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  Radiation
Protection
Radiation Protection is a preventive discipline which involves medical,
physical, technical and normative contents. It aims at preserving
workers' health by reducing health risks arising from ionizing radiations
in the different activities that entail exposure to these radiations.
Two professional figures are in charge of the medical and physical
surveillance of the radiation protection. The first figure is represented
by the authorised doctor (according to the law 230/95 that allows the
awarding of such title only to the Specialist in Occupational Medicine,
upon successfully sitting an examination with a special commission
established by the Ministry of Labour and Social Securety).
The second figure is the qualified expert, as decreed by the same law,
and it is reserved to physicists, technicians and engineers, who
successfully sat the appropriate examination.
The main dosimetric quantities of radiation protection indicated in the
ICRP (International Commission on Radiological Protection) Recommendation
n.60 of 1990 are:
- the average dose absorbed in a tissue or organ (DT), i.e. the energy
absorbed for a unit of mass;
- the equivalent dose in a tissue or organ (HT) obtained by multiplying
the absorbed dose by a pondering factor for the radiation (WR);
- the effective dose (ED) obtained by multiplying the equivalent dose
with the pondering factor specific of the tissue (WT).
The unit of measure of the absorbed dose is the Gray (Gy), whereas that
of the equivalent dose and of the effective dose is the Sievert (Sv).
The limits recommended by the IRCP n.60, to which the national normative
law complies (230/95), are indicated in the following table:
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workers
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peoples
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Effective
dose
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20
mSv/year
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1
mSv/year
|
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Equivalent
dose for organ
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|
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-crystalline
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150
mSv/year
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15
mSv/year
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-skin
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500
mSv/year
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50
mSv/year
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-hands,
feet
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500
mSv/year
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50
mSv/year
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As indicated in the law 230/95, radiation protection surveillance is
linked both to the presence of areas classified as controlled zone and
supervised zone that can be disconneted and to the presence of workers
classified as exposed.
For controlled zone it is meant any working area where workers can exceed
the following doses:
- 6 mSv of global exposure or of effective dose;
- 3/10 of one of the dose limits for the crystalline lens, the skin, the
hands, the forearms, the feet and the ankles.
For supervised zone it is meant any working area where workers are at
risk of exceeding the dose limits fixed for persons of the public.
The exposed workers are classified into category A or B depending on
whether they are at risk of exceeding one of the dose limits indicated
for the definition of the controlled zone.
The physical surveillance of the radiation protection is the duty of the
competent expert, as already mentioned. The competent expert has the duty
to delimit the zones, to evaluate both the exposures and the individual
doses absorbed by professionally and fortuitously exposed workers, to
check the effectiveness of the technical protective devices and to verify
both the functioning of the protective measuring instruments and their
correct employment. On the other hand, medical surveillance is the duty
of the authorised doctor. More precisely, according to the new
legislation, medical surveillance of category A workers must be carried
out every six months only by the authorised doctor. On the contrary,
medical surveillance of category B workers can be carried out by the
competent doctor yearly. Exceptional medical surveillance still falls
solely within the authorised doctor's competence.
Medical surveillance consists of a series of specific diagnostic,
prognostic and therapeutical actions. It is carried out through
assessments different in nature that concern altogether:
- the preventive assessment and the periodical check of the fitness for
work, on the basis of the specific risk the worker is exposed to, and also
the scheduling and evaluation of the specialistic and biological
dosimetry exams, including the written report of the fitness for work
evidence to the employer;
- the activity of diagnostic and therapeutical intervention in the case
of an accidental overexposure or contamination;
- the forensic medicine activity concerning the mandatory health and
dosimetric archives as well as the assessment and notification for any
occurred accident or occupational disease.
Measures to contain risk
Should any external irradiation risk exist, as in the case of assistance
to non-cooperating patients who need to have an exam taken or who need
therapy, the nurse must either wear the overall and the plumbed
protective gloves or stay behind a protective screen, avoiding the direct
beam of rays.
When attending patients who have received radionuclides for diagnostic or
therapeutical purposes, especially if highly radioactive preparations
have been employed, protective gloves must be employed during the
manipulation of biological liquids, clothes and linen to reduce exposure.
Other measures to reduce exposure in these cases include both the
collection of any excretion with the appropriate devices and the
delimitation of an area around the patient, as well as the reduction to
the minimum of the assistance time.
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