1. PERSONAL MONITORING DEVICES
Mr. Deepak Aheer
M.Sc.(Nuclear Medicine)
AIIMS New Delhi
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2. Ionization radiation can’t be seen ,felt or sensed by the human body in any way but excessive exposure to them may have adverse health effect
To avoid the excessive exposure, appropriate and efficient radiation monitoring needed
Radiation exposure must be monitored for both personal safety and regulatory purpose
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3. It should be carried out periodically
To assess workplace conditions and individual exposure
To ensure acceptably safe and satisfactory radiological conditions in the workplace
To keep records of monitoring, over a long period of time, for the purposes of regulation or as good practice
The atomic energy (radiation protection) rules, 2004 (earlier RPR-1971, Atomic Energy Act 1962) insists the radiation monitoring a mandatory one
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4. Many instruments are used for individual monitoring
The instruments used for recording the dose equivalents received by individuals working with radiation are referred to as personal dosimeters (or individual dosimeters)
All instruments must be calibrated in terms of appropriate quantities used in radiation protection
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5. Aim of personal monitoring 1. Monitor and control the individual dose
2. Report and investigate over exposure and recommend necessary remedial measure, if needed
3 . Maintain life time cumulative dose record
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6. PERSONAL MONITORING DEVICE PROVIDE
Occupational absorbed dose and cumulative life time dose
Assurance that dose is within permissible limit
Individual monitoring is also used to verify the effectiveness of radiation control practices in the workplace
It is useful for detecting changes in radiation levels in the workplace and to provide information in case of accidental exposures
In India, country wide monitoring service is offered by
Bhabha Atomic Research Centre (BARC) Mumbai
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7. IDEAL MONITORING DEVICE
Instantaneous response
Distinguish between different types of radiation
Accurately measure the dose equivalent from all forms of ionizing radiation with energy from KeV-MeV
Independent of angle of incidence
Small, light weight, rugged, inexpensive, easy to use
Unaffected by environmental condition (heat, humidity, pressure)
Unaffected by non-ionizing radiation
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8. Personal Monitoring Devices
FILM BADGE
TLD
OSL
RPL
POCKET DOSIMETER
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9. FILM BADGE It is used to measure the individual dose from: X rays
Beta particle
Gamma radiation
Thermal neutrons
It was developed by Ernest O Wollan whilst working on the Manhattan Project during 1942
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10. CONSTRUCTION
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11. FILM BADGE
Photographic Film
Filters
Badge Holder
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12. Photography Film
Photographic film is a sheet of transparent plastic film base coated on one/both side with a gelatin emulsion containing small light-sensitive silver halide crystals
Film size is 4 x 3 cm wrapped inside by a light tight polythene or paper cover
There are two films in the badge one is slow and another is fast
Supply of film is for a period of one calendar month (4 weeks)
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13. FILM HOLDER HAS SIX WINDOWS
1 First Window
Without any filter
It detects  (alpha) particles
Due to minimum penetration power of alpha particles no metallic filter is used 1
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14. 1 First Window 2 Second Window
Without any filter
It detects  (alpha) particles
Due to minimum penetration power of alpha particles no metallic filter is used 2
2 Second Window
Filter is made of Plastic
Light white colour
It detects  (beta) particles
Thickness of filter : 1 mm
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15. 3 Third Window Filter is made of Cadmium Yellow in colour
It detects Thermal Neutrons
Thickness of filter: 1mm 3
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16. 3 Third Window 4 Fourth Window
Filter is made of Cadmium
Yellow in colour
It detects Thermal Neutrons
Thickness of filter: 1mm 4
4 Fourth Window
Filter is made of thin copper
Green in colour
It detects low energy X-rays
Thickness of filter :0.15 mm
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17. 5Fifth Window 6 Sixth Window
Filter is made of thick copper
Pink in colour
It detects High Energy X-Rays
Thickness of filter : 1 mm
6 Sixth Window
Filter is made of Lead
Black in colour
It detects  (gamma) rays
Thickness of filter : 1mm 5 6
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18. FILM HOLDER
P HOTOGRAPHIC FILM
FILTERS
Film Badge consist of stainless steel holder, photographic film and all six filter fixed in particular window
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19. WORKING
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20. When radiation exposes the film after passing through the filters it cause formation of latent image on the film
Latent image has regions of different density under the different filters due to their different penetration power
After each months (4 weeks) it is returned to the agency where the film is processed and the optical density under different filters is measured by a densitometer
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21. Dose under each filter is evaluated using the standard calibration curve
After processing the film badge monthly dose report is sent to the institution This report contains current month’s report and up to date cumulative dose of the current year
Dose is reported in mSv
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22. PHOTOGRAPHIC FILM DENSITOMETER
Calibrated curve
FILM BADGE
DENSITOMETER
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23. DEEPAK AHEER (AIIMS)

24. Film Badge is of two types 1.Chest badge 2.Extremity badge
Minimum dose that can be detected by film badge is 0.2 mSv
Range of film badge is 10 KeV to 2 MeV
Can be used to measure radiation from 10 mR to 1000R with the accuracy of %
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25. Control Film Badge
Each institute should keep one film badge as control to assess background radiation level
This badge should be kept in cool, dry and control area
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26. ADVANTAGES It gives permanent record Wide exposure range
Independent of dose rate
Type of radiation and energy can be evaluated
Least expensive device
Small, light weight , easy to handle
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27. DISADVANTAGES Cant give instantaneous reading
It’s film fades at high temperature and humidity
High sensitivity to light, pressure and chemicals
Complete dark room procedure
Limited shelf life (one month)
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28. Thermo-luminescent Dosimeter
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29. Used to measure individual dose from x, beta and gamma radiation
Thermo-luminescent dosimeter (TLD) badge is used currently in India instead of film badge
It is based on phenomenon of thermo luminescence, the emission of light when certain material are heated after radiation exposure
In early 1960s, Cameron and co-workers from University of Wisconsin developed the TLD badge
Used to measure individual dose from x, beta and gamma radiation
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30. Response is directly proportional to the amount of radiation absorbed
Dose not respond to individual ionizing events, hence cannot be used as rate meter
Range : from 0.2 mSv to 10 Sv
TLD badge can cover a wide range of the dose from mR to R with the accuracy of +10 %
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31. Construction
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32. TLD Badge
TLD Card
TLD Cassette
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33. TLD Card Nickel coated aluminum (Al) Three CaSo4:Dy-teflon Disc
V notch type cut
Nickel coated aluminum (Al)
1 mm
Three CaSo4:Dy-teflon Disc
52.5 mm
0.8 mm thick and 13.2 mm diameter
29.9 mm
A cut is provided at one end of the card to ensure a fixed orientation of a card in the TLD cassette
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34. Disc is reusable after proper annealing
This card is enclosed by a paper wrap on which user’s personal data and period of use is written
This pouch protects the card from radioactive contamination while working with open sources
Disc is reusable after proper annealing
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35. TLD Cassette
It is made of high impact plastic (polythene)
There are three filters corresponding to each disc
These filters are used to make TLD disc energy independent.
Combination filter of 1mm Al and 0.9 mm Cu (thick:1000mg/cm2), for gamma rays
Thick plastic filter is 1.5 mm for beta rays(180 mg/cm2)
Circular open window for X- rays and beta
Cu + Al Filter
(Gamma)
PERSPEX
(Beta)
OPEN WINDOW
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36. Cu + Al Filter D 1 DISC PERSPEX D 2 DISC OPEN WINDOW D 3 DISC
When the TLD card is placed properly in the cassette
First disc (D1) is sandwiched between pair of metallic filter
Second disc(D2) is sandwiched between plastic filter
Third disc (D3) is positioned under a circular open window
Cu + Al Filter
D 1 DISC
PERSPEX
D 2 DISC
OPEN WINDOW
D 3 DISC
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TLD CASSETTE
TLD BADGE
TLD CARD

37. WORKING Working of the TLD can be divided into two part
1 Exposing the TLD
2 Reading the TLD
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38. Exposing the TLD
When the TLD is exposed to the radiation, electrons absorb the energy and jump to conduction band from the valance band
Excited electrons loose a part of their energy and are trapped in the forbidden energy gap
These trapped electrons store the remaining energy
Conduction Band
Electron Trap
Forbidden Energy gap
Valance Band
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39. Reading the TLD When this TLD card is heated in TLD reader
Trapped electrons absorb energy and are released from trap zone and are returned to their ground state
While returning to the ground state light is emitted which is captured by PMT tube and convert into digital signal
Conduction Band
VISIBLE LIGHT
PMT
Electron Trap
Valance Band
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Heating

40. TLD Reader
As the name suggests, TLD Reader is the instrument which is used to read TLD card
Reader has a heater, photomultiplier tube (PMT), amplifier, and a recorder
TLD disc is placed in the heater cup or planchet, where it is heated for a producible heating cycle
While heating, the electrons return to their ground state with the emission of light
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41. PMT signal is amplified and measured by a recorder
This emitted light is measured by PMT which converts light into electric signal
PMT signal is amplified and measured by a recorder
The reader is calibrated in terms of mR or mSv, so that we can get direct dose estimation
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42. Glow Curve
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43. TLD Glow Curve
Several prominent peaks occur in graph because of a specific electron transition in TL crystal
Both the height of the peak and total area under curve are directly proportional to energy deposited in TLD by ionizing radiation
TLD analyzer are electronic instruments designed to measure the height of glow curve or area under curve
Exposure or dose can be calculated from this using a conversion factor
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44. DEEPAK AHEER (AIIMS)

45. TYPE OF TLD BADGES Chest Badge Wrist Badge Finger Dosimeter
Whole Body Dose
Extremity Dose
Finger Dose
WORN AT CHEST LEVEL
WORN IN WRIST
WORN IN FINGURE
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46. Types Of TLD Materials Phosphors Lithium Fluoride Lithium Borate
Calcium Fluoride
Calcium Sulfate
Composition
LiF:Mg
LiB4O7:Mn
CaF2:Mn
CaSO4:Dy
Density x103 (kg/m3)
2.64
2.5
3.18
2.61
Effective atomic no
8.2
7.4
16.3
15.3
Temperature of
main peak
195
200
260
220
Principle use
Patient and personnel dosimeter
Research
Environmental monitoring
Personnel and environmental
LiF can also be used as TLD phosphor , which has wide dose response 10 mSv to 1000 Sv its effective atomic number is close to the tissue with an accuracy of + 2%
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47. ADVANTAGES Relatively good energy independence
Atomic number is approximate tissue equivalent
Unaffected by visible light, moisture and mechanical vibration
It is reusable, one TLD card can be used 100 times, so one card can be used for 300 months (25 years)
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48. Properly calibrated TLD monitors can measure exposure as low as 5 mR
It is more sensitive and more accurate than film badge and give reliable result because no fading is observed due to changes in environmental conditions
Properly calibrated TLD monitors can measure exposure as low as 5 mR
Can be worn for intervals up to 3 months at a time
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49. DISADVANTAGES Does not provide permanent record like film Badge
Does not give instantaneous result
Primary disadvantage of TLD personnel monitoring is cost but due to reuse it is cost effective
Instrumentation for reading TLD badge is expensive
Price is perhaps twice that of film badge monitoring
Skilled trained experts are required to run the service
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50. Guidelines For Using TLD Badge
TLD badges are to be used only by person directly working in radiation
Administrators, dark room assistant, sweeper etc need not be provided with TLD badges
TLD badge is used to measure the radiation dose It does not protect the user from radiation
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51. TLD badge issued to a person should not be used by any other person
Name, personal number, type of radiation measued (x or gamma), period of use, type of badge (chest or wrist) etc should be written in capital letters on the front side of the badge
TLD badge issued to a person should not be used by any other person
TLD badge should be worn compulsory at the chest level
If lead apron is used, TLD should be worn under the lead apron
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52. Each institute should keep one TLD badge as control to assess background radiation level
A badge without filter or damaged filter should not be used It should replaced by a new holder
All used or unused TLD badges should be returned after service period (three months)
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53. Contact for all corresponding regarding TLD badge services, to the
While leaving the premises of the institute worker should deposit their badge in the place where control TLD is placed and Worker must ensure that the badge is not left in radiation field or near hot plates, furnace, ovens, burners etc
Contact for all corresponding regarding TLD badge services, to the
OFFICER INCHARGE ,
PERSONAL DOSIMETRY & DOSE RECORD SECTION,
RADIOLOGICAL PHYSICS & ADVISORY DIVISION ,
BHABHA ATOMIC RESEARCH CENTRE ,
CT & CRS BUILDING
ANUSHAKTI NAGAR
MUMBAI
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54. OSL Dosimeter
Dosimetry using Optically Stimulated Luminescence (OSL) is also available now a days alternative to TLD
Measures radiation using a thin layer of aluminum oxide (Al2O3:C) as the detecting medium
Tiny crystal traps and stores the energy from exposure of ionizing radiation
Amount of exposure can be determined by shining green laser on crystal and measuring the intensity of blue light emitted
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55. The principle of OSL is similar to TLD except the heating
Instead of heating, laser is used to stimulate light emission
Small, lightweight, fast and efficient service
Minimum reportable level is 10 Sv for both x-rays and gamma radiation
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56. Range of OSL is from 5 keV to 40 MeV.
wide dose range : from 10 Sv to 10 Sv.
OSL Dosimeter can be used several times.
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57. OSL
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58. DEEPAK AHEER (AIIMS)

59. DEEPAK AHEER (AIIMS)

60. RPL Glass Dosimeter
Radiophotoluminescent (RPL) glass dosimeters are the accumulation-type solid-state dosimeters
It is based on the radiophotoluminecence phenomenon to measure the radiation dose
They are available in the shape of small glass rods
Material used is silver activated phosphate glass
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61. The readout technique uses pulsed ultraviolet laser excitation
When silver activated phosphate glass is exposed to radiation, stable luminescence centers are created in silver ions, Ago and Ag++
The readout technique uses pulsed ultraviolet laser excitation
A photomultiplier tube (PMT) registers the orange fluorescence emitted by the glass
RPL signal is not erased during the readout, thus the dosimeter can be re-analyzed several times
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62. They have a flat energy response within 12 keV to 8 MeV for Hp (10)
Accumulation of the dose is also possible that may be used for registration of the lifetime dose
Commercially available RPL dosimeters typically cover the dose range of 30 μSv to 10 Sv
They have a flat energy response within 12 keV to 8 MeV for Hp (10)
RPL signal exhibits very low fading and is not sensitive to the environmental temperature making it convenient in individual monitoring
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63. DEEPAK AHEER (AIIMS)

64. DEEPAK AHEER (AIIMS)

65. Pocket Dosimeter
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66. Film badge and TLD will not show accumulated exposure immediately
In addition to regular TLD radiation, dose received by the worker can be assessed by wearing pocket dosimeter
It is small and portable
Gives instant exposure /dose rate and total dose
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67. Can track dose received from day to day activities
It gives instantaneous radiation exposure and very useful in non routine work in which radiation level vary considerably and may be quite hazardous e.g. PET guided Biopsy, installation of Technetium generator, cardiac cath lab etc
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68. Type Of Pocket Dosimeter
Self Reading
Pocket Dosimeter
Electronic/Digital
Pocket Dosimeter
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69. Self Reading Pocket Dosimeter
Charger
Dosimeter
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70. CONSTRUCTION These detector are filled with gas (non-electronegative)
They are cylindrical in shape with two electrode
(a) Cathode : outer sheath made of graphite
(b) Anode : central wire which is insulating from he outer sheath
Radiation produced ionization in gas resulting positive ions and negative ion are produced inside the detector volume
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71. Positive and negative ion drift to the negative and positive electrodes respectively due to applied voltage between electrodes
In an outer circuit the current is measured which is proportional to the number of ion pair produced per second
These dosimeters should be fully charged prior to their use so that the initial reading of the dosimeter is set at zero
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72. ALUMINIUM TERMINAL HEAD CAP
CENTRAL ELECTRODE
WALL (LOW ATOMIC NUMBER)
GRAPHITE CYLINDER
INSULATING WASHER)
HANDLE
ALUMINIUM TERMINAL HEAD CAP
ALUMINIUM SLEEVE
ALUMINIUM CAP
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73. WORKING
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74. 0.23 mR HV Graphite sheath (Cathode) Central electrode (Anode)
POSITIVE ION
NEGITIVE ION
GAS MOLECULE
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75. Dosimeters are both types analog and digital
Available with digital display of instant reading measurement
Digital dosimeter are either GM tubes or Diodes and solid state electronics
Dose measurement range: 10 Sv to 100 Sv with the accuracy of %
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76. Digital Pocket Dosimeter
Records dose information and dose rate
Most often use Geiger-Muller counters
Output of radiation detector is collected and, when a pre-determined exposure has been reached, the collected charge is discharged to trigger an electronic counter
Counter then displays the accumulated exposure and dose rate in digital form
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77. Range : 1 Sv to 10 Sv with (Accuracy +10 %)
Some Digital Electronic Dosimeters include an audible alarm feature which emits an audible signal or chirp with each recorded increment of exposure
Some models can also be set to provide a continuous audible signal when a preset exposure has been reached
Range : 1 Sv to 10 Sv with (Accuracy +10 %)
Dose rate : 1 Sv/h to 1 Sv/h
Energy dependence : Within + 30 % from 50 keV to 1.5 MeV.
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78. ADVANTAGES Small in size and portable Easy to use
Give instantaneous radiation exposure
Reasonably accurate and sensitive
It also has the advantage of being reusable
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79. DISADVATNGES Does not provide permanent record
Sudden mechanical shock may result in wrong reading
Should be handled very carefully
limited range
and the potential of discharging and reading loss due to dropping or bumping
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80. Common Problems Associated With Personal Monitoring Devices
Leaving the dosimeter in radiation area, when not worn
Radionuclide contamination of the dosimeter
Lost or damaged dosimeter
Not wearing the dosimeter when working in radiation fields
Dosimeter is exposed by primary radiation e.g. in metro checking booth , medical examination (X-ray , CT Scan)
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81. THANK YOU
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82. Radiation dose limit recommended by ICRP-60 (1991)
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