From discovery to modern practice
Trace the journey from Röntgen's first X-ray to today's adaptive, image-guided treatments — the scientists, discoveries, and dates that built the field of radiation therapy.
Discoverer of X-rays
1845–1923 · Germany
Professor of physics at the University of Würzburg. His 1895 discovery of X-rays launched both diagnostic radiology and radiation therapy; he received the first Nobel Prize in Physics (1901).
Pioneer of radioactivity
1867–1934 · Poland / France
Coined "radioactivity," discovered polonium and radium with Pierre Curie, and isolated pure radium. Won two Nobel Prizes (Physics 1903, Chemistry 1911) and championed the medical use of radium, founding the Radium Institute.
Co-discoverer of radium
1859–1906 · France
Physicist who, with his wife Marie, isolated radium and polonium. Shared the 1903 Nobel Prize in Physics for work on radioactivity before his death in a street accident.
Discoverer of radioactivity
1852–1908 · France
Discovered in 1896 that uranium salts emit penetrating rays without an external source — the phenomenon Marie Curie would name radioactivity. Shared the 1903 Nobel Prize with the Curies.
Founder of fractionation
1870–1940 · France
Radiobiologist at the Radium Institute whose studies of testicular irradiation proved that splitting dose across days spares normal tissue while destroying tumors — the radiobiologic basis of fractionation.
Father of fractionated radiotherapy
1876–1950 · France
Radiation oncologist who established protracted, fractionated treatment for head and neck cancers in the 1920s–30s, demonstrating radiotherapy could cure cancer and defining the orthovoltage standard.
Inventor of the Coolidge tube
1873–1975 · United States
GE physicist who developed the tungsten-filament vacuum X-ray tube (1913), giving therapy reliable, controllable X-ray beams and powering therapeutic radiography for decades.
Cobalt-60 teletherapy pioneer
1915–1997 · Canada
Medical physicist who designed the first cobalt-60 teletherapy unit; the first patient was treated in 1951, opening the megavoltage era that made deep-tumor cure practical.
Inventor of CT
1919–2004 · United Kingdom
Engineer who developed computed tomography (first clinical scan 1971), which transformed treatment planning by letting clinicians see tumors and organs in 3D. Shared the 1979 Nobel Prize in Physiology or Medicine.
Discoverer of artificial radioactivity
1897–1956 · France
Daughter of Marie Curie. With husband Frédéric, discovered in 1934 that stable elements could be made radioactive — the basis for the man-made isotopes used in modern therapy. Shared the 1935 Nobel Prize in Chemistry.
German physicist Wilhelm Conrad Röntgen discovers a new form of radiation while experimenting with cathode-ray tubes. He calls it "X-rays" for the unknown. He images his wife Bertha's hand, showing her bones and ring — the first medical radiograph.
French physicist Henri Becquerel finds that uranium salts emit penetrating rays without an external energy source, discovering radioactivity. Within months, X-rays are first used to treat a patient (skin lesions), launching radiation therapy.
Marie and Pierre Curie discover the elements polonium and radium while processing pitchblende. Marie Curie coins the term "radioactivity." Their work provides the radioactive sources that would drive early brachytherapy.
Röntgen receives the inaugural Nobel Prize in Physics for the discovery of X-rays, formally recognizing the significance of his work for science and medicine.
Marie Curie, Pierre Curie, and Henri Becquerel share the Nobel Prize in Physics for their discoveries of radioactivity and the radioactive elements. The same year, Alexander Graham Bell suggests placing radium inside or near tumors — an early concept of interstitial brachytherapy.
Marie Curie wins a second Nobel Prize — this one in Chemistry — for isolating pure radium and studying its compounds. She remains the only person to win Nobel Prizes in two distinct sciences (physics and chemistry).
American engineer William D. Coolidge develops a vacuum X-ray tube with a tungsten filament, producing stable, controllable, and reproducible X-ray beams — the foundation of therapeutic X-ray machines for decades.
At the Radium Institute in Paris, biologist Claudius Regaud shows that fractionating radiation over days spares normal skin while still destroying tumor cells. This radiobiological insight underpins modern fractionation.
Henri Coutard reports cure of head and neck cancers using protracted, fractionated X-ray treatment, establishing the orthovoltage era's standard of care and proving radiation therapy could be curative.
Irène and Frédéric Joliot-Curie discover artificial radioactivity, producing radioactive isotopes artificially — the basis for the modern sources used in teletherapy and brachytherapy.
Canadian physicist Harold E. Johns builds the first cobalt-60 teletherapy unit (the "cobalt bomb"). Cobalt-60 — an artificial isotope emitting 1.17 and 1.33 MeV gamma rays (average 1.25 MeV) — is produced in nuclear reactors using the Joliot-Curies' 1934 discovery of artificial radioactivity. The first patient is treated on October 27, 1951, ushering in the megavoltage era and deep-seated tumor treatment.
Cobalt-60 units spread rapidly worldwide and become the backbone of radiation therapy for decades. Compared with 200–300 kVp orthovoltage X-rays, cobalt's megavoltage gammas achieve skin sparing (maximum dose below the skin surface) and deeper penetration, making curative treatment of deep-seated pelvic and abdominal tumors possible for the first time. Simple, reliable, and inexpensive, cobalt machines carry much of the early curative-era workload and remain in limited clinical use worldwide today.
The first patient is treated with a medical linear accelerator at Hammersmith Hospital, London. Linear accelerators soon become — and remain — the workhorse of modern external-beam radiotherapy.
Afterloading techniques are introduced, allowing applicators to be placed first and radioactive sources loaded afterward, sharply reducing staff exposure and improving brachytherapy safety.
Godfrey Hounsfield develops computed tomography (CT), later adapted for treatment planning in the 1980s, enabling 3D visualization of tumors and organs — a turning point for precision radiotherapy.
3D conformal radiation therapy (3DCRT) emerges, using CT-based planning and beam's-eye-view to shape dose to the target while sparing surrounding normal tissue.
Intensity-modulated radiation therapy (IMRT) is first delivered clinically using the NOMOS MIMiC multileaf collimator, allowing dose to be sculpted with varying intensities across the target.
Image-guided radiation therapy (IGRT) and volumetric modulated arc therapy (VMAT) become routine, with onboard imaging and cone-beam CT aligning the patient and target each day before treatment.
Proton therapy centers expand across the US; stereotactic body radiotherapy (SBRT) delivers ablative doses in a few fractions; MR-linacs enable real-time, adaptive, anatomy-guided treatment.
Ultra-high dose-rate "FLASH" radiotherapy moves into the clinic — the first-in-human FAST-01 and FAST-02 proton FLASH trials treat painful bone metastases with effective pain relief and minimal toxicity, and the FAST-02 results published in 2026 extend proton FLASH to thoracic bone metastases with complete pain relief in most participants and no treatment-related serious adverse events — while AI-driven adaptive platforms (Varian Ethos, Elekta Evo) and MR-linacs make replanning to the anatomy of the day part of routine practice.