1. History of Radiation
Section 2
Part I

2. At the end of the 19th century, many scientists did not realize they
were on the edge of a revolution in physics…
“The most important
fundamental laws and
facts of physical science
have all been discovered,
and these are now so
firmly established that the
possibility of their ever
being supplanted in
consequence of new
discoveries is exceedingly
remote… Our future
discoveries must be
looked for in the sixth
place of the decimals.”
-- Albert Michelson, 1894

3. Radiation Chronicle
• 1789 - The element uranium was discovered by Martin Klaproth
• 1869 - Dmitri Mendeleyev developed the periodic law of elements,
which later evolved in the Table of Elelments.
• 1885 - Balmer publishes an empirical formula that gives the observed
wavelength of hydrogen light spectra
1  1 1 
= R∞  2 − 2 
λ 2 n 
• 1890 - Thorium is first used in mantles for camping lanterns

4. 1895 - Wilhelm Roentgen
• Discovered X-rays on 8th
November 1895
• The World immediately
realised their medical
potential
• Won Nobel Prize in 1901

5. 1896 - Henri Becquerel
• Discovered radioactivity on
26 February 1896
• “Some atoms give off energy in
form of rays. Uranium gives off
radiation.”
• Shared Nobel Prize in 1903 with P.
Curie.

6. X-rays was quickly put to clinical use
Frau Roentgen’s hand, 1895
1896 (Pupin in New York City): using a screen as
well as film for advanced x-ray imaging.

7. Dr Rome Wagner and
assistant

8. Radiation Chronicle - cont.
• 1897 - J.J. Thomson discovers the electron.
• 1898 - Marie and Pierre Curie discover the first radioactive elements:
radium and polonium. Radioactivity is named by Marie Curie. Marie
Won Nobel Prize in 1911 for discovery of radium and polonium.
• 1899 - Ernest Rutherford concludes that radiation can be divided into
two types: alpha and beta rays. Won Nobel Prize in 1908.
• 1900 - Pierre Curie observes another type of radiation - the gamma
rays. Shared Nobel Prize in 1903 with Becquirel.
• 1905 - Albert Einstein develops the theory about relationship between
mass and energy: E = mc2. Won Nobel Prize in 1919 for discovery of
photoeffect.
• 1911 - Ernest Rutherford discovers that most of an atom is empty
space and identifies the atomic nucleus
• 1911 - George de Hevesy conceives the idea of using radio tracers -
applied later to medical diagnosis. (Won a Nobel Prize in 1943)
• 1913 - Niels Bohr introduces the first atom model, the mini solar
system.

9. Radiation Chronicle - cont.
• 1913 - Hans Geiger invents the Geiger counter form measuring
radioactivity.
• 1913 - Frederick Proesher publishes the first study on the intravenous
injection of radium for therapy of various diseases.
• 1920 - Ernest Rutherford discovered and named the proton.
• 1927 - Herman Blumgart, a Boston physician, first uses radioactive
tracers to diagnose heart disease.
• 1932 - James Chadwick discovers the neutron. Won Nobel Prize in
1935.
• 1932 - Ernest O. Lawrence and M. Stanley Livingston publish the first
article on "the production of high speed light ions without the use of
high voltages." It is a milestone in the production of usable quantities of
radionuclides. E. Lawrence wan Nobel Prize in 1939 - cyclotron.
• 1934 - Irene and Frederic Joliot-Curie discover artificial radioactivity. In
1935 - Irene and Frederic Joliot-Curie receive Nobel Prize for creating
the first artificial radioactive isotope.

10. Radiation Chronicle - cont.
• 1935 - Nuclear medicine comes into existance when cyclotron-
produced radioisotopes and nuclear radiation becomes available in the
U.S.
• 1936 - John H. Lawrence, the brother of Ernest, makes the first clinical
therapeutic application of an artificial radionuclide when he uses
phosphorus-32 to treat leukemia.
• 1937 - John Livingood, Fred Fairbrother and Glenn Seaborg discover
iron-59. 1938 John Livingood and Glenn Seaborg discover iodine-131
and cobalt-60 - all isotopes currently used in nuclear medicine. G.
Seaborg shared Nobel Prize with MacMillan in 1951.
• 1938 - Otto Hahn and Fritz Strassman, produce lighter elements by
bombarding uranium with neutrons. Irene Joliot-Curie and Pavle Savich
notice the same effect. However, it was Lise Meitner and Otto Frisch
that recognized it as splitting of the atom - “fission”. O. Hahn won a
Nobel Prize in 1944.
• 1938 - Enrico Fermi won a Nobel Prize forproduction of new
elements by neutron irradiation.

11. Radiation Chronicle - cont.
• 1939 - The principles of a nuclear chain reaction demonstrated. They
take a first patent on the production of nuclear energy. The principle of
nuclear reactors was first recorded and sealed in an envelope where it
remains secret during the WWII. Irene and Frederic Joliot-Curie
• 1939 - Emilio Segre and Glenn Seaborg discover technetium-99m - an isotope
currently used in nuclear medicine.
• 1939 - U.S. Advisory Committee on Uranium recommends a program to develop
an atomic bomb (this is later named the Manhattan Project).
• 1940 - The Rockefeller Foundation funds the first cyclotron dedicated for
biomedical radioisotope production at Washington University in St. Louis.
• 1942 - The Manhattan Project is formed to secretly build the atomic bomb before
the Nazis.
• 1942 - Fermi demonstrates the first self-sustaining nuclear chain reaction in a
lab at the University of Chicago.
• 1942 - The United States drops atomic bombs on Hiroshima and Nagasaki.
Japan surrenders.

12. First Reports of Injury
Late 1896
Elihu Thomson - burns from
deliberate exposure of a finger to
X-rays
Edison’s assistant - hair fell out &
scalp became inflamed & ulcerated

14. Mihran Kassabian (1870-1910)

15. Sister Blandina
(1871 - 1916)
• 1898, started work as
radiographer in Cologne
• held nervous patients &
children with unprotected
hands
• controlled the degree of
hardness of the X-ray tube
by placing her hand behind
of the screen.

16. Sister Blandina
• After 6 months strong flushing & swellings of hands
• diagnosed with an X-ray cancer,
• some fingers amputated
• then whole hand amputated
• whole arm amputated.
• 1915 severed difficulties of breathing
• extensive shadow on the left side of her thorax
• large wound on her whole front- and back-side
• Died on 22nd October 1916.

17. First Radiotherapy Treatment
Emil Herman Grubbé
• 29 January 1896
• woman (50) with breast cancer
• 18 daily 1-hour irradiation
• condition was relieved
• died shortly afterwards from
metastases.

18. William Rollins
• Rollins W. X-light kills . Boston
Med Surg J 1901;144:173.
• Codman EA. No practical
danger from the x-ray .
Boston Med Surg J 1901;144:197

19. Early Protective Suit
•Lead glasses
•Filters
•Tube shielding
•Early personal “dosemeters”
•etc.

20. Protection Progress
• 1898 Roentgen Society Committee of Inquiry
• 1915 Roentgen Society publishes recommendations
• 1921 British X-Ray and Radiation Protection
Committee established and issue reports
• 1928 2nd International Congress of Radiology
adopts British recommendations + the Roentgen
• 1931 USACXRP publishes the first
recommendations (0.2 r/d)
• 1934 4th ICR adopts 0.2 Roentgens per day limit

23. Life Span Study
• About 94,000 persons,
• > 50% still alive in 1995
• By 1991 about 8,000 cancer deaths
∀ ∼ 430 of these attributable to radiation
• 21 out of 800 in utero with dose > 10
mSv severely mentally retarded
individuals have been identified
• No increase in hereditary disease
• http://www.rerf.or.jp/eigo/glossary/lsspopul.htm

24. Theory came later : Birth of planetary
model – Part I: Rutherford
• 1900: Alpha, beta and gamma rays are
known
• 1909 Rutherford conclude from bombarding
thin gold foils with alpha particles (Po(214-
84)):
– Large angle deflection seen in 1/8000 alpha
particles suggests the existence of a very small
and massive nucleus
– Proposed the planetary model
• We now know:
– Rnuc ~ 1.3 A1/3 x 10-15 m
– Ratom ~ 1.5 x 10-10 m

25. Part II: Bohr’s hydrogen atom - 1913
• Bohr was not satisfied from classical
mechanics in the planetary model
– Unstable model, since an accelerated charge will
emit light and therefore lose E
• Bohr postulates the first semi-classical model
– Angular momentum of electron is quantized:
• mvr = nħ
– Then energy and orbital radii are also quantized
(derive radius on the board)
• rn = 0.529 n2/Z (Å)
• En = -13.6 Z2/n2 (eV)

26. Problem with Bohr’s model and classical
mechanics
• Could only predict correctly the energy levels
of H.
• The dual behavior of light (particle and wave)
could not be explained by classical
mechanics
• The approach of Bohr of mixing classical
mechanic with quantizing certain variables
was suddenly heavily used
– other accurate predictions were made with new
Semi-classical or relativistic models
– Prelude for Quantum Mechanics

27. Birth of Quantum Mechanics: 1925
• Simultaneously and independently:
– Heizenberg realized that the reason Bohr’s model failed was
that it was trying to predict none observable variables
(position, speed)
– Heizenberg actually created a model focusing on
measurable variable: Balm wave length:
• Showed that ∆p.∆x ≥ħ or ∆E.∆t ≥ħ
• This is the Heizenberg uncertainty principle, stating that it is
impossible to measure precisely the speed and location of a
particle
• Also showed that x.px was different from px.x. Others showed
in this a typical matrix property and called Heizenberg model
the MATRIX MECHANICS
– Schroendiger established a law defined by a differential
equation that describes matter as a wave (D2X and Dt)
– Later, Schroendiger equation will be formalized by linear
algebra and matrix simplification

28. Pauli principle: No two electrons in an atom
can be in the same state
• Quantization came naturally out of quantum mechanics
• Four quantum numbers fully described the electron
energy levels (derive atomic layer on the board)
– Principal quantum number : n
• Describes the orbital shells
– n=1, 2 and 3 for K, L and M shells respectively
• Corresponds to Bohr’s angular momentum quantization
– Azimuthal quantum number: l
• Fine structure (sommerfeld shows that elliptical orbits in relativity
implies this quantization)
– l = 0, 1, 2, …, n
– Magnetic quantum number: m
• An electron orbiting a nucleus is a current that produces a
magnetic field affecting the atom magnetic field
– m = [-l, l]
– Intrinsic spin of electron: s
– s = [-1/2, ½]

29. Summary on Atomic Structure
 Nucleus
 Contains protons and neutrons
 Small Size
 Relatively large mass
 Extremely large density
 Large amount of stored energy
 Orbiting Electrons
 Large size
 Low density
 Orbit nucleus near speed of light
 Small amount of energy relative to nucleus
 Responsible for chemical bonds

30. Nomenclature for Elements
"X" = Element Symbol
"Z" = # Protons
Each element has a unique "Z”
"N” = # Neutrons A
Atomic Mass # = "A"
"A" = Z + N = # Protons + # Neutrons Z X
Isotope: same Z, different N, thus different A

31. Continuous and characteristic X-rays
High Voltage
Power Supply
Current
Tungsten Filament
Anode Target Cathode
Glass Envelope
Tube Housing
• Roentgen discovered that electron that hit a target
produces photons
• Higher the A of the target, the more efficient the X-ray
production
• Range of energy of photon: [0,E of incident e-]

32. X-rays production
• Electron can produce
photons in two ways:
– Slowing down of incident
electron when hitting target
emits photons with minimum
wave length:
• λ = 12400 (Å.eV)/Ee
– K shell electron of target
ejected
• L e- fills it: Kα
• M e- fills it: Kβ

33. The Auger electron
• Non-radiative phenomenon
• Incident electron can eject a K shell electron
– Then and L electron makes a transition to fill K shell vacancy
without emitting a photon
– Instead, this energy leads to the ejection of another L shell electron,
leading to two missing electron in the target atom
– This can trigger a cascade of Auger electrons