Radiation
David M. Steinway, DO
AZCOM
Pitchblende [Uraninite]
• Uranium-rich radioactive with lead, thorium,
and rare earth elements
• Derivation of name
– Pitchblack color
– Blende minerals whose density suggested
metal content (German)
Uraninite minerals
• Decay process:
– Radium (decay product of Uranium)
– Uranium isotopes Lead isotopes
• uranium isotopes 238U 206Pb
• uranium isotopes 235U 207Pb
– Helium (result of alpha decay)
• Helium was first found on Earth in uraninite after having
been discovered spectroscopically in the Sun’s atmosphere.
• Spontaneous fission (SF)
– Technetium (produced by the SF of uranium-238)
Uraninite
History of Pitchblende
• Known at least since the 15th century from
silver mines in the Ore Mountains, on the
German / Czech border
• F.E.Brückmann described the mineral in 1727
• Uranium discovered by the German chemist
Martin Klaproth in 1789
• Polonium and radium by the French scientists
Pierre and Marie Curie in 1898
Maria Salomea Skłodowska Curie
Maria Curie
• Shared her 1903 Noble Prize in Physics with
her husband Pierre Curie and with the
physicist Henri Becquerel
• First woman to win a Nobel Prize
• Only woman to date to win in two fields
• Only person to win in multiple sciences
• Curie died in 1934 of aplastic anemia brought
on by her years of exposure to radiation
Curie’s Achievements
A theory of “radioactivity” (a term that she coined)
Techniques for isolating radioactive isotopes
Discovery of two elements polonium and radium
Conducted the world's first studies into the treatment of
neoplasms using radioactive isotopes
• Founded the Curie Institutes in Paris and Warsaw which
remain major centers of medical research today
• Named the first chemical element she discovered polonium
in 1898 after her native country
• Founded the Radium Institute in her home town, Warsaw
(now the Maria Skłodowska–Curie Institute of Oncology)
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Family Achievements
• Her daughter Irene Joliot-Curie and son-inlaw, Frederic Joliot-Curie shared a Nobel Prize
• Irene Joliot-Curie was the sole winner of the
1911 Nobel Prize in Chemistry
Wilhelm Rontgen
Wilhelm Rontgen
• German physicist
• Discovered X-rays on November 8, 1895
• Found X-rays to be emanating from Crookes
tubes
• Wrote an initial report "On a new kind of ray: A
preliminary communication" and on December
28, 1895 submitted it to the Wurzburg’s PhysicalMedical Society journal
• The name “X-rays” often referred to as “Röntgen
rays”
First Medical X-Ray
• Hand mit Ringen (Hand
with Rings): print of
Wilhelm Rontgen’s first
"medical" X-ray, of his
wife's hand, taken on
22 December 1895
X-Rays
• “Soft" X-rays from
about 0.12 to 12 keV
(10 to 0.10 nm
wavelength)
• "hard" X-rays from
about 12 to 120 keV
(0.10 to 0.01 nm
wavelength)
Cathode Ray Tube
Crookes Tube
• An early experimental
electrical discharge
tube invented by
English physicist
William Crookes around
1869-1875
• Cathode rays and
streams of electrons
were discovered
Crookes Tubes
• Free electrons are created by ionization of the
residual air in the tube by varying DC voltage
between a few kilovolts and 100 kV
• Increased voltage accelerates the electrons
coming from the cathode to a high enough
velocity that created X-rays upon impact with
the anode or the glass wall of the tube
Principles 1 Cathode Rays
• Electrons are generated by the ionization of the residual air by a
high DC voltage applied between the electrodes
• When high voltage is applied to the tube, the electric field
accelerates the small number of electrically charged ions present in
the gas
• These collide with other gas molecules knocking electrons off them
and creating more positive ions in a chain reaction
• All the positive ions are attracted to the cathode or negative
electrode
• When they strike it, they knock large numbers of electrons out of
the surface of the metal, which in turn are repelled by the cathode
and attracted to the anode or positive electrode
• Crookes tubes are cold cathode tubes
– they do not have a heated filament in them that releases electrons
like the later electronic vacuum tubes
Thomas Edison
• Investigated materials' ability to fluoresce when
exposed to X-rays in 1895
• Developed a fluoroscope around March 1896,
– This became the standard for medical X-ray
examinations
• Stopped X-ray research around 1903
– one of his glassblowers Clarence Dally acquired a
cancer in both arms that required amputations in a
futile attempt to save Dally’s life. Dally had a habit of
testing X-ray tubes on his hands
Historical Fact
• In 1901,U.S. President Wm McKinley was shot
twice in an assassination attempt
• One bullet only grazed his sternum, another had
lodged somewhere deep inside his abdomen and
could not be found
• "A worried McKinley aide sent word to inventor
Thomas Edison to rush an X-ray machine to
Buffalo to find the stray bullet. It arrived but
wasn't used. McKinley died of septic shock due to
bacterial infection” six days later
C Arm Fluoroscope
Conventional X-Ray Unit
Modern X-ray Unit
Basic Definitions
• R
• Rad
• cGy
Physics
Percent Depth Dose (10x10 cm)
Modalities
Accelerators
Cyclotrons