Deviations in delineated GTV caused by artefacts in 4DCT

TY - JOUR

T1 - Deviations in delineated GTV caused by artefacts in 4DCT

AU - Persson, Gitte Fredberg

AU - Nygaard, Ditte Eklund

AU - Brink, Carsten

AU - Jahn, Jonas Westberg

AU - Munck af Rosenschöld, Per

AU - Specht, Lena

AU - Korreman, Stine Sofia

N1 - Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

PY - 2010/7/1

Y1 - 2010/7/1

N2 - Background and purpose: Four-dimensional computed tomography (4DCT) is used for breathing-adapted radiotherapy planning. Irregular breathing, large tumour motion or interpolation of images can cause artefacts in the 4DCT. This study evaluates the impact of artefacts on gross tumour volume (GTV) size. Material and methods: In 19 4DCT scans of patients with peripheral lung tumours, GTV was delineated in all bins. Variations in GTV size between bins in each 4DCT scan were analysed and correlated to tumour motion and variations in breathing signal amplitude and breathing signal period. End-expiration GTV size (GTVexp) was considered as reference for GTV size. Intra-session delineation error was estimated by re-delineation of GTV in eight of the 4DCT scans. Results: In 16 of the 4DCT scans the maximum deviations from GTVexp were larger than could be explained by delineation error. The deviations were largest in the bins adjacent to the end-inspiration bin. The coefficient of variation of GTV size was significantly correlated to tumour motion in the cranio-caudal direction, but no significant correlation was found to breathing signal variations. Conclusion: We found considerable variations in GTV size throughout the 4DCT scans. Awareness of the error introduced by artefacts is important especially if radiotherapy planning is based on a single 4DCT bin.

AB - Background and purpose: Four-dimensional computed tomography (4DCT) is used for breathing-adapted radiotherapy planning. Irregular breathing, large tumour motion or interpolation of images can cause artefacts in the 4DCT. This study evaluates the impact of artefacts on gross tumour volume (GTV) size. Material and methods: In 19 4DCT scans of patients with peripheral lung tumours, GTV was delineated in all bins. Variations in GTV size between bins in each 4DCT scan were analysed and correlated to tumour motion and variations in breathing signal amplitude and breathing signal period. End-expiration GTV size (GTVexp) was considered as reference for GTV size. Intra-session delineation error was estimated by re-delineation of GTV in eight of the 4DCT scans. Results: In 16 of the 4DCT scans the maximum deviations from GTVexp were larger than could be explained by delineation error. The deviations were largest in the bins adjacent to the end-inspiration bin. The coefficient of variation of GTV size was significantly correlated to tumour motion in the cranio-caudal direction, but no significant correlation was found to breathing signal variations. Conclusion: We found considerable variations in GTV size throughout the 4DCT scans. Awareness of the error introduced by artefacts is important especially if radiotherapy planning is based on a single 4DCT bin.

U2 - 10.1016/j.radonc.2010.04.019

DO - 10.1016/j.radonc.2010.04.019

M3 - Journal article

SN - 0167-8140

VL - 96

SP - 61

EP - 66

JO - Radiotherapy & Oncology

JF - Radiotherapy & Oncology

IS - 1

ER -