Short answers, pulled from the story.
Engineer Godfrey Hounsfield unveiled the first computed tomography scanner in 1972 while working for the British company EMI. This device used computer algorithms to reconstruct cross-sectional images from X-ray projections through the human head. Hounsfield and physicist Allan Cormack later received the Nobel Prize in Physiology or Medicine in 1979 for this innovation.
CT scans use X-rays which involve ionizing radiation, whereas MRI uses powerful magnets and radio frequency pulses without ionizing radiation. There is no known limit to the number of MRI scans an individual can undergo, although safety protocols strictly control tissue heating and interactions with implanted devices like pacemakers. MRI emerged in the early 1980s and has become the gold standard for visualizing soft tissues.
The global market for medical imaging devices was estimated at 5 billion dollars in 2018 and is dominated by major manufacturers such as GE HealthCare, Siemens Healthineers, and Philips. Toshiba exited the industry by selling their medical imaging division to Canon in 2016, and Hitachi sold its business to Fujifilm in 2019 for approximately 1.6 billion dollars. Kodak held about 30 percent of the global market share for X-ray machines in 1998 before selling its medical imaging business in 2007 to become Carestream Health.
In the United States, the Copyright Office does not register works produced by machines that operate without creative human intervention, meaning X-ray images, ultrasounds, and MRI scans are generally considered public domain. Derivative works that include annotations and explanations may be copyrightable, creating a complex legal landscape where the image itself remains free for use while the added commentary is protected. The Health Insurance Portability and Accountability Act further restricts the use of protected health information to ensure biometric data is handled with strict confidentiality.
Imaging biomarkers are used as surrogate endpoints to determine whether a therapy is safe and effective, cutting down the time required to confirm clinical benefits. In oncology, measurement of tumor shrinkage via PET and MRI scans allows for faster and more objective assessment of anticancer drugs. In Alzheimer's disease, MRI scans can accurately assess the rate of hippocampal atrophy and PET scans can measure brain metabolic activity.