Radiation protection, Personnel monitoring devices, Radiation units, TLD, Film Badge, Pocket dosimeter

2. Flow of the seminar
•History
•Effects of Radiation
•Radiation Units
01
Radiation protection
•Principles of Radiation
protection
•Design of Radiation
facilities
•Radiation protection
Rule
02
Practical aspects
•Lost source
•Stuck source
•Off site accidents
03
Radiation monitoring
•Personnel monitoring
devices
•TLD
•Film Badge
•Pocket dosimeter
04
RADIATION

3. Thompson reported
deliberate exposure of
finger to the x-ray and
then cautioned against
overexposure.
Thomas Edison gave upon X-
rays, fearing they were too
dangerous after death of his
assistant.
Mihran Kassabian is an american
radiologist who documented his radiation
burns & published a paper on irritant
effect of X-rays.
History

4. Fukushima nuclear disaster
Chernobyl disaster Uranium miners– Radon exposureRadium Dial Painters

5. • The ICRP Non governmental organization that sets
acceptable limits of exposure
• Members - scientists, sociologists and experts in
various fields
• The IAEA is an autonomous inter-governmental
organization under the aegis of the United Nations.
• The NCRP provides advice & recommendations on
matters pertaining to radiation protection in US.
• The AERB constituted on November 15, 1983 by the
President of India.
• Ensure use of ionizing radiation & nuclear energy in
India does not cause any risk to health of people &
environment
Regulatory bodies

6. Stochastic EffectsDeterministic Effects
1. All or nothing effect
2. Probabilistic or random in
nature
3. No threshold level
4. Probability of effects is
proportional to the dose
5. Caused by modification of
cell
6. E.g. Carcinogenesis and
hereditary effects
1. Renamed as Tissue reaction.
2. Deterministic in nature
3. Have a threshold level of dose
4. Severity of effect increases with
dose above threshold
5. Caused by cell death or delayed
cell division
6. E.g. Organ failure, Radiation
induced dermatitis, cataract
Effects of Radiation Exposure

9. • Effects of radiation produced due to ionizing radiation
• Types of Ionizing radiation-
• Directly Ionizing Radiation : Alpha rays & Beta rays.
• Indirectly Ionizing Radiation : Gamma & X rays & Neutrons.
 Depth of Penetration of Ionizing Radiation
2-7cm in air
several meters in air
Very High. Several hundred feet

10.  Absorbed Dose (D)
Radiation Weighting Factor (WR)
Equivalent Dose(H)
 Tissue Weighting Factor (WT)
Effective Dose (E)
Committed Dose
Collective Dose

11. Absorbed Dose (D)
• Def: Amount of energy absorbed per unit mass
of medium at the point of interest
• Units:
• Dose 1 (Gy) = 1 joules/kg
• 1Gy= 100 rad
• 1 rad = 100 ergs/g

12. Radiation Weighting Factor (WR)
• Dimensionless multiplier used to place biologic effects
from exposure to different types of radiation on a
common scale .
Equivalent Dose(H)
•H(Sv)= D(Gy) x WR
•1 Sv of different type of radiation produce same biologic
effect.

13. • Relative contribution of each tissue or
organ to total detriment resulting from
uniform irradiation of whole body.
Tissue Weighting Factor (WT)
Effective Dose (E)
• Sum of all weighted equivalent doses in all
tissues or organs irradiated.
• Effective Dose= ΣD x WR x WT = ΣT HT WT

14. Committed Dose
• Committed dose: Total dose delivered throughout period of time for which radionuclide
inside body.
• Committed equivalent dose: Equivalent dose integrated over 50 years.
• Committed effective dose : Effective dose integrated over 50 years.
• Unit: Sievert

15. Collective Dose
• Collective equivalent dose : Avg equivalent dose to a population X n Persons exposed
• Collective effective dose: Avg effective dose to a population X n Persons exposed
• Unit - person- sievert .
• For population ingesting or inhaling radionuclides depositing dose over prolonged period,
integral of effective dose over entire population to a period of 50 years = Collective
committed effective dose.

16. OCCUPATIONAL
MPD
ICRP 60 NCRP AERB 2011
STOCHASTIC EFFECTS
CUMULATIVE
20mSv/yr
Avg over 5yrs
10mSv X age
20mSv/yr
100mSv over 5yrs
ANNUAL 50mSv/yr 50mSv/yr 30mSv/yr
DETERMINISTIC EFFECTS
Lens of eye
150mSv/yr
(new 20mSv/yr)
150mSv/yr 150mSv/yr
Skin, hands & feet 500mSv/yr 500mSv/yr 500mSv/yr

17. PUBLIC
EXPOSURE
ICRP 60 NCRP AERB 2011
Effective dose
limit
1mSv/yr
Cont exp 1mSv/yr
Infrequent 5mSv/yr
1mSv/yr
Lens of eye 15mSv/yr 15mSv/yr 15mSv/yr
Skin, hands & feet 50mSv/yr 15mSv/yr 50mSv/yr
STOCHASTIC EFFECTS
DETERMINISTIC EFFECTS
Embryo/Fetus
1mSv to
abdominal surface
0.5mSv/month
1mSv for
remainder of
pregnancy

18. • DE MINIMIS DOSE
• Dose below which further efforts to reduce radiation exposure to person unwarranted.
• Annual effective dose of 0.01mSv (NCRP)

19. 1. Justification
2. ALARA- Time, Distance, Shielding
3. Limitation
Benefits
Cost
NCRP

20. • Radiation Dose received ∝ Time
• To ensure thorough planning before entering radiation
area
• Have all necessary tools present
• Work efficiently and swiftly.
1. Minimizing Time

21. 2. Maximizing Distance
• Radiation dose follows Inverse
square law
• Dose reduced significantly by
increasing distance from source
• Double the distance, dose rate falls
to ¼ .

22. Half Value Layer
• HVT- thickness of material reducing intensity
of incident radiation into ½
• TVT- Thickness of material reducing
intensity of incident radiation to 1/10
• 1 TVT = 3.3 HVT

23. 23
3. SHIELDING

24. • Parameters involved in shielding design (NCRP 151)
1. Establishing dose value (P) in occupied area
2. Estimating dose (D) in occupied area in absence of any shielding
3. Obtaining attenuation factors necessary to reduce dose value from D to P
3. SHIELDING

25. 1. Primary Barrier : irradiated
directly by primary beam
2. Secondary Barrier : irradiated by
a) scatter radiation
b) leakage radiation

26.  Workload (W)
• No. of patients treated per week x Dose delivered per
patient at 1 m
Occupancy Factor (T)
• Fraction of operating time for which area of interest
occupied by an individual
Distance (d)
• In meters from radiation source to area to be protected.
Use Factor (U)
• For primary barrier -fraction of beam-on time during
which primary beam is directed towards a particular
barrier.
• Use Factor for secondary barriers is 1 as secondary
radiation always present when beam on.
Type of area Occupancy factor T
Offices, Reception, Play
areas, Nurse`s stations,
staff room
1
Control room, wards,
patient rooms
1
Corridors 0.25
Waiting rooms 0.125
Stairways, store room,
Toilets, bathrooms
0.0625
NCRP 49Factors influencing Barrier Thickness
Primary Barrier Use Factor
Floor 1
Walls 0.25
Ceilings 0.25
Secondary Barriers 1

27. Primary Radiation Barrier
B= P. d2
WUT
• P- Maximum permissible dose
• W- Workload
• U- Use Factor
• T- Occupancy Factor
For scatter radiation:
Ps = a.WT. F. Bs
d2
scad2
sec 400
a - Ratio of scattered dose to incident dose
dsca - Distance from source to scatterer
dsec - Distance from scatterer to area of interest
F - area of beam incident at scattered at 1m
Secondary Radiation Barrier

28. 6 TVL for Primary barrier
3 TVL for Secondary barrier
Thickness of Secondary Barrier:
• Beam intensity incident on scatterer
• Quality of radiation
• Area of beam on scatterer
• Scattering angle
Neutron shielding for >10MV
Shielding thickness of ordinary concrete (NCRP 151)
Rad Quality Primary Barrier (cm) Secondary Barrier (cm)
Co-60 130 65
10-25 MV 240 120
Materials used for shielding in construction of Radiation
facilities (NCRP 151)
Material Density (g/cm3
)
Ordinary concrete (RCC) 2.35
Heavy concrete (Ledite) Up to 5
Lead 11.3
steel 7.9
Polyethylene 0.95
Earth 1.5
Barite Concrete 3.2
RULE OF THUMB

29. According to BSS given by IAEA
1. Controlled Area
• Specific protection measures and safety
provisions needed
• Defined by physical boundaries.
• Identified with radiation area signs.
• All treatment rooms & Radioactive source
storage room.
• Dose Equivalent Limit: 0.1 rem/week
DESIGN OF RADIATION FACILITIES

30. 2. Supervised Area
• Kept under review
• Specific protection measures not normally needed.
• E.g: areas surrounding brachy patient rooms, around
radioactive source storage & handling areas,
operating consoles,waiting rooms.
• Dose Equivalent Limit: 0.02 rem/week
3. Uncontrolled Area
• Neither controlled nor supervised areas
• Same level of protection as members of public.
•Dose Equivalent Limit: 0.01 rem/week

32. Features of Good Design in EBRT installation:
• Maze Entrance
• Door Shielding
• Beam Stopper
• LMO
• Warning sign
• Emergency stop
• Patient Monitoring

33. Maze Entrance
• Maze connects treatment room with
control room.
• Ensures that photon radiation can only
exit room after attenuation by multiple
scattering
• Ideally - As long as and with as small a
cross-section as possible.
• Drastically reduces shielding
requirements of door
• Longer maze (>5 m) to reduce neutron is
fluence at door.

34. Door Shielding
• If maze absent - door must provide shielding equivalent to wall
surrounding door.
• Low energy accelerators (≤10Mv): Heavy motorized door not
necessary for shielding against scattered photons.
• High energy accelerators (>10 MV): special doors that shield
against neutrons required
• Fast neutrons attenuated efficiently by materials with high
hydrogen content - borated polyethylene.
• Door interlock: to ensure irradiation terminated when door
open

35. Beam Stopper
• Part of primary shielding incorporated into some
machines
• retractable or permanent
• adequate to attenuate the primary radiation beam
to 0.1% of its original.
• It reduces the need for primary barrier thickness.
• Useful in installations with space constraints
• Made of lead (10-15cm thick)

36. LAST MAN OUT SWITCH
• Supposed to be pressed by last person exiting treatment room.
• Interlock system remains deactivated unless done so.
• Treatment will commence thereafter.
WARNING SIGNS
• Trefoil sign
• Warning lights
• Audible alarms

38. EMERGENCY STOP
• For emergency interruption of radiation
• Multiple numbers
• Conveniently placed
Patient Monitoring
•Appropriate patient viewing facility
•Audio communication with the patient

39. F
Table
Stationary
structure
Zone
Monitor
Lead
Door
PC
monitor
Laser
ROOM
No.1
EQUINOX 80
Gantry
MEDICAL
PHYSICS
AB
E
C
Technician
Room
TELECOBALT UNIT

40. NATURAL EARTH
N
A
T
U
R
A
L
E
A
R
T
H
HDR CONTROL
ROOM
PASSAGE
6MV LA
(UNIQUE)
MAZE
DOOR
A B C
F
H J K
L M
N
O
P
I
E
NATURAL EARTH
D
G
Control
Consol
e
DOOR
Isocentre
DOOR
TRUEBEAM

41. Tomotherapy
Console
Corridor
Corridor
Patientwaitingarea
Hyperthermia Room
Conduit
• None of the walls have benefit of natural
earth.
• All walls surrounded by Occupied Area.
• 6MV low energy slit beam, scatter
contribution is low.
• Maze of is comparatively small.
• Beam stopper that prevents need of
adequate primary barrier thickness as
there is space constraint.
• Sky Shine Reading is measured during
Survey

42. 42
BRACHYTHERAPY
Intracavitary
Cs-137- LDR
Ir-192 - HDR
Interstitial
Ir-wires LDR
Ir-Pellet HDR
Surface Mould
Ir-wires LDR
Ir-Pellet HDR
Brachytherapy

43. Brachytherapy T/t Rooms
• Lockable door to control access
• A radiation warning sign
• Shielded storage container
• Devices for handling the sources- forceps, Tongs
• Area Survey meter
• Source transport trolleys
• Lead glass viewing window
• Emergency container
• Visible light signal

44. Staircase
Entrance
Conduit
Corridor
Console RT OT
Door
HBB Brachytherapy Room Design
Maze
• All walls - primary barriers.
• Concrete barriers 400–800
mm thick.
• Dose rate within room will
be > 7.5 mSv/hr
• Dose rate outside the T/t
room <2.5 mSv/hr

45. DOOR
C HDR CONTROL CONSOLE CONDUIT
TRUE BEAM CONTROL CONSOLE
HDR UNIT
EARTH
CTSIMULATOR
TRUEBEAM
Fig. Layout of a Remote After Loading Brachytherapy Facility
Annexe Brachytherapy Room Design
•All walls, floor, ceiling are primary
barriers.
•Advantage of natural earth
•Location
•No Maze
•Lead door

46. LDR Brachytherapy Room
•Room for individual patient
•Workbench with L-block shielding
•Mobile lead shields are used
•Lead shields thickness: 25mm
•Shielded area: 70–100 cm by 50–60 cm
• To protect the abdomen of a worker who stands
behind them.

47. EMERGENCY SITUATIONS
1. Lost source
2. Stuck source
3. Off-site accidents

48. LOST SOURCE
• It is critical for this type of event to happen
• An up to date inventory exists so that following can be determined immediately:
• Which sources are missing?
• What is their type and activity?
• Where they were last known to be, and when?
• Who last took possession of the sources?
• Restrict entry of the area where the sources were last known.
• Survey with radiation detection survey meter.

49. • Source driving mechanism to return source to shielded position
• Tell patient to get up & come out - if he is mobile.
• Restrict area from further entry.
• Obtain emergency T-bar.
• Enter the room, avoiding direct exposure to treatment beam.
• Insert end of T-bar over red indicator rod through head cover.
• Apply firm pressure to T-bar & push source back into fully shielded position.
• If Yellow colored position is entirely inside head cover  fully shielded position.
• If yellow colored position is visible & Red colored position is entirely inside cover Relatively
safe position.
• Inform radiation protection officer.
STUCK SOURCE- TELECOBALT

50. Stuck source in remote control
brachytherapy units
•Observation of error message at console.
• Recovery from console with emergency stop
• Entry into room with a portable radiation survey meter.
• Opening the door acivates interlock that retracts source.
• Recovery from afterloading unit emergency stop.
• Manual retraction of source using a hand crank.
•Applicator removal and placement into emergency container.
• Patient and HDR unit , emergency container survey to confirm
source is in the safe.
•Removal of patient & subsequent survey to monitor radiation
levels in the room.

51. OFF-SITE ACCIDENT
• Rare but can happen through loss of
security of teletherapy sources not in
use.
• Can cause large scale contamination
or external irradiation
• Require action by national and
international intervening organizations.
• E.g. Mayapuri Orphaned source 2010

52. Radiation Protection Rules 2004
1. Employer
• Ensure that provisions of these rules are implemented by licensee, RSO & worker.
• Custodian of radiation sources in his possession
• Ensure physical security of sources at all times.
• Inform competent authority, within 24Hrs of any accident involving a source or loss of source.
2. Licensee
• Responsible for controlling public exposure resulting from radiotherapy practice.
• Should notify regulatory authority & submit a plan for transfer & disposal of sources not in use.
• Inform the employer & competent authority of any loss of source.

53. 3. Radiation Safety Officer
• Establish & maintain radiation protection program.
• Ensure that staff observe safe work practices.
• Planning, Radiation Protection Survey of teletherapy, brachytherapy, diagnostic and radioisotope
labs installations.
• Periodic Survey & Quality Assurance.
• Personnel monitoring & radiological protection.
• Inventory of Radioactive Sources.
• Packing, Safe transport & Disposal of Radioactive Isotopes.
• Preparation of periodic Safety Report.
• Establish procedures for management of emergency situations & conduct periodic drills to ensure
their effectiveness

54. Monitoring
1. Workplace monitoring- Area Survey meters, GM counters, Proportional counters, Ionization
chambers
1. Personnel monitoring- TLD badges, Films, Pocket dosimeter.

55. Results of external exposure monitoring are used
• To assess workplace conditions & individual exposures.
• To ensure acceptably safe and satisfactory radiological conditions in workplace
• To keep records of monitoring over a long period of time
• For the purposes of regulation or as good practice

56. • Developed in 1962 by Cameron in University of Wisconsin
• Thermo luminescence - property exhibited by a large no. of crystalline materials which emit light from
an irradiated phosphor on heating.
• Intensity of the emitted light is proportional to radiation dose absorbed by material.
• Materials - LiB4O7:Mn, LiF, CaSO4:Dy, CaF2
• Available as - powder, rods, chips, discs
• Measurement of x-rays, gamma & beta rays
• Range-100microSv-10Sv.
• Types:
TLD
Wrist Badge Chest Badge Ring Dosimeter

57. Parts of TLD
1. TLD card
2. Ni coated Al plate
3. Cassette
4. Thin paper wrapper
5. Polythene pouch

58. Parts of TLD
1. TLD card consists of:
1. 3 CaSO4:Dy-Teflon TLD discs. Size: 13.2mm diameter
& 0.8mm thick
2. Ni coated Al plate: 52.5mm X 29.9mm X 1mm
3. 3 symmetrical circular holes 12mm in diameter
4. An asymmetric V cut provided at one end of the card to
ensure a fixed orientation of card in the TLD casstte.

59. Parts of TLD
3. Cassette
• TLD card is loaded in a cassette having suitable
metallic filters.
• Consists of 3 filters:
1. D1 between 1mm Al & 0.9mm Cu  X & γ
2. D2 between pair of 1.5 mm thick plastic filters β
3. D3 under a circular open window  control
• A clip attachment affixes the badge to the user`s
clothing.

60. Parts of TLD
4. Thin paper wrapper provides personal data & duration
of use
5. To protect the TLD discs from dust and mishandling, the
card along with its wrapper is sealed in a thin plastic
(polythene) pouch.
Pouch also protects the card from radioactive
contamination while working with open sources.

61. CONDUCTION BAND
VALENCE BAND
On Irradiation During reading (after heating)
Ionizing radiation
Electron traps
Energy
Mechanism of TLD

62. Advantages of TLD
• Availability of tissue equivalent Thermo
luminescent materials.
• High sensitivity & accuracy in desired dose
range.
• Can store doses for long periods.
• Reusability and therefore economy.
• Excellent resistance to environment.
• Sensitive than film.
• Worn for intervals up to 3 months at a time.
• Ease of handling
Disadvantages of TLD
• No permanent record of exposure
• Dose reading is retrospective.
• Reading & calibration is time consuming.
• Sensitivity varies with time of storage & with
sensitivity of reader
• Loss of data after heating and annealing. Only one
time reading.

63. APPLICATIONS
• Personnel Monitoring.
• Measurement of output from Co-60 units and accelerators used in medicine and industry.
• Area survey of medical and industrial radiographic installations.
• Measurement of stray and leakage radiation around X-ray tubes and source containers.
• Medical radiographic exposure measurement and population exposure survey studies.
• Estimation of activities of various radionuclides used in brachytherapy and nuclear medicine.
• To measure dose rates in rectum and bladder of patient undergoing treatment with Cobalt
on Cesium implants for carcinoma of uterine cervix.

64. GUIDELINES FOR USING TLD BADGE
1. Used only by person directly working in radiation.
2. Name, personal number, period of use, type of badge should be written in capital
letters on the front of the badge.
3. Badge issued to a person should not be used by any other person.
4. Should be compulsorily worn at chest level.
5. If lead apron is used,it should be worn underneath
6. Each Institute should keep 1 TLD badge as control to monitor background radiation
level.
7. All used/unused badges should be returned after 3 months.

65. FILM BADGE
Open
Pb
1mm
Cu
1mm
Cu
0.15mm
Cd
1mm
OpenPb
1mm
Cu
1mm
Cu
0.15mm
Cd
1mm
Plastic
1mm
Plastic
1mm
1. Alpha
2. Beta
4. Low energy X rays
5. High energy X rays
6. Gamma rays
A. Film Holder of
stainless steel B. Photographic Film
-4X3cm transparent plastic film
-Coated with gelatin emulsion of Silver halide
crystals
3. Thermal Neutrons
C. FILTERS
TYPES –
1. Chest Badge
2. Wrist Badge
3. Head Badge
Range - 0.1 mSv to 10 mSv

66. Mechanism
Radiation Exposure
4 weeks
•Optical density measured by densitometer
•Dose under each filter is evaluated & expressed in mSv
• ADVANTAGES:
1. Discriminate between X-ray, Gamma, Beta rays and
thermal neutrons.
2. Permanent Exposure Record.
3. Good Accuracy at higher exposures.
AgBr
Developer- Quinol
Fixer- NaThiosulphate
Metallic silver remains produce blackening
• LIMITATIONS:
1. Can’t give instantaneous reading.
2. Film fades at high temperature & humidity.
3. Less accuracy to lower exposure
4. Cannot be reused.
5. Processing takes more time.

67. Pocket dosimeter
Microscope
Eyepiece• The dosimeter records total exposure from the initial
charging to the time of reading.
•Ranges: 200mR, 500mR, 1R, 5R, 10R, 100R.
• Parts:
1. Ionization chamber .
2. Quartz electrometer - To measure the charge.
3. A capacitor- highly insulated to share the charge with
the electrometer.
4. The electrometer embodies two electrodes, one of
which a fixed support & the other movable quartz fiber.
5. Microscope- to read the fiber image off a reticle.
Reticle
Microscope
Objective
Lens
Ionisation
chamber
Protective
Barrel
Insulation
Quartz Fiber
Electrometer
Capacitor
Insulated
Charging pin
Glass
bottom seal
Bellows

68. Radiation Exposure
Ionization of gases
Discharges the capacitor
Current produced is directly proportional to exposure
Read as deflection of wire from original position
Quartz Fiber casts shadow on the scale provided
Advantages:
• Active device – Immediate reading
• Handy and portable
• Helpful in fluoroscopy, radioactive source
installations etc.
Disadvantages:
• Poor useful range & Poor sensitivity
• Charge leakage problems
Mechanism

69. THANK YOU