{"doi":"10.1093/bjr/tqaf103","title":"Reproducibility of lung density quantification across photon-counting and conventional energy-integrating CT: a comparative study","abstract":"OBJECTIVES: To evaluate how photon-counting CT (PCCT) reproducibly quantifies lung density compared to conventional CT (energy-integrating CT or EICT) and assess the relevance of image quality. METHODS: In this retrospective analysis of a prospective study, subjects underwent acquisitions using EICT and PCCT systems (August-December 2021) on the same day. PCCT projections were reconstructed with 4 kernels and 2 voxel sizes using 2024 reconstruction software (ReconCT, Siemens). PCCT and EICT data were compared using lung density measurements: percentage of low-attenuation areas <-950 Hounsfield unit (HU) (LAA-950), 15th percentile of lung density histogram (Perc15), and mean lung density (MLD). Measurement reproducibility and its relation to image quality parameters (modulation transfer function and noise) were analyzed. RESULTS: Fifty-four subjects (mean age, 67.4 years ± 9.6, 30 female) were studied. PCCT images had the closest agreement to EICT under identical voxel size and similar kernels, yielding lower LAA-950 (-0.9% ± 2.7, P < 0.05), higher Perc15 (1.4 HU ± 7.9, P > 0.05), and higher MLD (2.4 HU ± 10.8, P > 0.05). At higher PCCT resolution (1024 × 1024 matrix, 0.2 mm slice thickness), the smoother quantitative kernel (Qr36) improved agreement, with differences of -0.5% ± 3.0, -0.1 HU ± 9.8, and 2.8 HU ± 11.1, for LAA-950, Perc15, and MLD (P > 0.05). Image quality parameters strongly correlated with density measurements (RPerc152=85.3%). CONCLUSIONS: PCCT yields reproducible lung density measurements comparable to EICT, with optimal reproducibility dependent on optimized reconstruction parameters and explainable by image quality parameters. ADVANCES IN KNOWLEDGE: Lung density reproducibility is critical for integrating PCCT into EICT-based workflows. In our study, PCCT aligned more closely with EICT using similar kernels at identical voxel sizes, or smoother kernels at smaller voxel sizes.","journal":"British Journal of Radiology","year":2025,"id":552728,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":1,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9234,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":292053,"name":"Ehsan Samei","orcid":"0000-0001-7451-3309","position":1,"is_corresponding":false},{"id":688238,"name":"Ehsan Abadi","orcid":"0000-0002-9123-5854","position":2,"is_corresponding":false},{"id":1164509,"name":"Saman Sotoudeh‐Paima","orcid":"0000-0003-0170-2541","position":0,"is_corresponding":true}],"reference_count":47,"raw_metadata":null,"created_at":"2026-07-19T02:54:37.527189Z","pmid":"40347461","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}