Opportunistic Breast Cancer Screening Using Non-Contrast Chest CT

Inclusion Criteria: 1. Female patients who have undergone non-contrast chest CT examination; 2. Participants included in the comparative analysis must have undergone at least one comparator imaging modality (mammography and/or breast MRI); 3. If a breast lesion is detected, it must be confirmed by pathology or clinical follow-up at least 12 months; 4. No prior systemic or local therapy before imaging examinations; 5. Imaging data are complete and of sufficient quality for analysis. Exclusion Criteria: 1. History of other malignancies with potential impact on breast imaging interpretation; 2. Participants with suspected malignant breast lesions but no confirmation; 3. Prior radiotherapy, chemotherapy, or immunotherapy before imaging examinations; 4. Imaging data that are incomplete, of poor quality, or contain significant artifacts preventing reliable analysis; 5. Time interval between non-contrast chest CT and comparator imaging modalities exceeding three months, or with clinical events occurring between examinations that may alter lesion status.