呼吸运动对肺癌三维适形放疗肿瘤靶区影响的研究

目的：探索呼吸运动对肺癌三维适形放疗肿瘤靶区的几何中心和体积的影响，为肿瘤靶区的勾画提供参考依据。方法：27例病理证实的原发性非小细胞肺癌患者平静呼吸状态，行CT扫描，相同条件下行呼气末屏气扫描和吸气末屏气扫描。在治疗计划系统（TPS）中，分别勾画平静呼吸状态扫描图像和吸气末屏气状态扫描图像的肿瘤靶区，得到肿瘤靶区（GTV）及诊断图像的肿瘤靶区（GTVz），将呼气末屏气扫描和吸气末屏气扫描图像进行融合，得到融合图像，勾画得到融合图像的肿瘤靶区（GTVf），并进行比较。结果：肿瘤靶区几何中心在X、Y、Z方向移位的平均值，平静图像和诊断图像与融合图像相比分别为（0．34±0．21）、（0．21±0．27）、（0．84±0．42）cm和（0．36±0．24）、（0．28±0．31）、（0．91±0．43）cm。融合图像靶体积与平静图像靶体积、诊断图像靶体积相比，在肺的上、中、下部位分别增加37．29％、21．44％、44．82％和42．33％、25．39％、50．97％，差异都有统计学意义。平静图像靶区体积与诊断图像靶体积相比，在肺的上、中、下部位分别增加4．09％、4．28％、4．24％，差异有统计学意义。结论：呼吸运动引起肺癌肿瘤靶区中心坐标在X、Y、Z方向上发生不同程度的移位，同时伴随肿瘤靶区体积的改变，勾画肿瘤靶区时中应充分考虑这一点。

Effect of respiratory movement on gross target volume in three dimensional conformal radiotherapy for lung carcinoma

Objective To explore the impact of respiratory movement on gross target volume in 3-dimension conformal radiotherapy （3DCRT） for lung carcinoma, and provide reference for the contouring of gross target volume. Methods To begin with, 27 lung carcinoma patients pathologically confirmed with primary non-small-cell carcinoma underwent CT scanning under resting respiration, and also end-tidal scanning at breath holding and end-inspiratory scanning at breath holding. In treatment planning system （TPS）, the gross target volume was contoured for the case under resting respiration to obtain GTV, for the case at end-inspiratory breath holding to obtain GTVz and for the case merging the images at end-tidal breath holding and end-inspiratory breath holding to obtain GTVf. Then, the resuhs were compared. Results By comparing GTVz images with GTV images, it＇s found that the average displacements of target geometry center were （0.36±0.24）, （0.28±0.31） and （0.91±0.43）cm on X, Y and Z axis respectively, while those of GTVf images were （0.34±0.21）, （0.21±0.27） and （0.84±0.42）cm. Similarly,the increased volumes of lung in GTVf images were 37.29%, 21.44% and 44.82% for the upper part, the middle part and the lower part respectively, and those in GTVz images were 42.33%, 25.39% and 50.97%. Nevertheless, the increased target volumes in upper part, middle part and lower part of lung were 4.09%, 4.28% and 4.24% respectively. All of those discrepancies had statistical significances.Conclusion The movement of respiration somehow leads to variations of gross target volumes in different parts of lung and the changing of geometry center. Therefore, the above effect of respiratory movement has to be considered while contouring gross target volume in TPS.