腹部肿瘤患者不同呼吸时相的三维重建轮廓及靶区比较

The comparison of the targets and the reconstructed three dimensional contours at different respiratory phases of celiac tumor patient

目的:探讨腹部肿瘤患者不同呼吸时相CT扫描图像的三维重建轮廓及勾画靶区的差异。方法:在同一定位条件下,对13例腹部肿瘤患者分别进行平静呼吸状态下吸气完毕屏气及呼气完毕屏气时的CT扫描。将获得的2个呼吸时相的图像分别用治疗计划系统进行三维重建并由同一放疗科医师进行靶区勾画以比较两者间的轮廓差异、靶区体积差异并在假设采用相同角度射野照射的情况下比较准直器开口大小。结果:同一患者不同呼吸时相的三维重建轮廓存在差异。其中靶区除在三维方向上发生位移外,其体积也发生了变化。13例患者两个呼吸时相的靶区体积差异幅度在1.23%～22.3%之间,平均为(8.09±5.86)%。采用相同角度射野照射时,计划系统自动确定的准直器开口大小平均差异幅度为准直器A方向(jawA)(6.43±8.56)%,准直器B方向(jawB)(13.44±17.76)%。结论:呼吸运动导致的组织轮廓及靶区变化确实存在并且会影响到治疗计划设计,因此放射治疗中必须考虑呼吸运动的影响以提高疗效。

Objective ： To observe the difference of the targets and the reconstructed 3-D contours at different respiratory phases of celiac tumor patients. Methods： In the same orientational coordinate, the CT images of 13 celiac tumor patients were obtained at the end of inspiration and exhalation respectively, and these images were reconstructed to form the patient con- tours respectively. Then the target areas were drawn by the same doctor and they were supposed to be irradiated with the same angle field. Then the contour, and the volume of target and automatic matched field size for collimator at two respiratory phase were compared. Results ：At two respiratory phase, the reconstructed contours of the patient were different, the targets moves in 3-D direction and the volume of the target also changes. For 13 patients, between the observed value at two respiratory phases of these 13 patients, the range of difference for target volume was from 1.23% to 22.3%, the average value was （8.09±5.86）%, If the target was irradiated with the sameangle field, the average difference of automatic matched field size for collimator was （6.43±8.56）% in jaw A direction and was （13.44±17.76）% in jaw B direction. Conclusion： The effect of respiration dose exist,and may cause the change of reconstructed contour,the target area and the treatment project, so it must be considered in order to improve the radiotherapy.