Impact of coronal and sagittal views on lung gross tumor volume delineation.
OBJECTIVE
To study the impact of coronal and sagittal views (CSV) on the gross tumor volume (GTV) delineation on CT and matched PET/CT scans in non-small cell lung cancer.


METHODS
GTV delineations were performed by 11 experienced radiation oncologists on CT and PET/CT in 22 patients. Two tumor groups were defined: Group I: Primary tumors surrounded by lung or visceral pleura, without venous invasion, and without large extensions to the chest wall or the mediastinum. Group II: Tumors invading the hilar region, heart, large vessels, pericardium, and the mediastinum and/or associated with atelectasis. Tumor volumes and inter-observers variations (SD) were calculated and compared according to the use of axial view only (AW), axial/coronal/sagittal views (ACSW) and ACSW/PET (ACSWP).


RESULTS
CSV were not frequently used (57.4% out of 242 delineations on CT). For group I, ACSW didn't improve significantly mean GTVs. SDs were small on CT and on PET (SD=0.3cm). For group II, ACSW had 27-46% smaller observer variation (mean SD=0.7cm) than AW (mean SD=1.1cm). The smaller observer variation of ACSW users was associated with, on average, a 40% smaller delineated volume (p=0.038). Mean GTV of ACSWP was 21% larger than mean GTV of ACSW on CT.


CONCLUSIONS
For smaller lung tumors surrounded by healthy lung tissue the effect of multiple axis delineation is limited. However, application of coronal and sagittal windows is highly beneficial for delineation of more complex tumors, with atelectasis and/or pathological lymph nodes even if PET is used.
Georges Pompidou European Hospital, Paris, France.
Isabelle
I
Fitton
The Netherlands Cancer Institute/Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands.
Joop C
JC
Duppen
University Medical Center Groningen, Groningen, The Netherlands.
Roel J H M
RJ
Steenbakkers
University Medical Center Groningen, Groningen, The Netherlands.
Heidi
H
Lotz
ERASMUS University Medical Center, Rotterdam, The Netherlands.
Peter J C M
PJ
Nowak
Academic Medical Center, Amsterdam, The Netherlands.
Coen R N
CR
Rasch
University of Manchester, c/o Christie Hospital NHS Foundation Trust, Manchester, United Kingdom. Electronic address: marcel.vanherk@manchester.ac.uk.
Marcel
M
van Herk
D000465:Algorithms; D001918:Brachytherapy / Q000379:methods; D002138:Calibration; D003198:Computer Simulation; D004583:Electrons; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008168:Lung / Q000000981:diagnostic imaging*; D009010:Monte Carlo Method; D017785:Photons; D011336:Probability; D015203:Reproducibility of Results; D012984:Software; D035501:Uncertainty
Coronal view; Inter-observer variability; Lung cancer; Radiotherapy; Sagittal view; Target delineation