CT-based quantitative evaluation of radiation-induced lung fibrosis: a study of interobserver and intraobserver variations.
OBJECTIVE
The degree of radiation-induced lung fibrosis (RILF) can be measured quantitatively by fibrosis volume (VF) on chest computed tomography (CT) scan. The purpose of this study was to investigate the interobserver and intraobserver variability in CT-based measurement of VF.


METHODS
We selected 10 non-small cell lung cancer patients developed with RILF after postoperative radiation therapy (PORT) and delineated VF on the follow-up chest CT scanned at more than 6 months after radiotherapy. Three radiation oncologists independently delineated VF to investigate the interobserver variability. Three times of delineation of VF was performed by two radiation oncologists for the analysis of intraobserver variability. We analysed the concordance index (CI) and inter/intraclass correlation coefficient (ICC).


RESULTS
The median CI was 0.61 (range, 0.44 to 0.68) for interobserver variability and the median CIs for intraobserver variability were 0.69 (range, 0.65 to 0.79) and 0.61(range, 0.55 to 0.65) by two observers. The ICC for interobserver variability was 0.974 (p < 0.001) and ICCs for intraobserver variability were 0.996 (p < 0.001) and 0.991 (p < 0.001), respectively.


CONCLUSIONS
CT-based measurement of VF with patients who received PORT was a highly consistent and reproducible quantitative method between and within observers.
Department of Radiation Oncology, Ajou University School of Medicine, Suwon, Korea.
Jaesung
J
Heo
Department of Radiation Oncology, Ajou University School of Medicine, Suwon, Korea.
Oyeon
O
Cho
Department of Radiation Oncology, Ajou University School of Medicine, Suwon, Korea.
O Kyu
OK
Noh
Department of Radiation Oncology, Ajou University School of Medicine, Suwon, Korea.
Young-Taek
YT
Oh
Department of Radiation Oncology, Ajou University School of Medicine, Suwon, Korea.
Mison
M
Chun
Department of Radiation Oncology, Ajou University School of Medicine, Suwon, Korea.
Mi-Hwa
MH
Kim
Department of Radiation Oncology, Ajou University School of Medicine, Suwon, Korea.
Hae-Jin
HJ
Park
Fibrosis volume; Interobserver variation; Intraobserver variation; Quantitative CT; Radiation-induced lung fibrosis