Accurate localization of intracavitary brachytherapy applicators from 3D CT imaging studies.
Accurate localization of intracavitary brachytherapy applicators from 3D CT imaging studies.
复制标题
通过 3D CT 成像研究准确定位腔内近距离放射治疗探头。
DOI：
10.1118/1.1412243
复制
发表时间：
2002
期刊：
影响因子：
3.8
通讯作者：
Williamson,JF
中科院分区：
文献类型：
--
作者：
Lerma,FA;Williamson,JF
为了支持蒙特卡罗光子输运模拟，提出一种准确的方法来识别三维CT扫描中腔内（ICT）近距离放疗施药器的位置和方向，从而在施药器屏蔽和施药器间衰减的情况下实现准确的剂量建模。材料和方法该方法包括寻找转换，使每个涂抹器组件（colpostats和tandem）的已知3D形状与每个CT切片上相应表面的轮廓所定义的体积之间的一致性最大化。我们使用该技术为三名宫颈癌患者定位Fletcher-Suit CT兼容应用器，使用植入后CT检查（3毫米切片厚度和分离）。根据测量的定位转换，与剂量矩阵相关的每个涂抹器的内部几何结构（源封装、高密度屏蔽和涂抹器体）的1对1配准的剂量分布来源于三维蒙特卡罗光子传输模拟。我们的定位方法的精度和准确性是通过CT扫描来评估的，在CT扫描中，密集棒和球体（在精密加工的模体中）的位置和方向是相对于龙门架在不同方向上测量的。结果使用该方法，我们将三维蒙特卡罗剂量计算直接记录到插入后的患者CT研究中。通过对精密加工幻影的CT研究，发现该方法的绝对精度为平面±0.2 mm，轴向±0.3 mm，平面±0.2 mm，轴向±0.2 mm。我们已经开发了一种新的、准确的技术来定位三维CT成像研究中的腔内近距离治疗涂抹器，该技术支持三维剂量计划，包括详细的三维蒙特卡罗剂量计算、源位置建模、屏蔽和涂抹器间屏蔽，准确。
PurposeTo present an accurate method to identify the positions and orientations of intracavitary (ICT) brachytherapy applicators imaged in 3D CT scans, in support of Monte Carlo photon‐transport simulations, enabling accurate dose modeling in the presence of applicator shielding and interapplicator attenuation.Materials and methodsThe method consists of finding the transformation that maximizes the coincidence between the known 3D shapes of each applicator component (colpostats and tandem) with the volume defined by contours of the corresponding surface on each CT slice. We use this technique to localize Fletcher–Suit CT‐compatible applicators for three cervix cancer patients using post‐implant CT examinations (3 mm slice thickness and separation). Dose distributions in 1‐to‐1 registration with the underlying CT anatomy are derived from 3D Monte Carlo photon‐transport simulations incorporating each applicator's internal geometry (source encapsulation, high‐density shields, and applicator body) oriented in relation to the dose matrix according to the measured localization transformations. The precision and accuracy of our localization method are assessed using CT scans, in which the positions and orientations of dense rods and spheres (in a precision‐machined phantom) were measured at various orientations relative to the gantry.ResultsUsing this method, we register 3D Monte Carlo dose calculations directly onto post insertion patient CT studies. Using CT studies of a precisely machined phantom, the absolute accuracy of the method was found to be ±0.2 mm in plane, and ±0.3 mm in the axial direction while its precision was ±0.2 mm in plane, and ±0.2 mm axially.ConclusionWe have developed a novel, and accurate technique to localize intracavitary brachytherapy applicators in 3D CT imaging studies, which supports 3D dose planning involving detailed 3D Monte Carlo dose calculations, modeling source positions, shielding and interapplicator shielding, accurately.