ABSTRACT
Recent progress in combined modality treatments, incorporating radiochemotherapy, and the technical advances in radiation delivery and medical imaging, in particular PET, have yielded signicant improvements in treatment outcomes in NSCLC. In radiotherapy, accurate tumor delineation is crucial for preventing geographical misses, and consequently for improving local tumor control.118F-Fluorodyoxydoglucose (18FDG) PET imaging has been shown to add signicantly to the accuracy of conventional anatomic imaging (CT and MRI) in dening the extents of lung disease2,3 and to have higher sensitivity and specicity than CT. e superiority of PET over conventional imaging in detecting distant disease may also result in modifying patient disease management.4 Moreover, the newly developed PET radiotracers capable of targeting tumor growth, hypoxia, and tumor perfusion, enable the denition of new biological subvolumes within the gross target volume (GTV), known as biological target volumes (BTVs).5,6 Recent studies have proposed that escalating the dose to these targeted subvolumes (BTVs) within the GTV can improve local control, thus radiotherapy outcome. With the advances in radiation delivery techniques, in particular intensity-modulated radiotherapy (IMRT), as well as image-guided radiation therapy (IGRT), and with PET assisting in delineating subtarget BTVs, it has become plausible to escalate the dose to these radiation resistant regions (e.g., hypoxic subvolumes), while sparing normal tissues from high doses.7
