Perspectives of Nuclear Physics in Europe - European Science ...

4.6 Nuclear Physics Tools and Applications
to produce MRI scanners that are lightweight, open,
portable and cheaper than the current bulky and claustrophobic
cylindrical magnets.
Radioprotection
In radioprotection, it is normally assumed that the
risk of radiation-induced late effects is proportional
to dose, even at very low doses (linear-no-threshold
or LNT hypothesis). Recent results on non-targeted
radiation effects may radically challenge the current
LNT-based radioprotection paradigm. Non-targeted
effects include:
• bystander effect: radiation effects in cells not directly
exposed to radiation
• genomic instability: mutations and chromosomal rearrangements
in daughter cells, many generations after
the exposure
• abscopal effect: radiation effects in organs not exposed
to the radiation field (observed in radiotherapy)
• systemic reactions: inflammation and tissue-level
radiation damage
• hormesis: low doses of radiation protect cells from
subsequent high dose exposures.
These effects could potentially prove that our current risk
estimates at low doses are either underestimated (e.g. if
the bystander effect increase the risk in non-hit cells) or
overestimated (if hormesis proves to be a relevant adaptive
mechanism for ionizing radiation). The relevance of
hormesis for radiation protection is highly debated, and
the two conflicting recent reports from USA and French
government advisory groups clearly demonstrates that
more experiments are needed to clarify the mechanisms
underlying these processes. Non-targeted effects could
play a role not only in radiation protection, but also in
radiation therapy (Figure 3). For radiation teletherapy
(either by X-rays or charged particles), dose gradientdependent
responses may influence the effect. Tumour
heterogeneity may also lead to non-linear responses
within the treatment field and to longer-range, abscopal
or systemic effects. For radionuclide approaches (such as
those tagged to monoclonal antibodies), the signals from
a few labeled cells may be amplified by bystander signals
within tumours and may also have long-range, abscopal
or systemic effects. Research in this field should be given
high priority, using both X-rays and charged particles.
The impact of this research in other fields is potentially
very high especially in nuclear power plants safety and
radiodiagnostic, but also in imaging technology in other
fields (e.g. the use of body scanners in the airports),
high-altitude flights and space exploration etc.
The role of nuclear physics
in the future
Numerous techniques and tools that have been borrowed
to Nuclear Physics are now directly developed by the
end-users or are commercially available (for instance
cyclotrons for radiopharmaceutical production or protontherapy,
PET devices …). However, given the recent
developments and the growing interest in the subjects
described above, it is clear that fundamental Nuclear
Physics has still an important role to play in health sciences.
Examples are given in the following:
For radiopharmaceutical production:
• The production of novel radioisotopes implies study
of reaction cross sections with proton beams or
on neutron beams produced by light ions reactions,
development of production techniques with
for instance targets sustaining high-intensities, new
radiochemistry schemes….
• The much higher sensitivity of Accelerator Mass
Spectrometry (AMS) for 14 C detection compared to
conventional techniques permits a new approach in
the research of new pharmaceuticals, for instance
to study their metabolism and kinetics. These studies
can be carried out with such small quantities of
substances labelled with 14 C (microdosing) that no
pharmacological effect is detected, providing new
information about the metabolism of pharmaceuticals
particularly at a very early stage or allowing the
test of several substances simultaneously. The use
of a new generation of compact AMS systems dedicated
to biomedical applications allows high sample
throughput in short measurement times and with a
precise yet simple measurement device.
For particle therapy:
• Nuclear physics can contribute to improving codes
used in treatment planning system especially with
further measurements of fragmentation crosssections.
Only around 50% of the carbon ions are
eventually deposited in a deep tumour, the others
undergo nuclear fragmentation. Therefore, accurate
cross-sections are necessary to calculate the
dose-deposition patterns. Mots of the uncertainty is
however related to the RBE, and therefore research
in the field of radiobiology of energetic charged particles
is urgently needed to improve cancer therapy
and assess late effects. These research should be
based at accelerators. In Europe, GSI (Darmstadt,
Germany), GANIL (Caen, France), KVI (Groningen,
The Netherlands), and TSL (Uppsala, Sweden) have
important experimental programmes in the field of
particle radiobiology. Several experiments are also
carried out in many other accelerator facilities, as well
182 | Perspectives of Nuclear Physics in Europe – NuPECC Long Range Plan 2010