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Annex II Radiation and tissue weighting factors as referred to in points (25) and (33) of Article 4

United Kingdom

A.

Radiation weighting factors

Radiation type	w_R
Note: All values relate to the radiation incident on the body or, for internal radiation sources, emitted from the incorporated radionuclide(s).
Photons	1
Electrons and muons	1
Protons and charged pions	2
Alpha particles, fission fragments, heavy ions	20
Neutrons, E_n < 1 MeV	$2,5 + {18,2 e}^{- {[\ln (En)]}^{2} ∕ 6}$
Neutrons, 1 MeV ≤ E_n ≤ 50 MeV	$5,0 + {17,0 e}^{- {[\ln (2 En)]}^{2} ∕ 6}$
Neutrons, E_n > 50 MeV	$2,5 + {3,25 e}^{- {[\ln (0,04 En)]}^{2} ∕ 6}$

B.

Tissue weighting factors

Tissue	w_T
The w_T for the remainder tissues (0,12) applies to the arithmetic mean dose of the 13 organs and tissues for each sex listed below. Remainder tissues: adrenals, extrathoracic (ET) region, gall bladder, heart, kidneys, lymphatic nodes, muscle, oral mucosa, pancreas, prostate (male), small intestine, spleen, thymus, uterus/cervix (female).
Bone-marrow (red)	0,12
Colon	0,12
Lung	0,12
Stomach	0,12
Breast	0,12
Remainder tissues^f1	0,12
Gonads	0,08
Bladder	0,04
Oesophagus	0,04
Liver	0,04
Thyroid	0,04
Bone surface	0,01
Brain	0,01
Salivary glands	0,01
Skin	0,01

Annotations

Footnotes

f1: The w_T for the remainder tissues (0,12) applies to the arithmetic mean dose of the 13 organs and tissues for each sex listed below. Remainder tissues: adrenals, extrathoracic (ET) region, gall bladder, heart, kidneys, lymphatic nodes, muscle, oral mucosa, pancreas, prostate (male), small intestine, spleen, thymus, uterus/cervix (female).