92 / 1544
Patient History:
Male, 74 years old:
7/2009: primary disease: cT4N3M0, treated induction
chemo , consolidation RT
8/2010: metastatic disease: Tarceva
5/2012: progression of
solitary metastasis lower
left lobe
, RT 2x20 Gy
Delineation:
On 60% phase in stable exhale (
volume 4.30 ccm
)
Size: AP: 2.6 cm, CC: 2.2 cm, LR: 2.2 cm
Motion:
Visicoil marker 0.75 mm diameter, 10 mm length
Amplitude CC of 14mm p2p in 4D CT
PTV definition:
Tracking:
CTV=GTV,
PTV
TR
=CTV + 5mm isotropically
ITV backup plan:
ITV= sum CTV all phases + 5 mm isotropically
(for CBCT guidance)
PTV
ITV
=ITV+5mm isotropically
PTV
TR
= 18.3 ccm
,
PTV
ITV
=30.2
ccm
(39% PTV volume reduction)
Example ITV vs. Tracking approach