Radiation Protection. Internal/External Hazard Internal hazardInternal hazard arises through...

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