Radiation Field Modeling and Computerized Treatment Planning

辐射场建模和计算机化治疗计划

• 批准号: 8350045
• 负责人: Robert Miller
• 金额: $ 18.41万
• 依托单位: DIVISION OF CLINICAL SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8350045
• 关键词: 3-Dimensional; Affect; Agreement; Algorithms; Behavior; Calibration; Child; Clinical; Computer Simulation; Computer software; Computers; Custom; Development; Diagnostic; Diagnostic radiologic examination; Dose; Electrons; Environment; Epidemiology; Four-dimensional; Generations; Goals; Growth; Image; Legal patent; Link; Lung; Manuscripts; Maps; Measurement; Medical center; Methodology; Methods; Modality; Modeling; Motion; Organ; Output; Performance; Phase; Publishing; Radiation; Radiation therapy; Radiosurgery; Research; Scanning; Source; System; Techniques; Vendor; Work; X-Ray Computed Tomography; base; detector; dosimetry; improved; indexing; patient population; research study; response; simulation; tomography; treatment planning

We are using a commercial vendor of video processor boards (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. Our first manuscript on the CT Dosimetry System (CTDS) has just been published. Further research will be a direct comparison of traditional CT dosimetry methodology versus the new CTDS to highlight the advantages of individualized dosimetry and demonstrate organ-specific dose descriptions. Our next goal is to undertake the commissioning of a helical fan-beam CT scanner using a small point-dosimeter, as opposed to the traditional measurement of CTDI employed in diagnostic radiology. It is hoped that this system will provide the framework for a more complete dose assessment of patient populations for epidemiological dose-response studies. Additionally, we have begun to model the dosimetric behavior of low energy x-ray fields which have energy spectra different from standardized calibration conditions using the Monte Carlo dosimetry system described above. This mapping of dose-response is essential for the proper calibration of x-ray fields from cabinet x-ray units which are widely utilized for radiobiological experiments.

我们正在使用视频处理器板的商业供应商 (NVidia)，它们比上一代定制体积渲染板便宜得多，并且具有更大的性能增长潜力。该商业供应商还提供软件 (CUDA)，用于利用该板进行蒙特卡罗计算，这进一步支持我们的研究目标。我们已经从3维图像融合过渡到探索4维放射治疗成像。我们的研究已经建立了 3 维外部躯干体积的时间运动与内脏器官（尤其是肺部）的时间运动之间的基本关系。我们的研究开发了一种利用外部躯干体积变化进行图像跟踪的体积方法，并已申请专利。基于电子伽玛喷淋 (EGS-4) 的蒙特卡罗剂量计算引擎 (DCE) 已在 LINUX 和 Windows 环境中完全实现。在Windows环境中，DCE已集成到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，该系统用于研究小视野立体定向放射外科。由于场尺寸减小，边缘效应变得很重要，并且用于获取辐射输出的探测器的尺寸会影响测量结果。这些输出测量的蒙特卡罗模拟极大地帮助选择最适合这些测量的探测器系统。蒙特卡罗算法与小至 5 毫米的涂抹器的实验测量结果吻合良好。 在一个相关项目中，我们采用了代数 DCE 和蒙特卡罗 DCE 来预测从诊断 CT 扫描中接收到的器官剂量。国家儿童医学中心用于临床扫描的 GE CT 扫描仪的 X 射线束的表征已完成。我们还完成了绝对剂量测量，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。我们关于 CT 剂量测量系统 (CTDS) 的第一篇手稿刚刚发表。进一步的研究将直接比较传统 CT 剂量测定方法与新的 CTDS，以突出个性化剂量测定的优势并展示器官特异性剂量描述。我们的下一个目标是使用小型点剂量计调试螺旋扇束 CT 扫描仪，而不是诊断放射学中使用的传统 CTDI 测量。希望该系统将为流行病学剂量反应研究的患者群体提供更完整的剂量评估框架。此外，我们已经开始使用上述蒙特卡罗剂量测定系统对低能 X 射线场的剂量测定行为进行建模，这些 X 射线场的能谱与标准化校准条件不同。这种剂量响应图对于正确校准广泛用于放射生物学实验的柜式 X 射线装置的 X 射线场至关重要。