A moving target: Image guidance for stereotactic body radiation therapy for early-stage non-small cell lung cancer

Kilovoltage x-ray matching to bony anatomy is inadequate for accurate positioning when a conventional 3-5 mm margin is employed prior to lung SBRT. Given the treatment techniques used in this study, CBCT image guidance with a 5-mm planning target volume margin is recommended. Further work is required to find determinants of interfraction and intrafraction motion that may help guide the individualized application of planning target volume margins.