【作者】 张丽；

【导师】 王凡；

【作者基本信息】 安徽医科大学 ， 肿瘤学， 2010， 硕士

【摘要】 目的系统地比较常规放疗,三维适形放疗(three dimensional conformal radiation therapy ,3DCRT)和调强适形放疗(intensity modulated radiation therapy ,IMRT)三种不同的放射治疗方法,探讨应用3DCRT及IMRT治疗中晚期非小细胞肺癌(non-small cell lung cancer,NSCLC)较常规放疗在提高靶区剂量,保护邻近危及器官(organs at risk,OARs)上是否更具优势。方法对2008年5月～2009年5月入院治疗的10例中晚期NSCLC(Ⅲ～Ⅳ期)患者行回顾性研究,患者均采用仰卧位,双手上举抱肘,MED-TEC真空体袋固定体位,模拟机下定位,应用9点法标记平静呼吸状态下靶及靶上下3组激光摆位线,然后在西门子螺旋CT(PLUS FOUR)上重复摆位,行CT扫描,扫描范围自环状软骨至肋膈角,层厚通常3～5 mm,应用三维放射治疗计划系统(TPS,topslane公司Venus计划系统)进行CT图像的数字化传输和三维重建,根据CT断层图像所示,结合近期胸部增强CT或MRI或PET/CT影像,在计划系统中勾画肿瘤靶区和邻近危及器官:肺、心脏、脊髓、食管。肿瘤靶区根据ICRU50和ICRU62号报告勾画大体肿瘤体积(gross tumor volume,GTV),临床靶体积(clinical target volume ,CTV)和计划靶体积(planning target volume,PTV)。CTV为GTV三维方向上外扩7～10 mm;PTV为CTV三维方向上外扩8 mm,同时根据模拟机上观察到的肺呼吸运动范围及可能的摆位误差确定上下界,三种计划靶区相同。每个病例均设计三种放射治疗计划:应用TPS模拟常规放疗,6MV-X线垂直照射DT40 Gy(PTV)后改斜野避脊髓成角照射,补量至66 Gy,2Gy/次,分次33次。3DCRT及IMRT根据剂量体积直方图(dose volume histogram ,DVH),剂量分布及受照体积进行优化,遵循将高剂量区集中到肿瘤内,并尽可能地保护周围危及器官的原则,选用最佳治疗计划,靶区(PTV)处方剂量66 Gy,分次33次。通过DVH,比较三种计划对肿瘤靶区和正常组织器官的剂量分布。结果IMRT对靶区的适行度明显优于常规放疗,95%的PTV所达到的剂量及达处方剂量的PTV体积均比常规放疗要高,两者间差异显著(P值均<0.05)。IMRT较常规及3DCRT比较明显减少了肺V30、V40值(P值均<0.05),同时肺V20值亦为最低,但IMRT明显提高了受低剂量照射的肺体积,肺V5值增高(P<0.05)。3DCRT和IMRT计划食管平均剂量及食管V45均较常规计划降低;IMRT计划的心脏平均剂量及心脏V35为最低,其次为3DCRT计划;三种计划脊髓最大受照剂量均<45Gy,其中3DCRT脊髓剂量最小,IMRT较3DCRT脊髓剂量增大(P值均>0.05)。结论IMRT与3DCRT、常规放疗比较:肿瘤靶区有更好的剂量分布;明显减少了肺V30、V40值;心脏V35及食管V45亦减少;肺V5值提高;脊髓受量较3DCRT有所加大,但未达脊髓最低耐受剂量。IMRT在靶区剂量分布上明显优于常规放疗和3DCRT,同时能更好的保护正常组织,特别是肺组织,明显降低了肺受高剂量照射的体积。更多还原

【Abstract】 Objective: Conventional radiotherapy(RT), three-dimensional conformal radiotherapy (3DCRT) and intensity-modulated radiation therapy(IMRT) were designed for 10 patients with non-small cell lung cancer (NSCLC) and the three different kinds of radiotherapy plans were compared systematically by DVHs. Compared with conventional radiotherapy ,the advantage of 3DCRT and IMRT for patients with intermediate and advanced stage NSCLC in improving the target dose and reducing the dose of organs at risk (OARs) nearby.Methods: From May 2008 to May 2009, ten patients with intermediate and advanced stage NSCLC were treated by radiotherapy. A retrospective treatment planning study was performed to compare RT, 3DCRT and IMRT for these patients. All patients were immobilized by MED-TEC vacuum body bags when they lied supine with their hands up hold the elbows and with normal respiration, exposured to radiotherapy simulator, and marked three groups of laser lines nearby target with nine points. Repeated position and then scanned from the cricoid cartilage to the costophrenic angles on the CT (PLUS FOUR SPIRAL CT), the slice thickness was 3 to 5 mm. Using the three-dimensional radiation treatment planning systems (TPS, Topslane Venus Planning System),CT images were transformed and restructured in three dimensions. Delineated the tumor target and the organs at risk (OARs)such as lung, heart, spinal cord and esophagus on the CT cross-sectional images, combined with the recent chest-CT, or MRI, or PET / CT. The gross tumor volume (GTV), clinical target volume(CTV) and planning target volume(PTV) were delineated according to the ICRU50 Report and the ICRU62 Report. CTV was defined as the GTV plus a 7-10mm margin, and PTV as the CTV plus a 8mm margin, and then expanded the scope furthermore according to the breathing movement rang showed in the simulator and the potential set-up error, the three plans had the same target volume. Three kinds of radiation treatment plans were designed for each patient: RT plans, 3DCRT plans and IMRT plans. The RT plans were simulated on the TPS, irradiated vertically to 40Gy by 6MV-X ray, and then avoided the spinal cord adding to the total dose 66 Gy in 33 fractions. The 3DCRT plans and the IMRT plans was planned according to the dose volume histogram(DVH),and the principle was maximizing dose to the target volume and minimizing dose to the surrounding normal tissues, the best plan was selected to perform , one target volume was predefined: PTV which was given 66Gy in 33 fractions. Dose volume histograms were used to compare doses distributions for tumor and normal tissues in the three plans.Results: Target volume dosimetric distribution of IMRT were better than RT, because the doses in 95% PTV and the volume of the prescription doses of IMRT were higher than RT, all had statistical significance (P<0.05).The volume of lung V30 and lung V40 of IMRT were lower than RT and 3DCRT , had statistical significance (P<0.05),also the volume of lung V20 of the IMRT was the lowest, but the total lung volume receiving low dose radiation of IMRT improved significantly ,the volume of lung V5 of IMRT was the highest (P<0.05).The mean dose of esophageal and the volume of esophageal V45 of 3DCRT and IMRT were lower than RT. The mean dose of heart and the volume of heart V35 of 3DCRT were lower than RT, and the value of IMRT was the lowest .The maximum dose at the spinal cord were all under 45Gy in the three plans, and the dose of IMRT were higher than 3DCRT(P>0.05).Conclusions: Target volume dosimetric distribution of IMRT were better than RT and 3DCRT , the volume of lung V30,lungV40, esophageal and heart V35 of IMRT were lower than RT and 3DCRT ;the volume of lung V5 of IMRT was higher than RT and 3DCRT ;the dose at the spinal cord of IMRT was higher than 3DCRT,but lower than the minimum tolerated dose .The target volume dosimetric distribution of IMRT was more precise as compared with RT and 3DCRT.The IMRT plans decreased the surrounding normal tissues and organs radiation injury, especially the total lung volume receiving high dose radiation.更多还原