paediatrics Brussels 17

SIOP Ependymoma II - PTV1 target volume Intracranial ependymoma

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.