Computational techniques for studying interactions of radiation with matter and applications in radiotherapy physics

放射治疗通常被用作癌症的治疗方法。所有形式的放射治疗都旨在最大限度地杀灭肿瘤细胞，同时限制健康组织的辐射暴露。尽管放射治疗被广泛应用于癌症治疗，但与辐射与物质相互作用有关的基本问题仍然存在。此外，前瞻性放射治疗方法催生了新的研究领域。这项研究计划涉及开发和应用复杂的计算机代码，这些代码使用所谓的‘蒙特卡罗’(MC)方法来模拟辐射通过物质的过程。这些MC模拟可用于计算辐射在组织中沉积的能量剂量，以及研究与放射治疗相关的一系列问题。 将开发计算方法来研究从患者器官到组织中单个细胞的不同长度尺度上的剂量学和辐射相互作用。这些方法将被应用于当前和未来放射治疗方法的研究问题。现有的一种感兴趣的治疗方法是近距离放射治疗，即将放射源放置在肿瘤旁边或内部(例如，在前列腺、乳房或眼睛)。广泛使用的剂量计算方法不准确；一种快速、准确和全面的MC剂量计算算法正在开发中，并将用于研究近距离放射治疗物理学。在细胞成分和DNA水平上模拟辐射相互作用和辐射诱导的损伤越来越受到人们的关注。必须为这些研究开发新的计算方法，并将用于研究未来放射治疗方法的问题，例如通过纳米设备提供放射治疗和其他有针对性的放射治疗。 这项研究将促进我们对辐射与物质的相互作用和辐射剂量学的了解，并将在许多涉及辐射的领域产生影响，包括诊断成像、辐射防护和放射生物学。此外，这项研究的结果将在医学科学中得到应用。

Radiotherapy is commonly used as a treatment for cancer. All forms of radiotherapy aim to maximize tumour cell kill while limiting healthy tissue radiation exposure. Despite the widespread application of radiotherapy to treat cancer, fundamental questions relating to the interactions of radiation with matter remain. Further, prospective radiotherapy treatment methods prompt new areas of investigation. This research program involves the development and application of sophisticated computer codes which employ the so-called `Monte Carlo' (MC) method to model the passage of radiation through matter. These MC simulations can be used to compute dose, the energy deposited by radiation in tissue, as well as to study a wide array of issues relevant for radiotherapy treatments. Computational approaches will be developed to study dosimetry and radiation interactions at different length scales from patient organs down to the individual cells in tissue. These approaches will be applied to research questions for current and prospective radiotherapy treatment methods. An existing treatment method of interest is brachytherapy, in which radioactive sources are placed next to or inside a tumour (in, e.g., the prostate, breast, or eye). Widely-used dose calculation approaches are inaccurate; a fast, accurate, and comprehensive MC dose calculation algorithm is under development and will be used to study brachytherapy physics. There is increasing interest in simulating radiation interactions and radiation-induced damage at the level of cellular constituents and DNA. New computational approaches must be developed for these studies and will be used to study issues for prospective radiotherapy treatment methods, such as the delivery of radiotherapy via nanometre-sized devices and other targeted radiotherapies. This research will advance our knowledge of the interactions of radiation with matter and radiation dosimetry and will have implications in many fields involving radiation including diagnostic imaging, radiation protection, and radiobiology. Further, results of this research will find application in the medical sciences.