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PHENOMENOLOGICAL MODELS
• all models predict an
increase in
NTCP when increasing the dose
and the irradiated volume
• they describe the dose-NTCP
relationship through a
sigmoidal
curve
• the dose-volume relationship
differs
for each organ considered; it
may also differ for different endpoints
within the same organ
Parametrization:
Position
dose required to obtain a certain level of response (50%: D
50
)
Steepness
normalized dose response gradient
increase in response for a 1% increase in dose at D
50
level