Radiation Protection Course For Orthopedic Specialists Lecture 2 of 4 Radiation Hazards

1. Radiation Protection Course For
Orthopedic Specialists
Lecture 2 of 4
Radiation Hazards
Prof Amin E AAmin
Dean of the Higher Institute of Optics Technology
&
Prof of Medical Physics
Radiation Oncology Department
Faculty of Medicine, Ain Shams University

2. Dr Rome Wagner
and assistant

3. Thomas Edison

4. Testing X-ray Sets
The Early Days

5. X-Ray Early Days

6. First Reports of Injury
Late 1896
Elihu Thomson - burn from deliberate
exposure of finger
Edison’s assistant - hair fell out &
scalp became inflamed & ulcerated

7. Elihu Thomson
• In 1896, Thomson deliberately
exposed the little finger of his
left hand to an x-ray tube for
several days, half an hour per
day. The resultant effects —
pain, swelling, stiffness,
erythema and blistering — were
convincing for Thomson and
others, but not for all.

8. Clarence Dally
• Clarence Dally (1865-
1904), assistant to
industrialist Thomas Alva
Edison. The first
recognized American X
ray fatality.

9. Edmund Kells
• April 1896 built own X-ray
machine, packed films in rubber
and took X-ray of his dental
assistant
• 10 years on, cancer of right
hand
• 42 operations in next 20 years –
lost hand, arm and shoulder.

10. Hazards of X-Ray:
Disagreement
• 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

11. Mihran Kassabian (1870-1910)

12. What harm can X-rays do?

13. Neils Ryberg Finsen
• Neils Ryberg Finsen
1893 On the influence
of light on the skin
showed UV caused
sunburn and not radiant
heat. (1903 Nobel Prize
for UV treatment of
lupus vulgaris)

14. How does radiation cause
harm?
• LD(50/30) = 4 Gy
 280 J to 70 kg man
 1 milli-Celsius rise in body temp.
 drinking 6 ml of warm tea
• i.e. not caused by heating, but ionisation
• Damages DNA.

15. air
medium
(tissue)
exposure
C/kg102.58R1
(mass)
(charge)
4-
=


=
m
Q
X
kerma
rad100J/kg1Gy1
(mass)
ansferred)(energy trtr
==


=
m
E
K
Physical Dose
Radiation Dosimetry

16. Exposure
Exposure - the quantity that expresses the
ionisation produced in a volume element in
air by X-rays or gamma radiation
The SI unit of exposure is coulomb per
kilogram (C.kq-1)

17. The Roentgen
• Unit of exposure
• X = d Q/d m
• d Q is the absolute value of the total charge of the ions of one sign
produced in air when all the electrons liberated by photons in air of mass
dm are completely stopped in air
• 1 R = 2.58 x 10 -4 C/kg air

18. Kerma
• Kerma is defined as
dEtris the sum of the initial kinetic energies of all
charged ionizing particles liberated by uncharged
ionizing particles in a material of mass dm
The SI unit of kerma is the (J.kg-1), termed gray
(Gy)
dm
dE
K tr
=

19. Absorbed Dose
❖Energy imparted by ionising radiation to the matter
• Dd - Absorbed dose
• de - the mean energy imparted in a volume element
• dm - the mass of the volume element
❖The unit in SI - joule per kilogram - (J.kg-2) - gray
(Gy)
dm
d
Dd
e
=

20. Organ Dose
❖The average absorbed dose in an organ or tissue -
DT
▪ eT - the total energy imparted in a tissue or organ
▪ mT - the mass of that tissue or organ
❖The unit in SI of the organ dose is J.kg-1, termed
the gray (Gy)
D
m
T
T
T
=
e

21. Units of radiation dose
• Gray (Gy) is the SI unit of absorbed dose.
• One gray is equal to an absorbed dose of 1 Joule/kilogram
(100 rads).

22. Units of radiation dose
• Rad is the special unit of absorbed dose.
• One rad is equal to an absorbed dose of 100
ergs/gram or 0.01 joule/kilogram (0.01 gray).

23. Dose Equivalent
• Dose is a physical quantity
• We need a quantity to express stochastic radiation damage
• Dose equivalent (HT) is the quantity
• Traditional Units: rem
• SI Unit: sievert (Sv)

24. Dose Equivalent (HT)
• Dose equivalent is the quantity that expresses stochastic
radiation damage by relating the physical dose absorbed (D) to
the LET through the use of a radiation quality factor wR.

25. Equivalent Dose HT,R
A quantity derived from the organ dose-DT,R (the absorbed
dose averaged over a tissue or organ):
wR- the radiation weighting factor
When the radiation field is composed of various types or
energies of radiation:
The unit of equivalent dose is J.kg-1, termed the sievert (Sv)
H w DT R R T R, ,.=
H w DT
R
R T R=  . ,

26. Radiation Weighting Factor - wR
❖ wR- modifying factor based on the type and quality of the
radiation (affecting externally or internally) used for
radiation protection purposes to account for the relative
effectiveness of different types of radiation in inducing
health effects
❖ The reference radiation is 250 kVp x-rays.

27. Radiation Weighting Factor - 2
Type of radiation and energy range Radiation
weighting
factor
Photons, all energies 1
Electrons, all energies 1
Alpha particles 20
Protons, energy >2 MeV 5
Neutrons: energy <10 keV 5
Neutrons: energy 10 to 100 keV 10
Neutrons. Energy: >100 keV to 2MeV 20
Neutrons, energy: >2MeV to 20MeV 10
Neutrons, energy: > 20MeV 5

28. Units of dose equivalent
• Sievert is the SI unit of any of the quantities expressed as dose
equivalent.
• The dose equivalent in sieverts is equal to the absorbed dose in
grays multiplied by the quality factor (1 Sv=100 rems).

29. Units of dose equivalent
• Rem is the special unit of any of the quantities expressed as
dose equivalent.
• The dose equivalent in rems is equal to the absorbed dose in
rads multiplied by the quality factor (1 rem=0.01 sievert).

30. Effective Dose - E
The sum of the equivalent doses in all the tissues of the
body multiplied by the tissue weighting factors
wT- tissue weighting factor
The unit of effective dose is J.kg-1, termed the sievert
(Sv)
  ==
T T R
RTRTTT DwwHwE ,...

31. Effective Dose (E = wT H)
• If a patient undergoes a specific organ imaging nuclear medicine
procedure, how do we assess the risk?
• Situation: We measure the dose (physical quantity) to the
patient (0.25 Gy). We know the radiation weighting factor for
gamma radiation (I-131)
• Problem: A limited body-region of the patient is exposed. What
does “risk” mean when a “single” tissue is irradiated?
• Resolution: The “Effective dose” (E) assesses risk by
modifying the dose equivalent using a tissue weighting factor wT
provided in ICRP - 60.

32. Tissue Weighting Factor - 1
❖Multipliers used for radiation protection purposes to account for
the different sensitivities of the organs and tissues to the
induction of stochastic effects of radiation.
❖The relationship between the probability of the stochastic effect
and equivalent dose varies with the tissue irradiated. The
weighted tissue equivalent dose would produce the same degree
of the health detriment irrespective of the tissue involved.
❖The sum of the tissue weighting factors is equal to 1.

33. Tissue Weighting Factor - 2
Tissue or Organ Tissue weighing factor - wT
Gonads 0.20
Bone marrow – red 0.12
Colon 0.12
Lung 0.12
Stomach 0.12
Bladder 0.05
Breast 0.05
Liver 0.05
Oesophagus 0.05
Thyroid 0.05
Skin 0.01
Bone surface 0.01
Remainder 0.05

34. Summary of Radiation Quantities
Quantity Traditional SI Unit
Exposure Dose Roentgen (R) C/kg (air)
Absorbed Dose rad Gray (Gy)
Dose Equivalent (H) rem Sievert (Sv)
Effective Dose (E) rem sievert
Relationships
1 C/kg = 3881 R (air)
1 Gy = 100 rad
1 Sv = 100 rem

35. Prefixes
• The following prefixes are used to indicate decimal fractions:
• milli 10-3 or one thousandth
• micro 10-6 or one millionth
• nano 10-9 or one billionth
• pico 10-12 or one trillionth
• femto 10-15 or one millionth of a billionth
• atto 10-18 or one billionth of a billionth

36. First Medical Findings of
Radiation Hazards
• First skin-burn attributed
to radiation - 1901
• First radiation induced
leukemia described -1911
• First publication
describing “a clinical
syndrome due to atomic
bomb” - 1946

38. Summary of Biological
Effects

39. Radiation Causes Ionizations of:
ATOMS
which may affect
MOLECULES
which may affect
CELLS
which may affect
TISSUES
which may affect
ORGANS
which may affect
THE WHOLE BODY

40. X-ray passes straight
through cell

No change to cell
X-ray causes a
chemical reaction in
cell, but no damage
done or damage
repaired by cell

No change to cell
DNA damaged in a
“fatal” way”

Cell killed
DNA damaged,
causing cell to

Cancer?
*
*
*

41. Ionizing Radiation Effects
Absorption of Radiation
Ionization
Chemical Change
Repair or Damage
High Dose Effects
Cell killing
Tissue or organ effects
Whole body effects
Low Dose Effects
Mutations
Cancer
Effects to unborn

42. Ionising Radiation Can Cause
Chemical Reactions In The
Body’s Cells Which May
• do no harm
• kill the cell
• cause the cell to multiply out of control
(cancer)
• cause the cell to malfunction in some other way

43. DNA Damage And Its
Consequences
DNA
Damage
No
Repair
Mis-
RepairRepair

44. DNA damage and its
consequences
DNA Damage
Mis-RepairNo RepairRepair
Mutation
Cancer
Chromosom
AbberationCell Death

45. Radiation Action
❖When radiation is incident upon a biological system, it is
important to realize that the incident radiation may;
➢pass through the system without producing any damage, or
➢be totally or partially absorbed within the system resulting in
some degree of damage

46. Radiation Molecular Effects
In the 1920’s researchers found that biological effects from
radiation were due mostly to two different processes. These
processes are called direct and indirect effects

47. How Does Ionizing Radiation
Damage DNA?

48. Interactions of photons with
matter
• Coherent scattering (coh)
• Photoelectric effect ()
• Compton effect (c)
• Pair production ()
• Photo-disintegration (>10 MeV)
nXX A
Z
A
Z
1
0
1
+→+ −


49. Coherent Scattering
• Classical scattering or Rayleigh
scattering
– No energy is changed into electronic
motion
– No energy is absorbed in the medium
– The only effect is the scattering of the
photon at small angles.
• In high Z materials and with photons
of low energy
K
L
M



50. Photoelectric effect
• A photon interacts with an
atom and ejects one of the
orbital electrons.
• Probability of photoelectric
proportional with Z3/E3

51. Compton effect
The effect: Arthur
Compton in 1922
saw that the  of x
rays increases on
scatterings

52. • High energy photons, greater than 1.02 MeV.
Pair production process

53. Photo-Disintegration

54. TYPES OF RADIATION
DAMAGE

55. Somatic And Genetic Effects
• The effects of radiation on the human
population can be classified as either somatic or
genetic:
❖Somatic effects.
❖Genetic or hereditary effects

56. Somatic Effects
• Somatic effects are harm that exposed individuals suffer during
their lifetime, such as radiation induced cancers
(carcinogenesis), sterility, opacification of the eye lens and life
shortening.

57. Genetic Or Hereditary Effects
• Genetic or hereditary effects are radiation induced mutations to
an individual’s genes and DNA that can contribute to the birth
of defective descendants.

58. SPECIFIC EFFECTS OF RADIATION
Ionizing radiation causes two types of effects;
❖ Deterministic (Non-stochastic) effects of radiation: Those
are the effects that occur only above a threshold dose.
Once the threshold is exceeded, the severity of the effect
increases with dose.
❖ Stochastic effects of radiation: Those are the effects that
have a certain probability of occurring, and the probability
increases as the radiation dose increase. The stochastic
effects don’t need a threshold to occur.

59. Stochastic
effects of
radiation
Non-stochastic
effects of
radiation

60. Deterministic Health Effects

61. Deterministic Effect
• A deterministic effect (tissue reaction) is one that increases in
severity with increasing dose, usually above a threshold dose,
in affected individuals (organ dysfunction, fibrosis, lens
opacification, blood changes and decrease in sperm count).
These are events caused by damage to populations of cells,
hence the presence of a threshold dose.

62. DETERMINISTIC (NON-STOCHASTIC)
RADIATION EFFECTS I
Deterministic effects result from
the killing of cells which, if the
dose is large enough, causes
sufficient cell loss to impair the
function of the tissue. i.e.
exposure to high doses of
radiation can damage large
number of cells which produce
deterministic effects .
Severity
Radiation Dose
Threshold

63. Deterministic Health Effects
• A radiation effect for which
generally a threshold level of
dose exists above which the
severity of the effect is greater
for a higher dose
– many cells die or have function
altered
– occurs when the dose is above
given threshold (characteristic
for the given effect)
– severity increases with the dose
Acute dose
Probability
> ~1000 mSv
100%

64. Deterministic (Non-stochastic)
Radiation Effects
Some of these effects occur quite quickly - within days or
weeks after the exposure. For such effects to occur a
minimum radiation dose - a threshold - has to be exceeded.
Once the threshold is exceeded, the severity of the effect
increases with dose. This means that; the probability of
causing such harm will be zero at small doses (the threshold
for clinical effect) the probability will increase steeply to
unity (100%). Thresholds for these effects are often at doses
of a few Gy or dose rates of a fraction of a Gy per year.

65. Deterministic (Non-stochastic)
Radiation Effects
The most common non-stochastic effects are;
1-Radiation sickness
2-Skin burns
3-Hair loss
4-Sterility
5-Damage to the eye

66. Deterministic Health Effects
Organ or tissue
Dose in less
than 2 days,
Gy
Deterministic effects
Type of effect
Time of
occurrence
Whole body (bone
marrow)
1
Acute Radiation
Syndrome (ARS)
1 – 2 months
Skin 3 Erythema 1 – 3 weeks
Thyroid 5 Hypothyroidism 1st – several years
Lens of the eye 2 Cataract
6 months - several
years
Gonads 3 Permanent sterility weeks

67. Deterministic Health Effects
⚫ Chernobyl experience:
⚫ Acute Radiation Syndrome and Radiation burns

68. Skin injuries
• Radiation effects on the
skin can appear several
weeks after the
irradiation and can be
progressive
• After one coronary
angioplasty and stent
procedure

69. SKIN INJURIES AFTER A SINGLE
IRRADIATION
EFFECT Threshold (Gy) Onset
Temporary epilation 3 3 wk
Permament epilation 7 3 wk
Transient erythema 2 hours
Main erythema 6 10 days
Dry desquamation 10 4 wk
Dermal necrosis 18 >10 wk

70. Radiation Injuries
From Interventional Procedures
Skin injuries

71. Radiation Injuries
From Interventional Procedures
Skin injuries

72. Radiation Injuries
From Interventional Procedures
• Skin injuries (after several PTCA’s) (T. Shope,
Radiographics 1996; 16: 1195-99)

73. Hair Loss
• Hair loss is another non-stochastic radiation
effect which may occur after a dose to the
scalp of 3Sv or more.
• Recovery takes place in the months following
the exposure unless the hair follicles have
been exposed to high doses.

74. Sterility
• A dose to the tests as low as 0.1 Sv can depress
sperm production for up to a year. 2.5 Sv will produce
sterility for three years or longer.
• The ovary is not as sensitive to radiation as the testes,
but doses of 1 to 2 Sv will cause temporary sterility.

75. Damage To The Eye
• Radiation to the lens of the eye can cause cataract.
• The threshold radiation dose for production of detectable
damage to the lens is between 0.5 to 2 Sv, and for
production of visual impairment is about 5 Sv.

76. Damage To The Eye
Lens opacities can be produced if doses of 100 mSv/year
are received during several years

77. Radiation Injuries
from Interventional Procedures
Cataract in eye of
interventionalist after repeated
use of old x ray systems and
improper working conditions
related to high levels of scattered
radiation. (E. Vano et al British
Journal of Radiology 1998).

78. Dose Splitting
(Fractionation)
The threshold doses given here are for single
acute exposure to radiation. In general the body is
more able to tolerate a given dose of radiation
when the radiation dose is split (fractionated) into
smaller doses and delivered over longer period of
time.

79. Deterministic (Non-stochastic)
Effects In Children
Radiation dose of less than 0.1 Sv may cause
mental and growth retardation in children. The
younger children were more susceptible to these
effects than the older ones.

80. Deterministic Effects On The
Unborn Children I
Non-stochastic effects may occur on the unborn child if
the mother is exposed to radiation. Radiation doses higher
than 1Sv delivered during the period of 2 to 9 weeks of
pregnancy may produce congenital abnormalities and
sometimes death. Much lower doses can cause mental
retardation. The highest risk is between 8 and 15 weeks
after conception.

81. Deterministiceffects On The
Unborn Children II
Radiation exposure during that critical period
causes a downward shift in the distribution of
IQ. The probability of occurrence of mental
retardation is about 40% per Sv. The probability
of severe mental retardation increases with dose.
The effect is presumed to be deterministic with a
threshold related to the minimum shift in the IQ
that can be recognised.

82. Deterministic Effects to Fetus
Age Minimal dose (Gy) for:
(weeks) Lethality Gross malformation Mental retardation
0-1 No threshold at day 1? No threshold at day 1?
0.1 thereafter No effects observed to
2-5 0.25 - 0.5 0.2 about 8 weeks
5-7 0.5 0.5
7-21 > 0.5 Very few observed Weeks 8-15: no
threshold?
Weeks 16-25: threshold
dose 0.6 - 0.7 Gy
To term > 1.0 Very few observed Weeks 25-term: no effects
observed

83. Tissue Reactions
(Deterministic effects)
Very large doses only
The bigger the dose, the more severe the effect
5000
3500
3000
2500
2000
500 500
150
0
1000
2000
3000
4000
5000
6000
Cataracts
Perm.male
sterility
Temp.
epilation
Female
sterility
Transient
erythema
Detectable
opacities
(lens)
Supressionof
bonemarrow
Temp.male
sterility
milli-sieverts
Staff doses never this big

84. Stochastic Effect
• A stochastic effect is one in which the probability of
occurrence increases with increasing dose but the
severity in affected individuals does not depend on the
dose (induction of cancer, radiation carcinogenesis and
genetic effects).
• There is no threshold dose for effects that are truly
stochastic, because these effects arise in single cells and
it is assumed that there is always some small probability
of the event occurring even at very small doses.

85. Stochastic Effects
• Caused by cell mutation leading to cancer or
hereditary disease
• Current theory says, no threshold
• The bigger the dose, the more likely effect
• So how big is the risk?.

86. Stochastic Effects Of
Radiation
Low doses of radiation may affect only a few
cells, perhaps just one cell usually produce
stochastic effects. Stochastic effects may result
when an irradiated cell is modified rather than
killed. These effects appear after an interval of
years or even decades. There is no threshold for
a stochastic effect, and the probability of the
effect occurring increases steadily as the dose
increases.

87. Stochastic Health Effects
•A radiation-induced health effect, occurring without a
threshold level of dose:
•probability is proportional to the dose
•severity is independent of the dose
•Stochastic health effects:
•Radiation-induced cancers
•Hereditary effects
•Late appearance (years)
•Latency period:
•Several years for cancer
•Hundreds of years for hereditary effects

88. Stochastic Effects Of
Radiation
The Stochastic effects of radiation are;
❖ Production of cancer,
❖ Genetic effects and
❖ Effect on life span.
Radiation Dose
Risk

89. Stochastic Effects to Fetus
Procedure Average fetal
dose
Hereditary
disease
Fatal childhood
cancer
Chest < 0.01 mGy 1 in 4 million 1 in 3 million
Abdomen X-ray 1.4 mGy 1 in 30,000 1 in 24,000
Lumbar spine x-ray 1.7 mGy 1 in 24,000 1 in 20,000
Pelvic X-ray 1.1mGy 1 in 38,000 1 in 30,000
CT Abdomen 8.0 mGy 1 in 5,000 1 in 4,000
CT Pelvis 25 mGy 1 in 1,700 1 in 1,300
Tc-99m bone scan 3.3 mGy 1 in 13,000 1 in 10,000
Natural risk 1 in 50 1 in 1,300

90. Radiation Induced Cancer I
The production of cancer is the most important stochastic
effect of radiation. Modified somatic cells may
subsequently, after a prolonged delay, develop into a
cancer. There are repair and defence mechanisms that
make this a very improbable outcome. The probability of
cancer resulting from radiation increases with increments
of dose, probably with no threshold. The severity of the
cancer is not affected by the dose.

91. Radiation Induced Cancer II
❖The unborn child in the womb is more
susceptible to radiation-induced cancer.
❖Children under the age of ten are more
susceptible to radiation-induced cancer than
adults.

92. Nominal Risk Of Fatal Cancer
Cases per million per
m Sv
Tissue at riskEffect
FemaleMale
3
5
2
1
0.5
1
3
3
-
2
1
0.5
1
3
Red bone marrow
Female breast
Lung
Thyroid
Cells on bone
surface
Liver
All other tissues
Leukaemia
Breast cancer
Lung cancer
Thyroid cancer
Bone sarcoma
Liver cancers
Other cancers
15.510.5Whole bodyTotal

93. Cancer Risk
• For adult worker, average risk of inducing fatal cancer is 4%
per Sv
• i.e. risk from 0.1 mSv
= 0.04 x 0.0001
= 0.000004
= 1 in 250,000

94. Genetic Or Hereditary Effects
• Genetic or hereditary effects are radiation induced mutations to
an individual’s genes and DNA that can contribute to the birth
of defective descendants.

95. Genetic Effects (Hereditary
Effects)
The hereditary effects of radiation result from damage to
a cell whose function is to transmit genetic information
to later generation (reproductive cells). This damage
takes the form of genetic mutations in the hereditary
material of the cell. These effects may be of different
kinds and severity. The risk of serious hereditary illhealth
within the first two generations following the irradiation
of either parent is about 10 per million per mSv.

96. Effect On Life Span
There have been some suggestions that exposure
to ionizing radiation accelerates the process of
aging and accordingly reduce the life span.

97. Hormesis
• Some data indicate that low doses of
radiation are beneficial
• Not widely accepted
• Conservative is better
• But not impossible
Dose
DetrimentBenificial
Risk

98. Hormetic Effects Of Radiation
In contrast to the radiation hazards there have been some
claims that exposure to low levels of ionising radiation
might be beneficial. Effects of this kind are often referred
to as hormetic effects. Possible hormetic effects are:
1) An increased life span.
2) A reduction in cancer frequency.
3) Increased growth and fertility.

99. In Fact A Little Bit Of Radiation
‘May’ Be Good For You
• the physiological benefits of a low dose of IR have
been demonstrated in plants and animals
• benefits include
❖life lengthening
❖Growth
❖more offspring

100. Radiation Effects on Embryonic
Development And Foetal Life

101. Classical Triad Of Effects Of
Radiation On The Embryo
• Growth retardation
• Embryonic, fetal or neonatal death
• Congenital malformation

102. Factors Affecting Radiation Induced
Abnormalities On The Embryo
• Radiation dose
• Dose-rate
• Type of cell population irradiated
• Stage of gestation

103. Embryonic And Fetal Risks

104. Pre Implantation Stage
❖Stage
➢From time of fertilization to morula implantation in post. Uterine wall.
❖Duration
➢8 – 10 days.
❖Radiosensitivity
➢Embryonic cells have high rates of cell division and cell differentiation.
➢ It is composed of relatively few cells.
➢It has very high radiosensitivity.
➢The probability of death is very high.

105. Radiation Hazards During Pre
Implantation Stage
❖Cell death
❖Cell injury to morula leading to preventing further division and
accordingly abortion.
❖Severe malformations leading to incomplete life, then abortion.

106. Effects Of Radiation According To
Gestational Stage
Organogenesis: 7-13 weeks
– Embryo sensitive to lethal, teratogenic and growth-retarding
effects because of the criticality of cellular activities and the high
proportion of radiosensitive cells.
–IUGR, gross congenital malformations, microcephaly and mental
retardation are the predominant effects for doses > 50 rads
–There is no report of external irradiation inducing morphologic
malformation in humans unless the individual also had growth
retardation or a CNS anomaly

107. Radiation Hazards During
Implantation & Organogenesis Stage
❖Cell Death but with lower incidence.
❖Higher incidence of malformation.
❖Higher incidence of congenital malformations especially organs
formed during this stage, mainly;
➢Brain, spinal cord, n cells and sensation organs (ear, nose and eye).
➢Skeleton especially pelvic and thoracic cage malformations.
➢Muscular system.

108. Foetal Growth Stage
❖Stage
➢From end of organogenesis to birth.
❖Duration
➢180-200 days (6 months).

109. Radiation Effects On The Fetus
• Radiation effects during the period of foetal growth can be
categorized into three main parts.
Foetal Growth
period
1st Part
4-5 M
2nd Part
6-7 M
3rt Part
8-9 M

110. Radiation Effects On The Fetus
• Radiation effects during the 1st part of the period of foetal
growth (4th and 5th months) are similar to the effect during the
organogenesis period.

111. Radiation Effects On The Fetus
• Radiation effects during the 2nd part the period
of foetal growth (6th and 7th months) are;
– Mental retardation
– Diminution IQ
– Microcephaly
– Abnormal behaviour
– Cancer Induction

112. Radiation Effects On The Fetus
• Radiation effects during the 3rd part the period of foetal growth
(8th and 9th months) are similar to the effect on neonatal and
infancy life (1st 6 months).