Image-Guided Radiotherapy in Lung Cancer
Technological advances in image guidance have led to improvements in outcome for lung cancer patients treated with radiation therapy. In particular advancements in 2-Dimensional to now 3 and 4-Dimensional treatment planning as well as the use of functional imaging such as FDG-PET/CT have allowed for more accurate targeting of radiation therapy to areas of disease while limiting collateral damage to surrounding normal tissue. Patient specific margins are now applied to individual patients and are substantially less than what has been used in the previous era. This has allowed for radiation dose-escalation to the tumor while maximally sparing the surrounding organs at risk and has translated into improved tumor control and decrease in toxicities clinically. In-treatment room stereoscopic X-ray imaging with or without implanted fiducial markers as well as volumetric kilovoltage or megavoltage cone-beam CT have allowed clinician to reliably deliver the planned treatment daily to the intended target despite the smaller margins of error. Image-guidance is an important evolving component of radiation therapy for lung cancer and is an area of intense research interest.