The document discusses sources and effects of ionizing radiation. It provides data on background radiation levels from natural and man-made sources around the world. Radon gas contributes 42% of natural background radiation. Exposure to ionizing radiation can result in both stochastic effects like cancer where risk increases with dose, as well as deterministic effects like skin burns above a threshold dose where severity increases with higher doses. Both acute and long term radiation exposure effects in humans are examined.

1. PRESENTATIONTAGLINE
Presented by
AHMED YAMANI
M.Sc (Physics).,B.Ed.,DRP.,RSO

3. Radon gas
42%
terrestrial Radiation
18%
cosmic Radiation
14%
Internal Radiation
11%
Man made Radiation
15%
Natural background Radiation
Worldwide average of effective dose from background natural
radiation is about 2.4 mSv/year

4. USA
0.40 (0.88)
Guarapari,Brazil
5.5 (35)
Kerala,India
3.8 (35)
Ramsar,Iran
10.2 (260)
Yangjiang,China
3.51 (5.4)
Japan
0.43 (1.26)
China
0.54(3.0)
India
0.48 (9.6)
Ireland
0.36 (1.58)
Italy
0.50 (4.38)France
0.6 (2.2)
Germany
0.48 (3.8)
Denmark
0.33 (0.45)
Norway
0.63 (10.5)
World Avg. : 0.50 mGy/year
* Avg.(Max.)
Units: mGy/year

5. Radon is a colorless, odorless, radioactive gas. It
forms naturally from the decay (breaking down) of
radioactive elements, such as uranium, which are
found in different amounts in soil and rock
throughout the world. Radon gas in the soil and
rock can move into the air and into underground
water and surface water

7. Cosmic rays are a form of high-energy radiation,
mainly originating outside the Solar System and
even from distant galaxies. Upon impact with the
Earth's atmosphere

11. 11
Type of Radiation WR
beta 1
alpha 20
X Rays 1
gamma rays 1
neutrons <10 keV 5
neutrons (10 keV – 100 keV) 10
neutrons (100 keV – 2 MeV) 20
neutrons (2 meV – 20 MeV) 10
neutrons >2 MeV 5

17. Radiation Protection in Radiotherapy Part 3, lecture 1: Radiation protection 17
Genetic Risks
 Ionizing radiation is known to cause
heritable mutations in many plants and
animals
BUT
 intensive studies of 70,000 offspring of the
atomic bomb survivors have failed to
identify an increase in congenital
anomalies, cancer, chromosome
aberrations in circulating lymphocytes or
mutational blood protein changes.
Neel et al. Am. J. Hum. Genet. 1990, 46:1053-1072

19. Radiation Protection in Radiotherapy Part 3, lecture 1: Radiation protection 19
RADIATION EFFECT ON
CELLULAR LEVEL
Ionizing radiation
interacts at the
cellular level:
• ionization
• chemical changes
• biological effect
cell
nucleus
chromosomes
incident
radiation

21. Stage Process
Duration
Physical Energy absorption, ionization
10-15 s
Physico-chemical Interaction of ions with molecules,
10-6 s formation of free radicals
Chemical Interaction of free radicals with
seconds molecules, cells and DNA
Biological Cell death, change in genetic data
tens of minutes in cell, mutations
to tens of years

29. Dose to the tumor determines probability of cure (or
likelihood of palliation)
Dose to normal structures determines probability of
side effects and complications
Dose to patient, staff and visitors determines risk of
radiation detriment to these groups
Low dose:
Stochastic
effects
High dose:
Deterministic
effects

30.  Three basic types:
1) Stochastic : probability of effect
related to dose, down to zero (?) dose
2) Deterministic : threshold for effect -
below, no effect; above, certainty,
and severity increases with dose
3) Hereditary: (genetic) - assumed
stochastic incidence, however,
manifests itself in future generations

31.  Due to cell changes (DNA) and
proliferation towards a
malignant disease
 Severity (example cancer)
independent of the dose
 No dose threshold - applicable
also to very small doses
 Probability of effect increases
with dose
dose
Probability
of effect

32.  Due to cell killing
 Have a dose
threshold - typically
severalGy
 Specific to particular
tissues
 Severity of harm is
dose dependentdose
Severity of
effect
threshold

33. Coal mining 1 in 7,000
Oil and gas extraction 1 in 8,000
Construction 1 in 16,000
Radiation work (1.5 mSv/y) 1 in 17,000
Metal manufacture 1 in 34,000
All manufacture 1 in 90,000
Chemical production 1 in 100,000
All services 1 in 220,000
STOCHASTIC EFFECT

34. STOCHASTIC EFFECT

35. DETERMINISTIC EFFECT

36. DETERMINISTIC EFFECT
Radiation injury from an industrial sourceSkin damage from prolonged
fluoroscopic exposure

37. Early Observations of the
Effects of Ionizing Radiation
 1895 X Rays discovered by Roentgen
 1896 First skin burns reported
 1896 First use of X Rays in the treatment of cancer
 1896 Becquerel: Discovery of radioactivity
 1897 First cases of skin damage reported
 1902 First report of X Ray induced cancer
 1911 First report of leukaemia in humans and lung
cancer from occupational exposure
 1911 94 cases of tumour reported in Germany
(50 being radiologists)

38. Monument to radiation pioneers who
died due to their exposures

39. DETERMINISTIC EFFECT

40. DETERMINISTIC EFFECT

41. DETERMINISTIC EFFECT