Interobserver agreement between interpretations of acute changes after lung stereotactic body radiotherapy.

PURPOSE Stereotactic body radiation therapy (SBRT) is an effective treatment modality for inoperable early-stage lung cancer or metastatic lung lesions. Post-SBRT, acute radiological lung changes sometimes mimic tumor progression, so over-investigation may be applied. We aimed to reveal the interobserver agreement among physicians regarding acute radiographic changes on CT of the thorax obtained shortly after SBRT MATERIALS AND METHODS: Radiologic images of 20 lesions treated with SBRT were evaluated for acute lung changes. Two physicians, one senior and one junior, from diagnostic radiology, radiation oncology, nuclear medicine, and chest disease departments reviewed these images. The final interpretations were categorized as stable, regression/consolidation, progressive disease, and SBRT-related changes. The evaluations of the physicians were compared with the experienced reference radiation oncologist. The gold standard was accepted as the reference physician's final score. Unweighted Cohen's kappa (κ) coefficient was used for assessing interobserver agreement between physicians. RESULTS The evaluations of the physicians were compared with the reference radiation oncologist. The strongest coherence coefficient was found with the senior radiation oncologist (κ: 0.72). The kappa coefficients between the junior radiation oncologist, junior nuclear medicine physician, and the reference physician were 0.61 and 0.55, respectively. The disciplines with the lowest kappa coefficients were junior chest disease and senior radiologist, and the kappa values were 0.37 and 0.44, respectively. CONCLUSION Disciplines dealing with lung cancer treatment may not be aware of the various radiologic changes after SBRT or inexperienced in interpreting them from recurrence. Therefore, physicians must have detailed radiotherapy information such as planning target volume (PTV), dose/fractionation, etc. In addition, final evaluations should be performed in the multidisciplinary team dealing with the treatment of the patient.