Actualised Laws about Atomic Energy: How to Apply them at Workplaces
Exposed to Ionising Radiation?
T. Milassin, and Á. Kovács
State Public Health Service, Csongrád County Institute, Szeged,
Hungary
CEJOEM 1997, Vol.3. No.4.:340
As it is known, the laws about nuclear energy were reconstructed in a modernised
compact structure, conformably with the European laws in the years 1996
and 1997. The renewed laws reduced the upper limit of personal dose into
20 mSv/year from the former 50 mSv/year.
We have a problem now: how can they be enforced
in order to assure the compliance with the reduced dosage limit of employees?
We chose the most dangerous workplaces for judging what changes are needed
to be introduced to “keep up” with the new 60% reduced limits.
In our region the highest risk is to be found at
the medical radiotherapical institutions and the diagnostic laboratories
that are working with radiating isotopes, sometimes in open vials.
We checked the dose of ionising radiation in the
exam-rooms where the physicians, physicists and the manual operators spend
most of their working time. We measured the radiation in the immediate
neighbouring area of the radiotherapic equipment and also in the controller’s
zone. Measurements were also done in the waiting zones for the patients.
For this region there are convenient, very low dose rate limits, only 2
mSv/year – for the same person yearly.
Having completed all the measurements the personal
dose can be calculated at the working points. At each measurement point
there can be several persons, each of them with a different and individual
factor to his/her occupation. Considering all the variations would take
too much time, therefore we chose the modeling of a full-time man to be
the ICRP Reference Man.
The computed yearly doses based on the model agreed
well with the measured personal doses. In assessing the personal dose the
values evaluated by the Dosimetry Laboratory of the “Frédéric
Joliot-Curie” National Research Institute for Radiobiology and Radiohygiene,
were considered.
The largest diagnostic laboratory was also checked
where the full-time employees are working with radionuclides. According
to the measurements one of the sources of the radiation can be the patients
themselves. The practicing physician and the assistance can get irradiation
from their patients.
In this case the compiled dose was based on a statistically
modelled place-time configuration. Extreme personal dose was measured on
hands, eyes and forearms. The compiled dose was calculated by the weighting
factors of ICRP given the known number of the personal dose. Based on the
results the most dangerous areas in medicine are laboratories with radioisotopic
methods.
The good agreement between the dosimetric data and
the compiled dose gave us an idea: the irradiation of the personnel in
the examined Hungarian medical workplaces was lower than the confirmed
dose limit because of the protection against the ionising radiation was
more effective than it was expected by the old law. Consequently, it wont’t
be too difficult to comply with the new laws that gave more personal safety.
In special areas, e.g. at invasive radiology and
some other places using radionuclid-methods, we should expect more measurements
and other new measures to comply with the new rules that the higher safety
requires.
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