HDR 112
CHAPTER 1
RADIATION BIOLOGY AND RADIATION PROTECTION
INTRODUCTION
TO
RADIOBIOLOGY
PREPARED BY:MR KAMARUL AMIN BIN ABDULLAH
SCHOOL OF MEDICAL IMAGINGFACULTY OF HEALTH SCIENCE
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CHAPTER 1: Introduction to Radiobiology
LEARNING OUTCOMES
At the end of the lesson, the student should be able to:-
Explain the history of radiation injury.
Describe the firstly discovered of radiation injury.
Explain the types ionizing radiation.
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CHAPTER 1: Introduction to Radiobiology
TOPIC OUTLINES
INTRODUCTION
1.1 Significant Discoveries
1.2 New Dangers Come with Discoveries
1.3 Meeting the Need for Radiation Protection
1.4 Ionization
1.5 Types or Products of Ionizing Radiation
1.6 References
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CHAPTER 1: Introduction to Radiobiology
INTRODUCTION
Since ancient times, philosophers and scientists have been interested
in the basic building blocks of our physical universe.
In fact the ancient Greeks were the first to believe that all matter in
the universe must be made of tiny building blocks or atoms.
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CHAPTER 1: Introduction to Radiobiology
INTRODUCTION
Beginning with the earliest scholars of science throughout history and
into this century, scientists have been driven to learn more about the
atom and how to control it.
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CHAPTER 1: Introduction to Radiobiology
1.1 Significant Discoveries
It wasn't until the latter part of the 19th century that scientists truly
began to make advances in the study of atomic structure and
radiation.
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CHAPTER 1: Introduction to Radiobiology
1.1 Significant Discoveries
During the 1600s, Sir Isaac Newton had proven his theories on gravity.
Marie and Pierre Curie had begun their studies in chemistry and
physics, and Dmitri Mendeleev had introduced the periodic system of
elements.
Just before the turn of the century, Wilhelm Conrad Roentgen
discovered the basic properties of X-Rays; the properties of ionizing
radiation and the possibility of using radiation in medicine.
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CHAPTER 1: Introduction to Radiobiology
1.1 Significant Discoveries
Finally, in 1896, Henri Becquerel announced the discovery of
radioactivity to the Academy of Sciences in Paris.
By the early 1900s the study of radiation was a widely accepted
scientific endeavor.
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CHAPTER 1: Introduction to Radiobiology
1.2 New Dangers Come with Discoveries
But, these discoveries did not come without a price.
Scientists learned that radiation was not only a source of energy and
medicine, it could also be a potential threat to human health if not
handled properly.
In fact, early pioneers in radiation research died from radiation-
induced illnesses (too much exposure).
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CHAPTER 1: Introduction to Radiobiology
1.2 New Dangers Come with Discoveries
For instance, Thomas Edison's assistant died from a radiation-induced
tumor as a result of too much x-Ray exposure.
As new uses for radioactive elements were discovered, potentially
fatal incidents of overexposure increased.
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CHAPTER 1: Introduction to Radiobiology
1.2 New Dangers Come with Discoveries
Example 1: Radium Paint
During World War I, radium paint (a mixture of radium and phosphor)
was used on military aircraft instruments to make them glow in the
dark so they would be more visible to pilots flying at night.
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CHAPTER 1: Introduction to Radiobiology
1.2 New Dangers Come with Discoveries
Example 2: Luminous Dial Painters
After the war was over, the industry that supported this technology
changed their business to paint glow-in-the-dark clocks and watch
faces.
The young women who were employed in this vocation would form a
fine point on their paint brushes by pulling the freshly-dipped brushes
between their lips before applying the paint onto the watch faces.
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CHAPTER 1: Introduction to Radiobiology
1.2 New Dangers Come with Discoveries
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CHAPTER 1: Introduction to Radiobiology
1.2 New Dangers Come with Discoveries
Unknowingly, they were swallowing small amounts of radium and
damaging their bodies.
Over a two-year period, nine women who had worked as dial
painters died of severe and unexplained anemia, accompanied by
destructive lesions of the mouth and jawbones.
A dentist who had treated one of these women finally made the
connection between inflammation of the jawbone marrow, and the
radium dial painting.
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CHAPTER 1: Introduction to Radiobiology
1.2 New Dangers Come with Discoveries
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CHAPTER 1: Introduction to Radiobiology
1.2 New Dangers Come with Discoveries
Example 3: Radium Miners
Radium is chemically similar to
calcium.
Incorporated to bone tissue.
Caused: osteoporosis, osteogenic
carcinoma, carcinoma of
epithelial cells.
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CHAPTER 1: Introduction to Radiobiology
1.2 New Dangers Come with Discoveries
Example 4: Atomic Warfare
Is a military conflict or political strategy in which nuclear weaponry is
used to inflict damage on an opponent.
Could have severe long-term effects, primarily from radiation release.
Could last for decades, centuries, or even millennia after the initial
attack.
Only two nuclear weapons have been used in the course of warfare,
both by the United States near the end of World War II.
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CHAPTER 1: Introduction to Radiobiology
1.2 New Dangers Come with Discoveries
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CHAPTER 1: Introduction to Radiobiology
1.2 New Dangers Come with Discoveries
Example 5: Power Plant Accidents
Nuclear power plants - they have various kinds of accidents have
occurred, from the mundane to the catastrophic.
E.g: Employees have mishaps and equipment breaks down.
When accidents occur, they usually result in a minor release of
radioactive steam or water.
The incident at Chernobyl was the most extreme nuclear accident in history,
resulting in deaths from radiation, destruction of the plant and widely-dispersed
radioactivity.
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CHAPTER 1: Introduction to Radiobiology
1.2 New Dangers Come with Discoveries
The Three Mile Island nuclear power plant
accident March 28, 1979.
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CHAPTER 1: Introduction to Radiobiology
1.2 New Dangers Come with Discoveries
Year Events
1895 Discovery of x- ray
1896
a) Becquerel discover radiations emitted by
uranium compounds.
b) First biological effects e.g.: skin burns,
epilation.
1897 Discoveries of alpha-ray and beta-ray.
1903 Law of Bergonie and Tribondeau.
1911 Leukemia in five radiation workers reported.
1915British Roentgen Society introduces proposals for
radiation protection.
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CHAPTER 1: Introduction to Radiobiology
1.2 New Dangers Come with Discoveries
Year Events
1927First observation of mutations by x- rays in
Drosophila.
1928First international recommendations on radiation
protection.
1930 First survival curve for bacteria.
1945 Atomic bomb in Hiroshima & Nagasaki.
1951 Hereditary effects of radiation in mice reported.
1956First in- vitro radiation survival curve for
mammalian cells.
1986 Chernobyl nuclear reactor meltdown.
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CHAPTER 1: Introduction to Radiobiology
1.3 Meeting the Need for Radiation Protection
By 1915, the British Roentgen Society had adopted a resolution to
protect people from overexposure to X-rays.
This was probably the first organized effort at Radiation Protection.
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CHAPTER 1: Introduction to Radiobiology
1.3 Meeting the Need for Radiation Protection
By 1922, American organizations had adopted the British protection
rules.
Awareness and education grew, and throughout the 1920s and 30s,
more guidelines were developed and various organizations were
formed to address radiation protection in the United States and
overseas.
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CHAPTER 1: Introduction to Radiobiology
1.3 Meeting the Need for Radiation Protection
Radiation protection was primarily a non-governmental function until
the late 1940s.
After World War II, the development of the atomic bomb, and nuclear
reactors caused the federal government to establish policies dealing
with human exposure to radiation.
In 1959, the Federal Radiation Council was established.
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CHAPTER 1: Introduction to Radiobiology
1.3 Meeting the Need for Radiation Protection
The FDR Council was responsible for three things:
1. advising the President of the United States on radiological issues
that affected public health
2. providing guidance to all federal agencies in setting radiation
protection standards
3. working with the States on radiation issues.
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CHAPTER 1: Introduction to Radiobiology
1.3 Meeting the Need for Radiation Protection
In 1970, Congress created the Environmental Protection Agency
(EPA) and radiation protection became a part of EPA's responsibility.
Today, EPA's Radiation Protection Division (RPD) is responsible for
protecting the public's health and the environment from undue
exposure to radiation.
This is accomplished by setting safety standards and guidelines.
Now, organizations that deal with ionizing radiation must meet these
standards to comply with the law.
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CHAPTER 1: Introduction to Radiobiology
1.3 Meeting the Need for Radiation Protection
The Radiation Protection Program is responsible for other protection
activities too.
For example, there is a team of experts that respond to emergencies
involving radioactivity.
There is also a laboratory that monitors the environment to determine
how much radiation is in the air.
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CHAPTER 1: Introduction to Radiobiology
1.3 Meeting the Need for Radiation Protection
In Malaysia, there is MARPA (Malaysian Radiation Protection
Association/Persatuan Perlindungan Sinaran Malaysia) – is a non-
governmental organization that was established on 15 September
2002.
Visit http://www.marpa.org.my/ for more info.
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CHAPTER 1: Introduction to Radiobiology
1.3 Meeting the Need for Radiation Protection
It represents a pool of professionals of highest skill in radiation
protection and safety.
MARPA can be considered a national asset and a resource for experts
and specialists in radiation protection and safety.
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CHAPTER 1: Introduction to Radiobiology
1.4 Ionization
Ionizing radiation is produced by unstable atoms. Unstable atoms
differ from stable atoms because they have an excess of energy or
mass or both.
Unstable atoms are said to be radioactive. In order to reach stability,
these atoms give off, or emit, the excess energy or mass. These
emissions are called radiation.
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CHAPTER 1: Introduction to Radiobiology
1.5 Types or Products of Ionizing Radiation
1. Alpha particles
2. Beta particles
3. Gamma rays (or photons)
4. X-Rays (or photons)
5. Neutrons
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CHAPTER 1: Introduction to Radiobiology
1.5 Types or Products of Ionizing Radiation
or X-rayneutron
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CHAPTER 1: Introduction to Radiobiology
Alpha Particles: 2 neutrons and 2 protons
They travel short distances, have large mass
Only a hazard when inhaled
1.5 Types of Ionizing Radiation:Alpha Particles
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CHAPTER 1: Introduction to Radiobiology
1.5 Types of Ionizing Radiation:Beta Particles
Beta Particles: Electrons or positrons having small mass and variable
energy. Electrons form when a neutron transforms into a proton
and/or an electron.
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CHAPTER 1: Introduction to Radiobiology
1.5 Types of Ionizing Radiation:Gamma Rays
Gamma Rays (or photons): Result when the nucleus releases
energy, usually after an alpha, beta or positron transition.
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CHAPTER 1: Introduction to Radiobiology
1.5 Types of Ionizing Radiation:X-rays
X-Rays: Occur whenever an inner shell orbital electron is removed and
rearrangement of the atomic electrons results with the release of the
elements characteristic X-Ray energy.
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CHAPTER 1: Introduction to Radiobiology
1.5 Types of Ionizing Radiation:Neutrons
Neutrons are usually produced when a nuclear transformation is induced (that
is, is made to happen, rather than through occurring naturally), for example by
taking an atomic nucleus and firing another nuclear particle at it, or when
radioactive fission occurs (the breaking up of a large unstable nucleus into two
roughly equal nuclei, each around half the size of the original and with the
liberation of considerable amounts of energy) .
Most neutron sources occur in the laboratory (or nuclear reactor) under special
conditions
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CHAPTER 1: Introduction to Radiobiology
Nuclear fission is fundamental to the operation of many types of nuclear
reactor. During the fission process, large amount of energy are released from
the nucleus that undergoes fission, and this energy can be used to provide
electrical power by heating water.
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CHAPTER 1: Introduction to Radiobiology
1.6 References
Bushong, S.C. (2008). Radiologic science for technologist. 9th ed. Mosby
Elsevier