Electron Transport in Tissue-like Material

描述(由申请人提供)：本提案是2002年7月开始的三年资助金的修订后的竞争性续期。拟议的薄片电子发射研究旨在提供数据，以测试为描述生物材料中电离辐射能量沉积的初始空间模式而开发的计算模型。这些最初的损伤模式影响随后的化学和生化，从而影响导致生物修复、基因组不稳定、细胞凋亡和/或最终诱发癌症的关键细胞通路。我们关于辐射损伤初始模式的大部分知识是从逐个事件的蒙特卡罗径迹模拟模型中获得的，这些模型的横截面数据库中往往包含不确定性。目前的工作和拟议的扩展提供了数据，我们可以在电子传输物理水平上，即在化学反应修改和平均之前，测试径迹模拟模型。在最初的授权期内，已经获得了组织的主要成分水中的电子传输数据；在低能电子传输光谱中具有明确结构的独特分子SF6；以及帮助评估表面键合和分子结构对电子光谱的影响的几个分子的初步数据，例如，从固体(冷冻)CO2、C2H6、C3H6、C2F2H2和Xenon获得的数据。对碳氢化合物的持续研究正在进行中，正在开发目标技术，以将这项工作扩展到更大的生物分子和组织。低温靶标提供了一种独特的能力来研究生物分子和组织作为温度的函数，从而作为水分的函数。继续工作的一个主要目标是更好地了解水在生物分子和组织中电子传输中的作用。我们认为，这项扩大的研究将为组织成分在电子传输中的作用提供独特的见解，并提供数据，可以为电离辐射能量沉积后电子传输的演变模型提供灵敏的测试。这项工作将有助于提高对传递到细胞、细胞成分和关键生物分子的局部剂量分布的评估的准确性。这一结果将加强我们建立临床相关放射治疗的努力，同时更好地了解对健康组织的潜在损害。

DESCRIPTION (provided by applicant): This proposal is a revised competitive renewal of a three year grant initiated in July, 2002. The proposed study of electron emission from thin foils is designed to provide data to test computational models developed to describe the initial spatial pattern of energy deposition by ionizing radiation in biologic material. These initial damage patterns affect subsequent chemistry and biochemistry that influence crucial cellular pathways leading to biological repair, genomic instability, apoptosis, and/or finally cancer induction. Much of our knowledge of the initial patterns of radiation damage is obtained from event-by-event Monte Carlo track simulation models that often contain uncertainties in their cross section database. The current work, and the proposed extension, provides data on which we can test track simulation models at the level of the physics of electron transport, i.e., prior to modification and averaging by chemical reactions. During the initial grant period data have been obtained for electron transport in water, a major constituent of tissue; SF6, a unique molecule with well defined structure in the low-energy electron transport spectra; and preliminary data have been obtained for several molecules that aid in assessment of effects of surfaces bonding and molecular structure on electron spectra, e.g., data have been derived from solid (frozen) CO2, C2H6, C3H6, C2F2H2, and Xenon. Continuing study of hydrocarbons is underway and target technology is being developed to extend this work to larger bio-molecules and tissue. The cryogenic target provides a unique capability to study bio-molecules and tissue as a function of temperature and thereby as a function of water content. A major goal of the continued work is to better understand the role of water in the transport of electrons in bio- molecules and tissue. We feel this expanded study will provide unique insight into the role of tissue constituents on electron transport, and provide data that can provide sensitive tests of evolving models of electron transport following energy deposition by ionizing radiation. This work will contribute to increased accuracy in the assessment of local dose distributions delivered to cells, cellular components, and critical biomolecules. The results will enhance our effort to establish clinically relevant radiation treatment with a better understanding of potential damage to healthy tissue.