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首页> 外文学位 >Development of an optimization process for dose treatment planning for multiple arc stereotactic radiosurgery.
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Development of an optimization process for dose treatment planning for multiple arc stereotactic radiosurgery.

机译：为多弧立体定向放射外科制定剂量治疗计划的优化过程。

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摘要

The goal of stereotactic radiosurgery is to deliver conformal high dose irradiation to a lesion in the brain while simultaneously minimizing the radiation delivered to the surrounding normal tissue. The trial-and-error approach to dose treatment planning in stereotactic radiosurgery is very time-consuming, and there is no assurance that the resulting treatment plan is optimized. Previously used dose calculation methods and optimization algorithms like the downhill simplex and simulated annealing methods are slow.;A new and faster optimization process incorporating a new objective function was developed. The new objective function is consistent with the goal of stereotactic radiosurgery, which is the delivery of a high dose to the target and a low dose to the surrounding normal tissue. Mathematically, the new objective function involves maximizing the minimum difference between doses on the target boundary and doses in the surrounding normal tissue. It also allows the calculation of fewer doses, hence less CPU time, at each iteration than other objective functions that utilized all or pad of the 3-D dose calculation matrix. The new objective function is mathematically differentiable, and was optimized using the relatively fast sequential quadratic programming method.;When compared to existing optimization processes such as the downhill simplex and simulated annealing methods, the new optimization process achieved dose distributions at least equal to and most often better than those achieved using other optimization processes. Furthermore, the new optimization process is faster.;Since collimator diameters and beam weights had been used independently as adjustable parameters in optimized dose design, the two parameters were investigated. The results indicate that beam weight parameters alone are superior to collimator diameter parameters alone, or both beam weight and collimator diameter parameters, whenever emphasis is on low doses in the normal tissue. On the other hand, when the emphasis is on destroying the target as completely as possible, collimator diameter parameters alone produce superior treatment dose plans.;Often times, a lesion lies next to some critical tissue in the brain. The new optimization process can be and has been modified and used to determine optimized dosing of a target while avoiding high dose to neighboring critical tissue. For some irregularly shaped lesions, more than one isocenter is needed for a conformal dose. The new optimization process was also modified to determine a treatment plan for an ellipsoidal target requiring two isocenters. The resulting treatment dose is more conformal than those determined using a single isocenter. Finally, the new optimization process was used to determine an optimized treatment plan for a real tumor.
机译：立体定向放射外科手术的目的是向脑部病变传递适形的高剂量辐射，同时使传递到周围正常组织的辐射最小。立体定向放射外科手术中剂量治疗计划的试错法非常耗时，无法保证所得到的治疗计划是最佳的。以前使用的剂量计算方法和下坡单纯形法和模拟退火方法等优化算法的速度较慢。新的目标功能与立体定向放射外科的目标一致，立体定向放射外科是将高剂量输送至靶标，将低剂量输送至周围的正常组织。在数学上，新的目标函数涉及最大化目标边界上的剂量与周围正常组织中的剂量之间的最小差异。与利用3D剂量计算矩阵的全部或填充的其他目标函数相比，它还允许在每次迭代时计算更少的剂量，从而减少CPU时间。新的目标函数在数学上是可微的，并且使用相对快速的顺序二次规划方法进行了优化。与现有的优化过程（例如下坡单纯形法和模拟退火方法）相比，新的优化过程获得的剂量分布至少等于和最大通常比使用其他优化过程所获得的效果更好。此外，新的优化过程更快。由于在优化剂量设计中将准直器直径和光束权重分别用作可调参数，因此对这两个参数进行了研究。结果表明，只要重点在于正常组织中的低剂量，单独的光束重量参数就优于单独的准直器直径参数，或者优于光束重量和准直器直径参数。另一方面，当重点在于尽可能完全地破坏目标时，仅准直器直径参数就能产生更好的治疗剂量计划。通常，病变位于大脑某些关键组织的旁边。新的优化过程可以并且已经被修改并用于确定目标的优化剂量，同时避免了对邻近关键组织的高剂量。对于某些形状不规则的病变，保形剂量需要多个等中心点。还对新的优化过程进行了修改，以确定需要两个等中心点的椭圆形目标的治疗计划。所得到的治疗剂量比使用单个等中心线确定的剂量更保形。最后，使用新的优化过程来确定针对实际肿瘤的优化治疗方案。

著录项

  • 作者

    Richardson, William H., Jr.;

  • 作者单位

    Medical University of South Carolina.;

  • 授予单位 Medical University of South Carolina.;
  • 学科 Mathematics.;Engineering Biomedical.;Health Sciences Radiology.;Biophysics Medical.
  • 学位 Ph.D.
  • 年度 2000
  • 页码 212 p.
  • 总页数 212
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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