Developing computerized tools for cryosurgery planning

描述(由申请人提供)： 自1961年库珀和李发明第一个冷冻探头以来，冷冻外科一直被认为是一种侵入性的外科技术。在20世纪90年代，焦耳-汤姆逊冷却(与突然释放加压气体相关的冷却效果)的新发展导致低温探头的尺寸急剧减小，可同时使用的低温探头的数量增加。在一次前列腺冷冻手术中同时操作十几个或更多的冷冻探头已经是一种常见的做法。如果有效地定位，使用大量微型冷冻探头的主要好处之一是对冷冻过程进行更好的控制。 目前，为特定的手术选择正确的冷冻探头位置的过程是冷冻外科医生根据自己的经验和经验规则而掌握的一门艺术。低温探头通常以反复试验的方式操作，直到整个目标体积被认为是冻结的。目前，还没有办法确定低温探头的最佳位置。不理想的冷冻探头定位可能会使靶体积中的区域不冻结，可能会导致周围健康组织的冷冻损伤，可能需要不必要的大量冷冻探头，可能会增加手术过程的持续时间，并可能增加冷冻手术后并发症的可能性，所有这些都会影响医疗质量和成本。计算机化的规划工具将有助于缓解这些困难。 该研究小组最近提出了一种用于冷冻手术控制的新设备--“低温加热器”。低温加热器是一种温控电加热器。从广义上讲，低温加热器可以显著提高控制冻结区域形状和大小的能力，然而，为了实现低温加热器的全部好处，用于低温加热器本地化的计算机规划工具是必要的。 我们的目标是开发适用于所有可用的冷却技术的冷冻手术的计算机化计划工具。提出的研究内容包括：(1)开发一种高效的循环过程生物换热模拟的数值方案；(2)开发一种基于力场类比的高效优化技术。(3)基于知识的优化技术的发展。(4)规划工具的实验验证。 除了规划外，拟议工具的另一个重要应用是培训冷冻医生。拟议的工具将为冷冻医生提供可视化冷冻过程的3D体积性质的能力。 同样，它将允许外科医生探索各种配置的冷冻探头和冷冻加热器的性能，并观察每种配置可能导致的缺陷。这种可视化能力将为外科医生提供从物理实验或外科实践中难以获得的对低温外科物理的见解。

DESCRIPTION (provided by applicant): Cryosurgery has been known as an invasive surgical technique since 1961, when Cooper and Lee invented the first cryoprobe. In the 1990s, new developments in Joule-Thomson cooling (the cooling effect associated with a sudden relief of a pressurized gas) led to a dramatic decrease in the size of cryoprobes and an increase in the number of cryoprobes that could be used simultaneously. A dozen or more cryoprobes operating simultaneously in a single prostate cryosurgery is already common practice. If localized effectively, one of the primary benefits of using a large number of miniaturized cryoprobes is superior control over the freezing process. Currently, the process of selecting the correct placement of the cryoprobes for a specific procedure is an art held by the cryosurgeon, based on the surgeon's own experience and rules of thumb. Cryoprobes are typically operated in a trial-and-error fashion, until the entire target volume is thought to be frozen. Currently, there are no means to determine the optimal locations for the cryoprobes. Suboptimal cryoprobe localization may leave regions in the target volume unfrozen, may lead to cryoinjury of healthy surrounding tissues, may require an unnecessarily large number of cryoprobes, may increase the duration of the surgical procedure, and may increase the likelihood of post cryosurgery complications, all of which affect the quality and cost of the medical treatment. Computerized planning tools would help to alleviate these difficulties. The "cryoheater," a new device for cryosurgery control has recently been presented by the research team. The cryoheater is a temperature controlled electrical heater. In broad terms, cryoheaters can dramatically increase the ability to control the shape and size of the frozen region, however, to achieve the full benefits of cryoheaters, computerized planning tools for cryoheater localization are necessary. Our goal is to develop computerized planning tools for cryosurgery that are suitable for all available cooling techniques. The proposed research includes: (1) Development of an efficient numerical scheme for bioheat transfer simulations of cyroprocedures, (2) Development of an efficient optimization technique based on a force-field analogy. (3) Development of knowledge-based optimization techniques. (4) Experimental verification of the planning tool. Besides planning, another important application of the proposed tool is the training of cryosurgeons. The proposed tool will provide cryosurgeons with the ability to visualize the 3D volumetric nature of the freezing process. Likewise, it will allow the surgeon to explore the performance of various configurations of cryoprobes and cryoheaters, and observe the defects that would result from each. Such visualization capabilities will provide surgeons with insights into the physics of cryosurgery that are difficult to obtain from physical experiments or surgical practice.