3. INTRODUCTION
n When ionizing radiations , such as X-Rays and
Gamma rays, interact with living tissue, it is the
absorption of radiation energy in the tissues
which causes damage.
n All ionizing radiation is harmful ! This is the
premise that mandates a radiation protection
policy.
C-Slide 3
4. RADIOBIOLOGY
n Radiation biology is the branch of biology
concerned with the effects of ionising radiation
on living systems.
n The biological effects of ionising radiation
originate primarily from damage to the DNA of
a cell or cells.
C-Slide 4
6. Mechanisms of Biological
Damage by Ionizing Radiation
Direct damage to DNA Indirect damage
n • End Result: disruption cell membrane
integrity,cellular chemistry and DNA replication
C-Slide 6
7. Biological Damage by Direct
Mechanisms
DIRECT DAMAGE:
Ionizing event directly interacts with nuclear
DNA can break single or double strands.
• Damage may be (a) irreparable, or may be
(b) incorrectly repaired.
C-Slide 7
8. Biological Damage by Indirect
Mechanisms
INDIRECT DAMAGE:
Ionizing radiation produces free electrons , and
thus ion pairs.
• Ion pairs combine to form reactive chemical
species.
• Reactive chemical species disrupt cell
membrane integrity, cellular chemistry and
DNA replication C-Slide 8
10. 10
Outcomes after cell exposure
DAMAGE
REPAIRED
CELL DEATH
(APOPTOSIS)
TRANSFORMED
CELL
DAMAGE TO DNA
11.
12. 12
CELLULAR RADIOSENSITIVITY
n RS = Probability of a cell,
tissue or organ suffering
an effect per unit of dose.
n Bergonie and Tribondeau
(1906): “RS LAWS”: RS
will be greater if the cell:
• Is highly mitotic.
• Is undifferentiated.
• Has a high cariocinetic
future.
14. Whole Body Sensitivity Factors
Total Dose
Type of Cell
Type of Radiation
Age of Individual
Stage of Cell Division
Part of Body Exposed
General State of Health
Tissue Volume Exposed
Time Interval over which Dose is Received
C-Slide 14
16. 16
• Deterministic(Thresh
old/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
23. Why should we measure radiation?
In order to estimate and compare the biological
damage caused by different radiations.
measure radiation in terms of RADIATION
UNITS
C-Slide 23
24. RADIATION UNITS / DOSIMETRY
radiation in general is measured in terms of
a] the EXPOSURE
b] the ABSORBED DOSE
c] the ABSORBED DOSE EQUIVALENT
d] the EFFECTIVE DOSE.
e] the RADIOACTIVITY C-Slide 24
25. EXPOSURE
n Exposure is the quantity most commonly used
to express the amount of radiation delivered to
a point.
n The term exposure (X) refers to radiation
quantity measured in terms of ionisation in a
small volume of air.
C-Slide 25
27. UNIT FOR EXPOSURE
C-Slide 27
UNIT FOR
EXPOSURE
conventional unit Sl unit
Roentgen (R)
the coulomb per
kilogram of air
(C/kg):
28. THE ROENTGEN(R)
n THE ROENTGEN(R)
n the roentgen (R) is defined as a unit of
radiation exposure that will liberate a charge of
2.58x10-4 coulombs per kilogram of air.
n As a measure of exposure the roentgen is
independent of area or field size.
C-Slide 28
29. roentgen vs the coulomb per kilogram
of air
C-Slide 29
1R = 2.58 x 10-4 c/ kg of air
1 C/kg = 3876 R
30. ABSORBED DOSE (D)
n The term absorbed dose (D)
refers to the amount of energy
absorbed per unit mass of the
substance.
C-Slide 30
31. ABSORBED DOSE
n The absorbed dose is independent of
n a) composition of radiated material.
n b) energy of the beam.
n Absorbed dose ~ degree of attenuation.
C-Slide 31
32. UNIT FOR ABSORBED DOSE
C-Slide 32
ABSORBED DOSE
(D)
Conventional
unit
Sl unit
RAD GRAY
(Gy)
33. RAD vs GRAY
n One RAD is equal to the radiation necessary to
deposit energy of 100 ergs in 1 gram of
irradiated material.(100 erg/ g)
C-Slide 33
34. GRAY
C-Slide 34
n The ‘gray’ is a measure of the
n energy deposited in a material
n by incident ionising radiation.
(1 Gray = 1 Joule of energy
deposited in 1kg of tissue).
35. RAD vs GRAY
n The relationship between Gray and Rad is
C-Slide 35
1 Gy = 100 rads
1 rad = 1cGy
36. ABSORBED DOSE EQIVALENT
n The absorbed dose equivalent is equal to the
absorbed dose multiplied by a quality factor
(QF)
n Quality factor for x ray = 1
absorbed dose equivalent = rads x quality factor
C-Slide 36
absorbed dose equivalent =
absorbed dose x quality factor (QF)
37. UNIT FOR ABSORBED DOSE
EQUIVALENT
C-Slide 37
ABSORBED DOSE
EQUIVALENT
Conventional
unit
Sl unit
REM SEIVERT
(Sv)
38. REM
n Rem is a unit used only in radiation protection.
n Rem is a measure of the biologic effectiveness
of irradiation.
n Quality factor for x ray = 1
Rem = rads x quality factor
n
C-Slide 38
1R = 1 rad = 1 rem
39. rem vs seivert
n The ‘Sievert’ is the unit of dose of most interest
in radiationprotection.
n The relationship between seivert and rem is
C-Slide 39
1 sv =100 rems
41. Effective Dose
. Effective dose is becoming a very useful
radiation quantity for expressing relative
risk to humans, both patients and other
personnel It takes into account the specific
organs and areas of the body that are
exposed.
The point is that all parts of the body and
organs are not equally sensitive to the
possible adverse effects of radiation, such
as cancer induction and mutations. C-Slide 41
42. Effective Dose
n For the purpose of determining effective
dose, the different areas and organs have
been assigned tissue weighting factor (wT)
values. For a specific organ or body area
the effective dose is:
C-Slide 42
n Effective Dose (Gy) = Absorbed Dose (Gy) x wT
43. C-Slide 43
Tissue Weighting Factor
Gonads 0.25
Breast 0.15
Red Bone Marrow 0.12
Lung 0.12
Thyroid 0.03
Bone Surface 0.03
Remainder
0.3 (For the remaining organs a
value of 0.06 is used for each
of the five organs receiving
the highest dose.)
Total Body 1.0
44. EFFECTIVE DOSE
n If the the dose to the breast, MGD, is 300 mrad
for two views, the effective dose is 45 mrad
because the tissue weighting factor for the
breast is 0.15.
What this means is that the radiation received
from one mammography procedure is less than
the typical background exposure for a period of
two months.
C-Slide 44
45. Effective dose equivalent for diagnostic
medical x ray examinations
EXAMINATION EFFECTIVE DOSE EQUIVALENT
(MSV) PER EXAMINATION
CHEST
SKULL
LUMBAR SPINE
UPPER GI
ABDOMEN
BARIUM ENEMA
PELVIS
INTRVENOUS UROGRAM
EXTREMITIES
0.06
0.2
1.3
2.45
0.55
4.05
0.65
1.6
0.01
C-Slide 45
46. AIR KERMA
Air kerma is another radiation quantity that is
sometimes used to express the radiation
concentration delivered to a point, such as the
entrance surface of a patient's body. It is a
quantity that fits into the SI scheme.
n , KERMA, for Kinetic Energy Released per unit
MAss (of air). It is a measure of the amount of
radiation energy, in the unit of joules (J),
actually deposited in or absorbed in a unit
mass (kg) of air. Therefore, the quantity,
kerma, is expressed in the units of J/kg which
is also the radiation unit, the gray (G)
C-Slide 46
47. Mean Glandular Dose (MGD) in the
Breast
The Mean Glandular Dose (MGD) is the special
dose quantity used in mammography.
It is defined as the mean, or average, dose to
the glandular tissue within the breast. The
assumption is that the glandular tissue, and
not the fat, is the tissue at risk from radiation
exposure.
C-Slide 47
49. LINEAR ENERGY TRANSFER
n The amount of energy deposited Per unit
length of travel expressed in kev per micron is
called the linear energy transfer.(LET)
n The amount of biologic damage is determined
by the linear energy transfer of the radiation.
C-Slide 49
50. RELATIVE BIOLOGIC
EFFECTIVENESS [ RBE]
n It is an expression used to compare the
effectiveness of several types of radiation.
n The RBE depends upon the linear energy
transfer (LET) of the radiation in the medium.
n The RBE values of different radiations are
x rays,gamma rays, electrons = 1
thermal neutrons = 5
fast neutrons , protons = 10
heavy particles = 20
C-Slide 50
51. Radiation Units and Conversion Factors
Exposure Conventional
unit
SI Unit conversions
Exposure roentgen (R) coulomb/kg of
air (C/kg)
1 C/kg = 3876 R
1 R = 258
uC/kg
Absorbed Dose rad (R) gray (Gy) 1 Gy = 100 rad
Dose
Equivalent
rem sievert (Sv) 1 Sv = 100 rem
Radioactivity curie (Ci) becquerel (Bq) 1 mCi = 37 mBq
C-Slide 51
55. C-Slide 55
Relationship between radiation dose & sickness
Dose (Gy) Effect / Sickness
0 – 1 Nil (Late effects only)
1 – 2 Radiation sickness + mild haematopoietic
syndrome
2 – 5 More severe haematopoietic syndrome and
Radiation sickness
5 – 20 Severe radiation sickness severe
gastrointestinal syndrome severe
haematopoietic syndrome
Above 20 Above + SNS syndrome
56. CLASS OF EXPOSED
INDIVIDUAL
REMS mSv
Occupational
exposures(annual)
stochastic effects
Nonstochastic effects
lens of eye
All other areas( eg; red
bonemarrow,breast,lung,gonad
s,skin,extremities)
Life time cumulative exposure.
5
15
50
1(x age in years)
50
150
500
10 (x age in years)
Public exposure(annual)
Effective dose equivalent limit
Dose equivalent limits for lens
of eye,skin,extremities
0.5
5
5
50
Trainees under 18 years of age
Effective dose equivalent limit
Dose equivalent limits for lens
of eye,skin,extremities
0.1
5
1
50
Embryo-fetus exposure
Effective dose equivalent limit
Dose equivalent limits in a
month
0.5
0.05
5
0.5
C-Slide 56
58. 58
Relative Dose Received
number of chest x-rays
0 50 100 150 200
Arm, head,ankle & foot (1)
Head & Neck (3)
Head CT (10)
Thoracic Spine (18)
Mammography, Cystography (20)
Pelvis (24)
Abdomen, Hip, Upper & lower femur (28)
Ba Swallow (30)
Obsteric abdomen (34)
Lumbo-sacral area (43)
Cholangiography (52)
Lumber Myelography (60)
Lower abdomen CT male (72)
Upper Abdomen CT (73)
Ba Meal (76)
Angio-head, Angio-peripheral (80)
Urography (87)
Angio-abdominal (120)
Chest CT (136)
Lower Abd. CT fem. (142)
Ba enema (154)
Lymphan. (180)
mSv
.05
0.15
0.49
0.92
1.0
1.22
1.4
1.5
1.7
2.15
2.59
3.0
3.61
3.67
3.8
4.0
4.36
6.0
6.8
7.13
7.69
9.0
Radiation Doses in Radiological Exam.
(as multiple of chest x-ray)
59. 59
Staff Doses
Dose limit ICRP = 20 mSv/yr.
Radiography work 0.1 mS/yr.
i.e. 1/200th of
dose limit
60. 60
Effects of antenatal exposure (1)
n As post-conception time increases RS decreases
n It is not easy to establish a cause-effect relation because
there are a lot of teratogenic agents, effects are
unspecific and not unique to radiation.
n There are 3 kinds of effects: lethality, congenital
anomalies and large delay effects (cancer and hereditary
effects).
Time
%
Pre-implantation Organogenesis Foetus
Lethality
Congenital anomalies
61. 61
Effects of antenatal exposure (2)
n Lethal effects can be induced by relatively small
doses (such as 0.1 Gy) before or immediately after
implantation of the embryo into the uterine wall.
They may also be induced after higher doses
during all the stages during intra-uterine
development.
Time
%
Pre-implantation Organogenesis Foetus
Lethality
0.1 Gy
62. 62
n Mental retardation:
n ICRP establishes that mental retardation can be
induced by radiation (Intelligence Quotient score <
100).
n It occurs during the most RS period: 8-25 week of
pregnancy.
n Risks of antenatal exposure related to mental
retardation are:
Severe mental
retardation with a risk
factor of 0.1/Sv
Severe mental
retardation with a risk
factor of 0.4/Sv
15-25 week
8-15 week
63. 63
Dose Limits (ICRP 60)
Occupational Public
Effective dose 20 mSv/yr averaged* 1 mSv in a yr
over 5 yrs.
Annual equivalent
dose to
n Lens of eye 150 mSv 15 mSv
n Skin 500 mSv 50 mSv
n Hands & Feet 500 mSv
* with further provision that dose in any single yr > 30 mSv
(AERB) and =50 mSv (ICRP)
N.B.: M.P.D. 1931 = 500 mSv, 1947=150 mSv, 1977=50 mSv &
in 1990=20 mSv
65. RADIATION PROTECTION
PRINCIPLES
The system of Radiation
protection proposed by the
International Commission on
Radiological Protection (ICRP)
are based on the following three
core principles given below
C-Slide 65
66. 66
1. Justification of practices
2. Optimization of protection
by keeping exposure as
low as reasonably
achievable[ ALARA]
3. Dose limits for
occupational
67. JUSTIFICATION
n No practice involving radiation shall be
adopted unless its introduction produces a
positive net benefit.
n The benefit of the Radiation exposure should
be greater than the risk of using it whether it
applies to staff, visitor patients.
n A special case where individual justification is
needed is for patients who are (or) might be
pregnant. C-Slide 67
68. DOSE LIMITS
n The radiation dose to individuals shall not
exceed the limits recommended for the
appropriate circumstances by the commission.
n There are legal dose limits for workers and
members of the public, based on ensuring that
no deterministic effects are produced and that
the probability of stochastic effects is
reasonably low.
C-Slide 68
69. ALARA
n All Radiation exposures shall be kept As Low
As Reasonably Achievable, Economic and
social factors being taken into account.
n For members of staff or visitors the effective
dose should be as low as reasonably
practicable as constrained by the working
procedures.
n For a patient, the radiation exposure should be
as low as compatible with providing the
diagnostic information required.
C-Slide 69
70. ALARA: Management
Management commitment is
demonstrated by:
A documented policy statement
Instructions to Workers
Periodic monitoring of personnel
exposures and routine procedures
Providing employees with specific
instruction at the time of
employment
Providing annual refresher
training
Granting adequate authority to the
facility Radiation Safety Officer to
enforce safe operations
C-
Slide
71. METHODS OF PROTECTION
There are three methods used to control
radiation exposure levels
1] distance
2] time
3] shielding
C-Slide 71
72. DISTANCE
n Beam intensity is directly proportional to
inverse square law.
n So distance is important in controlling
radiation.
C-Slide 72
73. TIME
Exposures can be controlled with time in
various ways
A] by limiting the time that the generator is
turned on.
B] by limiting the time that the beam is
directed at a certain area.
C] by limiting the time that the
area is occupied.
C-Slide 73
74. SHIELDING
n Shielding:
n
n The term 'biological shield' refers to a mass of
absorbing material placed around a reactor, or
other radioactive source, to reduce the
radiation to a level safe for humans.
C-Slide 74
75. SHIELDING
It is of two types
PRIMARY BARRIER:
protect from primary radiation (useful
radiation)
SECONDARY BARRIER:
Protect from stray radiation ( a combination of
leakage and scatter radiation.)
C-Slide 75
77. PRIMARY BARRIER REQUIREMENT
n STEP 1:
n Evaluation of exposure per week.
n STEP 2:
Calculate barrier thickness by using half
value layer or table.
C-Slide 77
78. EVALUATION OF EXPOSURE
1] WORKLOAD PER WEEK:
it is the quantity of x rays generated per week
it is given by
tube current x time / week [ mA .min /week]
C-Slide 78
79. 79
Sample Shielding Calculation
n Using a typical x-ray room, we will calculate
the total dose per week at one point
Office
2.5 m
Calculation Point
80. EVALUATION OF EXPOSURE
CONVERSION OF WORKLOAD TO ROENTGEN
since all the recommendations regarding
maximal permissible dose is given in
roentgens
we must convert workload roentgens
usually it is expressed in terms of roentgens
/mA . Min at a distance of 1 m from x ray
source.
C-Slide 80
81. EVALUATION OF EXPOSURE
USE FACTOR:
it is the called as beam direction factor that is
the fraction of time that the beam is directed at
a particular barrier.
U for ceiling is always zero because the beam
is rarely directed at the ceiling.
U for secondary barrier is always 1 because
entire room is exposed to stray radiation.
C-Slide 81
82. EVALUATION OF EXPOSURE
OCCUPANCY FACTOR:
it is expressed as a fraction that represents
the amount of time that the area will be
occupied.
FULL OCCUPANCY- areas that will be
occupied by the same individuals for their full
work day such as offices , laboratories,and
nurses station.
C-Slide 82
83. EVALUATION OF EXPOSURE
PARTIAL OCCUPANCY:[ T= 1/4]
it includes corridors,restroom ,and elevators
using operators.
OCCATIONAL OCCUPANCY: [T= 1/16 ]
it includes waiting rooms, stairways,
unattended elevators.
If is an controlled area ( ie with in the x ray
department ) it is assaigned an occupancy
factor of one.
C-Slide 83
84. EVALUATION OF EXPOSURE
DISTANCE;
exposure changes inversely with the square
of the distance.
C-Slide 84
85. EVALUATION OF EXPOSURE
n Finally effective weekly exposure to any
particular point is given as
_
n E = E W U T x 1/d2
C-Slide 85
87. Calculation barrier thickness
n Two methods are used to calculate the barrier
requirements.
n 1] half value layers [HVL]
n
n 2] precalculated shielding requirement
tables.
C-Slide 87
88. Half value layer (HVL) thickness of lead
and concrete for various x ray energies.
PEAK
KILOVOLTAGE
(kvp)
LEAD
(mm)
CONCRETE
(in.)
50
70
100
125
150
0.05
0.15
0.24
0.27
0.29
0.17
0.33
0.6
0.8
0.88
C-Slide 88
90. Secondary radiation
n By law the maximum permissible
leakage exposure 1 m from a
diagnostic x ray tube is 0.1 R /hour
with the tube operating continously
at its maximum kvp mA .
C-Slide 90
93. PERSONAL MONITERING DEVICES
C-Slide 93
n The most likely condition that will require
personnel monitoring is one where one is likely
to exceed 10% of the applicable annual dose
limit.
n Additional conditions that may require
monitoring individuals, such as:
n Exposure to a dose equal or greater than 100
mrem/hour at a distance of 30 centimeters
n Exposure to absorbed dose of 500 rad/ hour at
a distance of one meter
n Exposure to fluoroscopic x-rays
94. Film batch
n The film badge is the oldest radiation
monitoring device.
C-Slide 94
95. FILM BATCH
n Contains photographic film with two coatings
of emulsion mounted in plastic and then over-
wrapped in light-tight paper.
n The radiation exposure forms a latent image on
the film and after development the
photographic density of the resultant blakening
is measured using desitometer.
n
● Contains 3 small metallic filters- usually Cu,
Cd, and lead, placed in different portions of
case to help distinguish among higher energy
C-Slide 95
96. FILM BATCH
n ● Each metal attenuates photons of different
energy values.
n Two emulsions on the film one fast and the
other slow enables the film to be used to
measure low as well as high level exposure.
C-Slide 96
98. FILM BATCH
n Advantages
1. Provides permanent record of individual
exposure
2. Relatively inexpensive
3. Requires no technical knowledge of user
4. Film can be re-read at later date
C-Slide 98
99. FILM BATCH
n Disadvantages
1. Takes 3-5 weeks for results of previous
month
2. Not very accurate (qualitative vs quantitative)
3. Not very sensitive at low levels (<40 mR)
4. Fair reproducibility
5. Affected by heat, e.g., sunlight; ruined by
washing machine cycle
C-Slide 99
100. Thermolumiscent Dosimeter
TLD’s are the most commonly used personnel
monitoring devices.
n Thermolumiscent dosimeters, referred to as
TLD Badges, are often the preferred method of
monitoring individuals exposed to ionizing
radiation.
n The TLD Badges contain a crystalline powder
of calcium sulphate which, after being
exposed to ionizing radiation gives off light
when heated. The amount of light given off
depends on how much radiation the dosimeter
received.
C-Slide 100
101. Tld badge
n When these crystals are exposed to radiation ,
a portion of the absorbed energy is stored in
the crystal structure of the calcium sulphate in
metastable state.
n This absorbed energy will remain in these state
for longer period of time.
n If the crystal is heated the absorbed energy is
released as visible light.
C-Slide 101
102. n The tld badge has an
1] open window
2] perspex in the middle.
3] aluminium and copper filter in the top
most
C-Slide 102
103. Tld batch
n Advantages
n 1] more sensitive to exposure.
n 2] inexpensive when compared to film batch
n
C-Slide 103
104. Different Types of TLD’s
n Whole Body TLD
Records dose to the whole body
n The dosimeter must be worn chest high on an
unshielded part of the body, preferably where
the dose potential is greatest, e.g collar or lapel
of lab coat.
n Other types of TLD’s include the Wrist TLD,
Ring TLD and Fetal Monitors
C-Slide 104
106. POCKET DOSIMETRY
n POCKET DOSIMETERS: Pocket dosimeters are
useful in those situations in which large
exposures are expected on an infrequent
schedule
C-Slide 106
107. POCKET DOSIMETRY
n Pocket dosimeters use an extremely sensitive
fiber electrometer type voltmeter and a small
volume of air to measure the total amount of
radiation to which the instrument has been
exposed.
n A reading may be made at any time by merely
looking at a source of light through the
eyepiece end of the instrument.
C-Slide 107
108. POCKET DOSIMETRY
n Advantages
1. Reusable
2. Easy to read exposure value
3. Immediate reading of cumulative radiation
exposure
Disadvantages
1. More expensive initially than other devices
2. More fragile than other devices
C-Slide 108
109. RAM Bioassay
n Bioassay is another form of personnel
monitoring.
n Bioassay is required by the State to monitor
occupational intake of radioactive material by
workers likely to receive an intake in excess of
10% of applicable Annual Limit of Intake.
C-Slide 109
111. RAM Bioassay
n Bioassay can be done several ways:
n Counting of thyroid, e.g. Iodine 131
n Analysis of a urine sample for radionuclides,
e.g. H-3
n Whole body counting for isotopes retained in
the body, e.g. Strontium 89 localizes in bone.
C-Slide 111
112. Using Personnel Dosimeters
n The Do’s
Do wear your dosimeter so the sensitive
element of the dosimeter faces the radiation
source being manipulated, e.g. on the inside of
the arm or finger.
n Do request a replacement immediately if a
badge is damaged or contaminated by
radioactivity during the wear period.
n Do, if you are wearing a lead apron, wear the
body dosimeter outside the apron at collar
level, if a second dosimeter has been assigned.
C-Slide 112
114. Using Personnel Dosimeters
n The Don’ts
n Do not leave dosimeters in closed cars or in
the sun or heat.
n Do not subject the dosimeters to wet or
chemical environments.
n Do not take dosimeters home.
C-Slide 114
115. Using Personnel Dosimeters
n Do not intentionally expose the dosimeter to
radiation or leave your dosimeter next to a
source of ionizing radiation.
n Do not lend your dosimeter to another
individual.
n Do not use your dosimeter to monitor personal
medical procedures such as your x-rays.
C-Slide 115
116. PRACTICAL REDUCTION OF DOSE
TO STAFF
n Good work practices will help very much to reduce the
personal exposure, the well known principle of Time, distance
and shield are to be applied by the technicians to minimize
their personal exposure.
n X-ray protection to staff has to be provided against the direct
beam, leakage radiation, and scatter particularly from the
patient.
n Staff working with X-ray equipment should be protected, either
with lead screens or with lead rubber apron and gloves.
n Holding of children or infirm patients for X-Ray examination
should be done only by a adult relative or escort of the patient
and not be a staff member. Such persons should be provide
with protective aprons and gloves.
n Protective flaps to be used in case of fluoroscopy equipment.
n All Radiation workers should use appropriate personnel
monitoring device such as TLD / pocket dosimeter.
C-Slide 116
117. SAFETY OF PUBLIC
n Appropriate structural shielding is provided for
the X-Ray room.
n X-Ray rooms should be located as far as away
from areas of high occupancy and general
traffic, such as maternity and pediatric wards.
n The number of doors for entry to the X-Ray
rooms shall be kept to the minimum.
n A suitable warning light and symbol shall be
provided
C-Slide 117
118. PROTECTION OF PATIENTS
n Every medical exposure to be carried out under
the direction of a person who is clinically
directing the exposure. Radiologist should
ensure that only accepted diagnostic practices
are used and that persons who are physically
directing the exposure select procedures which
ensures that the dose to the patient is as low
as reasonably practicable, consistent with the
requirements for diagnosis.
C-Slide 118
119. Practical measures for the Reduction of
Patient Dose
n Some dose-saving equipment / accessories
n Fast screen-film combinations (e.g. rare earth screens)
n Low attenuation (e.g. carbon filter) materials for cassette
fronts, Anti scatter grid interspacing, tabletops.
n Constant potential generators with appropriate kilo voltage.
n Appropriate beam total filtration (minimum 2.5mmA1 for
general radiography)
n Specialized equipment for mammography and pediatrics.
n Pulsed and frame hold (image storage) fluoroscopy
equipment.
n Digital Radiography equipment.
n Dose-area product meter to monitor patient exposure.
C-Slide 119
120. Some dose-saving techniques
n Use smallest possible field size and good collimation
n Collimate to exclude radiosensitive organs (gonads, breasts, eyes)
n Shield breasts, gonads and eyes.
n Use largest practicable focus to skin distance.
n Position the patient carefully, minimize the gap between patient and film-
screen.
n Use compression of patient where possible.
n Use nongrid techniques when examining children and small adults.
n Keep film reject rate due to all causes down to 5%. Check the factors
before exposure. Quality assurance, particularly of automatic film
processors is important.
n In fluoroscopy use the minimal field size and minimal screening time
essential for good diagnosis.
C-Slide 120
121. High risk examinations
n Keep pediatric radiation dose to an absolute minimum
consistent with adequate diagnosis as children up to the age
of 10 years are believed to be 3 – 4 times more radiosensitive
than adults.
n Mammography is not generally performed on women younger
than 50 years unless there is a family history of breast cancer
or the patient has related symptoms
n In CT scanning, take the minimum number of slices, position
the patient to avoid the eyes and other critical organs.
n Patients who are or might be pregnant.
n Interventional radiology needs care to avoid skin reactions,
use pulsed and frame hold systems, minimize screening times.
C-Slide 121
122. Radiation Safety Officer
n The Radiation Safety Officer (RSO) is the
key person within the group of radiation
protection personnel.
n The RSO monitors and investigates to
ensure that occupational exposures
remain well below the occupational limits.
Most ALARA programs have a program
review at weekly or monthly intervals to
maintain compliance.
n The RSO is responsible for ensuring that
proper equipment and supplies are
available and in good working order.
n To be effective the RSO must have the
authority to stop and/or prevent unsafe
practices. C-
Slide
123. Good Housekeeping
n Good housekeeping involves
several practices used together
to prevent exposures or spills.
n Use absorbent material around
or under the radioactive material
to help contain any accidental
spills.
n Wear lab coats and protective
equipment such as gloves,
goggles or respirators (as
appropriate) to prevent
exposures to the skin, eyes or
lungs.
n Do not eat, drink, smoke or store
food in areas containing
radioactive materials to help
prevent accidental exposures
through ingestion or inhalation.
n Use good technique and the
C-Slide 123
124. REGULATORY CONTROLS
n Type approval / No objection certificate
n Prior to marketing the X-ray equipment the manufacturer shall obtain a
Type Approval Certificate from the Component Authority (AERB) for
indigenously made equipment.
n For equipment of foreign make, the vendor shall obtain a NOC from
component Authority, prior to marketing the equipment.
n Approval of Room Layout
n No X-Ray unit shall be commissioned unless its layout of the proposed
X-Ray installation is approved by the Competent authority.
n Registration/License of X-ray/CT/Cath Lab Equipment.
n Registration shall be done for X-Ray Units, only after the installation is
approved from Radiation safety view point.
n License will be given for CT and Cath Lab Units, only after the
installation is approved from Radiation safety view point.
n Commissioning of X-Ray / CT / Cath Lab Equipment
n No X-ray equipment shall be commissioned unless it is registered with
the Competent Authority.
n No CT / Cath Lab equipment shall be commissioned unless the license is
C-Slide 124
![RADIATION PROTECTION
CONTENTS
A] INTRODUCTION
B] RADIOBIOLOGY
C] RADIATION UNITS
D] DOSE LIMITING
RECOMMENDATIONS
E] BASIC PRINCIPLES OF RADIATION
PROTECTION.
C-Slide 2](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)