Table 4.

Summary of probability distributions of radiation effectiveness factors (REFs) for photons and electrons in IREP.^a

Photonsb		95% confidence interval of REFLc
Energy	Exposure	2.5th percentile	50th percentile	97.5th percentile
>250 keVd	All	—	1.0	—
30–250 keV	All	1.0	1.9	4.7
<30 keV	All	1.1	2.4	6.1
Electronse		95% confidence interval of REFLc
Energy	Exposure	2.5th percentile	50th percentile	97.5th percentile
>15 keVf	All	—	1.0	—
<15 keVg	All	1.2	2.4	5.0

^aAdapted from Table 15 of Kocher et al. (2005). REFs apply to any cancer type.

^bProbability distributions are described in Table 11 of Kocher et al. (2005); distributions are not described by commonly used continuous distributions (e.g., lognormal).

^cREF_L is REF at low doses and low dose rates of reference high-energy (>250 keV) photons.

^dReference radiation with defined REF of unity.

^eProbability distributions are described in Table 13 of Kocher et al. (2005); distribution for electrons of energy >15 keV is lognormal.

^fAn REF_L for 15–60 keV electrons consistent with REF_L for 30-250 keV photons is indicated on theoretical grounds, but is not adopted; see Kocher et al. (2005), Table 13, footnote c.

^gAuger-emitting radionuclides incorporated into DNA are excluded. Beta particles produced in radioactive decay are included if average energy of continuous spectrum of electrons is < 15 keV.