TY - JOUR
T1 - Interobserver delineation variation in lung tumour stereotactic body radiotherapy
AU - Persson, Gitte Bjørnsen Fredberg
AU - Nygaard, Ditte Eklund
AU - Hollensen, C.
AU - Munck af Rosenschöld, Per Martin
AU - Berthelsen, Anne Kiil
AU - Due, Anne Kirkebjerg
AU - Korreman, Stine Sofia
AU - Roed, Henrik
AU - Nyman, J.
AU - Markova, E.
AU - Roed, A.P.
PY - 2012/9/1
Y1 - 2012/9/1
N2 - Objectives: In radiotherapy, delineation uncertainties are important as they contribute to systematic errors and can lead to geographical miss of the target. For margin computation, standard deviations (SDs) of all uncertainties must be included as SDs. The aim of this study was to quantify the interobserver delineation variation for stereotactic body radiotherapy (SBRT) of peripheral lung tumours using a cross-sectional study design. Methods: 22 consecutive patients with 26 tumours were included. Positron emission tomography/CT scans were acquired for planning of SBRT. Three oncologists and three radiologists independently delineated the gross tumour volume. The interobserver variation was calculated as a mean of multiple SDs of distances to a reference contour, and calculated for the transversal plane (SD trans) and craniocaudal (CC) direction (SD cc) separately. Concordance indexes and volume deviations were also calculated. Results: Median tumour volume was 13.0 cm 3, ranging from 0.3 to 60.4 cm 3. The mean SD trans was 0.15 cm (SD 0.08 cm) and the overall mean SD cc was 0.26 cm (SD 0.15 cm). Tumours with pleural contact had a significantly larger SD trans than tumours surrounded by lung tissue. Conclusions: The interobserver delineation variation was very small in this systematic cross-sectional analysis, although significantly larger in the CC direction than in the transversal plane, stressing that anisotropic margins should be applied. This study is the first to make a systematic cross-sectional analysis of delineation variation for peripheral lung tumours referred for SBRT, establishing the evidence that interobserver variation is very small for these tumours.
AB - Objectives: In radiotherapy, delineation uncertainties are important as they contribute to systematic errors and can lead to geographical miss of the target. For margin computation, standard deviations (SDs) of all uncertainties must be included as SDs. The aim of this study was to quantify the interobserver delineation variation for stereotactic body radiotherapy (SBRT) of peripheral lung tumours using a cross-sectional study design. Methods: 22 consecutive patients with 26 tumours were included. Positron emission tomography/CT scans were acquired for planning of SBRT. Three oncologists and three radiologists independently delineated the gross tumour volume. The interobserver variation was calculated as a mean of multiple SDs of distances to a reference contour, and calculated for the transversal plane (SD trans) and craniocaudal (CC) direction (SD cc) separately. Concordance indexes and volume deviations were also calculated. Results: Median tumour volume was 13.0 cm 3, ranging from 0.3 to 60.4 cm 3. The mean SD trans was 0.15 cm (SD 0.08 cm) and the overall mean SD cc was 0.26 cm (SD 0.15 cm). Tumours with pleural contact had a significantly larger SD trans than tumours surrounded by lung tissue. Conclusions: The interobserver delineation variation was very small in this systematic cross-sectional analysis, although significantly larger in the CC direction than in the transversal plane, stressing that anisotropic margins should be applied. This study is the first to make a systematic cross-sectional analysis of delineation variation for peripheral lung tumours referred for SBRT, establishing the evidence that interobserver variation is very small for these tumours.
U2 - 10.1259/bjr/76424694
DO - 10.1259/bjr/76424694
M3 - Journal article
C2 - 22919015
SN - 0007-1285
VL - 85
SP - E654-E660
JO - British Journal of Radiology
JF - British Journal of Radiology
IS - 1017
ER -