Diagnostic radiology transforms internal anatomy into actionable clinical images through a range of modalities and physics principles. Volume 1 explains imaging fundamentals — X-ray physics, CT, MRI basics, ultrasound principles — and links technique to normal anatomy and common pathologies. It emphasizes image acquisition, artifact recognition, and reporting essentials to improve diagnostic accuracy. System-based clinical correlations show how imaging guides patient management across specialties. Learning aids include annotated images, key-point boxes, and interpretation checklists for trainees and clinicians.