Siva, Shankar, et al. “Respiratory-Gated (4D) FDG-PET Detects Tumour and Normal Lung Response After Stereotactic Radiotherapy for Pulmonary Metastases”. Acta Oncologica, vol. 54, no. 8, Sept. 2015, pp. 1105-12, doi:10.3109/0284186X.2015.1027409.