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!
RBE is the ratio of the dose of some “standard”
radiation to the dose of the radiation of interest
to produce the same biological effect
!
The “standard” radiation is either orthovoltage
X rays (~250 kVp) or
60
Co gamma rays
!
RBE increases with increase in LET up to a
maximum at ~100 keVµm
-1
, and thereafter
decreases due to the “overkill” effect
Conclusions 3