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Reoxygenation
Oxygen is an
important enhancement factor
for
radiation effects
(very low O2-concentration (<0.5% / 3 mm Hg)
T
he process of reoxygenation is
time, fraction
interval
and probably
fraction size
dependent
Reoxygenation does not completely eliminate
hypoxia
Hypofractionation
Hypoxic cells in tumors dominate their response to
large single doses
of r
adiation
Cell inactivation
and/or
reduction of hypoxia
more
prominent
after high doses.
- highly
unlikely
that reoxygenation would occur
within 2–3 days after hypofractionation