Internal Dosimetry Concepts and Approach

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Internal Dosimetry - Concepts and Approach
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Committed Equivalent Dose

• HxT per unit intake ?wRDRxT

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Committed Effective Dose

• Ex ?wTHxT

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Calculation of Committed Equivalent Dose

• HxT (Integrated retention in S)
• (Equivalent dose in T from unit retention in S)

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Calculation of Committed Equivalent Dose

• HxT 1.6 10-10????(US ? (SEE(T?S)i)
• S j i

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Calculation of Specific Effective Energy

• SEE(T?S)i yi?iAF(T?S)iwRi/MT

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Absorbed Fractions for Photons
B(?d)exp(-?d)/4?d2
Target
Source
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Values of Absorbed Fraction for Alpha and Beta
Particles

• General rule AF1 for T identical to S and AF0
  for T not identical to S
• Special rules apply for the skeleton, the gut and
  the urinary bladder

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Absorbed Fractions for Alpha and Beta Particles
in the Gut

• AF(ML-C)/MML 0.5 ?/MC
• ? 1 for beta particles
• 0 for recoil atoms
• 0.01 for alpha particles and fission
  fragments

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Geometry of the Skeleton
Mineralised Tissue
Red Bone Marrow
Endosteum
Periosteum
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Generalised Compartment Model
k7
k1
Q1
Q2
I
k2
k3
k6
k5
Q3
Q4
k4
dQ1/dt I k1Q2 - (k2k3k7)Q1 -kRQ1
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One Pass Biokinetic Model
Transfer Compartment
Tissue Compartment 2
Tissue Compartment 3
Tissue Compartment 1
Excretion
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Recycling Biokinetic Model for Plutonium
Other Soft Tissue
Liver
Skeleton
Reticulo-endothelial cells
Cortical Volume
Cortical Surface
Cortical Marrow
Hepatocytes
Blood
Subcellular organelles
Trabecular Volume
Trabecular Surface
Trabecular Marrow
Cytoplasma and membranes
Urinary tract tissue
Faeces
Urine
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Biokinetic Model for Strontium
Trabecular Surfaces
Cortical Surfaces
Blood
Trabecular Volume
Cortical Volume
Other Tissues
Excretion
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Standard Ages at Intake

• 3 months (0-12 months)
• 1 year (1-2 years)
• 5 years (2-7 years)
• 10 years (7-12 years)
• 15 years (12-17 years)
• Adult gt17 years

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The New ICRP Lung Model

• Tissues at risk
• Deposition of aerosols
• Clearance of deposited aerosols
• Radiation dosimetry
• Treatment of gases and vapours

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Simplified Geometrical Model of Various Sources
and Targets Involved in Dosimetry of Bronchial
and Extrathoracic Epithelial Tissues
Air
Mucus (Gel)
Cilia (Sol)
Target Cell Nuclei Secretory and Basal Cells
Source in Connective Tissue Lamina
Propria Macrophages
Basement Membrane
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Simplified Geometrical Model of Various Sources
and Targets Involved in Dosimetry of Bronchial
Tissues
Thickness (microns)
Mucus (Gel)
5
Cilia Sol
6
Intermediate
10
30
Nuclei of secretory cells
Basal cells
15
Basement membrane
500
Macrophage layer
Alveolar interstitium
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Model of the Wall of the Nasal Vestibule
Thickness (microns)
Keratin layer
8
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Epithelium
Basal cells
10
Basement membrane
Lamina Propria
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Deposition Treated as a Series of Filters
Inhalability
ET1
ET2n
ET2m
BB
bb
Al
And back out again on exhalation
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Compartment Model of Particle Transport in the
Respiratory Tract
Extrathoracic
Environment
ET1
LNET
ETseq
ET2
GI Tract
Sequestered in tissue
Surface transport
BBseq
BB2
BB1
LNTH
bbseq
bb2
bb1
AI3
AI2
AI1
Thoracic
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Absorption to Blood
Particles in Initial State
Particles in Transformed State
Bound Material
Blood
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Reaction of Gases or Vapours at the Gas Blood
Interface
Airway Lumen
Uptake
Gas or Vapour
Reaction Product
Airway Liquid
Gas/Vapour
Reaction Product
Bound Material
Tissue
Gas/Vapour
Reaction Product
Blood
Gas/Vapour
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Regional Uptake of Inhaled Gases
Solubility
ET
All Regions
SR-2
SR-1
BB bb AI
SR-0
None
Reactivity
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Dose per Unit Intake Values by Inhalation by
Workers

• Radionuclide Dose per Unit Intake (Sv/Bq)
• ICRP30 ICRP61 ICRP68
• H-3 (vapour) 1.7E-11 2.0E-11 1.8E-11
• C-14 (dioxide) 6.4E-12 6.7E-12 6.5E-12
• Co-60 (Y/S) 4.1E-8 5.0E-8 2.9E-8
• I-129 (D/F) 4.7E-8 6.7E-8 3.7E-8
• Ra-226 (W/M) 2.1E-6 2.2E-6 1.6E-5
• Pu-239 (W/M) 1.4E-4 6.7E-5 4.7E-5
• Pu-239 (Y/S) 8.9E-5 6.7E-5 1.5E-5

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Effective Dose per Unit Intake (Sv/Bq) by
Ingestion for Members of the Public
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Dose Ratios Relative to Adult

• Radionuclide 1 year old 10 year old
• H-3 (water) 2.7 1.3
• C-14 2.9 1.4
• Ru-106 7.0 2.1
• I-129 2.0 1.7
• I-131 8.2 2.4
• Cs-137 0.92 0.77
• Pu-239 1.7 1.1
• Np-237 1.9 1.0
• Np-239 7.1 2.1