The document discusses the history of radiation protection, including early pioneers who discovered radiation hazards and effects. It describes some key events like the establishment of the ICRP and AERB, and definitions of key radiation terms. It also outlines the biological effects of radiation exposure, distinguishing between deterministic and stochastic effects. The three principles of radiation protection - justification, optimization and dose limitation - are explained.

1. RADIATION PROTECTION, ITS HAZARDS
& AERB GUIDELINES
PRESENTED BY
DR BHASKAR JYOTI SAIKIA
MODERATORS:
PROF DR R.K.GOGOI
PROF & HOD DR M.H.BHUYAN

2. Introduction
 Scientists were quick to realize the benefits of X-rays, but
slower to comprehend the harmful effects of radiation.
 The first recorded biologic effect of radiation was seen by
Becquerel, who developed erythema and subsequently
ulceration when radium container was left accidentally in
his left pocket.
 Elihu Thomson demonstrated that x ray causes erythema
and blisters in 1897

3.  Thomas Edison’s assistant, Clarence Dally, who had
worked extensively with X-rays, died of skin cancer in
1904, it was the first death attributed to radiation effect
 William Herbert Rollins developed leaded tube housings,
collimators , and other techniques to limit patient dose
during 1896-1904.
- Also demonstrated that exposure of a pregnant guinea pig
resulted in killing of the fetus
- He was a true pioneer of x-ray protection

4.  Rome Vernon Wagner, an x-ray tube manufacturer, had
begun to carry a photographic plate in his pocket and to
develop the plate each evening to determine if he had
been exposed (1907)
 Pioneer for personal monitoring
 Died of cancer in 1908
 Film badge came into effect from 1920

5.  The first tolerance dose or permissible exposure limit
was equivalent to about 0.2 rem per day.
 Rolf Sievert also put forth a tolerance dose- 10% of
the skin erythema dose
 Hermann Muller demonstrated the genetic effects of
radiation(1926)
 2nd International congress of radiation in 1928 set up
the International X-ray and radium protection
committee

6. EARLY CHRONOLGY OF RADIATION
PROTECTION
 Pioneer Era (1895-1905)- in which recognition of the
gross somatic hazard occurred, and relatively simple
means were devised to cope.
 Dormant Era (1905-1925)- little overt progress was
made, but in which great gains were made in
technical and biological knowledge which were later
applied to protection.
 Era of Progress (1925-1945), which saw the
development of radiation protection as a science

7. Atomic Age
 International X-ray and radium protection committee
was remodeled into The International Commission on
Radio logical Protection (ICRP) and The
International Commission on Radiation Units and
Measurements (ICRU)
 The International Commission on Radiological
Protection (ICRP) was the primary body created to
advance for the public benefit, the science of
radiological protection
 It is a registered charity, independent non-
governmental organization

8.  It provides recommendations and guidance on
protection against the risks associated with ionizing
radiation, from artificial sources widely used in
medicine, general industry and nuclear enterprises,
and from naturally occurring sources
 The first report Publication 1 (ICRP, 1959)---
>Publication 26(ICRP, 1977)--->Publication
60(ICRP, 1991b, international Basic Safety
Standards)--->Latest is Publication 103(ICRP,
2007)

9. OTHER GOVERNING BODIES
 IAEA (International Atomic Energy Agency) establishes
standards of safety and provides for the application of the
standards
 National commission on radiation protection
and measurement(NCRP) is recommendation
body of USA
 In India regulatory and recommendation authority is
Atomic Energy Regulatory Board (AERB)

10. Atomic Energy Regulatory Board(AERB)
 Was constituted in 1983 by government
of India
 Carries out certain regulatory and
safety functions under the Atomic
Energy Act,1962 and Environment Protection Act, 1986,
Radiation Protection Rules 2004
 It is the recommendation, research and licensing body in India

11. TERMINOLOGIES OF RADIATION PROTECTION

12.  Amount of radioactivity material expressed as the
nuclear transformation rate
 Conventional unit: curie
 SI unit: Bequerel
 1 curie = 3.7 x 1010 Bq
ACTIVITY

13. EXPOSURE
 Amount of ionization per mass of air due to x rays
and gamma rays
 The ICRU defines exposure (x) as quotient of dQ by
dm where dQ is the absolute value of total charge of
ions of one sign produced in air when all the
electrons liberated by photons in air of mass, dm are
completely stopped in air.
 X= dQ/dm
 Conventional units: Roentgen®
 SI unit: c/kg
 1R=2.58 x 10-4 c/kg

14. ROENTGEN
 The roentgen (R) is
defined as unit of
exposure that will
liberate a charge of 2.58
x 10-4 C/kg of air.
 1R=1 electrostatic
unit(esu)/cm3 air at
standard temp and
pressure(STP)

15. ABSORBED DOSE
 Deposition of energy in patient by
radiation exposure
 Independent of composition of
irradiated material and energy of
beam
 RAD: unit of absorbed dose
 GRAY: SI unit of absorbed dose
 Gray defined as the quantity of
radiation that results in an energy
deposition of 1 joule per kilogram.
 I GRAY = 100 RAD
 1RAD = 1 cGY

16. DOSE EQUIVALENT
 It is a measure of biological effectiveness of radiation
 REM: unit of absorbed dose equivalent
 SI unit : SIEVERT
 1 sievert = 100 rems
 H=D x Q (D is absorbed dose)
(Q is quality factor for radiation )
(H is absorbed dose equivalent)
 Rem = rads x quality factor

17. Quality factor
 It is the parameter used to describe the quality of beam.
 Gives the amount of energy deposited per unit length travel.
Expressed in KEV per micron.
Type of radiation Q factor
X rays 1
Gamma rays 1
Beta particle 1
Electrons 1
Thermal neutrons 5
Other neutrons 20
Protons 20
Alpha particle 20

18. EFFECTIVE DOSE EQUIVALENT
 Purpose – to relate exposure to risk
 It is calculated by multiplying the dose equivalent
received by each individual organ or tissue (DT) by
an appropriate tissue weighting factor (WT) and
summing for all the tissues involved.

19. obtain the
EFFECTIVE DOSE
to the pt in msv
sum of all the organs and tissues irradiated
multiply by the
TISSUE WEIGHING FACTORWt
for the tissue or organ concerned
EQUIVALENT DOSE
to the organ in msv
multiply by the
RADIATION WEIGHING FACTOR Wr
OR QUALITY FACTOR
for the radiation used
for each organ and tissue estimate the
ABSORBED DOSE
in mgy

20. EFFECTIVE DOSE EQUIVALENT
LIMITS
 NRCP recommendation on exposure limits of radiation workers are based
on following criteria.
a) At low radiation levels the nonstochastic effects are esentially avoided.
b) The predicted risk factor for stochastic effects should not be greater than
the average risk of accidental death among workers in safe industries.
c) Safe industries are defined as those having an associated annual fatality
accident rate of 1 or less per 10,000 workers.
d) The ALARA principle should be followed for which the risks are kept as
low as reasonable achievable.

21. RADIATION SOURSES
21
 NATURAL BACKGROUND RADIATION
- cosmic rays
External - gamma rays from rocks & soil
- ingested radioisotopes in certain foods
Internal - inhaled radon decay products (granite )
 ARTIFICIAL BACKGROUND RADIATION
- fallout from nuclear explosions
- radioactive waste
 MEDICAL AND DENTAL DIAGNOSTIC RADIATION
 OCCUPATIONAL EXPOSURE

22. 6 November 2016 Dr Saad Wahby Al Bayatti 22

23. RADIATION HAZARDS
23

24. 24
Nuclerar boms
nueclear reactors leaks
Whole body
radiation
Medical
(diagnostic &theraputic)
Dental
X- rays
Specific area
radiation
Radiation exposure

25. SPECIFIC VERSUS WHOLE-BODY RADIATION
25

26. 26
Indirect Direct
Somatic
Affects individual
No effect on offspring
Genetic
Do not affect individuial
Offspring is affected
Radiation damage

27. Radiation
 DNA /RNA molecule nuclear acid
breakdown
 Nuclear acid breakdown
Somatic cells radiation induced malignancy
Genetic cells radiation induced congenital
abnormality
27
DIRECT DAMAGE

28.  H 2 O H
+
+ OH
-
 H
+
+ H
+
H2
 OH
-
+ OH
-
H 2 O 2
28
Radiation
INDIRECT DAMAGE
WATER HYDROLYSIS

29.  H2O2 + DNA Molecular
breakdown
 H2O2 + Proteins
 Molecular breakdown Cell damage
29

30. 30
Direct
DNA/RNAhit
Radiationinducedmalignancy
Indirect
H2O2formation
TOXIC
breakdownoflargemolecules(protiens/DNA)
Somatic
Radiationdamage

31. 31
Direct
DNA/RNAhit
Radiationinducedcongenital
abnormality
Indirect
H2O2formation
TOXIC
breakdownlargemolecules(proteins/DNA)
Genetic
Radiationdamage

32. 32

33. 33

34. Radiation health effects
CELL DEATH BOTH
TYPE
OF
EFFECTS
CELL TRANSFORMATION

35. Radiation health effects
DETERMINISTIC
Somatic
Clinically
attributable in
the exposed
individual
CELL DEATH
STOCHASTIC
somatic &
hereditary
epidemiologically
attributable in
large populations
ANTENATAL
somatic and
hereditary
expressed in
the foetus, in
the live born or
descendants
BOTH
TYPE
OF
EFFECTS
CELL TRANSFORMATION

36. The Biological Effects Of Radiation
 Prompt personal effects
 Delayed personal effects
 Racial effects

37. PROMPT PERSONAL EFFECTS
On receiving very large doses
Occurs within few hours or days
Symptoms associated are
erythema,vomiting.diarrhoea
A single dose of 500 rad could result in death

38. DELAYED PERSONAL EFFECTS
 Chronic low dose irradiation over a considerable period of time
or few exposures giving a high dose
 Clinical Features
 Scaling ,warty growth on hands
 Skin cancer
 Thyroid cancer
 Cataract formation
 Bone marrow compromise leading to fatal anaemia and
leukaemia
 Premature ageing
 Growth and development of fetus and young children

39. • Deterministic
(Threshold/non-stochastic)
• Existence of a dose threshold
value (below this dose, the effect
is not observable)
• Severity of the effect increases
with dose
• A large number of cells are
involved
Radiation injury from an industrial source
Deterministic effects

40. • Cataracts of the lens of the eye 2-10 Gy
• Permanent sterility
• males 3.5-6 Gy
• females 2.5-6 Gy
• Temporary sterility
• males 0.15 Gy
• females 0.6 Gy
dose
Severity of
effect
threshold
Threshold Doses for Deterministic Effects

41. Stochastic Effects
 Stochastic(Non-Threshold)
 No threshold
 Probability of the effect increases with dose
 Generally occurs with a single cell
 e.g. Cancer, genetic effects

42. RADIATION EFFECTS
DETERMINISTIC EFFECT
 Mechanism is cell killing
 Has a threshold dose
 Deterministic in nature
 Severity increases with dose
 Occurs only at high doses
 Can be completely avoided
 Causal relationship between
radiation exposure and the
effect
 Sure to occur at an adequate
dose
STOCHASTIC EFFECT
Mechanism is cell modification
Has no threshold
Probabilistic in nature
Probability increases with dose
Occurs at even at low doses
Cannot be completely avoided
Causal relationship cannot be
established at low doses
Occurs only among a small
percentage of those exposed

43. RADIATION EFFECTS
DETERMINISTIC EFFECT
 Radiation Sickness
 Radiation syndromes
 Haematopoietic syndrome
 GI syndrome
 CNS syndrome
 Damage to individual organs
 Death
 Late damage
STOCHASTIC EFFECT
 Chromosomal damage
 Cancer Induction
(Several years after
exposure to radiation)
 Genetic Effects
(Hereditary in future
generations only)
 Somatic Mutations

44. CHAIN OF EVENTS FOLLOWING EXPOSURE TO IONIZING
RADIATION
CELL DEATH
DETERMINISTIC EFFECTS
CELLULAR TRANSFORMATION
MAY BE SOME REPAIR
STOCHASTIC EFFECTS
CELLULAR LEVEL
SUBCELLULAR DAMAGE
(MEMBRANES, NUCLEI, CHROMOSOMES)
molecular changes
(DNA,RNA, ENZYMES)
free radicals
(chemical changes)
ionisation
exposure

45. Radiosensitivity [RS]
 RS = Probability of a cell,
tissue or organ of suffering
an effect per unit of dose.

46. RS laws (Law of Bergonie & Tribondeau)
Radiosensitivity of living tissues varies with maturation
& metabolism;
 Stem cells are radiosensitive. More mature cells are
more resistant
 Younger tissues are more radiosensitive
 Tissues with high metabolic activity are highly
radiosensitive
 High proliferation and growth rate, high
radiosensitivty

47. Radiosensitivity
Muscle
Bones
Nervous
system
Skin
Mesoderm
organs (liver,
heart, lungs…)
Bone Marrow
Spleen
Thymus
Lymphatic
nodes
Gonads
Eye lens
Lymphocytes
(exception to the RS laws)
Low RSMedium RSHigh RS

48. Factors Affecting Radiosensitvity
 Dose: the amount of
radiation received. The
higher the dose, the greater
is the effect (consider the
threshold)
 Dose rate: the rate of
exposure.
e.g. a total dose of 5Gy can
be given as
- 5Gy/min (single dose) is
more destructive
- 5mGy/min(fractionized),
less destructive, injured cells
can recover
 Oxygen: the higher the O2
level in irradiated cells, the
greater is the damage.
(H2O2 formation)
 Linear Energy Transfer
(LET): the rate of loss of
energy from a particle as it
moves in its track through
matter (tissue)
e.g. alpha particles vs. X-ray
48

49. RADIATION PROTECTION

50. DEFINITION
 International Atomic Energy Agency (IAEA) as "The
protection of people from harmful effects of exposure
to ionizing radiation and the means for achieving
this".
 The IAEA also states "The accepted understanding of
the term radiation protection is restricted to protection
of people”

51. Three Principles Of Radiation Protection
 JUSTIFICATION: Any decision that alters the radiation
exposure situation should do more good than harm.
 OPTIMISATION: The likelihood of incurring exposure, the
number of people exposed, and the magnitude of their
individual doses should all be kept as low as reasonably
achievable, taking into account economic and societal factor.
 DOSE LIMITATION: The total dose to any individual from
regulated sources in planned exposure situations other than
medical exposure of patients should not exceed the
appropriate limits specified by the Commission

52. JUSTIFICATION
 A practice involving exposure to radiation should produce
sufficient benefit to the exposed individual or to society
 In the case of patients, the diagnostic or therapeutic benefit
should outweigh the risk of detriment
 In the occupational exposure, the radiation risk must be
added and compared with other risks in the workplace
 In cases in which the individual receives no benefit, the
benefit to society must outweigh the risks

53. OPTIMISATION
 The principle of optimisation is to keep the likelihood
of incurring exposures, the number of people exposed,
and the magnitude of individual doses as low as
reasonably achievable
 Optimisation is always aimed at achieving the best
level of protection under the prevailing circumstances
through an ongoing, iterative process that involves:
 evaluation of the exposure situation, including any
potential exposures (the framing of the process);

54. OPTIMISATION
 selection of an appropriate value for the constraint or
reference level;
 identification of the possible protection options;
 selection of the best option under the prevailing
circumstances; and
 implementation of the selected option.

55. ALARA
 As low as reasonable achievable
 In USA, ALARA has cash value of about 1,000$ per
10 mSv
 If the exposure of one person can be avoided by this
amount of money, it is considered reasonable
 At higher dose levels, additional exposure may
threatened worker's job by exceeding the lifetime
dose limit, here reasonable cost is 10,000$

56. DOSE LIMITATIONS
 In the 1930s, the concept of a tolerance dose was
used, a dose to which workers could be exposed
continuously without any evident deleterious acute
effects such as erythema of skin
 Early 1950s , emphasis shifted to late effects and
maximum permissible dose was designed to ensure
that probability of injury is so low that the risk
would be easily acceptable to the average person
 This was based on geneticist H.J Muller work who
had indicated that the reproductive cells were
vulnerable to even smallest doses of radiation

57. Permissible Dose
 The concept of tolerance dose indicated that there
was a level of radiation below which it was safe.
 The concept of stochastic effects of radiation
invalidated this dogma
 Most scientists rejected that there was a threshold
dose below which exposure to radiation was harmless
 The concept of permissible dose therefore introduced

58. Maximum Permissible Dose
 “There is no safe level of exposure and there is no
dose of radiation so low that the risk of a malignancy
is zero” — Dr. Karl Z. Morgan, father of Health
Physics
 Maximum Permissible dose (MPD) is defined as that
dose which in the light of present knowledge is not
expected to cause appreciable bodily injury to the
person at any point during his lifetime

59. Maximum Permissible Dose
 Advantages
- explicit acknowledgment that doses below
MPD have a risk of detrimental effects
- acknowledged danger due to stochastic
effects of radiation
- introduced the concept of acceptable risk-
probability of the radiation induced injury was to be
kept low to be easily acceptable to individual

60. Recommendations on exposure limits
 At low radiation levels non stochastic effects are
essentially avoided
 The predicted risk for stochastic effects should not be
greater than the average risk accidental death among
workers in “safe industries”
 As low as reasonably achievable principle should be
followed
( “safe” industries are defined as “those having an
associated annual fatality accident rate of 1 or less
per 10,000 workers i.e. Average annual risk is 10-4)

61. General recommendations on Dose Limitations
 The first general Recommendations were issued in
1928 and concerned the protection of the medical
profession through the restriction of working hours
with medical sources
 This corresponds to an individual dose of about 1000
millisievert (mSv) per year
 1956 Recommendations limits on weekly and
accumulated doses were set that corresponded to
annual dose limits of 50 mSv for workers and 5 mSv
for the public

62.  All the standard dose limitations are made for
“reference man”
 Reference man is defined as being 20-30 yrs of age,
weighing 73 kg, is 170 cm in height, lives in a
climate with an average temperature of 10 to 20oC,
he is Caucasian and is western European or north
American in habitat and custom
 Most countries have changed the concept of
reference man – e.g Indian reference man
 Enables base line calculations of organ doses

63. General guidelines on Dose limitations
 Individual doses due to combination of exposures from all
relevant practices should not exceed specified dose limits for
occupational or public exposure
 Different dose limits are specified for the radiation workers as
the expected benefit from the work they do while they do
while handling radiation will outweigh the small increase in
risk
 Pregnant radiation workers have to be protected so that the
fetus/embryo is given the same radiation protection as given to
public
 Dose limits are not applicable for medical exposure as the
benefits gained outweighs the harm
 Does not include natural background or radiation for medical
purposes

64.  LIMITS FOR OCCUPATIONAL EXPOSURE
 STOCHASTIC EFFECTS
1. No occupational exposure should be permitted until the
age of 18 years
2. The effective dose in any year should not exceed 50mSv(5
rem)
3. The individual worker's lifetime effective dose should not
exceed age in years Х 10mSv

65. PROTECTION OF THE EMBRYO/ FETUS
1. NCRP recommends 0.5 mSv to the embryo/ fetus once the
pregnancy is declared
2. ICRP recommends a limit of 2 mSv to the surface of
woman's abdomen for the remainder of her pregnancy
3 There is a provision that a declared pregnancy can later be
“undeclared” if the female worker so desires

66.  EMERGENCY OCCUPATIONAL EXPOSURE
 If possible, older workers with low life time accumulated
effective doses should be chosen among the volunteers
 If exposure do not involve saving life should be avoided
 If for lifesaving the exposure may approach 0.5 Sv to a large
portion of the body, the worker needs to understand potential
for acute effects, but also substantial increase lifetime risk of
cancer

67. EXPOSURE OF PUBLIC
 For continuous or frequent exposure, the annual effective dose
should not exceed 1 mSv
 Maximum permissible annual equivalent dose is 5 mSv for
infrequent dose

69. METHODS OF RADIATION
PROTECTION
Exposure
time
distance
Lead
barriers

70. Exposure time
 Exposure is the amount of light per unit area (the image
plane luminance times the exposure time) reaching a
photographic film or electronic image sensor, as
determined by shutter speed, lens aperture and scene
luminance
 Exposure is measured in lux seconds, and can be
computed from exposure value (EV) and scene luminance
in a specified region
 Total dose equivalent x time

71. DISTANCE
- Inverse square law applies.
- whenever possible , distance should be
2 meter from x-ray tube.
-Distance 1 m - 400 (exposure)
-Distance 2 m - 100

72. LEAD BARRIERS
- efficient absorber of x rays.
- great reduction of exposure by
placing it in between source and
person
- thickness stated in HALF VALUE
LAYER (HVL) for kilo voltage x
rays.
(HVL – any material thickness which
reduces exposure rate by one –half.)

73. HVL (HALF VALUE LAYER)
 Half-Value Layer . The thickness of any given material
where 50% of the incident energy has been attenuated is
know as the half-value layer (HVL).
 The HVL is expressed in units of distance (mm or cm).
Like the attenuation coefficient, it is photon energy
dependent. Increasing the penetrating energy of a stream
of photons will result in an increase in a material's HVL.

74. Protective barriers in radiation and fluoroscopy
 tube must enclosed in metal housing that reduces leakage
radiation ( is radiation which penetrates the protective
housing )

75. Wall protection
• Useful beam ( radiation pass through
aperture)
• Leakage radiation
• Scattered radiation (radiation undergoes
change in direction through its path)
• Stray radiations (scattered + leakage radiation)
4 types of radiations

76. PROTECTIVE BARRIER
PRIMARY
• In radiography up to 140 kV about 1/16
inch lead extending 7 feet up from the
floor when tube is 5-7 f.t from the wall.
• protects from useful beam(mainly).
SECONDARY
• is about 1/32 inch lead.
• - extends from the top of the 1ry barrier to
ceiling.
• - ordinary plaster often suffice as a 2ry
barrier without added lead.

77.  Lead apron – worn in fluoroscopy room.
- Pb equivalent 0.5 mm.
 Check lead protective apron periodically for cracks by
means of a radiography test.

78. DOSE REDUCTION
 BEAM FILTRATION:
- exposure greatly reduced by ALUMINIUM filter.
- removes lower energy photons.
- recommendations:-
operating kVp Minimum HVL Al
(mm)
< 50 0.3
50-70 1.2
> 70 2.3

79. COLLIMATION
(BEAM LIMITATION)
decrease in cross sectional area of the beam avoids
unnecessary exposure of tissues outside the area of
interest.
- also reduces amount of scattered radiation.
- modern equipment have automatic variable beam
limiting device with manual override.

80. GONADAL’THYROID SHIELDING
beam should be so restricted that direct exposure of
gonads does not occur.
- thyroid ,testes shield must have lead equivalent 0.5
mm.
- ovaries should be shielded whenever possible.

81. MODIFIED SHIELDING
In radiography of girls for scoliosis should be use PA view.
- Reduces breast dose at least 98 % without loss of
radiographic quality.

82.  HIGH KILOVOLTAGE :-
- high kVp with low mAs delivers smaller absorbed
dose to the patient.
 CAREFUL TECHNIQUE :-
- to minimize repeat examination.
 Radiographic examination in fertile women preferably
performed during 1st 10 days following onset of
menstrual period.
 Ovulation and pregnancy are much less apt during this
time than later menstrual cycle

83. PROTECTION IN MAMOGRAPHY
 Skillful technique minimizes breast dose.
 Goal achieved by molybdenum targets and filters in
mammographic tubes.
 Low dose screens and films, with/ without grid having
ratios of 3:1 or 4:1.
 Efficient breast compression device :- reduces breast
thickness and make more uniform.

84.  ADVANTAGES
1. decreases exposure factors with reduction of dose.
2. diminished amount of scattered radiation thereby
improving contrast.
3. improved recorded details by bringing breast closer to the
image receptor.

85. CT SCANNING
 Dose in CT scanning , by measuring absorbed dose at the
center of one “slice” with small dosimeter in water phantom.
 Scanning this slice and 3 adjoining slices on both side.
 Dosimeter record dose from direct beam through the center
slice, as well as scattered radiation from adjoining slices.
 Collimator should also be checked periodically to assure its
proper function.

86. PATIENT PROTECTION IN FLUORORSCOPY
 Intermittent fluoroscopy – decreases exposure and prolong
tube life.
 Restriction of field size – must be limited by suitably lead
shutters placed between tube and patient.
 Correct operating factors – exposure decreases as kVp
increases and mA is lowered.
 Recommended factors are 90-100 kVp, 2-3 mA and 2.0 mm
aluminium filter

87.  The source-skin distance must be at least 15 inch with
stationary and 12 inch with mobile fluoroscopic
equipment.
 Filtration :-
– increase in hardness of x ray beam by filter.
– Filter removed relatively more soft than hard x-
rays.

88. PROTECTON IN NUCLEAR MEDICINE
 Medical compounds containing radionuclide's are called
radiopharmaceuticals.
 Types of radiation
– alpha particles
– beta particles
– gamma rays
 radiopharmaceuticals emits beta and gamma rays

89.  Gamma rays are electromagnetic wave and have much
greater penetrability than beta particle.
 Beta particles consist of high-speed electrons.
 Beta particles are much less penetrating ,their effect
limited to the skin (external source) immediate
vicinity(internal source).

90. AERB GUIDELINES

91. Step- by-step guidelines for submission of layout
plan in diagnostic radiology facility
 1) Decide a suitable room for housing an X-ray unit to
facilitate the easy movement of staff and patient positioning.
 2) Room should have preferably one entrance door and
window if present, should be above 2m from the finished floor
level outside the x-ray room.
 3) Door should have a hydraulic mechanism to ensure that
door is closed during procedure and should be provided with
overlapping at the joints to avoid streaming.
 4) Identify the walls as Wall A, Wall B, Wall C & Wall D (in
any sequence)

92.  5) Position the location of the equipment for each modality as
follows:
 a) Radiography and Fluoroscopy equipment:
 Couch, Control console and chest stand placed in such a way that
chest stand is on the opposite wall of the entrance door and the
control console.
 Mobile protective barrier with lead equivalent glass viewing
window should be positioned in such a manner that the operator
is completely shielded during the exposure.
 Control console should be positioned as far away as possible
from the x-ray tube.

93. b) Computed Tomography and Interventional radiology
equipment: Gantry / C-Arm, Couch, Separate control
console room, viewing window, - Position the gantry
and couch such that the patient is completely visible
from the control console, during the scanning - The
entrance door to the gantry room from the control
console shall have similar requirements as the patient
entrance door.
c) Mammography/ OPG/ CBCT: Control console,
Equipment and Protective barrier Positioning of
equipment should be as far as possible from the door
and the control console.

94.  6) Decide on the material and thickness of walls and
door by referring to equipment specific table.
 7) Measure the distances of all the walls, doors,
windows from the centre of the couch
 8) Note that the required shielding of any material
shall be provided at least up to the height of 2m from
external finished floor of x-ray room

95. Dose Limits by AERB
 The limits on effective dose apply to the sum of effective
doses from external as well as internal sources. The limits
exclude the exposures due to natural background radiation and
medical exposures.
 Calendar year shall be used for all prescribed dose limits

96. Occupational exposures
1. An effective dose of 20 mSv/yr averaged over five consecutive years
(calculated on a sliding scale of five years);
2. An effective dose of 30 mSv in any year;
3. An equivalent dose to the lens of the eye of 150 mSv in a year;
4. An equivalent dose to the extremities (hands and feet) of 500 mSv in a year
and
5. An equivalent dose to the skin of 500 mSv in a year;
6. Limits given above apply to female workers also. However, once pregnancy is
declared the equivalent dose limit to embryo/fetus shall be 1 mSv for the
remainder of the pregnancy.

97. Apprentices and Trainees
The occupational exposure of apprentices and trainees between 16 and 18
years of age shall be so controlled that the following limits are not
exceeded:
1. An effective dose of 6 mSv in a year;
2. An equivalent dose to the lens of the eye of 50 mSv in a year;
3. An equivalent dose to the extremities (hands and feet) of 150 mSv
in a year and
4. An equivalent dose to the skin of 150 mSv in a year.

98. Dose Limits for Members of the Public
1. An effective dose of 1 mSv in a year;
2. An equivalent dose to the lens of the eye of 15 mSv in a year; and
3. An equivalent dose to the skin of 50 mSv in a year.

99. Conclusion
 The dosimetric quantity relevant to radiation protection is the dose
equivalent.
 Harmful effects of ionizing radiation are classified as stochastic and
non stochastic.
 Effective dose equivalent limits for occupational and general
population has been recommended by the regulatory board of that
country
 The values quoted for radiation workers are such that the hazards
that the doses represent to health is small compared with ordinary
hazards of life
 A radiation worker is far more likely to be involved in a motor car
accident an to suffer from ill effects of radiation,even if receiving
the MPD.

100. THANK YOU !!!