Timeline: A History of Innovation and Discovery

1895

• Wilhem Conrad Roentgen produces and discovers x-rays.

1896

• Antoine Henri Becquerel discovers natural radioactivity.

1898

• Marie Skłodowska-Curie and Pierre Curie announce the discovery of radium, a radioactive element.

1901

• The first Nobel Prize in Physics is awarded to Wilhelm Conrad Roentgen for discovering x-rays.

1903

• The Nobel Prize in Physics is awarded to Antoine Henri Becquerel for “his discovery of spontaneous radioactivity,” and to Pierre Curie and Marie Skłodowska-Curie for “their joint researches on the radiation phenomena discovered by Professor Henri Becquerel.”
• An afterloading technique for brachytherapy is proposed by Hermann Strebel.

1908

• The Nobel Prize in Chemistry is awarded to Ernest Rutherford for “his investigations into the disintegration of the elements, and the chemistry of radioactive substances.”

1911

• The Nobel Prize in Chemistry is awarded to Marie Skłodowska-Curie “in recognition of her services to the advancement of chemistry by the discovery of the elements radium and polonium, by the isolation of radium and the study of the nature and compounds of this remarkable element.”

1913

• William Coolidge invents the heated cathode X-ray tube, paving the way for both x-ray imaging and external beam radiotherapy.

1917

• Interstitial brachytherapy treatment for prostate cancer is introduced at Memorial Sloan-Kettering Cancer Center.

• George Eastman introduces photographic film for radiography.
• Austrian mathematician Johann Radon publishes a paper demonstrating reconstruction of a function from a set of projections.

1928

• The Geiger-Müller tube is invented to detect radioactivity.
• The first linear accelerator is prototyped and reported on by Rolf Widerøe in Acchen, Germany.

1934

• The Manchester dosage system for interstitial brachytherapy is developed by Ralston Paterson and H. M. Parker. The dosage system is later published in 1937.

1935

• The Nobel Prize in Chemistry is awarded jointly to Frédéric Joliot and Irène Joliot-Curie “in recognition of their synthesis of new radioactive elements.”

1937

• Isidor Isaac Rabi measures the magnetic properties of nuclei using nuclear magnetic resonance (NMR), a technique that later forms the basis of magnetic resonance imaging (MRI).

1939

• The Varian brothers, Russell H. Varian and Sigurd F. Varian, invent the klystron in the USA, and publish in the Journal of Applied Physics.
• The Nobel Prize in Physics 1939 was awarded to Ernest Orlando Lawrence for “the invention and development of the cyclotron and for results obtained with it, especially with regard to artificial radioactive elements.”

1940

• The magnetron is devised by Henry Albert Howard “Harry” Boot and Sir John Randall in the UK.

1943

• The Nobel Prize in Chemistry is awarded to George de Hevesy for “his work on the use of isotopes as tracers in the study of chemical processes.”

1944

• The Nobel Prize in Physics is awarded to Isidor Isaac Rabi for “his resonance method for recording the magnetic properties of atomic nuclei.”

1946

• Edward Purcell and Felix Bloch independently discover expanded uses for nuclear magnetic resonance (NMR).

1947

• The traveling wave electron linear accelerator is developed by William Webster Hansen at Stanford University.

1948

• The first telecobalt unit is installed (Hamilton, Canada).

1950

• The first positron imaging system using coincidence detection of annihilation photons is devised by Brownell and Sweet.
• Benedict Cassen invents the rectilinear scanner.

1951

• Lars Gustaf Fritiof Leksell at the Karolinska Institute in Stockholm, Sweden, pioneers stereotactic radiosurgery, a new technique for treating focused targets inside the brain using radiation.

1952

• The Nobel Prize in Physics is awarded to Edward Purcell and Felix Bloch for “their development of new methods for nuclear magnetic precision measurements and discoveries in connection therewith.”

1953

• The first linac-based radiation therapy patient is treated at the Hammersmith Hospital in London, UK, using a machine built by Metropolitan-Vickers.

1954

• The first people to receive proton beam therapy were treated with pituitary irradiation to control metastatic breast cancer at the Radiation Laboratory of the University of California, Berkeley (now named the Lawrence Berkeley National Laboratory).

1956

• Henry Kaplan treats the first radiation therapy patient in the USA at Stanford University Medical Center.
• Ultrasound is used for medical diagnosis.

1957

• Hal Anger invents the scintillation camera (aka gamma camera or Anger camera).

1960

• The x-ray image intensifier & video technology are introduced for fluoroscopy.

1963

• Allan Cormack publishes “Representation of a Function by Its Line Integrals, with Some Radiological Applications” in the Journal of Applied Physics. This paper describes the physical principles of CT scanning, for which Cormack shares the 1979 Nobel Prize in Physiology or Medicine with Godfrey Hounsfield.

1965

• The first dedicated mammography unit with a molybdenum x-ray tube anode and filter is devised by Charles Marie Gros.

1967

• Godfrey Hounsfield conceives the idea of computed tomography (CT) scanning.

1970

• 2D simulators are introduced to improve radiotherapy delivery using 2D projections.

1971

• The world’s first CT scan of a patient takes place at Atkinson Morley Hospital in London, England, on a brain patient.
• Raymond Damadian discovers that tumors can be detected in vivo by nuclear magnetic resonance (NMR) because of much longer relaxation times than normal tissue, suggesting that NMR can be used for cancer detection.

1973

• The first MRI image is produced.
• The first positron emission tomography (PET) image is obtained by Michael Phelps, Michel Ter-Pogossian and Edward Hoffman at Washington University.

1974

• A positron emission tomography (PET) system, then known as positron emission transaxial tomography (PETT), is developed.
• Peter Mansfield uses magnetic field gradients to produce a nuclear magnetic resonance (NMR) image.

1976

• Sokoloff, Wolf and Fowler develop 18F-fluorodeoxyglucose (FDG).
• Energy-selective CT scanning is first described by Alvarez and Macovski at Stanford.

1977

• The first whole-body MRI scanner is devised by Ray Damadian.
• Digital subtraction angiography (DSA) is introduced by Kruger and Mistretta.

1979

• The Nobel Prize in Physiology or Medicine is awarded to Allan M. Cormack and Godfrey N. Hounsfield for “the development of computer assisted tomography.”

1980

• Storage-phosphor-based digital radiography is introduced.

1981

• Mansfield discovers Echo-Planar Imaging (EPI), a very fast MRI acquisition method.

1984

• The first electron-beam cardiac CT scanner is developed by Douglas Boyd at UCSF.

1990

• Multileaf collimators driven by computerized treatment planning systems transforms 2D external beam radiotherapy to 3D conformal radiotherapy.
• The first simultaneous emission/transmission CT (SPECT/CT) prototype is introduced by Hasegawa at UCSF.
• Charge-coupled device (CCD) slot-scan digital radiography is born.

1991

• Helical (aka spiral) CT scanning is introduced.

1994

• The first clinical experience with carbon ion therapy takes place in Chiba, Japan. Carbon ion therapy offers increased relative biological effectiveness compared to proton therapy.
• Selenium drum digital radiography is born.
• The BEAM code system is released, a milestone in the use of Monte Carlo techniques for simulating radiotherapy linear accelerators.

1995

• Amorphous-silicon (aSi) cesium iodide (CsI) flat-panel x-ray detector image receptors are introduced.
• Photoconductor (amorphous-selenium) based flat-panel x-ray detector image receptors are introduced.

1996

• Intensity Modulated Radiation Therapy (IMRT) using multileaf collimators allows for optimized fluence in the treatment of irregular and concavely shaped tumors while sparing normal tissue.

1997

• Gadolinium oxysulfide (GOS) based flat-panel digital x-ray detector image receptors are introduced.

1999

2000

• Time Magazine names the PET-CT scanner the medical invention of the year.

2001

• Dynamic flat-panel digital x-ray detector image receptors for fluoroscopy are introduced.

2003

• The Nobel Prize in Physiology or Medicine is awarded to Paul C. Lauterbur and Sir Peter Mansfield for “their discoveries concerning magnetic resonance imaging.”

2005

• Volumetric modulated arc therapy (VMAT) further improves intensity modulated radiation therapy techniques.

2006

• The first commercial dual-source CT scanner capable of dual-energy CT imaging is born.

2009

• UMC Utrecht completes proof-of-principle testing using an experimental MR-linac.

2017

• The FDA approves for clinical use the first 7T MRI, the highest strength magnet for medical imaging used to date.
• Regina Barzilay wins a MacArthur Fellowship for her work using machine learning applied to detecting cancer.

2019

• The Radiological Society of North America (RSNA) and the American College of Radiology (ACR) launch a new 3D printing clinical data registry.

2020

• A clinical trial begins investigating ultra-high dose rates used in FLASH radiation therapy.

2020s

• Continued observation of Moore’s Law in effect as the future of the field trends in technological advancements involving automation, artificial intelligence, and deep learning.