EBRO 2017

Target volume definition

GTV:

Gross tumor volume: Use all information available from clinical examination and imaging (physician drawing target volume must have examined the patient!)

CTV:

GTV + potential routes of subclinical spread GTV - CTV margins: fixed margins generally don ’ t work

• Soft tissues: generous margins (1-1.5 cm) • Bone, cartilage, air cavities: tighter margins • Known routes of spread: Nasopharynx: cavernous sinus • Neck nodes: 0.5 cm; if extranodal growth ≥ 1.0 cm

PTV: CTV - PTV margins: • 5 mm is generally adequate

• Can be reduced to 2-3 mm with customized positioning and immobilization devices and DPI/CBCT-based correction protocols. To 1-2 mm with robust fixation and CBCT online.