Lotz Heidi T, Pos Floris J, Hulshof Maarten C C M, van Herk Marcel, Lebesque Joos V, Duppen Joop C, Remeijer Peter
Department of Radiation Oncology, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands.
Int J Radiat Oncol Biol Phys. 2006 Apr 1;64(5):1551-8. doi: 10.1016/j.ijrobp.2005.12.025.
First, to quantify bladder-tumor motion in 3 dimensions during a 4-week to 5-week course of external radiotherapy. Second, to relate the motion to the tumor location on the bladder wall. Third, to extensively evaluate gross tumor volume (GTV) shape and volume changes during the course of the treatment.
Multiple repeat computed tomography (CT) images were obtained for 21 bladder cancer patients. These scans were matched to the rigid bony anatomy. For each patient, the main direction and magnitude of the tumor movement was determined by use of principle-component analysis. To study GTV shape changes, all GTVs were registered to the GTV in the planning CT scan, and the residual shape errors were determined by measurement of edge variations perpendicular to the median surface.
Gross tumor volume translations were largest in cranial-caudal and anterior-posterior direction (SD, 0.1 to approximately 0.9 cm). The translations were strongly correlated with the tumor location on the bladder wall. The average value of the local standard deviations of the GTV shape ranged from 0.1 to approximately 0.35 cm.
Despite large differences in bladder filling, variations in GTV shape were small compared with variations in GTV position. Geometric uncertainties in the GTV position depended strongly on the tumor location on the bladder wall.
第一，量化在为期4至5周的外照射放疗过程中膀胱肿瘤的三维运动。第二，将该运动与肿瘤在膀胱壁上的位置相关联。第三，广泛评估治疗过程中大体肿瘤体积（GTV）的形状和体积变化。
为21例膀胱癌患者获取了多次重复计算机断层扫描（CT）图像。这些扫描与刚性骨骼解剖结构进行匹配。对于每位患者，通过主成分分析确定肿瘤运动的主要方向和幅度。为研究GTV形状变化，将所有GTV配准到计划CT扫描中的GTV上，并通过测量垂直于中间表面的边缘变化来确定残余形状误差。
大体肿瘤体积在头-尾方向和前-后方向上的平移最大（标准差，0.1至约0.9厘米）。这些平移与肿瘤在膀胱壁上的位置密切相关。GTV形状的局部标准差平均值范围为0.1至约0.35厘米。
尽管膀胱充盈情况存在很大差异，但与GTV位置的变化相比，GTV形状的变化较小。GTV位置的几何不确定性在很大程度上取决于肿瘤在膀胱壁上的位置。
