ONLINE DUAL BEAM IMAGING FOR TREATMENT VERIFICATION

局部失败仍然是癌症治疗中的一个严重问题。在更多的 今年将有100多万癌症患者前来接受治疗， 大约三分之一的人会因为局部复发而无法接受治疗，或者 局部复发伴远处转移。在放射治疗方面，少校 正在努力实施三维(3D)适形治疗 改善当地控制的技术。精确的治疗设置成为 至关重要，刺激了在线电子门户成像的发展 设备(EPID)，以加强常规治疗核查。不幸的是， 固有的较差的图像质量和较高的成像剂量 兆伏(MV)成像使当前EPID对适形无效 治疗验证。 我们的假设是，对治疗差错的充分评估不能 可进行在线MV成像。在质量上与 处方千伏(千伏)图像是必不可少的。A千伏电源上的 治疗机将使我们能够制造出低剂量的诊断质量 并极大地提高了对安装误差的检测和校正。在……里面 在为期4年的研究期间，我们的具体目标是：(1)设计、 一种小视场在线双光束成像系统的实现与优化 适形处理验证，(2)通过确定来检验假设， 通过体模成像研究，安装错误检测方面的改进 使用双束成像与常规MV成像相比，以及(3) 开发方法以改进设置错误纠正，使用其他 多投影千伏图像中的三维(3D)信息。 一个千伏X射线源和两个在线成像仪将安装在 加速器。通过获取具有诊断质量的双光束图像 患者在治疗位置的千伏开野图像和 将其与MV门户图像叠加。一群人的能力 观察者检测双光束和MV图像中的设置变化 将会被评估。因为可以用Low拍摄更多的投影图像 剂量千伏束流，将线性变换方法应用于图像 以更准确地解决3D设置误差的原因。最后， 千伏电子束的可用性也使我们能够实施CT扫描 加速器能够研究软组织在此期间的变化 关于治疗的问题。我们的发现将提高我们对 放射治疗中的设置准确性，并提供重要信息 实时设置纠错策略的发展 未来。

Local failure remains a serious problem in cancer treatment. Of the more than 1 million cancer patients who will present for treatment this year, about 1/3 will fail their treatment due to local recurrence alone, or local recurrence with distant metastasis. In radiation therapy, major efforts are being made to implement 3-dimensional (3D) conformal treatment techniques to improve local control. Accurate treatment setup becomes vital, spurring the development of on-line electronic portal imaging devices (EPIDs) to enhance routine treatment verification. Unfortunately, the inherently poor image quality and high imaging dose associated with megavoltage (MV) imaging render current EPIDs ineffective for conformal treatment verification. It is our hypothesis that adequate assessment of treatment errors cannot be made with on-line MV imaging. An image similar in quality to the prescription kilovoltage (kV) image is essential. A kV source on the treatment machine will allow us to make low dose, diagnostic quality images and greatly improve the detection and correction of setup error. In the 4 year research period, our specific aims are to: (1) design, implement and optimize an on-line dual beam imaging system for small field conformal treatment verification, (2) test the hypothesis by determining, with phantom imaging studies, the improvement in setup error detection using dual beam imaging as compare to conventional MV imaging, and (3) develop approaches to improve setup error correction using the additional 3-dimensional (3D) information in multiple projection kV images. A kV x-ray source and two on-line imagers will be mounted on an accelerator. A diagnostic quality dual beam image is produced by acquiring a kV open field image of the patient in treatment position and superimposing it with the MV portal image. The ability of a group of observers to detect setup variations in the dual beam and the MV images will be evaluated. As more projection images can be taken with the low dose kV beam, linear transformation methods will be applied to the images to more accurately solve for the cause of 3D setup error. Finally, the availability of a kV beam also enables us to implement CT scanning capability on the accelerator to study soft tissue changes during the time of treatment. Our findings will improve our knowledge about the limit of setup accuracy in radiation therapy and provide important information for the development of real-time setup error correction strategies in the future.