Radiation Protection

1. Radiation Protection
Dr. Muhammad Bin Zulfiqar
PGR 1

2. Why are x-rays harmful?
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13. 13

14. Permissible
Occupational Dose
• Annual dose:
• 5 rem / year 50 mSv / year
• Cumulative Dose
• 1rem x age 10mSv X age
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15. Occupational Dose
ANNUAL LIMITS
• WHOLE BODY = 5 rem / 5000
mRem
• LENS OF THE EYE = 15 rem
• EXTREMITIES = 50 rem
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16. PUBLIC EXPOSURE
• 10 % OF OCCUPATIONAL
• (MUST BE MONITORED IF ABOVE 10%)
• NON MEDICAL EXPOSURE
• .1 rem OR 100 mrem OR 1 mSv (Freq)
• .5 rem OR 500 mrem OR 5 mSv(Infreq)
• UNDER AGE 18 & STUDENTS
• .1 rem OR 1 mSv
• Pg 116 RTA BOOK
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17. OCCUPATIONAL EXPOSURES
• 5 rem / YEAR
BUT NOT TO EXCEED 1.25 rem/QUARTER
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18. 18

19. Reduction of Occupational
Radiation Exposure
• Radiography as a profession is very safe .. if
you follow the ALARA rules
• Most technologist exposure occurs from
fluoroscopy exams and mobile exams
– During all fluoroscopy and mobile exams
technologists should wear a protective apron
– The primary beam should never be pointed at the
tech or other staff… primary at the patient!
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20. ALARA
• ALWAYS KEEP RADIATION EXPOSURES AS LOW
AS REASONABLY ACHIEVABLE
• Can you think
of ways to do this?
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21. CARDINAL RULES
OF RADIATION PROTECTION
•TIME
•DISTANCE
•SHIELDING
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23. TIME
• The exposure is to be
kept as short as
possible because the
exposure is directly
proportional to time.
• 20 rem = 2min
• 10 rem = 1min
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24. DISTANCE
• Distance from the
radiation source
should be kept as
great as possible
• Physical Law:
–Inverse Square
Law
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25. INTENSITY IS SPREAD OUT…
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26. Position
• When primary beam is on.. Your distance
should be kept as great as possible
• The closer you are to the patient or primary
beam the more exposure you are receiving.
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27. Holding patients
• STUDENT RADIOGRAPHERS ARE NOT
PREMITED TO HOLD PATIENTS FOR PROPER
POSITIONG DURING EXPOSURES
• Mechanical devices should be used
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28. Holding patients
• Otherwise, a relative or friend accompanying
the patient should be asked to help
• Occasionally, other hospital employees such
as nurses and orderlies may be asked to help
• Radiology staff should never hold patients
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29. If holding a patient is required…
• Use shielding
–Apron, gloves, thyroid shield, glasses
• Avoid exposing assisting person to the primary
beam.
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30. SHEILDING
• A lead protective
shield is placed
between the x-ray
tube and the
individuals exposed,
absorbing
unnecessary
radiation
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31. Wall Shielding
Often unnecessary for labs
However, same principles employed for X-ray
rooms should be applied to assess
requirements for Radiochemical Laboratories

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33. Primary Barriers
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34. SHEILDING
TECHNOLOGIST . 25 mm LEAD
• LEAD APRON, GLOVES
• THYROID SHIELD, GLASSES
PATIENT –
GONAD SHEILDING
. 5 mm LEAD
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35. GONAD SHIELDING
• MUST BE . 5 MM OF LEAD
• MUST BE USED WHEN GONADS WILL LIE
WITHIN 5 CM OF THE COLLIMATED AREA
• KUB. Lumbar Spine Pelvis
• male vs. female shielding
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36. TYPES OF SHEILDING
•FLAT /CONTACT
•SHAPED
•SHADOW
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37. Flat/Contact
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39. Shadow
Shield
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40. Local Shielding 1
 Vial Shielding
– emitters - Perspex Vial shields & Storage
– emitters - Tungsten Vial shields &
lead-lined box for Storage

41. Local Shielding 2
Nuclear Medicine Syringes
– emitters - Tungsten syringe shields
lead-lined box for Storage

42. Perspex L Bench emitters

43. Minimizing radiation exposure
• Is easy when technologist and student
technologist are informed!
• Collimation
• Protective apparel/Gonadal shielding
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44. Personnel Dosimeters
• Desirable characteristics
– Should be lightweight, durable, and reliable
– Should be inexpensive
• Types of personnel dosimeters
– Film badge
– Pocket ionization chambers
– Thermo luminescent dosimeters (TLD)

45. Film Badge
• Most widely used and most economical
• Consists of three parts:
– Plastic film holder
– Metal filters
– Film packet
• Can read x, gamma, and beta radiation
• Accurate from 10mrem - 500rem
• Developed and read by densitometer
• A certain density value equals a certain level of radiation
• Read with a control badge
• Results generally sent as a printout

46. Advantages And Disadvantages Of The Film
Badge
• Lightweight, durable, portable
• Cost efficient
• Permanent legal record
• Can differentiate between scatter
and primary beam
• Can discriminate between x,
gamma, and beta radiation
• Can indicate direction from
where radiation came from
• Control badge can indicate if
exposed in transit
• Only records exposure where it’s
worn
• Not effective if not worn
• Can be affected by heat and
humidity
• Sensitivity is decreased above
and below 50 keV
• Exposure cannot be determined
on day of exposure
• Accuracy limited to + or - 20%

47. Pocket Dosimeter
• The most sensitive personnel
dosimeter
• Two types
– Self-reading
– Non self-reading
• Can only be read once
• Detects gamma or x-radiation

48. Advantages And Disadvantages Of The Pocket
Dosimeter
• Small, compact, easy to
use
• Reasonably accurate
and sensitive
• Provides immediate
reading
• Expensive
• Readings can be lost
• Must be read each day
• No permanent record
• Susceptible to false
readout if dropped or
jarred

49. Thermo luminescent Dosimeters
• Looks like a film badge
• Contains a lithium fluoride crystal
• Responds to radiation similarly to skin
• Measured by a TLD analyzer
• Crystal will luminescence if exposed to radiation, then
heated
• More accurate than a film badge

50. Advantages And Disadvantages Of The
Thermoluminescent Dosimeter
• Crystals contained in
TLD interact with
ionizing radiation as
tissue does
• Determines dose more
accurately
• The initial cost is
greater than that of a
film badge
• Can only be read once
• Records exposure only
where worn

51. Occupational radiation monitor does NOT
protect against radiation exposure!
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52. Occupational radiation monitor
• Should be a life time dose record
• Should NOT be worn when YOU are the
patient
• Should be left at the hospital for safe keeping
• Should be stored in a radiation free area
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53. Radiation Survey Instruments
• Area monitoring devices
• Detect and measure radiation
• Measures either quantity or rate
• Generally gas filled
• Major types of survey instruments
– Ionization chamber - cutie pie
– Proportional counter
– Geiger-Müller detector
– Calibration instruments

54. Ionization Chamber (Cutie Pie)
• Measures x or gamma radiation generally - can be equipped
to measure beta
• Measures intensity from 1mR/hr to several thousand R/hr
• Most commonly used to measure patients receiving
brachytherapy or diagnostic isotopes

55. Proportional Counter
• Generally used in laboratories to measure
beta or alpha radiation
• Can discriminate between these particles
• Operator must hold the counter close to the
object being surveyed to obtain accurate
reading

56. Geiger-Müller Detector
• Generally used for nuclear medicine facilities
• Unit is sensitive enough to detect individual particles
• Can be used to locate a lost radioactive source
• Has an audible sound system
• Alerts to presence of radiation
• Meter readings are generally displayed in mR/hr

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58. Pregnancy & Embryo
Mother –
occupational worker (5 rem)
• Baby – (500 mrem)
• .5 rem/ year .05 rem/month
• 5 mSv/ year 0.5 mSv/month
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59. Declared Pregnant Worker
• Must declare pregnancy – 2 badges
provided
• 1 worn at collar (Mother’s exposure)
• 1 worn inside apron at waist level
Under 5 rad – negligible risk
Risk increases above 15 rad
Recommend abortion (spontaneous)
25 rad
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60. Fetal Exposure
• (“Baby exposure” approx 1/1000 of ESE)
• ALWAYS ASK LMP before exposure made …
any females that could be exposed to primary
or scatter
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61. Reduction of unnecessary patient dose
•TIME
•DISTANCE
•SHIELDING
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62. Reduction of unnecessary patient dose
• Unnecessary exam
–If the order is unclear…clarify
–If the order is wrong.. Fix it
• Repeat exams
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63. Patient Positioning
• When ever possible primary exposure to the
gonads, breasts, lenses of the eyes and thyroid
should be avoided.
• Especially female patients… perform exams PA
as apposed to AP
– PA = posterior anterior
– AP = anterior posterior
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64. Minimizing radiation exposure
• Is easy the equipment is designed to !
• Filtration
• Protective barrier
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65. Filtration
REDUCES PATIENT EXPOSURES
• REMOVES LOW ENERGY PHOTONS
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66. Thank you…………..….Questions?
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