PO2 GUIDED FRACTIONATED RADIATION THERAPY FOR TUMORS

有强有力的证据表明，高肿瘤氧水平预示着 人类肿瘤对放射治疗的反应和假设， 照射后再氧合有助于 分次辐射 确定联合国作用的方法 在个体肿瘤对辐射的反应中的再氧合， 但尚未提供。 使用植入的EPR血氧测定法 顺磁材料（PM）能够重复，敏感的pO2 研究动物肿瘤中的再氧合所必需的评估， 临床应用的潜力。 EPR具有很高的时间分辨率， 具有空间分辨率，一旦植入PM， 非侵入性评估。 在这个项目中，我们正在测试 肿瘤pO2的变化发生在小的、临床相关剂量的 放射治疗和是否评估为肿瘤pO2的复氧， 预测通过电离辐射改善肿瘤局部控制。 尽管事实上所有动物都表现出复氧 肿瘤模型，其机制尚未得到很好的研究。 使用EPR 血氧测定法，以确定肿瘤依赖性时间进程 辐照后的pO2，我们将系统地检查一些 可能导致复氧的因素。 其中包括Cell 通过流式细胞术测定的周期变化和增殖，%坏死分数 通过组织学和MRI动态成像来评估肿瘤灌注。 如果该项目的总体目标得以实现， 对氧气所起作用的基本了解 肿瘤中的放射后再氧合。

There is strong evidence that high tumor oxygen levels predict the response of human tumors to radiation therapy and the hypothesis that post-irradiation reoxygenation contributes to the success of fractionated radiation. Methods for establishing the role of reoxygenation in the response to radiation of individual tumors, however, have not been available. EPR oximetry using implanted paramagnetic materials (PM) is capable of the repeated, sensitive pO2 assessments necessary to study reoxygenation in animal tumors and has the potential for clinical use. EPR has a high time resolution, is capable of spatial resolution and once the PM is implanted pO2 can be assessed non-invasively. In this project we are testing whether the changes in tumor pO2 occur after small, clinically relevant doses of radiation and whether reoxygenation assessed as tumor pO2 is predictive for improved tumor local control by ionizing radiation. Although reoxygenation has been shown to occur in virtually all animal tumor models, the mechanism have not been well worked out. Using EPR oximetry to determine the tumor dependent time course of post-irradiation pO2 we will examine systematically some of the factors that could contribute to reoxygenation. These include cell cycle changes and proliferation by flow cytometry, % necrotic fraction by histology, and dynamic imaging with MRI to assess tumor perfusion. If the overall goals of this project are realized it will improve the fundamental understanding of the role that oxygen plays in post-radiation reoxygenation in tumors.