Cone-beam-CT guided radiation therapy:: technical implementation
Cone-beam-CT guided radiation therapy:: technical implementation
复制标题
DOI：
10.1016/j.radonc.2005.03.001
复制
发表时间：
2005-06-01
影响因子：
5.7
通讯作者：
Martinez, AA
中科院分区：
文献类型：
--
作者：
Létourneau, D;Wong, JW;Martinez, AA
背景和目的：安装在直线加速器上的X射线体积成像系统（XVI）可用于图像引导应用。为了准备临床实施，进行了体模和患者成像研究，以确定会权衡图像质量、患者剂量和扫描时间的照射参数。患者和方法：将 XVI 图像质量和成像剂量与头部和身体体模的螺旋 CT 扫描仪获得的图像质量和成像剂量进行基准比较。照射参数各不相同，包括总成像剂量、投影数量、视野、重建分辨率和散射拒绝网格的使用。我们根据相对对比度、噪声、对比度噪声比 (CNR) 和点扩散函数 (PSF) 来表征图像质量。采集骨盆、头颈和肺部患者的 XVI 扫描，并将其提交给一系列观察者以确定有利的重建参数。结果：模型研究表明，散射排斥网格减少了光子散射并提高了图像均匀性。对于人体模型，螺旋 CT 和宽视野 XVI 技术产生相似的图像质量，表面剂量分别为 0.025 和 0.044 Gy。我们已经证明，与广域技术相比，局部断层扫描技术可以提高图像对比度和 CNR，同时减少皮肤剂量 40-50%。对头颈部、肺部和前列腺患者的临床扫描显示出良好的软组织对比度和良好的骨骼清晰度。结论：通过调整照射参数和小于0.05 Gy的成像表面剂量，模拟人体厚度的体模可以获得高质量的XVI图像。 XVI 目前可用于使用软组织和骨结构对头部和颈部、躯干和骨盆区域进行图像引导治疗。 (C) 2005 Elsevier Ireland Ltd. 保留所有权利。
Background and purpose: X-ray volumetric imaging system (XVI) mounted on a linear accelerator is available for image guidance applications. In preparation for clinical implementation, phantom and patient imaging studies were conducted to determine the irradiation parameters that would trade-off image quality, patient dose and scanning time.Patients and methods: The XVI image quality and imaging dose were benchmarked against those obtained with a helical CT scanner for a head and body phantom. The irradiation parameters were varied including the total imaging dose, number of projections, field of view, reconstruction resolution and use of a scatter rejection grid. We characterized the image quality based on relative contrast, noise, contrast to noise ratio (CNR) and point spread function (PSF). XVI scans of pelvis, head and neck and lung patients were acquired and submitted to a range of observers to identify the favorable reconstruction parameters.Results: Phantom studies have demonstrated that a scatter rejection grid reduces photon scattering and improves the image uniformity. For the body phantom, the helical CT and the wide field XVI technique produce similar image quality, with surface doses of 0.025 and 0.044 Gy respectively. We have demonstrated that the local tomography technique improves the image contrast and the CNR while reducing the skin dose by 40-50% compared to the wide field technique. Clinical scans of head and neck, lung and prostate patients present good soft tissue contrast and excellent bone definition.Conclusions: With adjustment of irradiation parameters and an imaging surface dose of less than 0.05 Gy, high quality XVI images can be obtained for a phantom simulating the body thickness. XVI is currently feasible for image-guided treatments of head and neck, torso and pelvic areas using soft tissue and bony structures. (C) 2005 Elsevier Ireland Ltd. All rights reserved.