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Geometrical uncertainties in brachytherapy
•
Reconstruction uncertainties
➢
Specification of sources relative to anatomy
➢
Equivalent to EBRT set-up uncertainties
•
Internal movement (relative to applicator)
➢
Target: depends on applicator
▪
Intracavitary cervix BT: applicator moves with cervix?
▪
Prostate (and breast) needle implant: movement along
needles
➢
OAR: volume and location changes relative to
BT implant
•
Translating geometric uncertainties to dosimetric
uncertainties for D
90
target, D
2cm³
OAR
© K Tanderup
Hoskin et al 2003, R&O 68