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Page 2
Oliver Jäkel
Medical Physics
Linear Energy Transfer (LET)
Replacing the maximum energy transfer by
the Bethe formula in relativistic form:
2
2
22 2
2
2
2
2 ln
I
cm N zC LET
e
e
For a typical cut-off of
=10keV (
m range), for a proton at 10 and 100 MeV,
the ratio of LET
to dE/dx is 0.93 and 0.8, resp.
Restricted
LET is the energy loss within a certain volume around the track
LET
is well defined quantity for single species of monoenergetic
particles (that we never have)…
For ions, mostly LET
is used, which equals dE/dx !