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Cell death
disregulation
Radioresistance
Qui cent clonogenic
tumor cells are more
resistant to
low-LET radia6on
!
Possible reasons:
hypoxic, endothelium,
stem cells ?
higher recovery
capaci6es
damage expression
inhibited due to
prolifera6on stop [G0]
squamous cell carcinoma (SCC) in mice,
con4nuous BrDU applica4on,
assessment of micronuclei
micronucleus
Masunaga et al. Radiat Med 2008
Numbers in parentheses are 95% confidence
limits
RBEs:
quiescent tumor cells
immediately aIer treatment
12 h aIer treatment
1.4
(1.35-1.45)
4.35
(4.2-4.5)
1.45
(1.35-1.55)
4.5
(4.35-4.65)
18 keV/µm
74 keV/µm
RBEs:
total tumor cells
immediately aIer treatment
1.25
(1.2-1.3)
3.1
(3.0-3.2)
Par6cles: effect on quiescent cells
(Carbon Ions)