食管癌常规放疗与三维适形放疗剂量学研究

Dosimetry Study on Conventional and Three Dimensional Conformal Radiotherapy for Esophageal Cancer

目的比较食管癌常规放射治疗和三维适形放射治疗2种不同方法的照射靶区与正常组织的剂量分布。方法对35例首程放疗的食管癌患者,进行常规模拟定位,体膜上标记射野中心后进行CT扫描,CT图像传送至治疗计划系统,勾画靶区。每例患者设计2种照射野,A为常规野,B为适形野,应用剂量体积直方图进行剂量学比较。结果 (1)食管造影所示病变平均长度为5.64 cm,CT扫描平均长度为9.02 cm(P=0.000)。常规野定位中心与适形野治疗中心在X、Y、Z轴上分别相差7.37 mm、10.21 mm、7.20 mm,其中在X轴上的差异有统计学意义(P=0.001);(2)常规野、适形野的GTV的D100%分别为4 121.2 c Gy、6 281.1 c Gy;GTV的D95%分别为4 580.4 c Gy、6 399.3 c Gy,CTV的D95%分别为3280.4 c Gy、6 200.3 c Gy;肺V30%分别为15.6%、12.4%。结论采用食管癌常规放射治疗技术的不仅肿瘤靶区的剂量分布不均匀,而且达不到理想的处方剂量;采用三维适形放射治疗技术不仅靶区剂量分布更理想,而且肿瘤靶区及正常组织均能达到理想剂量。

Objective To compare the dose distribution in the target volume and organs in conventional and 3 - dimentional radiotherapy in treating esophageal carcinoma. Methods 35 untreat esophageal carcinoma patients were immobilized and simulated by CT simulator in the treatment position.The field center was marked by barium meal while being simulated.The images were transferred to the treatment planning system.Outlining the gross tumor volume （GTV） , clinical target volume （CTV） and planning target volume （PTV） .Two treatment plans were designed：A,Conventional treatment plan （CTP） , B,Three dimensional conformal radiation （3DCRT） .Dose volume histogram was used to compare the dose distribution. Results （1） The average length of lesion was 5.64cm on esophageal barium meal and 9.02cm on CT scan, with a significant difference between the two methods （ P =0.000） .The deviation of field center along X,Y,Z axis was 7.37,10.21 and 7.20 mm,of which there was a significant difference in the X axis （ P =0.001） . （2） The GTV D100% was 4 121.2 cGy and 6 281.1 cGy for CTP,3DCRT,respectively.The GTV D95% volume was 4 580.4 cGy and 6 399.3 cGy, respectively.The CTV D95% was 3 280.4 cGy and 6 200.3 cGy, respectively.The lung V30 was 15.6% and 12.4%,respectively. Conclusion 3D CRT can well achieve ideal dose distribution and coverage to the target volume and spare the normal tissues at the same time,as compared with the conventional radiotherapy technique.