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Margins and number of fractions
•
If the number of fractions decreases (eg
HYPOFRACTIONATION
)
the “random” component becomes more “systematic” (ie a “shift”)
•
Effective systematic uncertainty (shift)
•
Effective random uncertainty (blur)
SBRT 2017 - D. Verellen
Σ
eff
= Σ
2
+
1
N
σ
2
σ
eff
=
1
−
1
N
⎛
⎝⎜
⎞
⎠⎟
σ
2
N
→
1