IAEA International Atomic Energy Agency

New Dose Limits for the Lens of the Eye

Implications and Implementation

Industrial Radiography

ISEMIR – WGIR Richard VAN SONSBEEK1, John C. LE HERON2, Gonzague ABELA3 ,

Francisco C.A. DA SILVA4 , Razak HAMZAH5 , Thomas A. LEVEY6 ,

Matthias PURSCHKE7 , Kamal SAHAIMI8 , Christian LEFAURE9

1Applus RTD; e-mail: richard.vansonsbeek@applusrtd.com

2International Atomic Energy Agency, Vienna, Austria; e-mail: J.Le.heron@iaea.org 3EDF; Saint Denis, France; e-mail: gonzague.abela@edf.fr

4Institute of Radiation Protection and Dosimetry; Rio de Janeiro, Brazil; e-mail: dasilva@ird.gov.br 5Malaysia Nuclear Agency; Kajang, Malaysia; e-mail: Razak_hamzah@nuclearmalaysia.gov.my

6Acuren Group Inc.; Edmonton, Canada; e-mail: tlevey@acuren.com 7German Society for Non-Destructive Testing (DGZfP); Berlin, Germany; e-mail: pm@dgzfp.de

8CNESTEN, Rabat, Morocco, sahaimi@cnesten.org.ma 9IAEA consultant; Paris, France; clefaureconsult@free.fr

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Industrial Radiography

• A method of Non-Destructive Testing

• Radiation sources:

• Radioactive sources

• X-ray tubes

• Linear accelerators

• Location:

• Shielded enclosures / Radiation Bunkers

• In the field / on the customer' s site

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Gamma Radiography Exposure Device

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Radioactive sources – Energy and Thickness

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Radioactive Sources – Activities and Dose Rates

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X-ray Radiography Equipment

• Typical specification:

• 300 kVp

• 6 mA

• Dosisrate (@ 1 m) 6 tot 20 Sv/h

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Background to ISEMIR

• Information System on Occupational

Exposure in Medicine, Industry & Research

• There are some areas in medicine, industry

and research where radiation uses can lead

to significant occupational exposures

• Both in normal operations and in accident

situations

• But detailed information at the operational

level is lacking

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ISEMIR – the launch

• January 2009, for an initial 3 year period, to

help improve occupational radiation protection

in targeted areas

• 2 Working Groups, initially

• Interventional Cardiology, commenced Feb 2009

• Industrial Radiography, commenced Jan 2010

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Working Group Industrial Radiography

(WGIR)

From left to right: Christian Lefaure, Francisco Da Silva, Kamal Sahaimi, Gonzague Abela,

Richard van Sonsbeek, Matthias Purschke, A. Razak Hamzah, John Le Heron

(Thomas Levey is not on the picture)

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Objectives of the efforts of WGIR

Supporting the Industry in keeping ALARA:

1. the dose due to normal exposure • if normal exposure is justified!

2. the risk of exposure due to accidents • (risk: combination of chance and consequence)

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Site Radiography – Gamma Radiography

Typical Stages during Normal Exposure

1. Storage of gamma source in storage facility

2. Movement of gamma source from store to vehicle

3. Transport of gamma source in vehicle to field location / client site

4. Movement of gamma source from vehicle to work site

5. Exposure(s) (after set up of equipment

a) Wind-out (gamma source in guide tube)

b) Exposure (gamma source in collimator)

c) Wind-in (gamma source in guide tube)

6. Movement of gamma source from work site to vehicle

7. Transport of gamma source in vehicle to store

8. Movement of gamma source from vehicle to store

9. Go to 1.

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When using databases on individual doses, be

aware that in general we are comparing…

Apples Pears

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≠

with

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Differences in average dose per person

Relatively high(er) dose Relatively low(er) dose

Single disciplinary technicians (RT) Multi disciplinary technicians (RT, UT, .)

Only RT technicians included Non RT technicians included

High workload (# films, # hours) Low workload (# films, # hours)

“Mobile” radiography (less shielding) “Fixed” Radiography (more shielding)

Thick objects tested Thin objects tested

High source strength Low source strength

High production requirement Low production requirement

Exposure due to accident Normal exposure

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Dose distribution

• The radiographer data are for

234 radiographers, the NDT

company data are for nearly

3500 radiographers, and the

regulatory body data are for

over 16,000 radiographers

• Average dose

• Radiographer data: 3.4 mSv

• RB data: 2.9 mSv

• 2% of radiographers in 2009

Effective doses > 20 mSv

• Causes?

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Dose versus workload

• No correlation found • Radiation protection in industrial

radiography is not being effectively

optimized

• Mean occupational dose per

radiographic exposure • 4.8 ± 2.3 μSv for all operators

• 2.9 ± 1.2 μSv for operators with

workload > 100 exposures

• No effect on dose per exposure

found with: • level of NDT training

• type of sources being used,

• activity of sources,

• use of collimation, or

• incidence of events

• But limited data numbers 10/8/2012 15

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Eye Lens Dose

Industrial Radiography

• Not monitored

• No information available

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New Dose Limits for the Lens of the Eye

Implications for Normal Exposures

• Current consensus of WGIR for Normal

Exposures during Industrial Radiography (After reading SSK report “Monitoring the Eye Lens Dose”)

• No need for additional monitoring

• Body is exposed uniformly (large distance to source)

• Effective Dose is a good estimate for Eye Lens Dose

• No need for additional protective measures

• Eye Lens Dose would obviously also benefit

from Dose Constraints / Action Levels put on

Effective Dose

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New Dose Limits for the Lens of the Eye

Implications for Accidental Exposures

• General Accident Scenarios

• Source not retrieved in shielded position

• Observed (proper survey) or not (improper survey)

• Source is lost at worksite

• Source is rupted

• Effective dose probably not good estimate

• Shorter distances between source and body

• No uniform exposure of body

• Higher exposure to eye lens very likely

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New Dose Limits for the Lens of the Eye

Implications for Accidental Exposures

• Additional monitoring and protective

measures in case of radiation incidents?

• Emergency preparedness and response

• Emergency equipment / tools

• Reconstruction of Eye Lens Dose in case of

radiation accidents?

• Is there any real benefit?

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Thank you!