Mammography is specialised X-ray imaging of the breast designed to detect and characterise abnormalities, particularly those associated with breast cancer. Because breast tissue contains relatively subtle differences in X-ray attenuation, mammographic systems use dedicated low-energy X-ray techniques, specialised detectors and breast compression to optimise image quality. Compression reduces breast thickness, decreases tissue overlap, limits motion and can reduce radiation exposure by allowing more efficient imaging. Standard mammographic views generally include projections designed to provide broad coverage of the breast, while additional views can be obtained when an abnormality requires further assessment.
Mammography can reveal masses, asymmetries, architectural distortion and calcifications. Microcalcifications can be particularly important because certain patterns may be associated with ductal carcinoma in situ or invasive cancer, although calcifications also commonly arise from benign processes. Breast density influences mammographic sensitivity because dense fibroglandular tissue appears relatively radiopaque and can obscure lesions. Digital mammography has replaced traditional film-screen systems in many settings and allows image processing, storage and computer-assisted analysis. Digital breast tomosynthesis extends mammography by acquiring multiple low-dose projections and reconstructing thin slices, reducing some effects of tissue overlap.
Screening Mammography is used in asymptomatic populations to detect breast cancer before it becomes clinically apparent. Screening programmes use age and risk-based criteria that vary by country and organisation. The purpose of screening is not to diagnose every abnormality definitively from the screening image but to identify findings that warrant further assessment. Screening can reduce mortality from breast cancer in appropriately selected populations, but it also has limitations including false-positive findings, false-negative examinations, overdiagnosis and additional investigations. The balance of benefits and harms depends on age, baseline risk, screening interval, breast density and the specific programme.
Diagnostic Mammography is performed when symptoms or a previously identified abnormality require targeted evaluation. It may involve additional magnified or focused views and is often combined with ultrasound. Diagnostic assessment can help determine whether a palpable lump, discharge, asymmetry or imaging abnormality has benign or suspicious characteristics. Imaging cannot always establish histological diagnosis, so suspicious findings may require tissue sampling. Mammographic interpretation therefore forms part of a diagnostic pathway rather than functioning as a standalone substitute for pathology when tissue diagnosis is required.
Breast compression is a defining technical component of mammography. Compression spreads tissue, reduces overlap and helps maintain a stable position during image acquisition. Although compression can be uncomfortable, it is important for image quality and dose optimisation. Positioning is also critical because inadequate inclusion of breast tissue can reduce diagnostic value. Radiographers or mammographers receive specialised training in positioning and image acquisition. Patient movement, poor positioning and technical artefacts can produce images that are difficult to interpret or can obscure pathology.
Mammography uses ionising radiation, but modern systems employ relatively low radiation doses appropriate for breast imaging. The radiation risk is considered alongside the potential benefit of detecting clinically important breast cancer. The balance is particularly relevant in screening, where large numbers of asymptomatic people undergo repeated examinations. Breast implants can affect imaging because they may obscure tissue, although specialised positioning techniques can improve visualisation. Mammography may be less sensitive in very dense breasts, and additional imaging such as ultrasound or MRI may be considered depending on clinical circumstances and risk.
Mammography has a long history beginning with early attempts to use X-rays to examine breast tissue, followed by improvements in dedicated equipment, compression, film-screen systems and digital detectors. Contemporary breast imaging incorporates digital mammography, tomosynthesis, computer-assisted tools and integration with ultrasound and MRI. The development of screening programmes has made mammography one of the most extensively studied forms of population-based cancer screening. Interpretation commonly uses standardised reporting frameworks so that findings and management recommendations can be communicated consistently.
Mammography must be distinguished from breast ultrasound and breast MRI because each modality has different physical principles and strengths. Mammography is particularly effective for detecting calcifications and many forms of early breast cancer, whereas ultrasound can characterise cystic versus solid lesions and is useful for targeted assessment, and MRI provides highly sensitive contrast-based imaging in selected situations. No single technique detects every breast abnormality. Mammography's clinical value therefore depends on appropriate screening or diagnostic context, high-quality acquisition, expert interpretation and follow-up of findings according to established breast-imaging pathways.
