Particle Therapy 2017

75 / 2605

indirecteffects directeffects
+ O2 to „stabilize“
damage
R
º
+ O2 RO2
º
normoxic
hypoxic
Effect of oxygen in sensitizing cells to radiation
Gray et al.1953
S u r vi vi n g fr a c ti o n
Dose
OER
=
the
ratio
of
dose
in the
absence of oxygen
to
dose
in the
presence
of oxygen needed to
produce the same biological effect.mammalian cells, ratio is usually
2.5 – 3.0
.