This timeline presents some important medical breakthroughs and inventions in the 20th century, and also other important world events occurring at the time. The green text indicates a link to a short explanatory notes.

1900 Walter Reed discovered cause of yellow fever Max Planck proposed quantum theory Gerhard Kuntscher was born 1901 Weston Price recommended the use of x-ray in root canal work Karl Landsteiner discovered blood groups Henri Alexandre Danlos and Eugene Bloch placed radium in contact with a tuberculous skin lesion Italy's Guglielmo Marconi conducted first transatlantic radio transmission The first endoscopic examinations of the peritoneal cavity was performed 1902 Hormones were discovered Reginald Watson-Jones was born Sir Lauder Brunton suggested the possibility of performing a transventricular valvotomy 1903 Willem Einthoven developed the electrocardiograph Wright brothers flown first motorized airplane 1904 Sir John Ambrose Fleming developed the vacuum tube Jackson designed the bronchoscope 1905 Einstein announced theory of relativity Einthoven developed telecardiogram Korotkoff described the auscultatory sounds 1906 Einhorn recommended novacaine and adrenalin combination for local anesthesia X-ray contrast medium first used for contrast filled image of the renal system Hopkins discovered vitamins Eduard Zirm, German surgeon, performed the first successful corneal transplant Lee de Forest invented the three-element vacuum tube	�
1910 Barium sulfate introduced as contrast agent for gastro-intestinal diagnosis 1911 Rutherford discovered structure of atom E Rutherford, H Geiger, and E Marsden discovered nucleus of the atom John Charnley was born Jacobaeus used the term laparothorakoskopie Gullstrand invented the slit lamp 1912 James B Herrick, an American physician, first described heart disease resulting from hardening of the arteries Casimir Funk coined the name vitamin Cushing discovered the role of pituitary gland 1913 Frederick Proescher published the first study on the intravenous injection of radium for therapy of various diseases Neils Bohr proposed 'solar system' model of the atom 1914 World War I began J Leon Williams developed typical tooth forms Tuffier successfully relieved a case of aortic stenosis with finger dilatation 1915 Constantin Chilowsky and Paul Lang�vin developed hydrophone 1917 Lenin led the Bolshevik Revolution Magill invented the endotracheal tube 1918 Edwin Armstrong developed superheterodyne circuit, the receiver-amplifier at the heart of radios and televisions today 1919 Shortwave radio is invented Flip-flop circuit invented Hugo Koch invented Enigma, a mechanical cryptography device used by Germany during World War II
1920 E Rutherford and J Chadwick showed that the nuclei of light elements could be disrupted by alpha particles Harold Pardee published the first ECG of an acute myocardial infarction First demonstration of point to point projection of retina onto lateral geniculate nucleus 1921 Insulin is isolated and used for the treatment of diabetes by Frederick Banting and Charles Best 1923 The first successful transventricular valvotomy 1924 Georg de Hevesy, J A Christiansen and Sven Lomholt performed the first radiotracer studies in animals Electroencephalogram (EEG) developed Pauli postulated nuclear magnetic moments 1925 Obstetricians experimented with transverse incisions in the uterus Holm demonstrated that vitamin A deficiency causes night blindness 1926 Ronald Huckstep was born 1927 Farnsworth demonstrated working model of a television Lemaitre proposed big bang theory Philip Drinker and Louis Shaw invented the iron lung 1928 George Papanicolaou discovered cervical cancer cells Penicillin is discovered by Scotsman Alexander Fleming Baird constructed first mechanical color television 1929 Hubble proposed theory of expanding universe U S stock market crashed, and precipitated global depression Cardiac catheterization first performed by Forssmann on himself Iron lung for polio victims developed AT&T patented coaxial cable Kalk introduced refinements for laparoscopic technique Hans Berger founded electroencephalogram
1930 Physicists observed that atoms gave off tiny radio signals when subjected to magnetic fields and radio waves Brunnell performed the first facial nerve graft 1931 Transmission electron microscope (TEM) constructed by German scientists Max Knoll and Ernst Ruska 1932 MIT's Vannevar Bush built 'Differential Analyzer', a mechanical computer James Chadwick discovered the neutron Irene Joliot-Curie (daughter of Marie Curie) and her husband Frederic discovered that some ordinary metals could be made radioactive when bombarded by alpha particles Ernest Lawrence founded nuclear medicine 1934 Moldavan counted cells in dilute erythrocyte suspension using a photoelectric device 1936 John H Lawrence made the first clinical therapeutic application of an artificial radionuclide, when he used phosphorus-32 to treat leukemia Alan Turing's 'On Computable Numbers' describes a general-purpose computer Walter identified abnormal electrical activity in the brain areas around a tumor 1937 John Livingood, Fred Fairbrother and Glenn Seaborg discovered iron-59 Carlson invented the photocopier Stibitz of Bell Labs invented the electrical digital calculator 1938 Robert E Gross, an American surgeon, performed first heart surgery John Livingood and Glenn Seaborg discovered iodine-131 and cobalt-60 First hip replacement operation Lempert developed the fenestration operation 1939 Hitler invaded Poland, and World War II began Emilio Segre and Glenn Seaborg discovered technetium-99m Alec Reeves developed pulse-code modulation system for converting analog information into digital-style on-and-off signals First computer that uses vacuum tubes built by John Atanasoff
1940 Howard Florey and Ernst Chain developed penicillin The Rockefeller Foundation funded the first cyclotron dedicated for biomedical radioisotope production at Washington University in St Louis Karl Dussik employed ultrasound in medical diagnosis 1942 Atanasoff Berry built the first electronic digital computer Emanuel Goldberger added the augmented limb leads 1943 Streptomycin discovered 1944 First successful open heart surgery Harvard's Mark I, first digital computer, put in service Infusion pump was invented by Harvey Hebb Raoul Palmer performed gynecological examinations using laparoscopy 1945 Atomic bombs were dropped on Hiroshima and Nagasaki John Mauchly and J Presper Eckert built ENIAC, the first fully electronic computer Turbidimetry was used to determine red blood cell concentration based on Kleine's light scattering method 1946 Samuel M Seidlin, Leo D Marinelli and Eleanor Oshry treated a patient with thyroid cancer with iodine-131 Felix Bloch and Edward Purcell developed magnetic resonance 1947 Benedict Cassen used radioiodine to determine whether a thyroid nodule accumulates iodine, helping to differentiate benign from malignant nodules Gandhi's civil disobedience movement led to an independent India William Shockley, Walter Brattain and John Bardeen invented the transistor at Bell Labs Helen Free developed test for urinalysis Claude Beck defibrillated a human heart 1948 Cortisone relieved rheumatoid arthritis pain Harken and Bailey performed the first transatrial commissurotomies Gabor described principles of holography Tuohy developed the modern contact lens 1949 Magnetic core computer memory was invented John Wild and Donald Neal developed A-mode ultrasound
1950 K R Crispell and John P Storaasli used iodine-131 labeled human serum albumin (RISA) for imaging the blood pool within the heart John Hopps invented the heart pacemaker Atomic absorption spectrophotometer was developed by Walsh Leyton and Ivanov developed flame photometry 1951 Charles Hufnagel, an American surgeon, developed a plastic valve to repair an aortic valve Mauchly and Eckert created UNIVAC, the first commercial computer. A year later it successfully predicted a landslide for Eisenhower George Ludwig used pulse-echo ultrasound on animal tissues 1952 C Walton Lillehei performed first successful open heart surgery Fourestier, Gladu, and Valmiere developed new imaging system for endoscopy 1953 First mechanical heart and blood purifier used Watson and Crick decoded the mystery of DNA Gordon Brownell and H H Sweet built a positron detector based on the detection of annihilation photons by means of coincidence counting Donald Neal and John Reid produced real-time ultrasound images 1954 David Kuhl invented a photorecording system for radionuclide scanning American Joseph Murray performed first successful organ transplant (kidney) Jonas Salk (1914-1995), American physician, developed and successfully tested a polio vaccine that worked against all three strains of polio 1955 X-ray image intensifier developed The first mitral valve replacement performed Flament measured the line-spread function of the human eye 1956 Coulter developed an automated blood cell counter 1957 Fiber endoscopy pioneered by Basil Hirschowitz at the University of Michigan Russia launched first satellite, Sputnik I Eisenhower formed the Advanced Research Project Agency (ARPA) to coordinate scientific research The 'pan-scanner' for ultrasound was developed Brown and Donald constructed the compound B-mode ultrasound Walter invented the toposcope 1958 Hal Anger invented the scintillation camera Jack Kilby and Robert Noyce independently invented the microchip Moore, Stein, and Sparkman developed the amino acid analyzer 1959 Major drug to fight leukemia invented
1960 Ultrasound imaging is developed to view the internal organs Mirowski began initial work on implantable defibrillator Kurst Semm invented the automatic insufflator C Townes, A L Schalow, and T H Maiman developed laser using a rod of ruby 1961 J R Jude, an American cardiologist, led a team performing the first external cardiac massage to restart a heart Oral polio vaccine developed MIT started 'time-sharing' computers, allowing several users to access one machine simultaneously 1962 David Kuhl introduced emission reconstruction tomography, which later became known as SPECT and PET Thomas Cronin utilized silicone in a breast implant device Howry and Homles invented multi-joint ultrasound scanner Moulopoulus, Topaz, and Kolff developed the intra-aortic balloon 1963 Henry Wagner first used radio-labeled albumin aggregates for imaging lung perfusion in normal persons and patients with pulmonary embolism Fogarty invented balloon embolectomy catheter 1964 IBM launched the System/360, the first commercial mainframe computer Leith and Upatnieks made the first hologram with laser 1965 Michael DeBakey and Adrian Kantrowitz, American surgeons, implanted mechanical devices to help a diseased heart 1966 The first dedicated mammography machine was developed 1967 Christiaan Barnard, a South African surgeon, performed the first whole heart transplant from one person to another Donald Davies devised 'packet switching' as a way to route information through networks Paul Lauterbur found that magnetic resonance could be used in making an image Willem Kolff invented the artificial kidney dialysis machine 1968 Normal Anderson developed a centrifuged analyzer 1969 Armstrong and Aldrin walked on the moon The ARPA Net - a network of university computers - was born Bell Labs created UNIX, an operating system that works across computer platforms
1970 X-ray mammography found widespread application in imaging the breasts Bird invented the pediatric ventilator 1972 Godfrey and Allen presented CAT scan Raymond Damadian obtained a patent for scanning with magnetic resonance imaging Bacus developed automated leukocyte differential analysers 1973 H William Strauss introduced the exercise stress-test myocardial scan DNA cloning was invented James Griffith and Walter Henry improved the oscillating ultrasound transducers 1974 Vinton Cerf and Robert Kahn designed Transmission Control Protocol (TCP) for linking different computer networks African American inventor, Phil Brooks, patented the first disposable syringe 1975 Chronic villus sampling developed by Chinese gynecologists as an aid to early diagnosis of genetic disorders High pressure liquid chromatography was developed 1976 Single photo emission computed tomography (SPECT) camera developed Coronary angioplasty introduced 1977 Steve Jobs and Steve Wozniak developed the Apple II 1978 First test-tube baby born David Goldenberg used radio-labeled antibodies to image tumors in humans Digital radiography introduced First digitally coded laser videodiscs appeared on the market Programmer Ward Christensen wrote MODEM (modulator-demodulator), allowing PCs to talk over public phone lines
1980 Magnetic resonance imaging (MRI) first used Smallpox eradicated Kurt Semm performed the first laparoscopic appendectomy 1981 J P Mach used radio-labeled monoclonal antibodies for tumor imaging Scientists identified AIDS Use of artificial skin to treat a third-degree burn IBM PCs launched using software from Bill Gates' Microsoft 1982 Willem DeVries, an American surgeon, implanted a permanent artificial heart Steve Larson and Jeff Carrasquillo treated cancer patients with malignant melanoma using iodine-131 labeled monoclonal antibodies 1983 John Wickham coined the term minimally invasive surgery 1984 Three dimensional images of bones and organs were first made Apple, with a little help from Xerox PARC, released the Macintosh First cochlear implant with FDA approval 1985 Clinical positron emission tomography (PET) scanning developed at University of California Clinical networks first implemented ARPA Net renamed the Internet 1987 Mouret performed video-laparoscopic cholecystectomy 1989 The FDA approved the first positron radiopharmaceutical (rubidium-82) for myocardial perfusion imaging Spiral CT allowed fast volume scanning of an entire organ MR angiography developed and allows non-invasive imaging of the blood vessels without radiation or contrast injection Fall of Communism in Eastern Europe
1990 Tim Berners-Lee created an Internet protocol called the World Wide Web 1991 Breakup of Soviet Union Apartheid ended in South Africa 1992 The FDA approved the first monoclonal antibody radiopharmaceutical for tumor imaging Rhodium was used in the mammogram 1993 Echo planar MR imaging (EPI) developed Open MRI systems developed 1994 A robotic arm was designed to hold the laparoscope 1995 Patent issued for unique blood substitute 1996 First live broadcast of laparoscopic surgery via Internet 1997 3D MR angiography developed 1998 Digital cassette for imaging was introduced Marshall Strome performed the first larynx transplant