Medical Imaging

Medical imaging — using physical phenomena (X-rays, magnetic fields, ultrasound, radioactive isotopes) to create images of the body's interior for diagnostic purposes — has revolutionized medicine by allowing non-invasive diagnosis of conditions that previously required surgery or were invisible until autopsy. The history spans 130 years from Wilhelm Röntgen's discovery of X-rays (1895, Nobel Prize 1901 — the first Nobel in Physics) to current AI-assisted imaging that can detect cancers earlier than any human radiologist. Major modalities: X-ray (1895, still the most common imaging — 3.6 billion annually); CT scan (computed tomography, Hounsfield/Cormack 1972 Nobel, Nobel 1979 — reconstructs 3D images from multiple X-ray angles, revolutionary for trauma and cancer); MRI (magnetic resonance imaging, Lauterbur/Mansfield 2003 Nobel — uses magnetic fields and radio waves, superior soft tissue contrast, no radiation); PET scan (positron emission tomography — shows metabolic activity, critical for cancer staging); and ultrasound (sound waves, primary diagnostic tool for fetal imaging). AI diagnostic imaging (Google DeepMind, 2019 — detecting eye disease; Paige.AI — pathology) is achieving radiologist-level diagnostic accuracy.