【作者】 王艳阳；

【导师】 傅小龙； 樊旼； 吴开良； 徐志勇；

【作者基本信息】 复旦大学 ， 肿瘤学， 2009， 博士

【摘要】 第一部分:影像引导放疗(IGRT)技术的建立1.千伏级锥形束CT引导放疗系统质量保证体系的建立目的建立千伏级锥形束CT(kilovoltage cone-beam CT,kVCBCT)引导放疗系统质量保证体系。材料与方法kVCBCT引导放疗系统质量保证体系包括三个部分:安全性与功能性、机械准确性与精确性以及kVCBCT图像质量。安全性与功能性质量保证检测的内容包括:系统连锁、碰撞示警、kV级X线球管预热和kVCBCT引导放疗系统与放疗计划系统之间的信息传递。机械准确性与精确性的检测是指:应用小球(Ball-Bearing,BB)体模检测kV容积影像系统与MV级治疗系统中心位置差异。kVCBCT图像质量检测应用Catphan 500体模,检测内容包括:kVCBCT图像的低对比度分辨率、空间分辨率和图像均匀性。结果安全性与功能性质量保证各项检测项目可以满足系统安全性与功能性检测的需要,每天逐一对这些项目进行检测,有助于保证系统的安全性与稳定性。kV容积影像系统与MV级治疗系统中心位置差异共分析4次,kV级系统中心与MV级系统中心的位置差异在侧向上最大为0.43 mm,纵向上最大为0.43 mm,垂直方向上最大为0.28 mm,均未超过验收标准规定的0.5 mm。kVCBCT图像的低对比度分辨率4次测得的均值为1.65%,空间分辨率4次测量的均值为7线对数(lp)/cm,图像均匀性4次测得的均值为1.20%。符合验收标准规定的kVCBCT图像质量:低对比度分辨率需小于2.0%;空间分辨率需大于或等于7lp/cm;图像均匀性需小于2.0%。结论本研究建立了系统安全性与功能性、机械精确性与准确性和kVCBCT图像质量的检测方法,通过在4个月研究中的反复应用,显示出这些方法的短期可重复性和系统本身的精确性与稳定性。系统安全性与功能性、机械精确性与准确性和kVCBCT图像质量的建议检测频率分别为:每天一次、每月一次和每半年一次。根据研究中建立的检测方法、获得的检测结果以及建议的检测频率,可以初步形成:医科达Synergy(?) kVCBCT引导放疗系统质量保证体系。2.影像引导肺癌放疗图像配准方法研究2.1肺癌影像引导放疗人工图像配准方法分析目的分析千伏级锥形束CT(kilovoltage cone-beam CT,kVCBCT)引导肺癌放疗人工图像配准法的重复性。材料与方法选择16例在我院行根治性放疗的非小细胞肺癌患者,每周行kVCBCT在线引导体位校正一次,获取患者kVCBCT影像。图像配准选择肺尖和椎体作为参考标记,在矢状位、冠状位和横断位等中心层面上配准患者kVCBCT影像和计划设计CT影像。比较同一名医生相隔一周两次配准,不同医生之间配准和医生与技术员之间配准结果的差异,用于评价kVCBCT引导肺癌放疗人工图像配准法的重复性。结果同一名医生相隔一周两次配准同一幅kVCBCT影像与计划设计CT影像,配准结果在患者左右(LR)、头脚(SI)和前后(AP)三个方向上,差值大于3 mm所占的比例分别为:0,13%和6%。不同医生之间的配准结果在LR、SI和AP三个方向上,差值大于3 mm所占的比例分别为:11%,19%和14%。医生与技术员的配准结果在LR、SI和AP三个方向上差值大于3 mm所占的比例,分别为:16%,27%和27%。结论kVCBCT引导肺癌放疗人工图像配准法的重复性有待进一步提高,尤其表现为不同医生,医生与技术员之间应用该方法的重复性较差。kVCBCT引导肺癌放疗的图像配准方法需要进一步研究。2.2 Clipbox范围确定对影像引导放疗图像配准影响的体模研究目的分析医科达Synergy(?)千伏级锥形束CT(kilovoltage cone-beam CT,kVCBCT)引导放疗系统灰度自动图像配准Clipbox范围(人为选定的用于图像配准计算的感兴趣区域)对图像配准结果的影响。材料与方法研究选择CIRS Model 002LFC胸部体模,获取体模的计划设计CT影像和kVCBCT影像,并在医科达Synergy(?)kVCBCT引导放疗系统ⅩⅥ(X-ray volume image)工作站上进行图像配准。图像配准选择灰度自动图像配准法,选取体模计划设计CT影像横断面上的不同区域作为Clipbox范围(整个横断面、1/2横断面、下1/4横断面和上1/4横断面),进行灰度自动图像配准,将其结果与由人工点标记法确定的参考标准进行比较,分析不同Clipbox范围对灰度自动图像配准结果的影响。结果只有将整个体模计划设计CT影像横断面作为Clipbox范围进行图像配准,配准结果与参考标准进行比较,侧向、纵向和垂直三个方向上的配准结果无显著统计学差别(侧向、纵向和垂直三个方向上比较的P值分别为:0.803、0.289和0.603)。采用不同的Clipbox范围进行灰度自动图像配准所用时间也各不相同,选择整个横断面作为Clipbox范围配准所用时间最长,选择下1/4横断面作为Clipbox进行图像配准所用时间最短。结论体模研究显示,选择包括完整计划设计CT影像信息在内的Clipbox范围进行灰度自动图像配准,结果较为准确。2.3肺癌锥形束CT影像引导放疗最优图像配准方法的筛选与评价目的筛选、评价适合应用于千伏锥形束CT(kilovoltage cone-beam CT,kVCBCT)在线引导肺癌放疗的图像配准方法。材料与方法选择16例行根治性放疗的非小细胞肺癌患者进入研究,每例患者每周行kVCBCT在线引导体位校正1次,共96幅kVCBCT图像用于研究。分别采用基于灰度的自动配准法、基于骨性结构的自动配准法、人工图像配准法和自动加手动图像配准法配准患者kVCBCT图像与计划设计CT图像。配准由1名医生完成,配准结果由另外1名医生在对所用配准方法设盲的情况下应用4点法对根据不同配准方法获得的配准结果进行评分,之后对筛选出的最优图像配准方法的可重复性进行评价。结果基于灰度的自动配准法、基于骨性结构的自动配准法、人工图像配准法和自动加手动图像配准法的平均得分分别为2.7、2.4、3.0和3.7分,4种不同配准方法评分的差异有统计学意义(F=42.197,P＜0.001)。采用自动加手动图像配准法左右(LR)、头脚(SI)和前后(AP)方向上,同一医生2次配准结果差值＞3 mm所占比例分别为0、3%和6%,不同医生的分别为0、14%和0,医生与技术员的分别为8%、14%和8%。结论自动加手动图像配准法以其配准结果好、所需时间较短、临床应用可重复性强等特点适合应用于肺癌kVCBCT在线引导放疗。第二部分:影像引导早期非小细胞肺癌立体定向放疗技术的建立3.锥形束CT与慢速CT确定肺癌放疗ITV的比较研究目的比较锥形束CT与慢速CT在确定肺癌放疗内在靶体积(internal targetvolume,ITV)中的作用。材料和方法选择在我院接受放疗的14例周围型肺癌(肿块距气管和支气管外1cm)患者进入研究,获得患者知情同意。其中,男性12例,女性2例,患者的中位年龄为72岁(范围:47-81岁)。肺内肿块T分期:T1期4例,T2期10例。肿块位于肺上叶者7例,肺中叶者3例,肺下叶者4例。进入研究的患者行不同方式的胸部CT扫描,其中包括:1次快速螺旋定位CT扫描(层厚3 mm,每层扫描时间1s);1次慢速CT扫描(层厚3 mm,每层扫描时间4s),慢速CT扫描范围仅为肿瘤上、下2 cm区域;3次千伏锥形束CT(kilovoltage cone-beamCT,kVCBCT)扫描,锥形束CT扫描时间为2 min,重建层厚为3 mm。将每位患者的5幅CT影像分别传输至放疗计划设计系统,以快速螺旋CT影像为基础影像,将其余4幅CT影像与之进行图像配准。之后,勾画各幅CT影像上的可见肿瘤病灶,根据计划设计CT勾画的可见肿瘤病灶称为大体肿瘤体积(grosstarget volume,GTV);根据慢速CT和kVCBCT勾画的可见肿瘤已包括呼吸运动信息,称之为内在大体肿瘤靶体积(internal gross target volume,IGTV)。在GTV╱IGTV外扩5 mm(临床靶体积边界),形成临床靶体积(clinical target volume,CTV)/ITV。基于慢速CT形成的ITV为ITV-s,基于kVCBCT形成的ITV为ITV-c。对CTV、ITV-s和ITV-c的体积进行两两比较;比较CTV叠ITV-s体积与CTV叠ITV-c体积。结果共有12例患者进入最终的研究分析。CTV的体积与ITV-s和ITV-c的体积分别做比较,均具有统计学意义差别,P值分别为:0.001和0.005。但是,ITV-s和ITV-c的体积无明显统计学意义差别(p=0.099)。CTV叠ITV-s体积与CTV叠ITV-c体积也无明显统计学意义差别(p=0.061)。结论锥形束CT和慢速CT均为包括了患者呼吸运动信息在内的CT影像,在确定肺癌患者放疗内在靶体积中的作用相似。4.锥形束CT引导肺癌立体定向放疗PTV外放边界研究目的量化分析肺癌患者影像引导后剩余摆位误差和治疗过程中患者体位变化情况,为采用锥形束CT引导肺癌立体定向放疗技术时,形成合理的计划靶体积(planning target volume,PTV)外放边界提供依据。材料和方法选择从2007年5月至2008年12月在我院接受立体定向放疗的20例肺癌患者进入研究。研究方法为:患者在根据体表标记线完成摆位后,行kVCBCT扫描;将获得的kVCBCT影像与计划设计CT影像进行配准,得出患者在左右(left right,LR)、头脚(superior inferior,SI)和前后(anterior posterior,AP)三个方向上的摆位误差,对任一方向上摆位误差大于2 mm者,借助引导系统提供的摆位误差校正对话框,通过移动治疗床纠正患者摆位误差;之后,再次行kVCBCT扫描。图像获取结束后患者开始治疗。将第二次获得的kVCBCT影像再次与计划设计CT影像进行配准,得出患者在LR、SI和AP三个方向上的摆位误差,这一摆位误差即为采用kVCBCT在线引导放疗技术后的剩余摆位误差。患者治疗结束后行第三次kVCBCT扫描,获得的影像与计划设计CT进行配准,配准的结果与剩余误差在相应的LR、SI和AP三个方向上分别相减,得到的即为患者在治疗过程中的体位变化。所有进入研究的患者,每次治疗均重复上述过程。结果来自20例患者的89幅kVCBCT影像用于剩余误差分析;9例患者完成了分次放疗结束后的kVCBCT扫描,共45幅kVCBCT影像用于治疗过程中患者体位变化分析。这9例患者的单次平均治疗(±标准差)时间为:23.7±2.2 min。采用kVCBCT在线引导放疗技术后,患者在LR、SI和AP三个方向上的剩余摆位误差分别为:-0.1±1.3 mm、0.3±1.5 mm和0.2±1.3 mm。患者在治疗过程中的体位变化在LR、SI和AP三个方向上分别为:0.5±1.3 mm、-0.5±2.1 mm和0.1±2.1mm。考虑剩余误差和患者在治疗过程中体位变化两个因素,PTV外放边界在LR、SI和AP三个方向上应分别设定为:3.2、4.5和3.7 mm。结论本研究采用医科达Synergy(?)kVCBCT引导放疗系统分析锥形束CT引导立体定向放疗技术治疗肺癌患者的剩余误差和患者在治疗过程中的体位变化,将这两个因素考虑入PTV的外放边界,PTV外放边界约需要5 mm。5.肺癌立体定向放疗射线束边界(beam margins)研究目的分析射线束边界大小对肺癌立体定向放疗靶区剂量分布和正常肺组织接受剂量的影响,为临床合理选择肺癌立体定向放疗射线束边界提供依据。材料与方法选择在我院接受立体定向放疗的三位肺癌患者进入研究,入选的三个患者大体肿瘤体积(gross target volume,GTV)的体积分别为:2.02cc,22.23cc和50.36cc。将患者的定位CT(包括常规定位CT和慢速定位CT)传输至放疗计划系统,对两幅CT进行图像融合,在肺窗上确定的肺部肿瘤范围即为内在大体靶体积(internal gross target volume,IGTV),IGTV外放5 mm形成PTV。同时,在IGTV外放6 mm(亚临床病变范围),之后再外放5 mm(摆位误差)形成PTVC。针对PTV,采用三维适形放疗技术设计肺癌立体定向放疗计划。处方剂量为5my/4次。选择不同射线束边界:0 mm,1 mm,2 mm,3 mm和4 mm,每位患者形成5套放疗计划,三位患者共形成15套放疗计划。计划评价指标包括:95%PTVC接受剂量;靶区剂量均匀指数(HI),剂量梯度指数(GSI),病变同侧肺接受的平均剂量,双肺平均剂量以及V20。结果95%PTVC体积接受剂量随着射线束边界的增大而增大,在射线束边界设定为2 mm时,95%PTVC1,95%PTVC2和95%PTVC3接受的剂量分别为:31.0Gy,29.5Gy和31.5Gy。PTV1,PTV2和PTV3的HI均随着射线束边界的增大而增大,射线束边界设定为0 mm时,HI值最大,PTV1,PTV2和PTV3的HI最大值分别为:1.682,1.386和1.381。PTV1,PTV2和PTV3的GSI最大值分别为:32.2,51.4和80.8,出现在射线束边界设定为1 mm,2 mm和1 mm时。患者1双肺和同侧肺接受的平均剂量最小值出现在将射线束边界设定为1 mm时,最大值出现在射线边界设定为4 mm时。患者2和患者3双肺和同侧肺接受的平均剂量随着射线束边界增大而增大。3例患者双肺V20均随着射线束边界的增大而增大。结论使不同大小的肿瘤95%PTVC体积均能受到亚临床病灶控制剂量:28.4Gy(相当于常规分割50Gy)的射线边界为2 mm。选择2 mm作为射线束边界时,三例患者的HI分别为:1.419,1.300和1.303,属于目前临床可接受范围。加之,GSI的大小并没有明显影响正常肺组织接受的剂量,所以选择选择2 mm作为射线束边界,可以兼顾95%PTVC接受的剂量,GSI和HI多项指标,形成合理的肺癌立体定向放疗计划。第三部分:影像引导肺癌立体定向放疗技术临床应用6.影像引导Ⅰ期非小细胞肺癌立体定向放疗临床研究结果报道目的观察影像引导体部肿瘤立体定向放疗(IG-SBRT)技术治疗Ⅰ期非小细胞肺癌患者的局部控制率、总生存率和治疗相关毒副反应。材料与方法患者的入组标准为病理证实的T1或T2N0M0期非小细胞肺癌,肿块最大径需小于7cm。中央型肿瘤和靠近胸壁的肿瘤采用的剂量分割为48Gy/6次,肺内其余部位的肿瘤采用的剂量分割为50Gy/4次,均为隔天照射。每位患者每次治疗均进行在线影像引导。结果从2007年5月到2009年2月,共有14例患者(15个病灶)入组这项研究,其中,T1期肿瘤3个,T2期肿瘤12个。患者GTV体积的中位值为:32.48cc(4.48-116.16cc)。所有患者均能按照计划完成治疗,中位随访14月(1.5-20月),1例患者死于脑转移,1例患者死于SBRT治疗后纵隔淋巴结复发,行二次放疗时引起的放射性肺炎。所有患者的1年局部控制率为100%,1年总生存率为90.6%。3例患者出现2级放射性肺炎,2例患者出现2级胸壁疼痛,无患者出现3级及以上治疗相关毒副反应。结论本研究采用IG-SBRT技术治疗早期NSCLC,根据目前随访结果,显示出这一技术治疗早期NSCLC患者的安全性和有效性;利用在线IGRT技术能提高SBRT技术精确性和保证治疗准确性的特点,可以扩大SBRT技术的应用范围。更多还原

【Abstract】 ⅠEstablishment of Image-guided Radiation Therapy（IGRT） Technique1.Quality Assurance Program for a Kilovoitage Cone-beam CT Guided Radiation Therapy SystemPurpose To establish the quality assurance（QA） program for a kilovoltage cone-beam computer tomography（kVCBCT） guided radiation therapy system.Materials and Methods The QA program of this study included three parts:safety and functionality,geometrical accuracy of the system and imaging performance of the kVCBCT.During the 4 months,we evaluated the functionality of safety features and the clinical operation of the entire system during the tube warm-up process.We assessed the displacement between the center of the kV X-ray volume image and the MV treatment center using the Ball-Bearing phantom.Qualitative evaluation of imaging performance was performed using the Catphan^?500 phantom.The test items of the imaging performance included low contrast resolutions,spatial resolutions and the Hounsfield Unit（HU） uniformity.Results All safety and functionality tests passed on a daily basis.Geometrical accuracy of the system was tested four times.The displacement between the center of the kV X-ray volume image and the MV treatment center was all less than 0.5mm. The maximal difference is 0.43 mm,0.43 mm and 0.28 mm in the lateral,longitudinal and vertical direction,respectively.The low contrast resolutions of the imaging ranged between 1.3%and 1.8%,and the HU uniformity ranged between 0.7%and 1.6%.The spatial resolutions of the four tests were all 71p/cm.Conclusions We have developed a comprehensive,yet practical,set of QA tests for the kVCBCT guided radiation therapy system.Use of the tests over extended periods show that the kVCBCT guided radiation therapy system can work safety and functionality with reliable mechanical accuracy and stable image quality. 2.Image Alignment Methods Evaluation of the Image-guided Lung Cancer Radiotherapy2.1 Reproducibility evaluation of the manual image alignment method for kilovoltage cone-beam CT guided lung cancer radiationPurpose To evaluate reproducibility of the manual image alignment method for kilovoltage cone-beam CT（kVCBCT） guided lung cancer radiotherapy.Materials and Methods Sixteen non-small cell lung cancer patients entered into this study.Weekly on-line kVCBCT guided set-up error correction was performed.A total of ninety-six pretreatment kVCBCT images were available for analysis.The landmarks of the manual alignment included the cranial part of the lung and spine. Images were aligned in three dimensions,and the LR（left-right）,SI （superior-inferior）,and AP（anterior-posterior） components of translation of the target isocenter were documented and analyzed for each registration.Intra-observer variability was investigated:at least one week after treatment all kVCBCT studies were reexamined by the same physician.Additionally,all kVCBCT studies were examined by a second physician,a radiation therapist and inter-observer variability was tested.Results The intra-observer variability of the manual registration method was investigated.All kVCBCT scans were re-evaluated by the same physician.Compared with the original results,the percentage of the more than 3 mm differences in LR,SI, and AP directions are 0,13%and 6%,respectively.The percentage of the more than 3 mm differences in LR,SI,and AP directions between two physicians are 11%,19% and 14%.The difference of the registration results between radiation therapist and physician in LR,SI,and AP directions are 16%,27%and 27%.Conclusions The reproducibility of the manual alignment method was poor, especially in the inter-observer evaluation.The optimal alignment method for kVCBCT guided lung cancer radiation needs further research.2.2 Impact of the Clipbox size on the image registration results for image-guided radiotherapy:a phantom studyPurpose To investigate the impact of the Clipbox size（region of interesting for automatic image registration） on the results of gray value based automatic image alignment method for kilovoltage cone-beam CT（kVCBCT）guided radiotherapy.Materials and methods The CIRS Thorax phantom Model was used in this study. Three fiducial markers were attached on the phantom.And the phantom was aligned with the laser using attached fiducial markers.This setup assumes that a laser-based phantom alignment represents an accurate alignment.After setup,kVCBCT of the phantom was acquired.The procedure was repeated ten times and ten kVCBCT scans of the phantom were acquired.A reference model for the image alignment comparison was made before the evaluation.The acquired ten kVCBCT scans of the phantom were retrospectively matched with planning CT using gray value based automatic image registration method with four different Clipbox.Four groups of registration result with different Clipbox were compared with the reference model,respectively.Results There is only one Clipbox,which include the whole region of the thoracic, can get the exact image registration result when compared with the reference model, but it take more time than any other three Clipboxes to complete the image alignment.Conclusions Based on the phantom study,the Clipbox,which include the whole region of the thoracic,was selected as the optimal regions for automatic image registration.2.3 Study of different registration methods for on-line kilovoltage cone-beam CT guided lung cancer radiation:selection and evaluationPurpose To select the optimal registration method for on-line kilovoltage cone-beam CT（kVCBCT） guided lung cancer radiation and evaluate the reproducibility of the selected method.Materials and Methods Sixteen non-small cell lung cancer patients were entered into this study.A total of ninety-six pretreatment KVCBCT images from sixteen patients were available for analysis.Bone-based automatic registration,gray-based automatic registration,annual registration and semi-automatic registration method were used for image registration.All registrations were accomplished by one physician.Another physician evaluated the results of each registration and selected the optimal registration method in blind.Intra-observer and inter-observer variability of this selected image registration protocol were investigated. Results The score of the bone-based automatic registration,gray-based automatic registration,annual registration and semi-automatic registration method was 2.4,2.7, 3.0 and 3.7,respectively.The score of the four different groups has statistics significant difference（F=42.197,P＜0.001）.The intra-observer variability of the selected registration method was investigated.Compared with the original results,the differences in LR（left-right）,SI（superior-inferior）,and AP（anterior-posterior） directions have no statistics significant difference.The inter-observer variability of the SI directions has statistics significant difference（t=-2.790,P=0.008）.The difference of the registration results between radiation therapist and physician in SI（t=-2.490, P=0.018） and AP（t=-2.425,P=0.021） directions both have statistics significant difference.Conclusions Because of the highest score and accepted reproducibility, semi-automatic registration method was selected for kVCBCT guided lung cancer radiation. ⅡEstablishment of Image-guided Stereotactic Body Radiation Therapy（IG-SBRT） Technique for Lung Cancer3.The Comparison of CBCT and Slow CT in Determining the ITV for Lung Cancer PatientPurpose To compare the role of kilovoltage cone-beam CT（kVCBCT） and slow CT in determining the internal target volume（ITV） for lung cancer patient.Materials and Methods Fourteen patients with pathologically confirmed peripheral non-small cell lung cancer were entered into this study.There were two females and twelve males.The median age of these patients was 72 years（range:47-81）.T-stages of these tumors were T1 in four patients,T2 in ten patients.There were seven tumors located in upper lobe,three in middle lobe and four in lower lobe.One fast CT（slice thickness 3 mm,revolution time 1s/slice）,one slow CT（slice thickness 3 mm, revolution time 4s/slice）which limited to the tumor region and three kVCBCT scans were performed during quiet respiration for each patient.The scanning time of one kVCBCT was 2 minutes and the reconstructed slice thickness is 3 mm.Slow CT and kVCBCT were all aligned to the fast CT.After contouring the gross target volume （GTV）/ITV,5 mm margin was performed to generate clinical target volume（CTV）. The volume of ITV-c（generated from the first kVCBCT） and ITV-s（generated from slow CT） were compared.Overlap volume of CTV（generated from fast CT） and ITV-c were compared with overlap volume of CTV and ITV-s.Results The volume of ITV-s and ITV-c had no statistics difference（p=0.099）.The overlap volume of CTV and ITV-c was 64.1 cc and the overlap volume of CTV and ITV-s was 59.6 cc.These two overlap volume meet no significant statistics difference （p=0.061）.Conclusions KVCBCT has the same role as slow CT in capturing the tumor movement and determine the ITV for lung cancer patient. 4.The Determination of Planning Target Volume（PTV） Margin for Cone-beam CT Guided Stereotactic Lung Cancer RadiationPurpose To assess the planning target volume（PTV） margin,which based on the residual set-up error and intrafraction patient motion,of the kilovoltage cone-beam CT（kVCBCT） guided stereotactic radiotherapy for lung cancer patients.Materials and Methods From Mar 2007 to Dec 2008,20 lung patients,who received stereotactic radiotherapy in our hospital,were included in this study.After patients were positioned using their skin marks,kVCBCT scans were performed before treatment and aligned to planning CT scans using the self-developed semi-automatic alignment method.Treatment table were repositioned according to the alignment results.A second kVCBCT scan was acquired immediately after the table correction. Residual set-up errors were calculated by aligning the second kVCBCT with the planning CT,using the semi-automatic alignment method.The third kVCBCT was got after each fraction of treatment.The intrafraction patient motion was evaluated according the alignment of the third kVCBCT and planning CT.Results 89 kVCBCT scans were used for residual error evaluation.The average residual set-up error（±SD） was -0.2±1.3mm,0.1±1.3mm and 0.3±1.3mm in the left-right（LR）,superior-inferior（SI） and anterior-posterior（AP） direction, respectively.45 kVCBCT scans were used for intrafraction patient motion assessment. The intrafraction patient motion（±SD） was 0.5±1.3 mm,-0.5±2.1 mm and 0.1±2.1 mm in the LR,SI and AP direction,respectively.According to the results of residual set-up error evaluation and intrafraction patient motion assessment,3.2,4.5 and 3.7 mm should be applied to the margin of PTV in the LR,SI and AP direction, respectively.Conclusions On the basis of the residual set-up error and intrafraction patient motion measurements,the margin required for the cone-beam CT guided stereotactic lung cancer radiation would be approximatively 5 mm. 5.The Optimal Beam Margin Selection for Imaging-guided Stereotactic Lung Cancer RadiationPurpose To select the optimal beam margin for kilovoltage cone-beam CT（kVCBCT） guided stereotactic lung cancer radiotherapy.Materials and Methods Three lung cancer patients with different volume of gross target volume（GTV）（2.02cc,22.23cc and 50.36cc） were entered into this study.In order to evaluate the impact of beam margin on the dose distribution of stereotactic radiotherapy plan,five plans with different beam margin（0 mm,1 mm,2 mm,3 mm and 4 mm） were generated for each patient.All the plans were normalized to ensure that 95%of the planning target volume（PTV） at least receives the prescription dose and compared quantitatively.Based on these plans,the relationships between the beam margin and quantities such as the percentage of PTVC received dose, homogeneity index（HI）,gradient score index（GSI） and the normal lung dose were assessed for different patients.In this study,clinical target volume（CTV） was established 0 mm.PTVC was the region of potential CTV to receive the incidental dose.Results The dose of 95%PTVC and HI were enlarged when beam margin become bigger and bigger.The 95%PTVC received dose of the three different patients was 31.0Gy,29.5Gy and 31.5Gy with 2 mm beam margin.The biggest GSI of the three patients were 32.2,51.4 and 80.8,when beam margin was established as 1 mm,2mm and 1mm,respectively.The minimal mean lung dose of the first patient was 333.3cGy with 1mm beam margin.The minimal mean lung dose of the other two patients was 464.0cGy and 493.3cGy,when beam margin established as 0 mm.Conclusions Based on the dose of 95%PTVC,the relationship between GSI and normal lung dose,2 mm may be the optimal beam margin for the imaging-guided stereotactic radiation lung cancer patients. ⅢClinical Application of the Image-guided Stereotactic Body Radiation Therapy（IG-SBRT） Technique for Lung Cancer6.Clinical Outcomes of the Image-guided Stereotactic Body Radiation Therapy （IG-SBRT） for StageⅠNon-Small Cell Lung CancerPurpose To evaluate the safety and efficacy of kilovoltage cone-beam CT（kVCBCT） guided stereotactic body radiation therapy for stageⅠnon-small cell lung cancer （NSCLC）.Materials and Methods Eligible patients included clinical staged T1 or T2（≤7 cm）, N0,M0,biopsy-confirmed NSCLC.SBRT treatment dose was 50Gy total in four fractions for peripherally located tumor or 48Gy in six fractions for centrally located tumor within 1-2 weeks.Daily kVCBCT guidance was performed for all patients to ensure the precise and accuracy of the treatment.Results From May 2007 to Feb 2009,14 patients with 15 tumors（3 with stage T1 and 12 with stage T2） were entered into this study.The median volume of GTV was 32.48cc（4.48-116.16cc）.Of 14 patients,1 died of brain metastases and 1 died of pneumonia for the re-radiation of the recurrent mediastinal lymph node at a median follow-up period of 14 months.The 1-year crude local control rates and the 1-year overall survival rates were 100%and 90.6%,respectively.Three patients developed Grade 2 pneumonitis.Two patients developed Grade 2 chest wall pain.No therapy-related toxicity of Grade≥3 was observed.Conclusions IG-SBRT seems feasible and effective for stageⅠNSCLC.With the help of image guidance,even bigger tumor can be treated safely by this precise and accuracy method.更多还原