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ICRP: What It Does and Why
Dr Jack Valentin
Scientific Secretary, ICRP
 
International Commission on Radiological Protection
ICRP: Who, why, what?
 
The 2007 Recommendations
Justification (political) – optimisation – limits & constraints
Focus on the exposure situation; include non-human species
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Related guidance
Recent reports; work in the pipeline
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Topical advice
Recent reports; work in the pipeline
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About ICRP
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ICRP, an Independent Registered
Charity
Established to advance for the public benefit
the science of Radiological Protection,
in particular by providing recommendations
and guidance
on all aspects of protection against ionising
radiation.
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Structure of ICRP, 2005 – 2009
Main Commission
Chair: Dr L-E Holm, SE
12 other members
C1- Radiation Effects Dr R J Preston, US
Scientific
Secretariat
Dr J Valentin, SE
C2- Doses from Radiation Exposure Dr H Menzel, CH
C3- Protection in Medicine Dr C Cousins, UK
Task Groups
C4- Application of ICRP Recommend:s Dr A Sugier, FR
Working Parties
C5-Prot. of the Environment Prof J Pentreath, UK
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Structure of ICRP, 2005 – 2009
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Structure of ICRP, 2005 – 2009
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ICRP In The Cosmic Scheme
Basic Scientific Studies
Scientific Evaluations (UNSCEAR, BEIR etc.)
ICRP Recommendations
Regional (PAHO, EC,
NEA) & Topical (ILO,
WHO, FAO) Stand’s
International Safety
Standards: BSS (IAEA)
National
Regulations
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Industry Stand’s
(ISO, IEC)
Demonstration
of Compliance
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The 2007
Recommendations
of ICRP
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Why Are We Updating…
 
New biological & physical information
Validity of the LNT model? (Linear, No Threshold)
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Increasing use of radiation in medicine
Increase professional awareness?
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Post-Chernobyl lessons; inclusion of natural exposures
Coherent, consistent implementation of ICRP Publication 60?
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Protection of the environment
Scientific proof of adequate protection?
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ICRP 1990 Rec’s: Logical But
Complex
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Aims of the Revision
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Take account of new science
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Feed back experience of current radiation safety standards
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Improve & streamline the presentation
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Use an open, transparent process (9 years gestation!)
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Maintain as much stability as is consistent with the new
information
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To Get the
Recommendations…
 
Buy printed or electronic copies
IRPA Associated Societies are eligible for a discount
 
Developing countries: free download at HINARI
 
Junior staff: summary in JRP
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For all of this, see www.icrp.org
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Or translate them
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In Brief, the
Recommendations…
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Retain the fundamental principles of protection
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Clarify how they apply to sources and the individual
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Change the focus from process (practice/intervention)
to exposure situation (planned/emergency/ existing)
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Extend the concept of source-related constraints to
all situations
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Update weighting factors and detriment
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Maintain the current dose limits
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And for more details, welcome to Background
Plenary II, tomorrow afternoon!
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In Support of The
2007 Recommendations
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Publication 99: Low-Dose
Cancer Risk
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Focus on doses below dose limits
Validity of the LNT model? (Linear, No Threshold)
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LNT: Scientifically plausible but not unambiguous
(cf. Central Limit Theorem, i.e., valid at the population level)
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Fractionation / protraction of dose  lower risk
For low dose, divide solid cancer risk by DDREF (Dose, Dose
rate
REduction Factor) = 2
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Uncertain possibility of a threshold ≈ uncertainty in
DDREF
Anyway, evidence not in favour of a universal threshold
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Publication 101: (a) Representative
Person
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Replaces ‘average member of the critical group’
Representative of the 5% ‘more highly exposed’ – not the most extreme
Check: Reasonable? Sustainable? Homogeneous?
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Dose assessment: deterministic or probabilistic
Prospective (hypothetical person) or retrospective (can be real person)
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Simplified age averaging
Intake coefficients: 6 age groups – Modelling Repr. Person – 3 groups
(age 0-5, 6-15, 16-70)
Remember: age-specific biokinetics, but age-averaged cancer risk
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Involve stakeholders to identify characteristics
Improves quality, understanding, and acceptability
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Publ. 101: (b) Optimisation of
Protection
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Source-related process to keep doses / number exposed /
probability of accidents as low as reasonably achievable
With individual doses below appropriate constraints
Taking account of economic & social factors
An ongoing, cyclical process
A frame of mind – have I done all that I reasonably can?
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Applies to all exposure situations: Planned-EmergencyExisting
Extends and updates, but does not cancel, old advice
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Involve stakeholders
But do not surrender responsibility for final decision!
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Publ. 101: (b) Optimisation, cont’d
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Decision-aiding techniques are, just, useful tools
Optimisation is sound judgement, not mathematics
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Collective dose: a useful, but not
sufficient, input – use matrix!
E.g., local-regional-global;
short-medium-long term;
low-medium-high doses
 
A key parameter (at least in worker
protection), but we usually also need:
average dose, number exposed, range, etc
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Perhaps give more weight to
a few large doses than to many small doses
doses now than to doses in the far future
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Publ. 104: Scope of Radiological
Protection
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Exclusion: Uncontrollable exposures
E.g., natural radionuclides in the body; cosmic radiation at ground level
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Exemption from specified requirements: If unwarranted
In planned situations
Activities conducted justified
Individual risk acceptably small
Protection optimised
No appreciable probability of failure to meet these conditions
<10 uSv/y often exempted – but NOT the sole criterion; exempt on basis of
optimisation, not triviality of dose
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Clearance: a sub-case of exemption
When material/site changes so that a regulatory requirement is no longer
warranted
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Publ. 104: Scope of
Radiol.Protection, cont’d
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Publ. 104: Scope of
Radiol.Protection, cont’d
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Generically derived exemption / clearance levels
Exemption levels: basically, a national regulatory decision
International intergovernmental organisations: useful standardisation
Activity – Activity concentration in low amounts – Activity concentration in
any amount (in a given situation / for unrestricted release)
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Emergency situations: exclusion / exemption irrelevant
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Existing situations: is an intervention justified? Is protection
optimised?
There is no single look-up number!
Regulatory control should achieve net benefit
Requirements should be applied such that protection is optimised
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Publ. 105: Radiation Protection in
Medicine
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Focus on justification and optimisation
Justification for a defined purpose; for an individual patient
Limits and constraints could do more harm than good
Medical condition often more critical than the radiation exposure
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Diagnostic and interventional radiology
Equipment should facilitate dose management
Diagnostic Reference Levels (national/regional/local) for peer achievement
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Radiation therapy
Accident avoidance
Reduction of side effects (including 2nd cancers)
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Comforters / carers, and volunteers in research
Dose constraints appropriate
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Publ. 107: Nuclear Decay Data (in
press)
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An electronic database: half-lives, decay chains, yields, etc
Supersedes Publication 38
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1292 radionuclides of 97 elements, of which 329 with halflives <10 min.
Publ. 38 had 820 radionuclides, of which 56 with half-lives < 10 min
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Data are provided on a CD-ROM in the report
Data presented in a format suitable for dosimetrists
Continuous energy distributions of beta and fission neutrons are given
Tabulation of emitted radiations not restricted by page size!
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Publ. 108, with ICRU:
Reference Phantoms (in press)
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Voxel-based, sex-specific
Adjusted to agree with Reference Man and Woman
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Phantom data provided on a CD-ROM in the report
To permit your own calculations
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Will be the basis of dose [conversion] coefficients for
internal [and external] exposure
Some examples given in the report
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Fetus and child phantoms are in the pipeline
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And in Due Course….
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Dose coefficients for intakes of radionuclides
For occupational and public exposures
Including fetus and breast-feeding infants
Replacing Publ. 30 / 56 / 72 / etc.
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Dose conversion coefficients for external exposures
Together with ICRU
Replacing ICRP Publ. 74 = ICRU Report 57
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Topical reports
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Recent & Current Reports
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Publication 100 – the Human Alimentary Tract (HAT)
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Supporting Guidance 5 – Criteria behind ICRP levels
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Publ 102 – Multi-Detector CT
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Publ 106 – Radiopharmaceuticals, P 53 Add. 3 (in press)
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Publ XX – Reference Animals and Plants
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Publ XX – Radiological protection in cardiology
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Publ XX – 2nd cancers and new radiotherapy techniques
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Publ XX – Avoiding accidents with new radiotherapy
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…and ICRP Work Continues – Thank
You!
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