ionizing and non ionizing radiation

1. Radiation
Dr . Ehab Hegazy

2. Radiation
Nonionizing
Ultraviolet, visible, infrared, microwaves, radio & TV, power transmission
Ionizing
Radiation capable for producing ions when interacting with matter – x-rays, alpha,
beta, gamma, cosmic rays

3. Electromagnetic Spectrum
10-14
10-12
10-10
10-8
10-6
10-4
10-2
1 102
104
106
108
Wavelength in Meters
1010
108
106
104
102
1 10-2
10-4
10-6
10-8
10-10
10-12
10-14
Broadcast
Short wave
TV
FM
Radar
Infrared
Near Far
Visible
Ultraviolet
X Rays
Gamma Rays
Cosmic Rays Power
Transmission
Ionizing Radiation Nonionizing Radiation
Energy - Electron VoltsHigh Low

4. Nonionizing Radiation
Sources
• Ultraviolet light
• Visible light
• Infrared radiation
• Microwaves
• Radio & TV
• Power transmission

5. Ultraviolet - Sources
• Sun light
Most harmful UV is absorbed by the
atmosphere

6. Biological effect of UV
• High ultraviolet
kills bacterial and other infectious agents
sun burn – increased risk of skin cancer
• Pigmentation that results in suntan
Suntan lotions contain chemicals that absorb UV radiation ( e.g Vitocare sun
protection )
• Reaction in the skin to produce Vitamin D that
prevents rickets.
disease of childhood, characterized by softening of the bones as a result of inadequate intake of vitamin and
insufficient exposure to sunlight, also associated with impaired calcium and phosphorus metabolism

7. Infrared Radiation (IR)
• The energy of heat
• Can damage – cornea, iris, retina and lens of the eye

8. Microwaves & Radio Waves
• Wave length between 0.1 cm to 1 kilometer
• Varity of industrial and home uses for heating
and information transfer (radio, TV, mobile
phones)
• Health effects – heating, cataracts

9. Microwave heating
 Many molecules (such as those of water) are electric
dipoles, meaning that they have a partial positive charge at
one end and a partial negative charge at the other, and
therefore rotate as they try to align themselves with the
alternating electric field of the microwaves.
 Rotating molecules hit other molecules and put them into
motion, thus dispersing energy. This energy, when
dispersed as molecular vibration in solids and liquids

10. Ionizing Radiation
Ionization Defined
Radiation capable for producing ions when interacting
with matter – in other words enough energy to remove
an electron from an atom.
Sources
x-rays, radioactive material produce alpha, beta, and
gamma radiation, cosmic rays from the sun and space.

11. Radioactive Material
• Either natural or created in nuclear reactor or accelerator
• Radioactive material is unstable and emits energy in order to return to
a more stable state (particles or gamma-rays)
• Half-life – time for radioactive material to decay by one-half

14. Ionizing Radiation
Paper Wood Concrete
Alpha
Beta
Gamma
Energy
Low
Medium
High

15. Alpha Particles
• Two neutrons and two protons
• Charge of +2
• Emitted from nucleus of radioactive atoms
• Transfer energy in very short distances (10 cm in air)
• Shielded by paper or layer of skin
• Primary hazard from internal exposure
• Alpha emitters can accumulate in tissue (bone, kidney,
liver, lung, spleen) causing local damage

16. Beta Particles
• Small electrically charged particles similar to electrons
• Charge of -1
• Ejected from nuclei of radioactive atoms
• Emitted with various kinetic energies
• Shielded by wood, body penetration 0.2 to 1.3 cm depending
on energy
• Can cause skin burns or be an internal hazard of ingested

18. • Beta particles are electrons or positrons (electrons with positive electric
charge, or antielectrons).
• Beta decay occurs when, in a nucleus with too many protons or too many
neutrons, one of the protons or neutrons is transformed into the other.
• In beta minus decay, a neutron decays into a proton, an electron, and an
antineutrino
• In beta plus decay, a proton decays into a neutron, a positron, and a
neutrino:

19. Electron capture
one of the orbital electrons, usually from the K or L electron
shell (K-electron capture, also K-capture, or L-electron
capture, L-capture), is captured by a proton in the nucleus,
forming a neutron and an electron neutrino.

20. Gamma-rays
• Electromagnetic photons or radiation (identical to x-rays
except for source)
• Emitted from nucleus of radioactive atoms – spontaneous
emission
• Emitted with kinetic energy related to radioactive source
• Highly penetrating – extensive shielding required
• Serious external radiation hazard

24. Since the proton is changed to a neutron in electron capture,
the number of neutrons increases by 1, the number of
protons decreases by 1, and the atomic mass number remains
unchanged. By changing the number of protons, electron
capture transforms the nuclide into a new element. The atom,
although still neutral in charge, now exists in an
energetically excited state with the inner shell missing an
electron. While transiting to the ground state, the atom will
emit an X-ray photon (a type of electromagnetic radiation)
and/or Auger electrons. Often the nucleus exists in an excited
state as well, and emits a gamma ray in order to reach the
ground state energy of the new nuclide just formed.

26. PET
• Positron emission tomography (PET) is a test that uses a special type of camera
and a tracer (radioactive chemical) to look at organs in the body. The tracer usually
is a special form of a substance (such as glucose) that collects in cells that are using
a lot of energy, such as cancer cells.
• During the test, the tracer liquid is put into a vein (intravenous, or IV) in your arm.
The tracer moves through your body, where much of it collects in the specific
organ or tissue. The tracer gives off tiny positively charged particles (positrons).
The camera records the positrons and turns the recording into pictures on a
computer.
• PET scan pictures do not show as much detail as computed tomography (CT)
scans or magnetic resonance imaging (MRI) because the pictures show only the
location of the tracer. The PET picture may be matched with those from a CT scan
to get more detailed information about where the tracer is located.
• A PET scan is often used to evaluate cancer, check blood flow, or see how organs
are working.

28. X-rays
• Overlap with gamma-rays
• Electromagnetic photons or radiation
• Produced from orbiting electrons or free electrons – usually machine
produced
• Produced when electrons strike a target material inside and x-ray
tube
• Emitted with various energies & wavelengths

29. Ionizing Radiation Health Effects
We evolved with a certain level of naturally occurring
ionizing radiation from cosmic radiation, radioactive
materials in the earth.
We have mechanisms to repair damage.

30. Dose Response Tissue
Examples of tissue Sensitivity
Very High White blood cells (bone marrow)
Intestinal epithelium
Reproductive cells
High Optic lens epithelium
Esophageal epithelium
Mucous membranes
Medium Brain – Glial cells
Lung, kidney, liver, thyroid,
pancreatic epithelium
Low Mature red blood cells
Muscle cells
Mature bone and cartilage

31.  Time
Reduce the spent near the source of radiation.
 Distance
Increase the distance from the source of radiation.
 Shielding
Place shielding material between you and the source of
radiation.
Reducing Exposure

32. Biological Effects of Radiation
•Somatic
–Affects cells originally
exposed (cancer)
–Affects blood, tissues,
organs, possibly entire
body
–Effects range from slight
skin reddening to death
(acute radiation
poisoning)
•Genetic
–Affects cells of future
generations
–Keep levels as low as
possible (wear lead)
–Reproductive cells most
sensitive
32

33. 33
Units of Measurement
• Effect of ionizing radiation is determined by:
– Energy of radiation
– Material irradiated
– Length of exposure
– Type of effect
– Delay before effect seen
– Ability of body to repair itself

34. 34
Radiation Units of Measurement
Roentgen (R) - expression of exposure to x-
rays/gamma rays
Radiation Adsorbed Dose (rad) – amt of energy released to
/ absorbed by matter when radiation comes into contact
with it
Radiation Equivalent Man (rem) - Injury from
radiation (depends on amt of energy imparted to matter)

35. 35
Permissible exposure radiation doses
Body Part
Exposed
Permissible Dose
(rem per quarter)
Whole body 1.25
Hands, forearms, feet,
ankles
18.75

36. 36
Purple and yellow
Radiation Symbol

37. 37
Basic Safety Factors
• Keep exposures As Low As Reasonably
Achievable (ALARA)
– Time - Keep exposure times to a minimum
– Distance - Inverse square law: by doubling distance
from a source, exposure is dec by a factor of 4
– Shielding – wear lead, use lead wall