Radiation Field Modeling and Computerized Treatment Planning

我们使用的是一个商业视频处理器供应商（NVidia），它比上一代的自定义体积渲染板便宜得多，而且在性能上有更大的增长潜力。商业供应商还提供软件（CUDA），用于利用板进行蒙特卡罗计算，这进一步支持了我们的研究目标。我们已经从三维图像融合过渡到探索四维放射成像。我们的研究建立了三维躯干外部体积的时间运动与内部器官，特别是肺的时间运动之间的基本关系。我们的研究开发了一种使用外部躯干体积变化进行图像跟踪的体积方法，该方法已申请专利。基于电子伽马阵雨（EGS-4）的蒙特卡罗剂量计算引擎（DCE）已经在LINUX和Windows环境中完全实现。在Windows环境中，DCE已经集成到一个功能齐全的治疗计划系统中。现在的工作集中在相空间源模型的开发上。目前，该系统用于小视野立体定向放射外科的研究。由于场尺寸减小，边缘效应变得重要，用于访问辐射输出的探测器的尺寸影响测量结果。这些输出测量的蒙特卡罗模拟极大地有助于选择最适合这些测量的探测器系统。蒙特卡罗算法提供了良好的协议与实验测量小至5毫米的涂抹器。在一个相关的项目中，我们已经采用了代数和蒙特卡罗dce来预测从诊断性CT扫描中接受的器官剂量。在儿童国家医疗中心的临床扫描中使用的GE CT扫描仪的x射线束的表征是完整的。我们还完成了将计算机断层扫描剂量指数（CTDI）的标准诊断测量与实际吸收剂量联系起来的绝对剂量学测量。我们正在等待一位新的博士后研究员的到来，以取代我们之前的博士后，他出乎意料地离开了，接受了美国食品和药物管理局（FDA）的一个职位。被选为该职位的候选人具有图像引导放射治疗的经验，可以扩展这些项目，但要到2009年秋季完成学位要求才能开始。图像跟踪的下一步将是为加速器提供一个接口来控制沙发运动，以补偿患者的运动，或者，改变多叶准直器叶片的顺序。蒙特卡洛CT项目需要扩展到多层CT扫描仪，规范化方法需要从CTDI转移到Bragg-Gray空腔方法，类似于传统的放疗物理学家使用的方法。我们使用的是一个商业视频处理器供应商（NVidia），它比上一代的自定义体积渲染板便宜得多，而且在性能上有更大的增长潜力。商业供应商还提供软件（CUDA），用于利用板进行蒙特卡罗计算，这进一步支持了我们的研究目标。我们已经从三维图像融合过渡到探索四维放射成像。我们的研究建立了三维躯干外部体积的时间运动与内部器官，特别是肺的时间运动之间的基本关系。我们的研究开发了一种使用外部躯干体积变化进行图像跟踪的体积方法，该方法已申请专利。基于电子伽马阵雨（EGS-4）的蒙特卡罗剂量计算引擎（DCE）已经在LINUX和Windows环境中完全实现。在Windows环境中，DCE已经集成到一个功能齐全的治疗计划系统中。现在的工作集中在相空间源模型的开发上。目前，该系统用于小视野立体定向放射外科的研究。由于场尺寸减小，边缘效应变得重要，用于访问辐射输出的探测器的尺寸影响测量结果。这些输出测量的蒙特卡罗模拟极大地有助于选择最适合这些测量的探测器系统。蒙特卡罗算法提供了良好的协议与实验测量小至5毫米的涂抹器。在一个相关的项目中，我们已经采用了代数和蒙特卡罗dce来预测从诊断性CT扫描中接受的器官剂量。在儿童国家医疗中心的临床扫描中使用的GE CT扫描仪的x射线束的表征是完整的。我们还完成了将计算机断层扫描剂量指数（CTDI）的标准诊断测量与实际吸收剂量联系起来的绝对剂量学测量。我们正在等待一位新的博士后研究员的到来，以取代我们之前的博士后，他出乎意料地离开了，接受了美国食品和药物管理局（FDA）的一个职位。被选为该职位的候选人具有图像引导放射治疗的经验，可以扩展这些项目，但要到2009年秋季完成学位要求才能开始。图像跟踪的下一步将是为加速器提供一个接口来控制沙发运动，以补偿患者的运动，或者，改变多叶准直器叶片的顺序。蒙特卡洛CT项目需要扩展到多层CT扫描仪，规范化方法需要从CTDI转移到Bragg-Gray空腔方法，类似于传统的放疗物理学家使用的方法。

We are using a commercial vendor of video processor boasrds (NVidia) which are both substantially less expensive than the previous generation of custom volume rendering boards as well as haveing a greater potential for growth in performance. The commercial vendor also provides software (CUDA) for utilizing the boards for Monte Carlo calculations, which further supports our research objectives. We have transitioned from 3-dimensional image fusion to exploring 4-dimensional radiotherapy imaging. Our research has established a fundamental relationship between the temporal motion of the 3-dimensional external torso volume and those of internal organs, especially the lungs. Our research has developed a volumetric methodology for image tracking using external torso volume change for which a patent has been applied for. The Electron-Gamma Shower (EGS-4)-based Monte Carlo Dose Calculation Engine (DCE) has been fully implemented in both a LINUX and Windows environment. In the Windows environment, the DCE has been integrated into a full featured treatment planning system. Work is now centered on the development of phase-space source models. Currently, this system is used to investigate small field stereotactic radiosurgery. Due to the reduced field size, edge effects become important and the size of detectors used to access the radiation output affect the measurement results. Monte Carlo simulation of these output measurements greatly assisted in the selection of the detector system that is most suitable for these measurements. The Monte Carlo algorithm provided good agreement with experimental measurements down to applicators as small as 5mm. In a related project, we have adapted both algebraic and Monte Carlo DCEs to predict organ doses received from diagnostic CT scans. The characterization of the x-ray beam from a GE CT Scanner used for clinical scanning at Children's National Medical Center is complete. We have also completed absolute dosimetry measurements linking the standard diagnostic measurement of Computer Tomography Dose Index (CTDI) to actual absorbed dose. We are awaiting the arrival of a new postdoctoral research associate to replace our former postdoc, who left unexpectedly to accept a position within the Food and Drug Administration (FDA). The candidate selected for this position has experience in image guided radiotherapy to expand on these projects, but will not be able to start until she completes her degree requirements in the Fall of 2009. The next step for image tracking will be to provide an interface to an accelerator to control couch morion in order to compensate for patient motion or, alternatively, to alter the sequence of multi-leaf collimator leaves. The MOnte Carlo CT project needs to be expanded to multi-slice CT scanners and the normalization methodology needs to be shifted away from CTDI to a Bragg-Gray cavity approach, similiar to that employed traditionally by radiotherapy physicists.We are using a commercial vendor of video processor boasrds (NVidia) which are both substantially less expensive than the previous generation of custom volume rendering boards as well as haveing a greater potential for growth in performance. The commercial vendor also provides software (CUDA) for utilizing the boards for Monte Carlo calculations, which further supports our research objectives. We have transitioned from 3-dimensional image fusion to exploring 4-dimensional radiotherapy imaging. Our research has established a fundamental relationship between the temporal motion of the 3-dimensional external torso volume and those of internal organs, especially the lungs. Our research has developed a volumetric methodology for image tracking using external torso volume change for which a patent has been applied for. The Electron-Gamma Shower (EGS-4)-based Monte Carlo Dose Calculation Engine (DCE) has been fully implemented in both a LINUX and Windows environment. In the Windows environment, the DCE has been integrated into a full featured treatment planning system. Work is now centered on the development of phase-space source models. Currently, this system is used to investigate small field stereotactic radiosurgery. Due to the reduced field size, edge effects become important and the size of detectors used to access the radiation output affect the measurement results. Monte Carlo simulation of these output measurements greatly assisted in the selection of the detector system that is most suitable for these measurements. The Monte Carlo algorithm provided good agreement with experimental measurements down to applicators as small as 5mm. In a related project, we have adapted both algebraic and Monte Carlo DCEs to predict organ doses received from diagnostic CT scans. The characterization of the x-ray beam from a GE CT Scanner used for clinical scanning at Children's National Medical Center is complete. We have also completed absolute dosimetry measurements linking the standard diagnostic measurement of Computer Tomography Dose Index (CTDI) to actual absorbed dose. We are awaiting the arrival of a new postdoctoral research associate to replace our former postdoc, who left unexpectedly to accept a position within the Food and Drug Administration (FDA). The candidate selected for this position has experience in image guided radiotherapy to expand on these projects, but will not be able to start until she completes her degree requirements in the Fall of 2009. The next step for image tracking will be to provide an interface to an accelerator to control couch morion in order to compensate for patient motion or, alternatively, to alter the sequence of multi-leaf collimator leaves. The MOnte Carlo CT project needs to be expanded to multi-slice CT scanners and the normalization methodology needs to be shifted away from CTDI to a Bragg-Gray cavity approach, similiar to that employed traditionally by radiotherapy physicists.