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only principles applicable remain those of justification
and optimisation (see introduction to this chapter).
The patient’s exposure situation differs depending on
whether diagnostic or therapeutic medical applications
are being considered. In the first case, it is necessary
to optimise the exposure to ionising radiation in order
to deliver the minimum dose required to obtain the
appropriate diagnostic information or to perform the
planned interventional procedure; in the second case, it
is necessary to deliver the highest possible dose needed
to destroy the tumour cells while at the same time
preserving the healthy neighbouring tissues to the best
possible extent.
Whatever the case however, control of the doses delivered
during imaging examinations and treatments is a vital
requirement that depends not only on the skills of the
patient radiation protection professionals but also on the
procedures for optimising and maintaining equipment
performance.
The steps undertaken by ASN since 2011 in collaboration
with the health Authorities and medical imaging
professionals are designed to progressively ensure fully
effective control over the doses delivered to patients.
Manymeasures have been taken in this respect, including
the updating and reinforcement of training in patient
radiation protection for interventional practitioners in
particular, the development of a quality assurance baseline
in the radiology departments and centres provided for
in Cancer Plan 3, the development of access to MRI
and the defining of reference levels for the most highly
irradiating interventional procedures.
5.1.3 Exposure of the general public
and environmental impact
With the exception of incident situations, the potential
impact of medical applications of ionising radiation is
likely to concern:
•
members of the public who are close to facilities that
emit ionising radiation but do not have the required
protection;
•
persons close to patients having received a treatment or a
nuclear medicine examination, particularly those using
radionuclides such as iodine-131, or a brachytherapy
with iodine-125;
•
the specific professional categories (e.g. sewage
workers) liable to be exposed to effluents or waste
produced by nuclear medicine unit.
The available information concerning radiological
monitoring of the environment carried out by IRSN
(Institute of Radiation Protection and Nuclear Safety), in
particular the measurement of ambient gamma radiation,
on the whole reveals no significant exposure level
above the variations in the background radiation. On
the other hand, radioactivity measurements in major
rivers or wastewater treatment plants in the larger towns
occasionally reveal the presence of artificial radionuclides
used in nuclear medicine (e.g. iodine-131) exceeding
the measurement thresholds. The available data on
the impact of these discharges indicate doses of a few
tens of microsieverts per year for the most exposed
individuals, in particular people working in the sewerage
networks and wastewater treatment plants (source: IRSN
studies, 2005 and 2014). Furthermore, no trace of these
radionuclides has ever beenmeasured in water intended
for human consumption (see chapter 1).
The persons close to patients having been treated with
radiopharmaceuticals (e.g. treatment of thyroid cancer
or hyperthyroidism with iodine-131) can be exposed
to ionising radiation for a few days due to the residual
activity in the patient. ASN published recommendations
in this subject in 2007, and in February 2012, the
association of Heads of European Radiological Protection
Competent Authorities (HERCA) proposed a model
of a European card to be given to each patient leaving
hospital after treatment with iodine-131. This card
provides information to those who may be concerned,
such as health professionals having to treat the patient or
border authorities, that the person has been administered
radionuclides.
5.2 Some general indicators
5.2.1 Licences and declarations
In 2015, ASN issued:
•
4,794 acknowledgements of receipt of declarations of
medical and dental diagnostic radiology devices, of
which nearly 77%concerned dental radiology devices;
•
663 licenses (for entry into service, renewal or
cancellation), of which 48% were in computed
tomography, 26% in nuclearmedicine, 20% in external-
beam radiotherapy, 5% in brachytherapy and 1% for
blood product irradiators.
5.2.2 Dosimetry of health professionals
According to the data collected in 2014 by IRSN,
226,013 peopleworking in sectors using ionising radiation
for medical and veterinary purposes were subject to
dosimetricmonitoring of their exposure.Medical radiology
(52%) and dental care (22%) alone account for nearly
74% of the medical personnel exposed.
More than 98%of the health professionals monitored in
2014 received an annual effective dose below1millisievert
(mSv). Seven exceedances of the annual effective dose
limit of 20mSv were recorded (one in nuclear medicine
and 6 in interventional and diagnostic radiology) and
one case where the annual dose limit at the extremities
(500 mSv) was exceeded was reported in diagnostic
radiology.
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CHAPTER 09:
MEDICAL USES OF IONISING RADIATION
ASN report on the state of nuclear safety and radiation protection in France in 2015