High-frequency microwave ablation for targeted, minimally invasive cancer therapy

本项目的主要研究目标是开发一种利用高频微波消融治疗癌症的微创新技术。根据美国癌症协会的估计，2013年预计将有超过160万新的癌症病例被诊断出来。死亡率最高的前十种癌症都是微波消融的候选对象。这项技术避免了目前最常见的癌症治疗方法--手术的高成本、侵袭性、全身麻醉的长时间使用等风险，以及较长的恢复时间。本项目的目的是研究高频微波摧毁癌细胞的基本机制，并开发适合于微创向肿瘤传递微波能量的微型天线。还将探索使用纳米颗粒来提高加热效率。总的来说，这些技术将使几乎位于身体任何地方的肿瘤能够进行微创、有针对性的治疗。这个项目是将研究和教育相结合，并促进工程多样性的一个典型例子。一个名为“拓展你的视野”的研讨会将针对中学女生开展，重点是癌症的微创治疗。每年，麦迪逊大都会学区科学研究实习计划的一名高中生将获得暑期研究机会。将利用机构计划，让少数族裔和本科生参与研究活动。该项目将在招收和留住电气工程本科和研究生阶段的女学生方面特别有效，因为它强调的是一个具有世界意义的保健问题。所有参与该项目的学生将在电磁学和医学的界面上接受宝贵的跨学科培训。微波消融术使用间隙天线将微波能量直接传输到肿瘤中，并将其加热到细胞毒性温度。以前的绝大多数研究都使用了2.5 GHz以下的频率，部分原因是担心高频下较小的电磁波穿透深度将阻止创建足够大的消融区。然而，最近获得了相反的实验证据。高频微波消融提供了许多尚未被探索的优势。首先，高频微波天线，特别是本项目中提出的新型天线类型和馈电技术，比低频天线小得多。其次，在体内使用更高的频率可以更快地达到所需的消融区域。第三，高频微波的使用使得能够开发具有可定制加热模式的紧凑型和微型天线阵列，这是传统的单元件低频天线所不具备的。总而言之，这些特性有望克服现有热消融技术的缺点，扩大微波消融系统的能力领域，使位于身体几乎任何位置的肿瘤能够进行微创、有针对性的治疗。将利用混合电磁/热模拟的计算试验台和涉及体外组织实验的物理试验台来完成以下研究目标：1)阐明高频MWA的基本机制并研究新颖的间质天线设计概念；2)研究纳米颗粒介导的MWA以提高加热选择性和降低功率需求；3)确定使用灵活的HF MWA天线通过导管或内窥镜进入消融区的可行性；以及4)研究用于定制消融区的大小和形状的高频微波间质天线阵列。

The main research goal of this project is to develop a new minimally-invasive technology for thermal treatment of cancerous tumors using high-frequency microwave ablation. According to American Cancer Society estimates, over 1.6 million new cancer cases are expected to be diagnosed in 2013. The top ten cancers with the highest mortality rates are all candidates for microwave ablation. This technology avoids the high costs, invasiveness, prolonged use of general anesthesia and other risks, and long recovery times associated with surgery, which is currently the most common method of treatment of cancer.The objective of this project is to investigate the fundamental mechanisms of destroying cancerous cells using high-frequency microwaves as well as to develop miniature antennas suitable for minimally invasive delivery of microwave energy to the tumor. The use of nanoparticles to enhance heating efficiency will also be explored. Collectively, these technologies will enable minimally invasive, targeted treatment of tumors that are located nearly anywhere in the body. This project is a prime example of integrating research and education, and fostering diversity in engineering. An 'Expanding Your Horizons' workshop focused on minimally invasive treatment of cancer will be developed for middle-school girls. Each year, a summer research opportunity will be offered to a high school student from the Madison Metropolitan School District Science Research Internship Program. Institutional programs will be leveraged to involve minorities and undergraduates in the research activities. The project will be particularly effective in recruiting and retaining female students in electrical engineering at both the undergraduate and graduate levels due to its emphasis on a health care issue of worldwide significance. All students involved in the project will receive invaluable interdisciplinary training at the interface of electromagnetics and medicine.Microwave ablation employs an interstitial antenna to deliver microwave energy directly into the tumor and heat it to cytotoxic temperatures. The vast majority of prior studies have made use of frequencies below 2.5 GHz, in part due to concerns that smaller penetration depths of electromagnetic waves at higher frequencies would preclude the creation of sufficiently large ablation zones. However, experimental evidence to the contrary has been recently obtained. High-frequency microwave ablation offers a number of advantages that have not yet been explored. First, high-frequency microwave antennas, particularly the novel antenna types and feeding techniques proposed in this project, are radically smaller than their low-frequency counterparts. Second, the desired ablation zone can be achieved much faster in vivo using higher frequencies. Third, the use of high-frequency microwaves enables the development of compact and miniature antenna arrays with customizable heating patterns that are not available from conventional single-element low-frequency antennas. Collectively, these attributes are expected to overcome the shortcomings of existing thermoablative technologies and expand the realm of capabilities of microwave ablation systems to enable minimally invasive, targeted treatment of tumors located nearly anywhere in the body. Computational test beds involving hybrid electromagnetic/thermal simulations and physical test beds involving experiments with ex vivo tissue will be employed to accomplish the following research objectives: 1) elucidate fundamental mechanisms of HF MWA and investigate novel interstitial antenna design concepts; 2) investigate nanoparticle-mediated MWA for improving heating selectivity and reducing power requirements; 3) establish the feasibility of using flexible HF MWA antennas for gaining access to the ablation site via a catheter or endoscope; and 4) investigate arrays of HF microwave interstitial antennas for customizing the size and shape of the ablation zone.