Set-up errors due to endorectal balloon positioning in intensity modulated radiation therapy for prostate cancer
Set-up errors due to endorectal balloon positioning in intensity modulated radiation therapy for prostate cancer
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DOI：
10.1016/j.radonc.2007.06.009
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发表时间：
2007-08-01
影响因子：
5.7
通讯作者：
Cheng, Jason Chia-Hsien
中科院分区：
文献类型：
--
作者：
Wang, Chun-Wei;Chong, Fok-Ching;Cheng, Jason Chia-Hsien
目的：为探讨前列腺放射治疗中每日放置直肠内球囊的摆位误差和变形，材料与方法：对20例接受放射治疗的前列腺癌患者每日放置直肠内球囊。每周从前后位（AP）和侧位视图收集电子射野图像（EPI）。将EPI与预处理期间获得的计算机断层扫描的数字重建X线照片进行比较，以估计位移。结果：共对154个EPI进行了评价。球囊相对于骨性标志的平均位移在上-下（SI）中为1.8 mm，AP中为1.3 mm，左右（LR）方向1 mm。SI、AP和LR方向的系统误差分别为3.3 mm、4.9 mm和4.0 mm。相对于骨性标志或治疗等中心点，SI方向（4.5 mm和4.5 mm）的随机（分次间）位移大于AP方向（3.9 mm和4.4 mm）和LR方向（3.0 mm和3.0 mm）。治疗等中心点到骨性标志点的随机误差在SI、AP和LR方向上分别为2.3 mm、3.2 mm和2.6 mm。在治疗过程中，SI、AP和LR方向分别发生2.8 mm、2.5 mm和2.6 mm的球囊变形。结论：SI方向是直肠内球囊组间位移最大、变形最显著的方向。(c)2007爱思唯尔爱尔兰有限公司保留所有权利。
Purpose: To investigate the set-up errors and deformation associated with daily placement of endorectal balloons in prostate radiotherapy.Materials and methods: Endorectal balloons were placed daily in 20 prostate cancer patients undergoing radiotherapy. Electronic portal images (EPIs) were collected weekly from anterior-posterior (AP) and lateral views. The EPIs were compared with digitally reconstructed radiographs from computed tomography scans obtained during pretreatment period to estimate displacements. The interfraction deformation of balloon was estimated with variations in diameter in three orthogonal directions throughout the treatment course.Results: A total of 154 EPIs were evaluated. The mean displacements of balloon relative to bony landmark were 1.8 mm in superior-inferior (SI), 1.3 mm in AP, and 0. 1 mm in left-right (LR) directions. The systematic errors in SI, AP, and LR directions were 3.3 mm, 4.9 mm, and 4.0 mm, respectively. The random (interfraction) displacements, relative to either bony landmarks or treatment isocenter, were larger in SI direction (4.5 mm and 4.5 mm), than in AP (3.9 mm and 4.4 mm) and LR directions (3.0 mm and 3.0 mm). The random errors of treatment isocenter to bony landmark were 2.3 mm, 3.2 mm, and 2.6 mm in SI, AP, and LR directions, respectively. Over the treatment course, balloon deformations of 2.8 mm, 2.5 mm, and 2.6 mm occurred in SI, AP, and LR directions, respectively. The coefficient of variance of deformation was 7.9%, 4.9%, and 4.9% in these directions.Conclusions: Larger interfractional displacement and the most prominent interfractional deformation of endorectal balloon were both in SI direction. (c) 2007 Elsevier Ireland Ltd. All rights reserved.