Repeat CT assessed CTV variation and PTV margins for short- and long-course pre-operative RT of rectal cancer
Repeat CT assessed CTV variation and PTV margins for short- and long-course pre-operative RT of rectal cancer
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DOI：
10.1016/j.radonc.2011.11.011
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发表时间：
2012-03-01
影响因子：
5.7
通讯作者：
Sonke, Jan-Jakob
中科院分区：
文献类型：
--
作者：
Nijkamp, Jasper;Swellengrebel, Maurits;Sonke, Jan-Jakob
目的：为了量化的CTV在直肠癌患者治疗与5 × 5（SCRT）和25 × 2戈伊（LCRT）和派生PTV margins.Methods和材料：33 SCRT与每日重复CT扫描和30 LCRT患者在第一周，然后每周扫描每日扫描的分数间形状变化。在所有扫描上描绘CTV，并相对于计划CT计算局部形状变化。边缘估计使用局部形状变化，以确保至少90%patients.Results 95%的最小剂量：使用482 CT扫描，系统和随机CTV形状变化是异质性的，范围从0.2厘米接近骨性结构高达1.0厘米SD在上前CTV区域。LCRT期间直肠体积显著减少导致上前CTV平均后移0.5 cm。所需的利润率范围从0.7厘米接近骨性结构高达3.1和2.3厘米，在上前区SCRT和LCRT，分别为。结论：异质性的形状变化需要各向异性PTV利润率。与当前临床切缘相比，所需的前向切缘明显更大。然而，这些较大的利润率是基于严格划定的CTV，与目前的做法相比，导致PTV较小。(c)2011爱思唯尔爱尔兰有限公司保留所有权利。放射治疗和肿瘤学102（2012）399-405
Purpose: To quantify the inter-fraction shape variation of the CTV in rectal-cancer patients treated with 5 x 5 (SCRT) and 25 x 2 Gy (LCRT) and derive PTV margins.Methods and materials: Thirty-three SCRT with daily repeat CT scans and 30 LCRT patients with daily scans during the first week followed by weekly scans were included. The CTV was delineated on all scans and local shape variation was calculated with respect to the planning CT. Margin estimation was done using the local shape variation to assure 95% minimum dose for at least 90% of patients.Results: Using 482 CT scans, systematic and random CTV shape variation was heterogeneous, ranging from 0.2 cm close to bony structures up to 1.0 cm SD at the upper-anterior CTV region. A significant reduction in rectal volume during LCRT resulted in an average 0.5 cm posterior shift of the upper-anterior CTV. Required margins ranged from 0.7 cm close to bony structures up to 3.1 and 2.3 cm in the upper-anterior region for SCRT and LCRT, respectively.Conclusions: Heterogeneous shape variation demands anisotropic PTV margins. Required margins were substantially larger in the anterior direction compared to current clinical margins. These larger margins were, however, based on strict delineated CTVs, resulting in smaller PTVs compared to current practice. (c) 2011 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 102 (2012) 399-405