Flat-panel cone-beam computed tomography for image-guided radiation therapy
Flat-panel cone-beam computed tomography for image-guided radiation therapy
复制标题
DOI：
10.1016/s0360-3016(02)02884-5
复制
发表时间：
2002-08-01
影响因子：
7
通讯作者：
Martinez, AA
中科院分区：
文献类型：
--
作者：
Jaffray, DA;Siewerdsen, JH;Martinez, AA
目的：在辐射计划和输送过程中的几何不确定性限制剂量升级并诱导正常组织并发症。已经开发出一种成像系统来在治疗时生成患者的高分辨率，软组织图像，以指导治疗和减少这种不确定性。评估了成像系统的性能，并讨论了图像引导的放射疗法的应用。方法和材料：能够进行射线照相，荧光镜检查和锥形梁计算机断层扫描（CT）的千伏成像系统已与医疗线性整合加速器。千线X射线是由常规X射线管安装在90度上的可伸缩臂上的常规X射线管产生的。 41 x 41 cm（2）平板X射线检测器安装在KV管对面。整个成像系统在计算机控制下运行，单个应用程序提供校准，图像采集，处理和锥形束CT重建。锥束CT成像涉及获取多个KV X射线照片，因为龙门在360度的旋转中旋转。使用过滤后的反射算法来重建体积图像。在重建过程中测量和纠正了龙门系统旋转中的几何不持有性。使用拟人化的头幻影和冠状对比幻影对成像性能进行定性评估。检查了几何非理想性的影响。收录：获取了头幻影的图像，并说明了通过锥形梁方法实现的亚毫升空间分辨率。高分辨率矢状和冠状视图几乎表现出各向同性的空间分辨率。需要在0.2 cm的订单上进行挠性校正，以补偿源和检测器支撑臂中的重力诱导的flex，以及整个龙门结构的轻微轴向运动。未经挠性校正的图像损失了细节，误导和条纹伪像。对比幻影的重建证明了系统的软组织成像能力。在0.1厘米厚的重建中很容易检测到47个Hounsfield单元的对比度，以使成像暴露于1.2 R（空气中，在没有幻影的情况下）。与幻影的常规CT扫描的比较进一步证明了锥形束CT方法的空间分辨率优势。结论：基于大面积的KV锥束CT成像系统，已成功适应了扁平面板检测器医疗线性加速器。该系统能够在可接受的成像剂量下生产具有出色空间分辨率的软组织图像。该技术与医疗加速器的集成将为高精度，图像引导的放射疗法提供理想的平台。 （c）2002 Elsevier Science Inc.
Purpose: Geometric uncertainties in the process of radiation planning and delivery constrain dose escalation and induce normal tissue complications. An imaging system has been developed to generate high-resolution, soft-tissue images of the patient at the time of treatment for the purpose of guiding therapy and reducing such uncertainties. The performance of the imaging system is evaluated and the application to image-guided radiation therapy is discussed.Methods and Materials: A kilovoltage imaging system capable of radiography, fluoroscopy, and cone-beam computed tomography (CT) has been integrated with a medical linear accelerator. Kilovoltage X-rays are generated by a conventional X-ray tube mounted on a retractable arm at 90degrees to the treatment source. A 41 X 41 cm(2) flat-panel X-ray detector is mounted opposite the kV tube. The entire imaging system operates under computer control, with a single application providing calibration, image acquisition, processing, and cone-beam CT reconstruction. Cone-beam CT imaging involves acquiring multiple kV radiographs as the gantry rotates through 360degrees of rotation. A filtered back-projection algorithm is employed to reconstruct the volumetric images. Geometric nonidealities in the rotation of the gantry system are measured and corrected during reconstruction. Qualitative evaluation of imaging performance is performed using an anthropomorphic head phantom and a coronal contrast phantom. The influence of geometric nonidealities is examined.Results: Images of the head phantom were acquired and illustrate the submillimeter spatial resolution that is achieved with the cone-beam approach. High-resolution sagittal and coronal views demonstrate nearly isotropic spatial resolution. Flex corrections on the order of 0.2 cm were required to compensate gravity-induced flex in the support arms of the source and detector, as well as slight axial movements of the entire gantry structure. Images reconstructed without flex correction suffered from loss of detail, misregistration, and streak artifacts. Reconstructions of the contrast phantom demonstrate the soft-tissue imaging capability of the system. A contrast of 47 Hounsfield units was easily detected in a 0.1-cm-thick reconstruction for an imaging exposure of 1.2 R (in-air, in absence of phantom). The comparison with a conventional CT scan of the phantom further demonstrates the spatial resolution advantages of the cone-beam CT approach.Conclusions: A kV cone-beam CT imaging system based on a large-area, flat-panel detector has been successfully adapted to a medical linear accelerator. The system is capable of producing images of soft tissue with excellent spatial resolution at acceptable imaging doses. Integration of this technology with the medical accelerator will result in an ideal platform for high-precision, image-guided radiation therapy. (C) 2002 Elsevier Science Inc.