Key Considerations for Photon-Counting CT versus Energy-Integrating Detector CT in the Evaluation of Lung Cancer

Commentary on Zhou Y et al. Photon-counting CT versus energy-integrating detector CT performance for various BMI and tumor sizes in lung cancer. Radiology 2026;318:e251663 (https://doi.org/10.1148/radiol.251663).

SUMMARY

Recent advances in photon-counting CT (PCCT) have enabled chest imaging with finer spatial detail and lower radiation exposure compared with conventional energy-integrating detector (EID) CT (1,2). In the study by Zhou et al. (3), 459 patients were screened, and 200 propensity score–matched patients with lung cancer were included in the final comparison. Relative to standard-dose EID CT, low-dose ultrahigh-resolution PCCT achieved markedly lower radiation exposure (1.36 mSv vs. 4.04 mSv) and a smaller iodine dose (20.62 mg vs. 28.08 mg; p < 0.001), while also reducing adverse reactions (2% vs. 9%; p = 0.03) and contrast-induced acute kidney injury (1% vs. 7%; p = 0.03). Beyond these safety advantages, PCCT improved the visualization of lung cancer morphologic findings (such as the vessel convergence or invasion, angiogram sign, detection of speculation and lobulation, bronchial stenosis or cutoff sign, and calcification), and increased reader confidence, with 0.4-mm reconstructions showing particular benefit for normal-weight patients (18.5–24.9) and for lesions measuring 3 cm or less. The study suggests that PCCT may offer a more efficient and diagnostically advantageous approach to contrast-enhanced lung cancer CT than conventional EID CT (3,4).

COMMENT

Cadmium-telluride–based ultrahigh-resolution PCCT offers several technical advantages over EID CT by increasing photon conversion efficiency and enabling higher spatial resolution without the structural limitations of conventional detectors (4,5). These characteristics make it possible to reduce radiation exposure while preserving, and in some settings enhancing, diagnostic performance for lung cancer imaging. PCCT images, particularly those reconstructed at a 0.4-mm section thickness, demonstrated superior overall image quality, improved visualization of enhancement-related features suggestive of malignancy, and increased diagnostic confidence. These advantages were observed across a range of body mass indices and were particularly beneficial for evaluating small T1-stage lesions. The study has a number of limitations, including its single-center design, the inclusion of only a Chinese lung cancer population, the absence of a direct head-to-head comparison, and potential bias arising from differences in tumor characteristics and reconstruction parameters between EID CT and PCCT. As PCCT is likely to be adopted more widely in South Korea in the future, it will be important to apply reconstruction strategies selectively rather than uniformly. In normal-weight patients, PCCT with 0.4-mm reconstruction outperformed both EID CT and 1-mm PCCT in most image quality parameters, except for lesion sharpness. In overweight patients, 1-mm PCCT achieved higher scores than 1-mm EID CT for most parameters, again with the exception of lesion sharpness. For lesions 3 cm or smaller, PCCT with 0.4-mm reconstruction provided superior visualization of internal structures compared with 1-mm reconstruction. In contrast, for lesions larger than 3 cm, 1-mm PCCT showed higher structural scores than 0.4-mm PCCT. These findings suggest that the optimal reconstruction thickness may should be tailored to lesion size and patient body mass index.