IMRT has increased the local-regional control and decreased the complications from treating nasopharyngeal cancer （NPC）. Therefore studying IMRT is important. CT and MRI are complementary, and their joint use is cur...IMRT has increased the local-regional control and decreased the complications from treating nasopharyngeal cancer （NPC）. Therefore studying IMRT is important. CT and MRI are complementary, and their joint use is currently considered to be the optimal modality to delineate the extent of the primary spread of NPC. The key problem in delineation of the neck nodes is how to translate anatomic node regions into the CT boundaries. The consensus guideline which narrowed the gap among different cancer centers is recommended in delineating the boundary of the cervical lymph node regions. The definition of the NPC GTV is clear and almost the same among the main cancer centers in their IMRT planning protocols. The suggested biological dose to the GTV is close to or more than 80 Gy; the main differences are the definitions of the CTVs and their schemes for the prescribed dose, and also the dosage to the high cervical region is different among those centers. According to their long-term follow-up results, it is suggested that, besides adding 5-10 mm margins to the primary lesions, the immediate high-risk structures （including the entire nasopharyngeal cavity, retropharyngeal space, clivus, base of the skull, pterygoid plates and muscles, parapharyngeal space, the sphenoid and partial ethmoid sinuses, the posterior third of the maxillary sinuses and the nasal cavity） should also be included with a prescription of more than 60 Gy, and the bilateral Ib, II and Va node levels should be ranked as high-risk regions and differentially prescribed for treatment with no less than 60 Gy.展开更多
Currently there are many unanswered questions concerning contouring a target with PET/CT in radiotherapy planning. Who should contour the PET volume-the radiation oncologist or the nuclear medicine physician？ Which f...Currently there are many unanswered questions concerning contouring a target with PET/CT in radiotherapy planning. Who should contour the PET volume-the radiation oncologist or the nuclear medicine physician？ Which factors will contribute to the dual-observer variability between them？ What should be taken as the optimal SUV threshold to demarcate a malignant tumor from the normal tissue？ When the PET volume does not coincide with the local area CT findings, which portion should be contoured as the target？ If a reginal lymph node,draining area or a remote region is shown to be PET positive but CT negative, or PET negative but CT positive, how is the target identified and selected？ Further studies concerning the relationship between PET/CT and the cancerous tissue are needed. The long-term clinical results showing an increased therapeutic ratio will finally verify the applicability of guidelines to contour the target with PET/CT in radiotherapy planning.展开更多
文摘IMRT has increased the local-regional control and decreased the complications from treating nasopharyngeal cancer （NPC）. Therefore studying IMRT is important. CT and MRI are complementary, and their joint use is currently considered to be the optimal modality to delineate the extent of the primary spread of NPC. The key problem in delineation of the neck nodes is how to translate anatomic node regions into the CT boundaries. The consensus guideline which narrowed the gap among different cancer centers is recommended in delineating the boundary of the cervical lymph node regions. The definition of the NPC GTV is clear and almost the same among the main cancer centers in their IMRT planning protocols. The suggested biological dose to the GTV is close to or more than 80 Gy; the main differences are the definitions of the CTVs and their schemes for the prescribed dose, and also the dosage to the high cervical region is different among those centers. According to their long-term follow-up results, it is suggested that, besides adding 5-10 mm margins to the primary lesions, the immediate high-risk structures （including the entire nasopharyngeal cavity, retropharyngeal space, clivus, base of the skull, pterygoid plates and muscles, parapharyngeal space, the sphenoid and partial ethmoid sinuses, the posterior third of the maxillary sinuses and the nasal cavity） should also be included with a prescription of more than 60 Gy, and the bilateral Ib, II and Va node levels should be ranked as high-risk regions and differentially prescribed for treatment with no less than 60 Gy.
文摘Currently there are many unanswered questions concerning contouring a target with PET/CT in radiotherapy planning. Who should contour the PET volume-the radiation oncologist or the nuclear medicine physician？ Which factors will contribute to the dual-observer variability between them？ What should be taken as the optimal SUV threshold to demarcate a malignant tumor from the normal tissue？ When the PET volume does not coincide with the local area CT findings, which portion should be contoured as the target？ If a reginal lymph node,draining area or a remote region is shown to be PET positive but CT negative, or PET negative but CT positive, how is the target identified and selected？ Further studies concerning the relationship between PET/CT and the cancerous tissue are needed. The long-term clinical results showing an increased therapeutic ratio will finally verify the applicability of guidelines to contour the target with PET/CT in radiotherapy planning.
