dose, 3.49 mSv ± 0.91 vs 7.82 mSv ± 2.15; <i>P</i> < .001) while lowering contrast agent injection rate, volume, and concentration by 33% (<i>P</i> < .001), 22% (<i>P</i> < .001), and 9% (<i>P</i> < .001), respectively. PCCT reduced the incidence of contrast-induced nephropathy (CIN) compared with EID CT (0% [0 of 120] vs 7.9% [24 of 305], <i>P</i> = .02). PCCT also exhibited higher objective SNR and CNR in lung lesions and parenchyma, with superior subjective image quality scores and increased diagnostic confidence for imaging features (all adjusted <i>P</i> < .001). Results remained consistent in sensitivity analysis. Conclusion Compared with EID CT, PCCT with a quadruple-low protocol reduced the incidence of CIN and enhanced image quality and diagnostic confidence in imaging features in patients with lung cancer. © RSNA, 2026 <i>Supplemental material is available for this article</i>.