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Target volume definition
Clinical Target Volume (
CTV
): the
CTV includes the GTV
with
an added margin to treat subclinical microscopic disease
and is
anatomically confined
(i.e. the CTV is limited to the confines of the
bony calvarium, falx and tentorium or extend up to but not beyond
neuroanatomic structures surely not invaded by tumor).
The
CTV margin will be 0.5 cm
for all patients.
Planning Target Volume (
PTV
): the PTV is a geometric expansion
of the CTV to take in to account for uncertainties in immobilisation,
daily patient positioning and image registration.
The
PTV margin will be 0.3 cm - 0.5
cm in all directions.
The size of the required margins will depend on the quality of the
immobilization device chosen and the departmental reproducibility
records for the patient position and chosen device.
SIOP Ependymoma II -
PTV1 target volume
Intracranial ependymoma