Radiation Protection Glossary
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The term 'Background' can be applied to either natural 'Background Radiation', or anywhere where a measurement of Ionising Radiation
is required. In analytical Contamination
measurements it is usual to subtract the background count from the source counts of interest.
in our environment which we are all exposed to, the exact magnitude depending on our location in the world. Examples include Radon Gas
, Cosmic Rays
The SI unit for Activity
. The Becquerel (Bq) is equivalent to 1 disintegration per second (dps) . Also see the older unit of activity, the Curie
The beta particle has the form of a high speed negatively charged electron
(or a positively charged electron in the case of the positron
). In beta decay (electron emission) a neutron
in the nucleus
is converted to a proton
with the release of a high speed electron and an antineutrino
. In the example C-14 decays to N-14. Note the atomic number
has increased by one whilst the mass number
at 14 is unchanged. The beta particle is more penetrating than alpha particles
but still much less so than gamma rays
. For every beta emitter there is a unique energy spectrum characterised by average and maximum beta energy. For Tritium (H-3) this is around 18.5 KeV, for C-14 its 156 KeV and for P-32 itís about 1.7 MeV.
Biological dosimetry is a branch of the field of Dosimetry
which uses biological samples, usually taken from individuals who have been exposed to radioactive
materials, as a means to assess intakes by Inhalation
. For example analysis of urine can be used to assess Tritium uptake whilst analysis of faecal matter can be used to determine Actinide
uptake. Biological sampling can also be used to assess direct body Irradiation
from External Radiation
The biological half-life is the time taken for half of a Radioactive
material, (present in a body as a result of Inhalation
), to be eliminated by the biological processes in that body.
Brachytherapy is a cancer treatment where Radioactive
seeds (Sealed Sources
) are placed in or near a tumour, therefore giving a high Radiation
to the tumour while reducing the radiation exposure in the surrounding healthy tissues
Bremsstrahlung, also known as Braking Radiation
occurs when ever a charged particle undergoes a change of velocity as it interacts with an absorber. Electromagnetic Radiation
) are the result. For Radiation Protection purposes, Bremsstrahlung radiation resulting from the interaction of fast moving Electrons
) with shielding materials, are of particular concern. Here, the degree of conversion to Bremsstrahlung radiation and the magnitude of its energy is proportional to the incident electron energy and the atomic number of the absorber. Hence shielding for high energy Beta emitters like P-32, needs low atomic number material such as Perspex.