Radiation Protection
Internal/External Hazard
• Internal hazardInternal hazard arises through ingestion or inhalation of a radiation material – not a problem in radiology.
Internal/External Hazard
• External hazardsExternal hazards
Arise from exposure to external sources. X-ray sets, emissions from sources etc
Reducing Radiation Dose from external hazard
TIMETIME
DISTANCEDISTANCE
SHIELDINGSHIELDING
PERSONNAL PROTECTION PERSONNAL PROTECTION CLOTHINGCLOTHING
Reducing Radiation Dose from external hazard - TIME
The longer you are exposed to a field The longer you are exposed to a field of ionising radiation the higher the of ionising radiation the higher the
dose you will receive.dose you will receive.
Double to time double the doseDouble to time double the dose
Reducing Radiation Dose from external hazard - DISTANCE
The nearer you stand to an source of The nearer you stand to an source of radiation the higher the dose – so stand radiation the higher the dose – so stand
away!away!
Double the distance quarter the Double the distance quarter the dosedose
Reducing Radiation Dose from external hazard - Shielding
Lead shielding can be used to attenuate X-Lead shielding can be used to attenuate X-raysrays
Room shieldingRoom shieldingScreensScreens
Protective clothing Protective clothing
Shielding
Need to know type of radiation– Nuclear Imaging uses radiation– Radiochemical Labs use radiation
Plan to use Local Shielding
May also need Wall Shielding
Local Shielding 1
Vial Shielding emitters - Perspex Vial shields & Storage emitters - Tungsten Vial shields &
lead-lined box for Storage
Vial Shielding emitters
Vial Shielding emitters
Local Shielding 2
Nuclear Medicine Syringes emitters - Tungsten syringe shields
lead-lined box for Storage
Syringe Shields emitters
Local Shielding 3
L- Bench Shielding emitters - Lead-lined shields & Lead-
glass emitters - Perspex L shields
Lead L- Bench emitters
PET Dispensing Station
Perspex L Bench emitters
Local Shielding 4
Radioactive Waste Shielding emitters - Sharps bins & Lead-lined
containers emitters - Perspex waste containers, often
lined with polythene bags
Sharps bins & Lead-lined containers emitters
Perspex waste containers emitters
Wall Shielding
Often unnecessary for labsHowever, same principles employed for
X-ray rooms should be applied to assess requirements for Radiochemical Laboratories
Room shielding
Lead lined plaster board
Lead glass viewing window
Reducing Radiation Dose from Internal hazard
PERSONNAL PROTECTION PERSONNAL PROTECTION CLOTHINGCLOTHING
(Training, technique, experience)(Training, technique, experience)
Personal Protective Equipment
Fig 3. OvershoesOften worn routinely in the
Radiopharmacy for sterility reasons.Not always otherwise worn routinelyto prevent the spread ofcontamination, but widely used forthis purpose following a spillage.
Radiation protection in X-ray
Personal Monitoring Why monitor non-classified
workers?• Not likely to receive > 3/10 relevant dose
limit – (e.g. effective dose > 6 mSv / yr)
• How do you prove this?
• Easiest way is to provide ongoing monitoring
Thermoluminescent dosemeters
• Measurement range 0. 1 mSv to 5 Sv
• Only issued if risk assessment concludes they are required
Electronic Dosimeters
• Give an instant reading of dose.
• Measurement range 0.001 mSv to 1 Sv
Other Monitoring
• Extremity– rings - tlds or electronic
• Eye - tlds
• Internal– e.g Iodine uptake– doserate measurements– swabs– samples
ContaminationContamination• Spilt or misapplied radionuclides adheres to or
lies on surface of skin, clothing, equipment or furniture.
• Spills give rise to:– external radiation– activity entering body via
• ingestion
• inhalation
• absorption
– leading to internal radiation
Instrumentation for detecting ionising radiation
• Gas based detectors –
•Geiger- Muller counter,
•GM tube, or
•Geiger counter
• Scintillation detectors -
•Solid state
•Liquid
Gas filled detectorsGas filled detectors
V
R C
Gas
Electrodes
V = Voltage source R = High resistance C = All the capacitance in the detector circuit
Scintillation detectorsScintillation detectors
Conversion of to uv orvisible lightpulse
Conversion of light pulse toan electrical signal
Scintillator
Light detector PMT
Scintillation detectorScintillation detector
PMT
PMT
Co-incidence electronics
Scintillator with radioactive sample
Liquid scintillation - coincidence detectionLiquid scintillation - coincidence detection
Liquid scintillation vialLiquid scintillation vial
Contaminant in intimate contact with scintillation medium
Pulse of light produced with radiation absorbed
Swab
Liquid scintillant
Mini 900 series EP15 probe GM gas counterMini 900 series EP15 probe GM gas counter
Mini 900 series E type probe GM gas counterMini 900 series E type probe GM gas counter
Mini 900 series 44A probe Solid state Mini 900 series 44A probe Solid state scintillation counterscintillation counter
Using the right detectorUsing the right detector
Beta Tritium (Hydrogen-3)
Carbon-14
Sulphur-35
Phosphorus-32
Phosphorus-33
18.6 keV
157 keV
167 keV
1.7 MeV
2.5 keV
Liquid scint
GM tube EP15
GM tube EP15
GM tube EP15 / Scint 44A
GM tube EP15
Gamma Iodine-125
Cobalt-60
Caesium-137
36 keV
1.17 MeV & 1.33 MeV
662
Scint 44A / GM tube EP15
Scint 44A
Scint 44A
Identifying the detector typeIdentifying the detector type
• Look at the label on probe
• Scintillation probe heavier
• Scintillation detector higher background rate, switch it on.
•When in doubt ASK YOUR RPS
Wipe testingWipe testing
• Use a swab and wipe surface using tweezers
• Present to appropriate contamination monitor in low background area
• For low energy Beta use liquid scintillation counting
Wipe testingWipe testing
• low level contamination and low energy Beta. Contamination lifted using absorbent material and counted in a gamma counter or liquid scintillation counter
Radiation spill /incident
Don’t Panic !!!Don’t Panic !!!
When dealing with spillage of radioactive material
• Do not to delay medical care unnecessarily
• Protect yourselves• Attend to contaminated persons first• Prevent the spillage becoming worse• Prevent additional people from becoming
contaminated• Clear up and decontaminate the area so it
can be put into use
Urgent medical care
1. If anyone requires urgent medical care, either by immediate first aid or transfer to A&E DO THIS FIRST .
– Inform A&E that the casualty is contaminated. Take any obvious steps to reduce or eliminate the hazard to the casualty, to yourselves or anyone attending the casualty.
– Contact Radiation Protection Service
Protect yourselves
• Pause, take stock and gather information
• Don protective clothing
• If in doubt and there are no casualties involved, GET HELP – but bear in mind that you should always try and ensure the incident is not made worse by your actions
Contaminated persons
• Washing with soap and water. Always try to localise the contaminated area and just wash that bit. A whole body shower is seldom the best approach.
• Remove contaminated clothing• Washing out any open wound, eyes,
mouth, nose etc.• If contamination persists contact radiation
protection.
Prevent spillage becoming worse
• Use temporary barriers or close the door.
• Prevent people walking through the contaminated or potentially contaminated.
• Use an appropriate contamination monitor to assess the extend of the spill.
• Check personnel for contamination before they leave the vicinity.
Clear up and decontaminate
• Purpose is to transfer the radioactive material from the floor or person to the waste store.
• Use absorbent material i.e. paper towels to soak up the material.
• Dispose in appropriate bin.• Estimate activity.• For stubborn areas of contamination use a
normal detergent or decon.• When clearing up a spill always work from the
outside in.• Use your contamination monitor!!!
Contamination monitoring
• Know which is the correct monitor to use.
• Take care not to contaminate the monitor.
• Get down close to the contamination.
• Monitor area systematically.
• Be thorough .
Other points to note
• Some one should take charge of the situation.
• Work as a team not as teams of individuals.
• Have a plan
