Posology study on 3DCRT and IMRT for lung cancer with mediastinum lymphonode metastasis.

Objective To provide a reference to the clinical application by comparing the posology difference of 3DCRT(three-dimensional conformal radiation therapy) and IMRT(intensity modulated radiation therapy) for lung cancer with mediastinum lymphonode metastasis. Methods From Aug.2007 to Feb.2008,11 patients of lung cancer with mediastinum lymphonode metastasis were treated by IMRT. IMRT plan and 3DCRT plan were designed by CT-simulator image. The conformity index, PTV uniformity and the organs at risk were compared by the target isodose curve and dose volume histogram(DVH) in two plans. The prescribe dose was 66 Gy/33 fracinations in 6 weeks, and 95 % dose curve covered 95 % target volume. The data were analyzed by t-test in SPSS 14.0. Results The conformity index in IMRT was superior than 3DCRT (P＜0.05).PTV above 110 % volume in IMRT was reduced than 3DCRT. On the protection of lung tissue,the volumes of V20,V30,V40 in IMRT were obviously less than 3DCRT (P＜0.05). Conclusion IMRT is a better selection to larger volume and irregular shape of CTV for lung cancer with mediastinum lymphonode metastasis. Key words: Lung neoplasms; Radiotherapy, conformal; Intensity modulated radiation therapy