Extrusion International 4-2016

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33 Extrusion International 4/2016
endogenous repair mechanism in
the cells. Is this not possible, the
defect cell is replaced by a new cell.
Evidence of radiation damages
Exposure to ionized radiation
contains relative risk. Today, the
biological dosimetry is an interna-
tional recognized method to esti-
mate the dose of a possible exces-
sive radiation exposure. Therefore,
special biological marker are used,
which are like fingerprints in irradi-
ated cells.
Save handling with X-ray devices
Just as clothes offer protection
against the ultraviolet radiation of
the sun, also X-rays can be shield-
ed by suitable materials. Materials
with a so called high atomic num-
ber are especially suitable. Relevant
in this context are steel, copper and
lead. By using this materials, the X-
ray radiation of medium energy, as
it is used in industrial measurement
technology, can be weakened so
much that the omnipresent back-
ground radiation on the outside of
such a device is only slightly or not
at all increased.
Unlike radioactive isotopes, whose
radiation can only be shielded but
not turned off, the radiation of an
X-ray device can be switched off.
Without the anode voltage for
the X-ray tube, no X-ray radiation
is produced. Also, X-ray radiation
cannot cause radioactivity in irradi-
ated materials as the energy of the
X-ray radiation is too low to create
radiant, radioactive isotopes. Even
the X-ray tube, just like all other
inner components of the X-ray de-
vice, is completely free of radiation
after the deactivation of the anode
voltage and can therefore be han-
dled unconcernedly.
Blessing and risks
An especially positive aspect of the
X-ray radiation is its usage when
treating malignant tumors in order
to destroy degenerated cells of the
tumor with high-energy X-ray radi-
ation. This energy sector of about
10 MeV is called gamma radiation.
According to the European directive
96/29/Euratom, X-ray based measur-
ing devices have to be built in a way
that its radiation does not exceed the
maximum value of 1 μSv/h at a dis-
tance of 0.1 m on the outside of the
device. This limit is so low that a sig-
nificant statistical proof for a possible
cancer is not possible.
It may sound astounding, but mod-
ern researches point to the com-
plete opposite direction. Namely,
a small dose of X-ray radiation,
similar to the UV radiation of light,
stimulates the immune system and
therefore, can even be healthy.
X-rays