Radiation weighting factor

The radiation weighting factor or radiation weighting factor , is a term used in radiation protection . It is used for the simplified calculation of the organ dose and thus the effective dose . The radiation weighting factor depends on the type of radiation and the kinetic energy of the particles. In 1990 it replaced the term “ quality factor ”. ${\displaystyle w_{\mathrm {R} }}$

Difference to the relative biological effectiveness

The relative biological effectiveness (RBE) is based on experimentally determined values. On the basis of this scientifically determined relative biological effectiveness, radiation weighting factors were specified for (simplified) use in laws and regulations. The determination of radiation weighting factors is therefore subject to political processes. The values ​​for the radiation weighting factor are set by legal standard in such a way that they reflect the relative biological effectiveness with sufficient accuracy for practical purposes.

Typical radiation weighting factors

Radiation weighting factors according to ICRP 60

Type of radiation	Energy sector	Radiation weighting factor ${\displaystyle w_{\mathrm {R} }}$
Photons (typically gamma rays, x-rays)	all energies	1
Electrons and muons	all energies	1
Neutrons	<10  keV	5
	10-100 keV	10
	0.1-2  MeV	20th
	2 - 20 MeV	10
	> 20 MeV	5
Protons , except for recoil protons	> 2 MeV	5
Alpha particles , fissure fragments , heavy nuclei , recoil nuclei	all energies	20th

To calculate organ doses and the effective dose for neutron radiation in accordance with ICRP 60, in addition to the tabulated values, the continuous function

${\displaystyle w_{\mathrm {R,60} }(E_{N})=5+17\cdot e^{-{\tfrac {1}{6}}\ln ^{2}(2\,E_{N})}}$

can be used, where E _{N is} the numerical value of the neutron energy in MeV. For the types of radiation and energies not included in the table, w _R can be equated to the mean quality factor Q at a depth of 10 mm in an ICRU sphere .

With the ICRP 103, the International Commission on Radiation Protection recommended new radiation weighting factors in 2007.

Radiation weighting factors according to the German Radiation Protection Ordinance in accordance with ICRP 103

Type of radiation	Radiation weighting factor ${\displaystyle w_{\mathrm {R} }}$
Photons	1
Electrons and muons	1
Neutrons	depending on the neutron energy general: ${\displaystyle w_{\mathrm {R,103} }(E_{N})}$ below 30 keV and above 90 MeV: 2.5… 5 for neutrons of just under 1 MeV: 20.7
Protons and pions	2
Alpha particles, fissure fragments, heavy ions	20th

The formula consists of functions combined depending on the energy range:

${\displaystyle w_{\mathrm {R,103} }(E_{N})={\begin{cases}2{,}5+18{,}2\cdot e^{-{\frac {1}{6}}\ln ^{2}(E_{N})},&E_{N}<1{\text{ MeV,}}\\5{,}0+17{,}0\cdot e^{-{\frac {1}{6}}\ln ^{2}(2\,E_{N})},&1{\text{ MeV}}\leq E_{N}\leq 50{\text{ MeV,}}\\2{,}5+3{,}25\cdot e^{-{\frac {1}{6}}\ln ^{2}(0{,}04\,E_{N})},&E_{N}>50{\text{ MeV.}}\end{cases}}}$

See also

• Tissue weighting factor
• Sievert (unit)

References

1. ↑ The StrlSchV does not name any energy range, but it is about ionizing radiation, which actually begins in the ultraviolet
2. ↑ StrlSchV Annex 18 (to §§ 171, 197) dose and measurement parameters
3. ^ The recommendations of the International Commission on Radiological Protection (ICRP) from 2007. ICRP Publication 103. Adopted in March 2007. Publications of the International Commission on Radiological Protection. German edition published by the Federal Office for Radiation Protection. ( pdf Online 1.1 MB) p. 60
4. ↑ ICRP publication 103 p. 62

Please note the information on legal issues!