三维放疗射野挡块数据转换及传输的意义

随着三维放疗计划系统和自动切割机的普及使用，可能面临适形射野数据与自动切割机软件不兼容的问题．手工输入档块轮廓图形不可避免将产生一定误差。分析了转换和传输三维放疗计划系统适形射野数据的意义．结果表明档块轮廓复杂之处，使用自编转换软件处理这些数据能有效提高精度并减少工时。还介绍了自编转换软件功能及潜在意义。     

胸段食管癌三维适形放疗摆位误差研究

Objective To study the setup errors in three-dimensional conformal radiotherapy (3DCRT) for thoracic esophageal carcinoma using electronic portal imaging device(EPID) and calculate the margins from CTV to PTV. Methods Forty-one patients with thoracic esophageal carcinoma who received 3DCRT were continuously enrolled into this study. The anterior and lateral electronic portal images (EPI) were aquired by EPID once a week. The setup errors were obtained through comparing the difference between EPI and digitally reconstructed radiographs(DRR). Then the setup margins from CTV to PTV were calculat-ed. By using self paired design,22 patients received definitive radiotherapy with different margins. Group A: the margins were 10 mm in all the three axes;Group B: the margins were aquired in this study. The differ-ence were compared by Paired t-test or Wilcoxon signed-rank test. Results The margins from CTV to PTV in x,y and z axes were 8.72 mm, 10.50 mm and 5.62 mm, respectively. Between the group A and group B, the difference of the maximum dose of the spinal cord was significant(4638.7 cGy±1449.6 cGy vs. 4310.2 cGy±1528.7 cGy; t=5.48, P=0.000), and the difference of NTCP for the spinal cord was also significant (4.82%±5.99% vs. 3.64%±4.70%;Z=-2.70,P=0.007). Conclusions For patients with tho-racic esophageal carcinoma who receive 3DCRT in author's department,the margins from CTV to PTV in x, y and z axes were 8.72 mm, 10.50 mm and 5.62 mm, respectively. The spinal cord could be better protected by using these setup margins than using 10 mm in each axis.     

胸段食管癌三维适形放疗摆位误差研究

Objective To study the setup errors in three-dimensional conformal radiotherapy (3DCRT) for thoracic esophageal carcinoma using electronic portal imaging device(EPID) and calculate the margins from CTV to PTV. Methods Forty-one patients with thoracic esophageal carcinoma who received 3DCRT were continuously enrolled into this study. The anterior and lateral electronic portal images (EPI) were aquired by EPID once a week. The setup errors were obtained through comparing the difference between EPI and digitally reconstructed radiographs(DRR). Then the setup margins from CTV to PTV were calculat-ed. By using self paired design,22 patients received definitive radiotherapy with different margins. Group A: the margins were 10 mm in all the three axes;Group B: the margins were aquired in this study. The differ-ence were compared by Paired t-test or Wilcoxon signed-rank test. Results The margins from CTV to PTV in x,y and z axes were 8.72 mm, 10.50 mm and 5.62 mm, respectively. Between the group A and group B, the difference of the maximum dose of the spinal cord was significant(4638.7 cGy±1449.6 cGy vs. 4310.2 cGy±1528.7 cGy; t=5.48, P=0.000), and the difference of NTCP for the spinal cord was also significant (4.82%±5.99% vs. 3.64%±4.70%;Z=-2.70,P=0.007). Conclusions For patients with tho-racic esophageal carcinoma who receive 3DCRT in author's department,the margins from CTV to PTV in x, y and z axes were 8.72 mm, 10.50 mm and 5.62 mm, respectively. The spinal cord could be better protected by using these setup margins than using 10 mm in each axis.     

射野挡块范围的勾画在适形铅块制作中产生误差的原因分析

射野加挡块不仅是为了适应靶区和计划区形状的需要，更重要的是为了保护射野内的重要器官和正常组织免受不必要的照射。但在适形铅块制作中射野挡块范围的勾画常出现误差。本文在头颈部放疗适形铅块的制作过程中将放疗射野挡块范围的勾画分3组进行并比较分析，以探讨放疗射野挡块范同的勾画在适形铅块制作中可能产生误差的原因，现报告如下。     

放射治疗射野影像系统的应用

放射治疗射野影像系统EPID是治疗计划所实施的重要质量保证工具,其主要功能是射野验证和剂量验证.     

Photoshop在鼻咽癌整体挡铅中的应用

目的：探讨一种利用photoshop在鼻咽癌放射治疗中制作与靶区治疗区域相一致的整体铅模及其在加速器中的射野验证的方法。方法：利用扫描仪将模拟定位机拍摄的鼻咽癌沟画好的定位片及加速器上拍摄的验证片图像输入计算机中，调整图像大小、灰度、对比度、图像配准、测量。结果：使用这种方法治疗病人97例。完全重合率达95％以上，这种整体挡铅技术在治疗时根据患者不同情况将小脑、垂体、眼球等重要组织和器官保护起来，大大减少了正常组织的受量，提高了鼻咽部肿瘤组织的照射剂量。结论：利用photoshop完全可以对鼻咽癌制作与靶区治疗区相一致的整体铅模和进行射野位置的准确测量，操作简单、安全可靠。     

鼻咽癌旁受侵不同射野放射治疗长期疗效比较

目的 评价鼻咽癌咽旁受侵不同射野放射治疗的长期疗效。方法 从1988年3月至1992年3月，经CT诊断鼻咽癌咽旁受侵的病人101例，所有病人均经病理确诊，被随机分为2个组，一组采用面颈联合野，另一组采用双耳前野加面前野，鼻咽部外照射总肿瘤量均为DT68-72Gy，照射34-46次，6.8-7.2周，所有病例均随访5年以上，生存曲线按寿命表法计算后绘制，经log-rank检验。结果 2个组生存曲线比较；面颈联合野组高于非面颈联合野组（P<0.05)；无复发生存曲线一比较；面颈联合野组显著高于非面颈联合野组（P<0.01)；单纯茎突前区受侵的病人，面颈联合野与非面颈联合野放射治疗在生存曲线差异无显著意义（P>0.05)。非面颈联合野组发生1例放射性颈脊髓损伤，2个组急性和慢性放射损伤差异无显著意义。结论 对鼻咽癌咽旁受侵的病人宜选用面颈联合野放射治疗。     

独立准直器调强技术在鼻咽癌放射治疗的应用评估

目的 利用直接射野优化技术和加速器独立准直器进行调强放射治疗计划设计及测试运行,探索其用于鼻咽癌临床治疗应用的可行性.方法 使用一种基于直接射野优化技术的商业化治疗计划系统,对10例鼻咽癌患者分别设计独立准直器调强(JO-IMRT)和多叶准直器调强(MLC-IMRT)治疗计划.比较两种计划的靶区剂量适形度和均匀性参数,以及剂量监测器跳数和执行时间等差别.结果 两种计划均能满足鼻咽癌简单调强的临床剂量要求.JO-IMRT与MLC-IMRT的计划靶区剂量适形度指数分别为0.941±0.015和0.981±0.013(P＜0.001).肿瘤靶区的剂量均匀性指数分别为0.904～0.012和0.915～0.019(P＞0.05),前者的计划质量略差于后者;简单调强条件限制下两种计划的子野数接近,但总剂量监测器跳数平均值分别为474.3和419.6(P＜0.05),执行时间的平均值分别为8.0与7.5 min(P＜0.01),JO-IMRT的执行效率稍差于MLC-IMRT.结论 JO-IMRT可以满足较简单的鼻咽癌调强治疗要求.尽管其计划质量与执行效率略差,JO-IMRT对没有配置多叶准直器的放疗单位作为MLC-IMRT的替代方法具有实际应用价值.     

EPID在盆腔肿瘤放疗中的摆位误差分析

目的 探讨电子射野影像系统在盆腔肿瘤放疗中的摆位误差,以供临床参考.方法 对17例盆腔肿瘤接受放疗的患者给予摆位误差的量化测定.所有病例给予CT的定位和放疗.将治疗过程中的电子射野影像系统所拍摄的正位和侧位片,与数字化重建图像的验证片进行对比分析,计算误差.结果 17例患者在每日摆位误差中,主要为前后的误差,在2mm~22mm之间,平均为(13.21±7.17)mm;其次为头脚,在1mm~23mm之间,平均为(8.01±5.32)mm;左右误差发生最小,在0.2mm~8.7mm之间,平均(5.27±3.99)mm.结论 使用电子射野影像系统能够有效地对盆腔肿瘤放疗期间的摆位误差进行测定,为放疗提供初步的参考依据.     

Photoshop在射野验证中的应用和治疗机托架对整体挡铅位置影响的质量控制

目的:介绍一种利用Photoshop在放射治疗中的位置验证的方法和治疗机托架对鼻咽癌整体挡铅挡块的影响及采取的相应的控制措施进行探讨.方法:(1)利用扫描仪将加速器拍摄的验证片、定位片或CT重建图像输入计算机中,调整图像大小、灰度、对比度、图像配准、测量.(2)在BJ-6B型直线加速器上设置90°的机架角度和0°的准直器角度,在托架里插入有机板,有机板上设置与照射野灯光十字投影线相重合的十字定位刻线,然后变换机架角为270°.观察有机板在有、无整体挡铅时十字刻线与照射野灯光十字投影线误差的程度.结果:(1)通过射野验证图像与参考图像的对比可以发现.在水平(RL)方向、上下(SI)方向和前后(AP)方向,对于头颈部摆位误差为:(1.11±1.37)mm,(1.33±1.25)mm,(0.83±0.79)mm;胸部:(2.44±1.03)mm,(2.6±1.52)mm,(2.34±1.17)mm;腹部:(2.53±1.86)mm,(2.83±1.19)mm,(2.67±1.68)mm;盆腔部:(1.93±1.83)mm,(1.59±1.7)mm,(1.85±1.72)mm.(2)整体挡铅固定有机板与治疗机托架之间等机械因素存在固有的安装间隙,在机架角270°时有机板会因重力的缘故朝这些间隙位移,从而使有机板上的整体挡铅块也随之在照射野中出现位置偏移,折算到源轴距位置处有0mm-5.2mm的位置误差.结论:(1)利用Adobe Photoshop完全可以进行射野和摆位位置的准确测量,操作简单、安全可靠.(2)在整体挡铅固定有机板上设置准确的十字定位线,以此作为整体挡铅在固定有机板上的浇铸和位置检验的基准,并作为整体挡铅在托架位置处与照射野十字灯光投影线对准的标记线,可以预先了解整体挡铅位置偏移情况进而采取控制措施.