Biomedical Engineering Reference
In-Depth Information
Chapter 22
Chromosome Aberrations by Heavy Ions
Francesca Ballarini and Andrea Ottolenghi
Abstract
It is well known that mammalian cells exposed to ionizing radiation
can show different types of chromosome aberrations (CAs) including dicentrics,
translocations, rings, deletions and complex exchanges. Chromosome aberrations
are a particularly relevant endpoint in radiobiology, because they play a fundamental
role in the pathways leading either to cell death, or to cell conversion to malignancy.
In particular, reciprocal translocations involving pairs of specific genes are strongly
correlated (and probably also causally-related) with specific tumour types; a
typical example is the BCR-ABL translocation for Chronic Myeloid Leukaemia.
Furthermore, aberrations can be used for applications in biodosimetry and more
generally as biomarkers of exposure and risk, that is the case for cancer patients
monitored during Carbon-ion therapy and astronauts exposed to space radiation.
Indeed hadron therapy and astronauts' exposure to space radiation represent two
of the few scenarios where human beings can be exposed to heavy ions. After
a brief introduction on the main general features of chromosome aberrations, in
this work we will address key aspects of the current knowledge on chromosome
aberration induction, both from an experimental and from a theoretical point of
view. More specifically,
in vitro
data will be summarized and discussed, outlining
important issues such as the role of interphase death/mitotic delay and that of
complex-exchange scoring. Some available
in vivo
data on cancer patients and
astronauts will be also reported, together with possible interpretation problems.
Finally, two of the few available models of chromosome aberration induction by
ionizing radiation (including heavy ions) will be described and compared, focusing
on the different assumptions adopted by the authors and on how these models can
deal with heavy ions.
