Physics and Engineering of Radiation Detection

11.2. Quantities Related to Dosimetry 607

Table 11.2.1: Quality Factors for Different Types of Particles.

Type of Radiation Quality Factor (QR)

x-rays,γ-rays 1

Electrons, Muons 1

α-Particles 20

Fission Fragments 20

Heavy Nuclei 20

Protons 5-10

Neutrons with E < 10 keV 5

10-100keV 10

> 100 keVup to 2MeV 20

2-20MeV 10

> 20 MeV 5

The equivalent doses due toγ-rays and neutrons are given by

HT,γ = wγ·DT,γ

= (1)(20)

=20mSv

HT,n = wn·DT,n

= (5)(2)

=10mSv

The total dose received by the person is then sum of these individual doses,

that is

HT = HT,γ+HT,n

=20+10

=30mSv

A.4 EffectiveDose

The equivalent dose as described above can be used for one tissue type only as it
does not address the sensitiveness of tissue types to the same type of radiation.
Thequestionis,howwecandeterminethewholebodyequivalentdosetoestimate
the risk associated with a certain type of radiation environment. Or how one can
estimate the whole body dose if the dose received by a particular organ is known.
This is done by using the quantityeffective dose, defined through the relation

E=wT·HT, (11.2.4)