Improvement of CT-based treatment-planning models of abdominal targets using static exhale imaging
Improvement of CT-based treatment-planning models of abdominal targets using static exhale imaging
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DOI：
10.1016/s0360-3016(98)00130-8
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发表时间：
1998-07-01
影响因子：
7
通讯作者：
Ten Haken, RK
中科院分区：
文献类型：
--
作者：
Balter, JM;Lam, KL;Ten Haken, RK
目的：不考虑通气运动的基于CT的患者模型可能无法准确预测关键腹部结构的形状和位置。用于成像和治疗的呼吸门控技术尚未广泛使用。目前的研究的目的是探索一个中间步骤，以提高患者模型的准确性，并通过采集CT数据与患者屏住呼吸，在正常exhale.Methods和材料减少治疗体积：15例患者（没有特殊的呼吸指令）的膈肌运动的解释性时间过程进行了测量，在模拟过程中使用数字化的电影从荧光镜。基于呼气CT模型开发了后续的临床方案用于治疗。使用螺旋扫描仪在正常呼气时采集CT扫描（通常为3.5 mm层厚）。扫描体积被分成两到三个部分，以允许患者在其间呼吸。边缘被放置在肝内靶体积的基础上的解释性偏移低于目标，并仅在呼气位置上级目标的再现性。结果：在42%的典型呼吸周期中，平均患者的横膈膜保持在从平均呼气位置的呼吸偏移范围的25%内，并且对于15%的周期，在距离平均吸气位置的范围的25%内。多个呼吸周期内呼气位置的再现性为0.9 mm（2 sigma），而吸气位置的再现性为2.6 mm。结合呼气位置的变化和来自CT切片的横膈膜位置的不确定性，导致在目标上方10 mm上级和目标下方19 mm的典型边缘，相比之下，在我们基于自由呼吸CT研究的边缘的先前协议下，在两个方向上的边缘为19 mm。对于典型的肝内目标，这些较小的体积导致肝脏的V-eff降低3.6%。门静脉片的分析显示适当的目标覆盖范围的基础上治疗患者的呼气modeled plannes.Conclusions：模拟腹部治疗呼气，而不是实现所有的收益门控治疗，提供了一个立即减少的正常组织治疗的体积，并提高了可靠性的NTCP建模的患者数据，相比，目前的“自由呼吸”的CT模型的患者。(C)1998年爱思唯尔科学公司
Purpose: CT-based models of the patient that do not account for the motion of ventilation may not accurately predict the shape and position of critical abdominal structures. Respiratory gating technology for imaging and treatment is not Set widely available. The purpose of the current study is to explore an intermediate step to improve the veracity of the patient model and reduce the treated volume by acquiring the CT data with the patients holding their breath at normal exhale.Methods and Materials: The ventilatory time courses of diaphragm movement for 15 patients (with no special breathing instructions) were measured using digitized movies from the fluoroscope during simulation. A subsequent clinical protocol was developed for treatment based on exhale CT models. CT scans (typically 3.5-mm slice thickness) were acquired at normal exhale using a spiral scanner. The scan volume was divided into two to three segments, to allow the patient to breathe in between. Margins were placed about intrahepatic target volumes based on the ventilatory excursion inferior to the target, and on only the reproducibility of exhale position superior to the target.Results: The average patient's diaphragm remained within 25% of the range of ventilatory excursion from the average exhale position for 42% of the typical breathing cycle, and within 25% of the range from the average inhale position for 15% of the cycle. The reproducibility of exhale position over multiple breathing cycles was 0.9 mm (2 sigma), as opposed to 2.6 mm for inhale. Combining the variation of exhale position and the uncertainty in diaphragm position from CT slices led to typical margins of 10 mm superior to the target, and 19 mm inferior to the target, compared to margins of 19 mm in both directions under our prior protocol of margins based on free-breathing CT studies, For a typical intrahepatic target, these smaller volumes resulted in a 3.6% reduction in V-eff for the liver. Analysis of portal films shows proper target coverage for patients treated based on exhale modeled plans.Conclusions: Modeling abdominal treatments at exhale, while not realizing all the gains of gated treatments, provides an immediate reduction in the volume of normal tissue treated, and improved reliability of patient data for NTCP modeling, when compared to current "free breathing" CT models of patients. (C) 1998 Elsevier Science Inc.