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Studies show that interplay effect can
alter the dose distribution of a single
fraction
, but not a fractionated course of treatment.
Dose variation (Jiang et al. )
1 fraction, 1 field: 30%
1 fraction, 5 fields: 18%
30 fractions: 1-2%
SABR
: interplay effect is
negligible
, effects are averaged out due to
•
larger number of MU
•
increased treatment time
Strategies to reduce
interplay effect:
•
↑
n
°
of arcs
•
↓
dose rate
prolonging treatment time
•
avoid MLC motion perpendicular to the tumor motion.
Potential risks: interplay effect
Interplay effect: Lung cancer
Chan JTO 2014, Jiang Phys Med Biol 2003