To observe and analysis the rule of esophageal tumor volume changes in 3DCRT with conventional fraction. Methods: This study was performed on eight patients with esophageal cancer who were treated with radical three-dimensional conformal radiotherapy between July 2010 and September 2010. Thoracic contrast-enhanced CT scan were performed-during early RT (second weekend), mid-RT (forth weekend), late-RT (sixth weekend) and at follow-up (1 months after RT completion). ROI-based volumetry was derived by tracing the entire tumor region in each CT slice on the computer work station. Image J software was used to calculate tumor volume. Results: Tumor volume of one patient with poorly differentiated squamous-cell carcinoma increased with rapid tumor cell proliferation rate during radiotherapy time. Tumor volume of another patient had no change with radiotherapy. Tumor volume of the third patient increased in early RT and constantly decreased in subsequent radiotherapy, mostly eliminated in two months after the end of radiotherapy. Other 5 patients had similar tumor volume change during radiotherapy time, whose tumor volumes gradually reduced in the former and had little volume change in the latter. Conclusions: Half-time extinction and recession rate of esophageal carcinoma were calculate with exponential fitting from 5 patients' tumor volume change ,which being 1.27%/d and 44.3d respectively and similar to that of lung cancer and cervical cancer. As a result, the average of tumor volume reduced by one-third after 4 weeks radiotherapy, we should modify radiation plan to avoid the influence by tumor volume change, especially with precise radiotherapy.%目的:观察分析食管癌三维适形常规分割放疗过程中肿瘤体积变化规律.方法:选择2010年7月～2010年9月进行常规分割根治性三维适形放射治疗的8例食管癌患者,在放疗期间第2、4、6周及放疗后1月复查胸部增强扫描CT并采用放疗计划系统融合不同时期的CT图像,采用生物图像处理软件ImageJ,根据断层扫描图像构图的物理和数学依据以及图像本身的灰度和色度,用Java语言编写局部实体肿瘤断层扫描图像的轮廓自动勾画与面积计算插件,选择相对精确的ROI测量法计算出放疗不同时期的肿瘤体积.结果:1例食管低分化食管鳞癌患者在放疗过程中,肿瘤细胞增殖速度较快,肿瘤体积不断增加,放疗对肿瘤没有抑制作用；1例患者在放疗过程中,肿瘤体积基本不变；1例患者的肿瘤体积在治疗前两周有所增加,可能是肿瘤死亡细胞清除速率慢的影响,在随后的放疗中肿瘤体积不断减小,在放疗结束两个月后肿瘤大部分消除；其他5例患者在放疗过程中肿瘤体积逐渐减小,体积变化趋势基本一致,在放疗前四周变化较大,四周以后肿瘤体积变化不大.结论:通过对5例食管癌患者体积变化数据进行指数拟合,食管癌放疗肿瘤体积的平均衰减速率1.27％(1.13％～1.56％)/天,半衰退期T1/2为44.3天,与文献报道的肺癌、宫颈癌肿瘤放疗体积变化情况相近.根据食管癌平均衰减速率计算,食管癌放疗4周后肿瘤体积平均减少1/3左右,需要考虑是否修改放疗计划,减少肿瘤体积的变化对放疗剂量分布的影响,特别是肿瘤精确放疗技术中更要注意肿瘤体积的变化.
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