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Protons
→
D
eff
(Gy (RBE))= D
abs
(Gy) x 1.1
Protons Gy (RBE) – constant value
ICRU 78 - 2007
All protons are equal
→
the RBE of protons is
1.1
•
Available evidence
→
the magnitude of RBE variation with treatment
parameters is small relative to our abilities to determine RBE.
•
In vitro and in vivo data
→
statistically significant increase in RBE for
(independent on LET, dose, end point,
a/
)…
lower doses per fraction, much smaller for in vivo systems.
•
There is agreement that there is a measurable increase in RBE over the
terminal few millimeters of the SOBP, which results in an extension of the
bio-effective range of the beam in the range of 1–2 mm.