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PTV in practice: oesophagus
Systematic uncertainty
(confidence level)
Σ
(mm)
Σ
2
Snapshot CT
1.32 1.74
Delineation (intra observer)
4.00 16.00
Random uncertainty
(dose blurring)
σ
(mm)
σ
2
Intrafraction organ mobility 1.00 1.00
Interfraction setup (laser)
4.52 20.43
Interfraction setup (laser)
19.13 365.96
Interfraction setup (IGRT)
(intra observer registration)
0.3 0.09
End2end IGRT
(eg PentaCheck)
1.08 1.17
…
QUADRATIC SUM
384.96
Intrafraction patient motion 1.99 3.96
σ
p
3.2 10.24
…
QUADRATIC SUM
35.63
σ
5.97
The PTV 2017 - D. Verellen
Σ
19.62
σ
p
3.2
PTV margin (mm)
53.59
M
=
a
S +
b s
2
+
s
p
2
-
bs
p
α=2.5
β=1.64